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Opioids were the most common drug class resulting in overdose deaths in the United States in 2019. Widespread clinical use of prescription opioids for moderate to severe pain contributed to the ongoing opioid epidemic with the subsequent emergence of fentanyl-laced heroin. More potent analogues of fentanyl and structurally diverse opioid receptor agonists such as AH-7921 and MT-45 are fueling an increasingly diverse illicit opioid supply. Overdose from synthetic opioids with high binding affinities may not respond to a typical naloxone dose, thereby rendering autoinjectors less effective, requiring higher antagonist doses or resulting in a confusing clinical picture for health care providers. Nonscheduled opioid drugs such as loperamide and dextromethorphan are associated with dependence and risk of overdose as easier access makes them attractive to opioid users. Despite a common opioid-mediated pathway, several opioids present with unique pharmacodynamic properties leading to acute toxicity and dependence development. Pharmacokinetic considerations involve half-life of the parent opioid and its metabolites as well as resulting toxicity, as is established for tramadol, codeine, and oxycodone. Pharmacokinetic considerations, toxicities, and treatment approaches for notable opioids are reviewed., (© 2021, The American College of Clinical Pharmacology.)

Chronic intrauterine exposure to psychoactive drugs often results in neonatal opioid withdrawal syndrome (NOWS). When nonpharmacologic measures are insufficient in controlling NOWS, morphine, methadone, and buprenorphine are first-line medications commonly used to treat infants with NOWS because of in utero exposure to opioids. Research suggests that buprenorphine may be the leading drug therapy used to treat NOWS when compared with morphine and methadone. Currently, there are no consensus or standardized treatment guidelines for medications prescribed for NOWS. Opioids used to treat NOWS exhibit large interpatient variability in pharmacokinetics (PK) and pharmacodynamic (PD) response in neonates. Organ systems undergo rapid maturation after birth that may alter drug disposition and exposure for any given dose during development. Data regarding the PK and PD of opioids in neonates are sparse. Pharmacometric methods such as physiologically based pharmacokinetic and population pharmacokinetic modeling can be used to explore factors predictive of some of the variability associated with the PK/PD of opioids in newborns. This review discusses the utility of pharmacometric techniques for enhancing precision dosing in infants requiring opioid treatment for NOWS. Applying these approaches may contribute to optimizing the outcome by reducing cumulative drug exposure, mitigating adverse drug effects, and reducing the burden of NOWS in neonates., (© 2020, The American College of Clinical Pharmacology.)

Background: Preterm neonates are usually not part of a traditional drug development programme, however they are frequently administered medicines. Developing modelling and simulation tools, such as physiologically based pharmacokinetic (PBPK) models that incorporate developmental physiology and maturation of drug metabolism, can be used to predict drug exposure in this group of patients, and may help to optimize drug dose adjustment., Objective: The aim of this study was to assess and verify the predictability of a preterm PBPK model using compounds that undergo diverse renal and/or hepatic clearance based on the knowledge of their disposition in adults., Methods: A PBPK model was developed in the Simcyp Simulator V17 to predict the pharmacokinetics (PK) of drugs in preterm neonates. Drug parameters for alfentanil, midazolam, caffeine, ibuprofen, gentamicin and vancomycin were collated from the literature. Predicted PK parameters and profiles were compared against the observed data., Results: The preterm PBPK model predicted the PK changes of the six compounds using ontogeny functions for cytochrome P450 (CYP) 1A2, CYP2C9 and CYP3A4 after oral and intravenous administrations. For gentamicin and vancomycin, the maturation of renal function was able to predict the exposure of these two compounds after intravenous administration. All PK parameter predictions were within a twofold error criteria., Conclusion: While the developed preterm model for the prediction of PK behaviour in preterm patients is not intended to replace clinical studies, it can potentially help with deciding on first-time dosing in this population and study design in the absence of clinical data.

We compared inter-species sensitivity to a model narcotic compound, 2-Methylnaphthalene, to test if taxonomical relatedness, feeding guilds, and trophic level govern species sensitivities on species distributed in different regions. We fitted a toxicokinetic-toxicodynamic model to survival patterns over time for 26 species using new and raw data from the literature. Species sensitivity distributions provided little insight into understanding patterns in inter-species sensitivity. The range of no-effect concentrations (NEC) obtained for 26 species showed little variation (mean 0.0081 mM; SD 0.009). Results suggest that the NEC alone does not explain the complexity of the species tolerances. The dominant rate constant and the derived time to observe an effect (t 0 ), a function of concentration, might provide the means for depicting patterns in sensitivity and better ecotoxicological testing. When comparing the t 0 functions, we observed that Arctic species have shorter time frames to start showing effects. Mollusks and second trophic level species took longer to build up a lethal body burden than the rest. Coupling our results with fate and transport models would allow forecasting narcotic compounds toxicity in time and thus improve risk assessment.

Chronic morphine exposure upregulates adenylate cyclase signaling and reduces analgesic efficacy, a condition known as opioid tolerance. Nonopioid neurotransmitters can enhance morphine tolerance, but the mechanism for this is poorly understood. We show that morphine tolerance was delayed in mice lacking vasopressin 1b receptors (V1bRs) or after administration of V1bR antagonist into the rostral ventromedial medulla, where transcripts for V1bRs and μ-opioid receptors are co-localized. Vasopressin increased morphine-binding affinity in cells expressing both V1bR and μ-opioid receptors. Complex formation among V1bR, β-arrestin-2, and μ-opioid receptor resulted in vasopressin-mediated upregulation of ERK phosphorylation and adenylate cyclase sensitization. A leucine-rich segment in the V1bR C-terminus was necessary for the association with β-arrestin-2. Deletion of this leucine-rich segment increased morphine analgesia and reduced vasopressin-mediated adenylate cyclase sensitization. These findings indicate that inhibition of μ-opioid-receptor-associated V1bR provides an approach for enhancing morphine analgesia without increasing analgesic tolerance.

Objectives: Pregnancy profoundly alters drug metabolism, accelerating clearance and confounding medication management, primarily through induction of CYP450 enzymes. Methadone is a CYP450 substrate with altered pharmacokinetics during pregnancy. We report on the use of serum methadone/metabolite ratios (MMRs) to monitor changes in methadone metabolism through the perinatal period and to objectively guide methadone dosing. Previous research found average MMRs in nonpregnant populations of between 11.3 and 12.7., Methods: Serum methadone and its major metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine concentrations were analyzed in 67 samples from 23 pregnant patients treated for opioid use disorder, and their calculated ratio was used to document changes in methadone clearance across trimesters and postpartum. Lower ratios indicate increased clearance., Results: The average MMR during pregnancy was 6.1. Ratios declined significantly from trimester 1 to trimester 3 (P = 0.007), and then rose significantly from trimester 3 to postpartum (P = 0.001). The per cent of ratios that were 4 or less, indicating ultrarapid metabolism, increased from 8% to 30% to 38% across trimesters, and decreased to 5% postpartum. Forty-four per cent of individual patients had at least 1 prepartum ratio of 4 or less., Conclusions: This study documents significant metabolic changes occurring perinatally, which indicate the need for both changes in methadone dose and dose frequency to maintain maternal/fetal stability, and also dose reductions as hypermetabolism reverses postpartum. MMRs provide an objective tool to more efficiently improve the safety and efficacy of methadone dosing perinatally.

Previous studies demonstrated that nalbuphine, medetomidine, and azaperone (NalMed-A) can effectively immobilize adult elk ( Cervus elaphus nelsoni), and be antagonized using naltrexone and atipamezole, with or without tolazoline. To assess duration of tissue residues for this immobilization package, we immobilized 14 captive adult elk with NalMed-A, then euthanized animals and collected tissues 0, 3, 6, 14, 21, or 28 d later. Except for two animals euthanized immediately, all elk were recovered using naltrexone, atipamezole, and tolazoline. Tissue residues (≥0.01 parts per million) for the tranquilizers nalbuphine, medetomidine, and azaperone were detected in liver and muscle tissue samples from elk euthanized within 40 min postinjection (PI) and one animal that died 12-24 h PI, but not in tissues from any of the animals euthanized at 3, 6, 14, 21, or 28 d PI. Tissue residues for the antagonists naltrexone, atipamezole, and tolazoline were detected in liver and muscle of the animal that died 12-24 h PI. Only naltrexone was detected in liver from the two elk euthanized at day 3, and no antagonist residues were detected thereafter.

The aim of the present study was to investigate the pharmacokinetic effect of silibinin on methadone in rats. Twenty-four male Sprague-Dawley rats were randomly divided into 4 groups: control group, single dose of 100 mg/kg group, multiple doses of 100 mg/kg group, and multiple doses of 30 mg/kg group. A single dose of 6 mg/kg methadone was administrated to rats orally without or with silibinin. Plasma samples were collected via tail vein at different time points and concentrations of methadone and its metabolite, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), were determined by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Compared with the control group (without silibinin), both 30 and 100 mg/kg silibinin significantly increased the C max of methadone, but only 100 mg/kg silibinin significantly increased the AUC (0-t) of methadone and decreased its clearance. Pharmacokinetics parameters of EDDP were not altered by 30 mg/kg silibinin; its T max was decreased by 100 mg/kg silibinin and the C max was increased by single dose of 100 mg/kg silibinin. It is concluded that silibinin significantly altered the pharmacokinetics of methadone in rats by increasing the exposure of methadone. Further investigations in human should be conducted. Therapeutic drug monitoring of methadone in individuals undergoing methadone maintenance therapy is recommended when silibinin is concomitant., (Copyright © 2017 John Wiley & Sons, Ltd.)

The objective of the present study was to evaluate the effect of morphine on exertional breathlessness and exercise endurance in advanced chronic obstructive pulmonary disease (COPD).In a randomised crossover trial, we compared the acute effect of immediate-release oral morphine versus placebo on physiological and perceptual responses during constant-load cardiopulmonary cycle exercise testing (CPET) in 20 adults with advanced COPD and chronic breathlessness syndrome.Compared with placebo, morphine reduced exertional breathlessness at isotime by 1.2±0.4 Borg units and increased exercise endurance time by 2.5±0.9 min (both p≤0.014). During exercise at isotime, morphine decreased ventilation by 1.3±0.5 L·min -1 and breathing frequency by 2.0±0.9 breaths·min -1 (both p≤0.041). Compared with placebo, morphine decreased exertional breathlessness at isotime by ≥1 Borg unit in 11 participants (responders) and by <1 Borg unit in nine participants (non-responders). Baseline participant characteristics, including pulmonary function and cardiorespiratory fitness, were similar between responders and non-responders. A higher percentage of responders versus non-responders stopped incremental CPET due to intolerable breathlessness: 82 versus 33% (p=0.028).Immediate-release oral morphine improved exertional breathlessness and exercise endurance in some, but not all, adults with advanced COPD. The locus of symptom-limitation on laboratory-based CPET may help to identify patients most likely to benefit from morphine., Competing Interests: Conflict of interest: Disclosures can be found alongside this article at erj.ersjournals.com, (Copyright ©ERS 2017.)

Medico-legal experts are increasingly enlisted to assess the methamphetamine and amphetamine serum concentrations after a criminal offense. However, since criminal users rarely provide useful information to medico-legal experts regarding the substances abused, when the substance(s) was/were used, dose of ingestion tools are needed to interpret the analytical data, which can be used as objective evidence in such cases. A comparative series of methamphetamine and amphetamine serum concentrations were used to analyze the frequency of concentrations, to determine methamphetamine/amphetamine concentration ratios, and prove them as a tool to distinguish pure methamphetamine from mixed amphetamine/methamphetamine ingestion. Additionally, two cases of survived accidental methamphetamine intoxication, resulting from ingestion smuggling which was longitudinally monitored, and pharmacokinetic parameters were assessed. In a series of 628 samples where the most frequent concentration of methamphetamine exceeded the therapeutic level, there was a strong correlation suggesting pure methamphetamine consumption, when the ratios of methamphetamine/amphetamine concentrations were within the range between 3 and 10. In the two cases of methamphetamine bodypacking, the relevant serum concentrations of methamphetamine and amphetamine, which could be measured up to 9 days after ingestion, indicated a decrease of the methamphetamine/amphetamine ratios in an exponential manner. However, the ratios were not always within the range between 3 and 10. Lastly, the course of the serum concentrations suggested an increase of the apparent elimination half-life of methamphetamine. In terms of the objective evidence required in criminal law, calculating methamphetamine/amphetamine concentration ratio is not a suitable to means to distinguish pure methamphetamine intake and that of mixed amphetamine/methamphetamine abuse in an individual case. Instead, methamphetamine high serum concentrations and the possible increase in apparent elimination half-life suggest that an extended detection period may be used to distinguish between "illicit use" as compared to "therapeutic use" of methamphetamine.

Interpretation of postmortem morphine concentrations in forensic toxicology provides several pitfalls such as missing information on tolerance, analyte stability, or postmortem redistribution (PMR). Recently, it had been shown that computed tomography (CT)-guided collection of biopsies using a robotic arm (virtobot) provides a valuable strategy for systematic studies on time-dependent PMR. Using this technique, time-dependent PMR of morphine and its metabolites was investigated in 12 cases. At admission to the institute (t1), femoral and heart blood (right ventricle) as well as biopsies from the right lung, the right kidney, liver, spleen, and muscle tissue were collected. At autopsy approximately 24 h later (t2), samples from the same body regions were collected again. Additionally, gastric contents, urine, brain tissue, and heart blood from the left ventricle was collected. Morphine, normorphine, hydromorphone, morphine-3-glucuronide, morphine-6-glucuronide, and morphine-sulfate were quantified with LC-MS/MS. In femoral blood, significant increase of morphine concentrations was observed, although ultimately not relevant for forensic interpretation. In the alternative matrices, increases as well as decreases were observed without a clear trend. The morphine metabolites did not exhibit relevant concentration changes. Investigation of underlying redistribution mechanisms indicated that concentration change (i.e., increase) of morphine in femoral blood rather resulted from diffusion processes than from release of morphine from its conjugates. Concentration changes in heart blood might have been caused by redistribution from lung tissue or gastric content. This study also proved that CT-guided collection of biopsies using a virtobot arm is an invaluable tool for future studies on PMR redistribution of other substance groups.

According to the free drug hypothesis, only the unbound fraction (f u ) of a given drug is biologically available in terms of its pharmacologic activity. Methadone shows large interpersonal variation in toxicity. The goal of the work presented here was to examine whether isolating the unbound fraction of the active R-methadone enantiomer from brain matter could be of value as a forensic tool. A method applying equilibrium dialysis to postmortem brain samples was validated and showed good reproducibility for the previously published f u values for eight common drugs (alprazolam, citalopram, codeine, methadone, morphine, diazepam, oxycodone, tramadol), as well as methadone enantiomers. This method was then applied to approximately 50 authentic case samples with R-methadone and S-methadone concentrations ranging from 0.03 to 13 and 0.6 to 6.8 mg/kg, respectively; median f u values (R-and S-methadone) were 3.9 % (range 3.0-5.3 %) and 3.7 % (range 2.9-4.9 %). No overall correlation between the active R-methadone concentration and f u were found. Small but statistically significant differences in median f u for the R-methadone enantiomer were identified between case-categories (i.e., poisoning with multiple drugs, methadone poisoning, and deaths unrelated to methadone), but these are thought to be too low to be of any forensic value.

Prediction of passive permeation rates of solutes across lipid bilayers is important to drug design, toxicology, and other biological processes such as signaling. The inhomogeneous solubility-diffusion (ISD) equation is traditionally used to relate the position-dependent potential of mean force and diffusivity to the permeability coefficient. The ISD equation is derived via the Smoluchowski equation and assumes overdamped system dynamics. It has been suggested that the complex membrane environment may exhibit more complicated damping conditions. Here we derive a variant of the inhomogeneous solubility diffusion equation as a function of the mean first passage time (MFPT) and show how milestoning, a method that can estimate kinetic quantities of interest, can be used to estimate the MFPT of membrane crossing and, by extension, the permeability coefficient. We further describe a second scheme, agnostic to the damping condition, to estimate the permeability coefficient from milestoning results or other methods that compute a probability of membrane crossing. The derived relationships are tested using a one-dimensional Langevin dynamics toy system confirming that the presented theoretical methods can be used to estimate permeabilities given simulation and milestoning results.

A novel dynamic fugacity-based model is described, developed, and tested that simulates the uptake of narcotic organic chemicals in fish from water as occurs in aquatic bioconcentration and toxicity tests. The physiologically based toxicokinetic model treats the time course of chemical distribution in 4 compartments (tissue groups) in the fish, including the liver, in which biotransformation may occur. In addition to calculating bioconcentration and toxicokinetics, 5 possible toxic endpoints are defined corresponding to chemical concentration, fugacity, or activity reaching a critical value that causes 50% mortality. The mathematical description of multicompartment uptake is simplified by expressing the equations in the fugacity format. The model is parameterized and tested against reported empirical data for the bioconcentration of pentachloroethane in rainbow trout and for uptake and mortality from aquatic exposures to naphthalene and 1,2,4-trichlorobenzene in fathead minnows. Model performance is evaluated, and it is concluded that with suitable parameterization it has potential for application for assessment of both bioconcentration and toxicity expressed as median lethal concentrations, critical body residues, and chemical activity as a function of time to death., (© 2015 SETAC.)

Limited oral fluid (OF) pharmacokinetic data collected with commercially available collection devices after controlled cocaine administration hinder OF result interpretations. Ten cocaine-using adults provided OF, collected with Oral-Eze(®) (OE) and StatSure Saliva Sampler™ (SS) devices, an hour prior to and up to 69 h after 25mg intravenous (IV) cocaine administration. Cocaine and benzoylecgonine (BE) were quantified by a validated 2D-GC-MS method. Large inter-subject variability was observed. Cocaine was detected in OF in the first 0.17 h sample after IV administration, with much more rapid elimination than BE. OE observed Cmax median (range) concentrations were 932 (394-1574)μg/L for cocaine and 248 (96.9-953)μg/L for BE. SS observed cocaine and BE Cmax median (range) concentrations trended lower at 732 (83.3-1892)μg/L and 360 (77.2-836)μg/L, respectively. OE and SS cocaine OF detection times were 12.5 and 6.5h and for BE 30.5 and 28.0 h, respectively at 1 μg/L. There were no significant pharmacokinetic differences between OE and SS OF collection devices, except cocaine half-life was significantly shorter in SS OF specimens. This difference could be attributed to differences in stabilizing buffers present in OF collection devices, which may affect cocaine stability in OF specimens, or decreased recovery from collection pads. Both OE and SS OF collection devices were effective in monitoring cocaine and metabolite concentrations with similar detection windows. Furthermore, we demonstrated that different confirmatory OF cutoffs can be selected to produce shorter or longer cocaine and metabolite detection windows to address specific needs of clinical and forensic drug testing programs., (Published by Elsevier Ireland Ltd.)

The interpretation of postmortem drug levels is complicated by changes in drug blood levels in the postmortem period, a phenomena known as postmortem drug redistribution. We investigated the postmortem redistribution of the heroin metabolites morphine and morphine-3-glucuronide in a rabbit model. Heroin (1 mg/kg) was injected into anesthetised rabbit; after 1 h, an auricular vein blood sample was taken and the rabbit was euthanised. Following death rabbits were placed in a supine position at room temperature and divided into three groups namely (1) immediate autopsy, (2) autopsy after 30 minutes and (3) autopsy 24 h after death. Various samples which included femoral blood, cardiac blood, lung, liver, kidney, vitreous humour, subcutaneous and abdominal fat, liver, bone marrow and skeletal muscle were taken. The samples were analysed with a validated LC-MS/MS method. It was observed that within minutes there was a significant increase in free morphine postmortem femoral blood concentration compared to the antemortem sample (0.01 ± 0.01 to 0.05 ± 0.02 mg/L).Various other changes in free morphine and metabolite concentrations were observed during the course of the experiment in various tissues. Principal component analysis was used to investigate possible correlations between free morphine in the various samples. Some correlations were observed but gave poor predictions (>20 % error) when back calculating. The results suggest that rabbits are a good model for further studies of postmortem redistribution but that further study and understanding of the phenomena is required before accurate predictions of the blood concentration at the time of death are possible.

Introduction: 'Body packer' syndrome with severe intoxication or sudden death may happen in persons who smuggle drugs in their body cavities. In case of lethal outcome when carrying cocaine, it is important, but sometimes difficult to determine whether death was due to intoxication or due to other causes. Therefore, it is necessary not only to quantify cocaine and its metabolites in biological material, but also based on their distribution in body fluids and tissues to conclude whether it is acute intoxication. We described a well-documented case of fatal poisoning in a body packer and post mortem distribution of the drug in biological samples., Case Report: A 26-year-old man was brought to hospital with no vital signs. Resuscitation measures started at once, but with no success. Autopsy revealed 66 packets of cocaine in his digestive tract, one of which was ruptured. Hyperemia of the most of all internal organs and pulmonary and brain edema were found. High concentrations of cocaine, its metabolites benzoylecgonine and ecgonine methyl ester, as well as cocaine adulteration levamisole were proven in the post mortem blood and tissues by liquid chromatography-mass spectrometry (LC-MC) method with selective-ion monitoring., Conclusion: The ratio of cocaine and its metabolites concentrations in the brain and blood obtained by LC-MS method can be used for forensic confirmation of acute intoxication with cocaine.

In the last two years, an epidemic of fatal narcotic overdose cases has occurred in the Tampa area of Florida. Fourteen of these deaths involved fentanyl and/or the new designer drug, acetyl fentanyl. Victim demographics, case histories, toxicology findings and causes and manners of death, as well as, disposition of fentanyl derivatives and their nor-metabolites in postmortem heart blood, peripheral blood, bile, brain, liver, urine and vitreous humor are presented. In the cases involving only acetyl fentanyl (without fentanyl, n=4), the average peripheral blood acetyl fentanyl concentration was 0.467 mg/L (range 0.31 to 0.60 mg/L) and average acetyl norfentanyl concentration was 0.053 mg/L (range 0.002 to 0.086 mg/L). In the cases involving fentanyl (without acetyl fentanyl, n=7), the average peripheral blood fentanyl concentration was 0.012 mg/L (range 0.004 to 0.027 mg/L) and average norfentanyl blood concentration was 0.001 mg/L (range 0.0002 to 0.003 mg/L). In the cases involving both acetyl fentanyl and fentanyl (n=3), the average peripheral blood acetyl fentanyl concentration was 0.008 mg/L (range 0.006 to 0.012 mg/L), the average peripheral blood acetyl norfentanyl concentration was 0.001 mg/L (range 0.001 to 0.002 mg/L), the average peripheral blood fentanyl concentration was 0.018 mg/L (range 0.015 to 0.021mg/L) and the average peripheral blood norfentanyl concentration was 0.002 mg/L (range 0.001 mg/L to 0.003 mg/L). Based on the toxicology results, it is evident that when fentanyl and/or acetyl fentanyl were present, they contributed to the cause of death. A novel ultrahigh performance liquid chromatography (UPLC) tandem mass spectrometry (MS/MS) method to identify and quantify acetyl fentanyl, acetyl norfentanyl, fentanyl and norfentanyl in postmortem fluids and tissues is also presented., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Background: Biphasic immediate-release (IR)/extended-release (ER) hydrocodone bitartrate (HB)/acetaminophen (APAP) 7.5/325-mg tablets are formulated with gastroretentive ER drug delivery technology that has been associated with clinically meaningful food effects in other approved products. Two phase 1 studies evaluated potential effects of food on single-dose pharmacokinetics of IR/ER HB/APAP tablets., Methods: These were single-center, open-label, randomized, single-dose, 3-period crossover studies in healthy volunteers (aged 18-55 years). IR/ER HB/APAP was administered as a single 2-tablet dose (study 1) or 3-tablet dose (study 2) under fed (high- and low-fat) and fasted conditions. Area under the plasma concentration-time curve from 0 h to time t (AUC0-t) and from time 0 extrapolated to infinity (AUC0-inf) and maximum observed plasma concentration (Cmax) of hydrocodone and APAP under fed versus fasted conditions were compared using analysis of variance. A 90% confidence interval of the geometric least squares mean ratio fully contained within 80 to 125 % indicated no treatment difference. Safety and tolerability were assessed., Results: Forty of 48 participants in study 1 and 21 of 30 in study 2 completed all treatments. In both studies, under fed (high- or low-fat meal) versus fasted conditions, 90% CIs for AUC0-t and AUC0-inf for both hydrocodone and APAP were entirely contained within the bioequivalent range (80-125%), indicating that high- and low-fat meals did not affect the extent of exposure. In both studies, a high-fat meal did not affect the Cmax for hydrocodone. Hydrocodone Cmax was not affected by a low-fat meal in study 1 but increased by approximately 19% in study 2. A high-fat meal decreased APAP Cmax by approximately 20 % (study 1) and 13 % (study 2); a low-fat meal decreased APAP Cmax by 22% (study 1) and 21% (study 2). Approximately 50% of participants in both studies reported ≥1 treatment-emergent adverse event (TEAE), with no notable difference based on food intake. There were no serious or severe AEs. The most common TEAEs were nausea, vomiting, and dizziness., Conclusions: Pharmacokinetic and safety findings were similar regardless of food intake. TEAEs were consistent with those reported with low-dose combination opioids. IR/ER HB/APAP can be administered without regard to food., Trial Registration: ClinicalTrials.gov NCT02561650 and NCT02561741 .

This literature review is focused on the studies of metabolism of designer drugs, with special reference to fentanyl derivatives. Certain physicochemical characteristics of the main metabolites most frequently encountered in the illegal trade of the fentanyl group analgesics have been calculated. The proposed recommendations include the methods for the identification of certain fentanyl derivatives during analysis of biological media.

Methadone is a long-acting opioid with considerable unexplained interindividual variability in clearance. Cytochrome P450 2B6 (CYP2B6) mediates clinical methadone clearance and metabolic inactivation via N-demethylation to 2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP). Retrospective studies suggest that individuals with the CYP2B6*6 allelic variant have higher methadone plasma concentrations. Catalytic activities of CYP2B6 variants are highly substrate- and expression-system dependent. This investigation evaluated methadone N-demethylation by expressed human CYP2B6 allelic variants in an insect cell coexpression system containing P450 reductase. Additionally, the influence of coexpressing cytochrome b5, whose role in metabolism can be inhibitory or stimulatory depending on the P450 isoform and substrate, on methadone metabolism, was evaluated. EDDP formation from therapeutic (0.25-1 μM) R- and S-methadone concentrations was CYP2B6.4 ≥ CYP2B6.1 ≥ CYP2B6.5 >> CYP2B6.9 ≈ CYP2B6.6, and undetectable from CYP2B6.18. Coexpression of b5 had small and variant-specific effects at therapeutic methadone concentrations but at higher concentrations stimulated EDDP formation by CYP2B6.1, CYP2B6.4, CYP2B6.5, and CYP2B6.9 but not CYP2B6.6. In vitro intrinsic clearances were generally CYP2B6.4 ≥ CYP2B6.1 > CYP2B6.5 > CYP2B6.9 ≥ CYP2B6.6. Stereoselective methadone metabolism (S>R) was maintained with all CYP2B6 variants. These results show that methadone N-demethylation by CYP2B6.4 is greater compared with CYP2B6.1, whereas CYP2B6.9 and CYP2B6.6 (which both contain the 516G>T, Q172H polymorphism), are catalytically deficient. The presence or absence of b5 in expression systems may explain previously reported disparate catalytic activities of CYP2B6 variants for specific substrates. Differences in methadone metabolism by CYP2B6 allelic variants provide a mechanistic understanding of pharmacogenetic variability in clinical methadone metabolism and clearance., (Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.)

Chronic renal failure results in reduced elimination of a variety of substances within the blood, including numerous drugs and their metabolites. This report describes a case of a man who died in jail, after less than 48 hours of being incarcerated, wherein postmortem toxicology testing revealed a blood benzoylecgonine level of 0.25 mg/L with no cocaine detected, suggesting possible recent cocaine use in jail. Autopsy and investigation revealed severe underlying cardiovascular disease and dialysis-dependent CRF, thus accounting for the elevated benzoylecgonine levels and allaying concerns that the man obtained and used cocaine in jail.

The compulsion to seek and use heroin is frequently driven by stress and craving during drug-cue exposure. Although previous neuroimaging studies have indicated that craving is mediated by increased prefrontal cortex activity, it remains unknown how heroin administration modulates the prefrontal cortex response. This study examines the acute effects of heroin on brain function in heroin-maintained patients. Using a crossover, double-blind, placebo-controlled design, 27 heroin-maintained patients performed functional magnetic resonance imaging 20 minutes after the administration of heroin or placebo (saline) while drug-related and neutral stimuli were presented. Images were processed and analysed with statistical parametric mapping. Plasma concentrations of heroin and its main metabolites were assessed using high-performance liquid chromatography. Region of interest analyses showed a drug-related cue-associated blood-oxygen-level-dependent activation in the orbitofrontal cortex (OFC) in heroin-dependent patients during both treatment conditions (heroin and placebo). This activation of the OFC was significantly higher after heroin than after placebo administration. These findings may indicate the importance of OFC activity for impulse control and decision-making after regular heroin administration and may emphasize the benefit of the heroin-assisted treatment in heroin dependence., (© 2014 Society for the Study of Addiction.)

Fentanyl deaths have increased with availability of transdermal patches. Interpretation of postmortem fentanyl levels may be complicated by postmortem redistribution and absorption of fentanyl from a patch. We applied an unused 100-μg/h fentanyl patch onto the lower abdomen of a decedent with no premortem fentanyl exposure. Ocular fluid, blood, and urine were collected prior to placement, and the decedent was refrigerated for 23 h. Prior to the autopsy, urine, subcutaneous tissue under the patch, and samples from the same anatomic sites were obtained. We observed no fentanyl in any postpatch placement samples (LOD: 0.1 ng/mL for blood and vitreous fluid, 1.0 ng/mL urine, 2.0 ng/g for tissues). Although we observed no postmortem absorption of fentanyl, this was only a single case; therefore, we recommend that patches be removed after receipt of a cadaver before initiation of an autopsy, with the location of removed patch documented., (© 2015 American Academy of Forensic Sciences.)

Purpose: A hydrocodone extended-release (ER) formulation was developed to provide sustained pain relief with twice-daily dosing. Developed using the CIMA abuse-deterrence technology platform (CIMA Labs Inc, Brooklyn Park, Minnesota), this formulation also provides resistance against rapid release of hydrocodone when tablets are comminuted and resistance against dose dumping when tablets are taken with alcohol. Two open-label studies evaluated hydrocodone ER pharmacokinetics (PK) after single- and multiple-dose administration in healthy, naltrexone-blocked subjects., Methods: In the single-dose period of both studies, healthy subjects aged 18 to 45 years of age received hydrocodone ER (study 1, 45 mg; study 2, 90 mg). In the multiple-dose period of study 1, subjects received one 45-mg hydrocodone ER tablet twice daily from the morning of day 1 through the morning of day 6. In the multiple-dose period of study 2, subjects received hydrocodone ER twice daily, titrated to 90 mg over 10 days (days 1 and 2, 45 mg; days 3 and 4, 60 mg; days 5-10, 90 mg). All subjects received naltrexone to block opioid receptors. Blood samples were collected pre-dose and through 72 hours post-dose in the single-dose period and after the final dose in the multiple-dose period. PK measures included maximum observed plasma drug concentration (C(max)), area under the plasma drug concentration by time curve from time 0 to the time of the last measurable drug concentration (AUC(0-t)), time to C(max) (T(max)), observed accumulation ratio (R(obs)), and steady-state plasma concentration (C(ss)). Safety and tolerability were assessed., Findings: The PK analyses included 36 subjects from study 1 and 33 from study 2. Plasma hydrocodone PK parameters after single- and multiple-dose administration of hydrocodone ER 45 mg (study 1) were dose-normalized to 90 mg and pooled with data from study 2. As expected, C(max) was higher (125.4 vs 57.2 ng/mL), AUC(0-t) was higher (2561 vs 1095 ng·h/mL), and T(max) occurred earlier (5.0 vs 8.0 hours) with multiple-dose administration. Mean R(obs) after multiple-dose administration of hydrocodone ER was also slightly higher than predicted from single-dose data (2.8 vs 2.4). C(ss) were achieved within 5 days of twice-daily administration of both doses. Mean fluctuation with hydrocodone ER 45 or 90 mg was 36.4% and 33.9%, respectively, and mean swing was 46.9% and 43.5%, respectively. The incidence of adverse events was similar in the single-dose (33%) and multiple-dose (29%) periods in study 1 and slightly higher in the multiple-dose (76%) than in the single-dose (53%) period in study 2., Implications: The PK profile of hydrocodone ER was qualitatively similar after single- and multiple-dose administration. The steady-state profile demonstrated sustained exposure with limited swing and fluctuation. Single and multiple doses of hydrocodone ER (45 and 90 mg) were generally well tolerated in healthy subjects receiving naltrexone; however, exposure to naltrexone may have confounded the interpretation of safety findings., (Copyright © 2015 Elsevier HS Journals, Inc. All rights reserved.)

Knowledge concerning the distribution of methadone in postmortem human tissue and the effect of postmortem redistribution on methadone is today limited making the choice of a suitable substitute for femoral blood difficult when this is not available. Cardiac blood, femoral blood, muscle, and brain tissue concentrations of the enantiomers of methadone and its metabolite 2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolinium were recorded for 155 postmortem cases. Brain and muscle tissue concentrations exceeded the femoral blood concentrations with a median fold of 2.3 and 1.6, respectively, but both had a better correlation than cardiac blood to femoral blood concentrations. The Kruskal-Wallis test showed a significant dependency on time and body mass index for some of the matrix ratios over femoral blood. We conclude brain or muscle tissue may constitute a better alternative for measurement of methadone than cardiac blood for situations in which femoral blood is not available, despite concentrations in both matrices being systematically higher., (© 2014 American Academy of Forensic Sciences.)

In this research we will show the advantages of using a time-independent dose metric in a mechanistic model to evaluate toxic effects for different narcotic compounds on different species. We will show how different already existing QSARs can be combined within a mechanistic framework to 1) make predictions of lethal thresholds; 2) show some limitations in the use of existing QSARs; 3) show how a mechanistic framework solves some conceptual problems in current approaches and 4) show how such a framework can be used to be of aid in an experimental setup in predicting the outcome of a survival experiment. The approach we chose is based on the simplest mechanistic model available, a scaled one-compartment model to describe uptake and elimination and hazard model to link the exposure to effects on survival. Within this theoretical framework a prediction for an internal threshold for effects on survival of 3 mmol/kg bw can be made, which should be similar for different species and independent of the partitioning characteristics of the toxicant. To demonstrate this, a threshold for 51 different species was derived, which indeed appeared to lie in a relatively small range, typically between 1 and 10 mmol/kg bw.

Purpose: The pharmacology, pharmaco-kinetic properties, and clinical efficacy of naloxone injection administered intranasally for the reversal of opioid overdose are reviewed., Summary: Naloxone is an opioid-receptor antagonist that is used in the treatment of opioid overdose to reverse the respiratory and central nervous system-depressant effects of the opioid. Naloxone injection is traditionally given by intravenous, intramuscular, and subcutaneous routes. Paramedics also administer naloxone injection intranasally in the prehospital setting to treat suspected opioid overdose. The nasal mucosa has a rich blood supply that allows for efficient drug absorption and the avoidance of first-pass hepatic metabolism that would be seen with oral administration. Obtaining vascular access can be difficult in known drug users, prolonging the time required to administer the antidote. Patients awakening from an overdose may be agitated, confused, and even combative, thus increasing the risk of needle-stick injury to first responders. The intranasal route avoids the need for establishing vascular access and can be associated with speedier patient recovery. In two randomized controlled trials, intranasal naloxone alone was shown to be sufficient for reversing opioid-induced respiratory depression in 74% and 72% of the respective study populations of patients experiencing opioid overdose. In addition, the safety profile of intranasal naloxone appears to be no different than that of naloxone injection in the treatment of opioid overdose in the prehospital setting., Conclusion: Intranasal administration of naloxone appears to be effective in treatment of opioid overdose when i.v. administration is impossible or undesirable., (Copyright © 2014 by the American Society of Health-System Pharmacists, Inc. All rights reserved.)

Fentanyl is a synthetic opioid agonist used for pain control. Often administered as a transdermal patch, it is an interesting drug for study of postmortem redistribution. We hypothesized that fentanyl concentrations would increase over time after death, as measured in blood drawn on the day prior to autopsy and in blood drawn at the time of autopsy in ten cases where fentanyl patches were identified at the scene. Concentrations were compared, and heart blood to femoral blood ratios were calculated as markers of postmortem redistribution. Fentanyl concentrations measured in peripheral blood drawn the day of autopsy (peripheral blood 2 [PB2]) were higher than those drawn the day prior to autopsy (peripheral blood 1 [PB1]) with a mean ratio (PB2/PB1) of 1.80. The ratio of heart blood concentrations (HB) to femoral blood concentrations drawn at autopsy (PB2) had a mean ratio (HB/PB2) of 1.08. Some cases had blood from the same source analyzed at two different laboratories, and concentrations of fentanyl in those samples showed inter- and intralaboratory differences up to 25 ng/mL. Postmortem fentanyl concentrations may be affected by antemortem factors, postmortem redistribution, and laboratory variability. Forensic pathologists must use caution in interpreting fentanyl levels as part of death investigation., (© 2014 American Academy of Forensic Sciences.)

Introduction: Ethanol and heroin are both depressant drugs on the central nervous system, and combined use is known to be dangerous due to pharmacodynamic interactions, leading to an even higher risk of respiratory depression and death. In addition, previous studies have suggested a pharmacokinetic interaction between ethanol and the metabolism of heroin. The aim of the present study was to investigate if there was a pharmacokinetic interaction between heroin and ethanol, by comparing concentrations of heroin metabolites in cases with and without ethanol, as detected in blood samples collected from a large material of forensic autopsy cases., Methods: The material consisted of 1583 forensic autopsy cases, all containing 6-monoacetylmorphine (6-MAM), as evidence of heroin intake, in either blood or urine samples, from the time period between the 1st of January 2000 and the 31st of December 2012. Due to the high risk of post-mortem ethanol formation in cases revealing blood ethanol concentrations between 0.1 and 0.3‰, these cases were excluded from the study, along with cases where the analysis for ethanol was missing. After this exclusion of cases, the material (n=1474) was divided into two groups; one group where ethanol was not detected in blood (n=1160), and another group where ethanol was detected in blood at or above the concentration of 0.4‰ (n=314). Furthermore, the material was also divided into two other subgroups; one group where 6-MAM was detected in blood samples, indicating a very recent intake of heroin, and another group where 6-MAM was detected in the urine, but not in blood, indicating a less recent heroin intake., Results: The concentration ratios of morphine/6-MAM, morphine-3-glucuronide (M3G)/morphine, and morphine-6-glucuronide (M6G)/morphine in blood samples, were all significantly lower in the ethanol positive cases compared with that of the ethanol negative cases. For the subgroup of cases revealing a very recent intake of heroin (n=645), only the morphine/6-MAM ratio was significantly lower in the ethanol positive cases than in the ethanol negative cases. For the subgroup of cases with a less recent heroin intake (n=817), lower M3G/morphine and M6G/morphine ratios were found among the ethanol positive cases., Conclusions: The results indicate that ethanol inhibits two steps in the heroin metabolism; the hydrolysis of 6-MAM to morphine, and the glucuronidation of morphine to M3G and M6G. This pharmacokinetic interaction could further complicate the outcome after combined use of heroin and ethanol, in addition to the already well-known pharmacodynamic interactions., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Objectives: To review the product information (PI) for various brands of the same generic drugs and investigate the extent to which information is currently available on dosing in renal impairment and the concordance between the dosing recommendations for the same generic drug., Method: The Monthly Index of Medical Specialities (MIMS) was examined for 28 generic drugs recommended to be used with caution in renal impairment. For each generic drug all available brands listed as having solid oral dosage form were recorded. For each identified brand, the current PI was consulted and data referring to renal impairment was collated. The dissimilarity between these PI regarding the renal dosage recommendation was determined., Results: There was generally a lack of detailed information in the PI on the use of drugs in patients with renal impairment. The majority of PI documents (88 of 155 PI; 57%) provided quantitative dosage recommendations, but this was often not detailed enough to help users to make an informed decision. For 37 PI documents (24%), an altered dosage regimen was proposed without a quantifiable measure of renal function reported in the dose recommendation. The renal function severity category terms used and the associated quantitative values were also not consistent. It was observed that the recommendations varied among different brands of hydromorphone, morphine, oxycodone, tramadol, metformin and topiramate., Conclusion: The reporting of renal function quantification methods, and associated dosage recommendations, in PI requires standardisation to ensure optimal drug dosing. Regularly updating of PI is also necessary., (© 2014 The Authors; Internal Medicine Journal © 2014 Royal Australasian College of Physicians.)

The objective of this study was to assess the relationship between genetic polymorphisms and drug interactions on codeine and morphine concentrations in codeine-related deaths (CRD). All CRD in Ontario, Canada between 2006 and 2008 were identified. Post-mortem blood was analyzed for 22 polymorphisms in 5 genes involved in codeine metabolism and response. Sixty-eight CRD were included in this study. The morphine-to-codeine ratio was significantly correlated with the presence of a CYP2D6 inhibitor at varying potencies (p=0.0011). The presence of other central nervous system (CNS) depressants (i.e. benzodiazepines, hypnotics, and/or alcohol) was significantly associated with lower codeine concentration as compared to CRD in which other CNS depressants were not detected (p=0.0002). Individuals who carried the ABCB1 1236T variant had significantly lower morphine concentrations (p=0.004). In this population of individuals whose cause of death was related to codeine, drug interactions and genetic polymorphisms were significantly associated with post-mortem codeine and morphine concentrations., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

Background: Opioid switching or rotation is reported to be a common practice in palliative care. Published tables of opioid conversion ratios have been found to vary in their recommendations, potentially leading to significant differences in clinical practice., Aims: To identify common practices in the calculation of opioid equianalgesia by specialist palliative medicine practitioners and trainees., Method: An anonymous, cross-sectional, online survey completed by 85 Australian palliative care specialists or advanced trainees. Questions focused on conversion ratios used in switching between oral and parenteral opioid doses; conversion ratios used when switching from other opioids to oral morphine; and practice of commencing methadone., Results: The majority of respondents calculated equianalgesic doses for morphine, oxycodone and hydromorphone using the same conversion ratios. Methadone was used almost equally as either the sole opioid or as a 'co-opioid'. The majority surveyed converted slow-release hydromorphone differently to the manufacturer's recommendations., Conclusion: Further discussion among Australian palliative care specialist organisations is recommended in order to produce uniform conversion guidelines to improve consistency and safety in the prescribing of opioids., (© 2014 The Authors; Internal Medicine Journal © 2014 Royal Australasian College of Physicians.)

The rapid and direct delivery of a neuroactive endomorphin 1 derivative to the brain via nasal delivery is reported. A synthetic derivative of the native opioid peptide, endomorphin 1 bearing a lactose unit on the N-terminus of the peptide has been previously reported to exhibit antinoceceptive activity similar to morphine after both intravenous and oral administration. This compound has been administered nasally to rats and appeared in the olfactory bulb within 10 min of administration with negligible levels appearing in the circulating blood or in the rest of the brain. These results indicate that the peptide is absorbed into the brain via the olfactory epithelial pathway suggesting nasal delivery may be a viable alternative route of delivery in clinical applications., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The change in frequency of cocaine self-administration as a function of the unit dose is widely assumed to represent a graded pharmacodynamic response. Alternatively, a pharmacological theory states that during maintained self-administration, a quantal response occurs at a minimum maintained cocaine concentration (satiety threshold). Rats self-administered cocaine at unit doses spanning an 8-fold range from 0.75 to 6 µmol/kg. Despite an approximately 7-fold difference in the interinjection intervals, there were no differences in the plasma cocaine concentration at the time of lever press across this range of unit doses, consistent with the satiety threshold representing an equiactive cocaine concentration. Because self-administration always occurs when cocaine concentrations decline back to the satiety threshold, this behavior represents a process of automatic back titration of equiactive agonist concentrations. Therefore, the lower frequency of self-administration at higher unit doses is caused by an increase in the duration of the cocaine-induced satiety response, and the graded dose-frequency relationship is due to cocaine pharmacokinetics. After the interinjection intervals at a particular unit dose were stable, rats were injected with the competitive D₁-like dopamine receptor antagonist R-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine (SCH23390; 15 nmol/kg intravenously) and the session continued. At all cocaine unit doses, SCH23390 accelerated self-administration with a concomitant increase in the calculated satiety threshold, and these equiactive cocaine concentration ratios were independent of the cocaine unit dose. Therefore, the measurement of antagonist potency requires only a single unit dose of cocaine, selected on the basis of convenience, and using multiple cocaine unit doses is redundant.

Efficient and safe pediatric perioperative pain therapy in the context of a multimodal pain therapy concept requires a slight to moderate opioid analgesic. Nalbuphine is a nearly ideal opioid for this purpose due to its unique pharmacological properties as a μ-receptor antagonist/κ-receptor agonist and a high safety profile. Nalbuphine is used clinically primarily in postoperative pain therapy administered as a bolus, continuous infusion and patient-controlled analgesia. Furthermore, it is administered in different regimens for pediatric diagnostic and interventional sedation.

Interactions between HIV and opioid dependence therapies are known to occur. We sought to determine if such interactions occurred between methadone and elvitegravir boosted with cobicistat (EVG/COBI). We performed a within-subject open-label pharmacokinetic and pharmacodynamic study of 11 HIV-seronegative subjects stabilized on at least 2 weeks of methadone. Subjects underwent baseline and steady-state evaluation of the effect of elvitegravir 150 mg once a day (QD) boosted with 150 mg QD of cobicistat (EVG/COBI) on methadone pharmacokinetic parameters. Safety and pharmacodynamics were monitored throughout the study. Compared to baseline values, the R-methadone mean area under the concentration-time curve to the end of the dosing period (AUCtau) (5,550 versus 6,210 h · ng/ml) and mean maximum concentration of drug in serum (Cmax) (316 versus 337 ng/ml) did not significantly increase in the presence of EVG/COBI. Compared to baseline values, the S-methadone mean AUCtau (7,040 versus 7,540 h · ng/ml) and mean Cmax (446 versus 452 ng/ml) did not significantly increase in the presence of EVG/COBI. The AUCtau, Cmax, and Ctau of elvitegravir and cobicistat did not significantly differ from those of historical controls. Opioid withdrawal or overdose was not observed among subjects in this study. The addition of EVG/COBI to stabilized patients receiving methadone did not affect methadone pharmacokinetics and pharmacodynamics. These two agents can be safely coadministered.

Background: Dolutegravir (DTG) is an investigational integrase inhibitor for treatment of HIV infection. As intravenous drug use is a common risk factor for HIV, this study evaluated the effect of DTG on the pharmacokinetics (PK) of methadone., Methods: This was an open-label, 2-period study in adult, opioid-dependent, HIV-seronegative subjects. Subjects received their current individual methadone doses once daily for 3 days (Period 1) followed by DTG 50mg twice daily (BID) for 5 days while continuing their stable methadone therapy (Period 2). Serial PK samples for R- and S-methadone were collected after each Period. Pharmacodynamic (PD) measures and safety assessments were obtained throughout the study. Non-compartmental PK analysis was performed, and geometric least-squares mean ratios and 90% confidence intervals were generated., Results: Plasma exposures of total, R-, and S-methadone were not affected by co-administration of DTG. Mean ratios for AUC were 0.98, 0.95, and 1.01 for total, R-, and S-methadone, respectively, alone compared with in combination with DTG. No statistically significant differences were noted between the 2 treatment periods in methadone PD measures. The combination of DTG and methadone was well tolerated. No deaths, serious adverse events, or grade 3/4 adverse events occurred. No clinically significant changes in laboratory values, vital signs, or electrocardiograms were observed., Conclusion: Co-administration of methadone with repeat doses of DTG 50mg BID had no effect on total, R-, and S-methadone PK or on methadone-induced PD markers. No dose adjustment in methadone is required when given in combination with DTG., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Patients being treated with buprenorphine usually have a history of opioid dependence and may be predisposed to misuse of drugs. Concurrent drug misuse increases the risk of life-threatening drug interactions. This retrospective data analysis observed which nonprescribed and illicit drugs were most commonly detected in the urine of patients from pain management clinics taking buprenorphine with or without a prescription. GC, LC/MS and LC-MS-MS were used to quantify 20,929 urine specimens. The most prevalent illicit drug used in both the groups (prescribed and nonprescribed buprenorphine) was marijuana, followed by cocaine. The most prevalent nonprescribed medications abused by both the groups were benzodiazepines, followed by oxycodone and hydrocodone. The overall prevalence of illicit and nonprescribed drug use was significantly higher in subjects who used buprenorphine without a prescription versus prescribed use. Of the concurrent use of marijuana and cocaine with buprenorphine, cocaine is most concerning since it decreases exposure to buprenorphine (lower area under the concentration-time curve and maximum concentration). The concurrent use of nonprescribed benzodiazepines with buprenorphine can cause excess sedation leading to respiratory depression and even death. These findings highlight the importance of educating patients about these potential toxicities. Furthermore, pain providers should consider expanding the spectrum of drugs that they monitor in patients under treatment.

Hepatitis C virus (HCV) antibody is present in most patients enrolled in methadone maintenance programs. Therefore, interactions between the HCV protease inhibitor telaprevir and methadone were investigated. The pharmacokinetics of R- and S-methadone were measured after administration of methadone alone and after 7 days of telaprevir (750 mg every 8 h [q8h]) coadministration in HCV-negative subjects on stable, individualized methadone therapy. Unbound R-methadone was measured in predose plasma samples before and during telaprevir coadministration. Safety and symptoms of opioid withdrawal were evaluated throughout the study. In total, 18 subjects were enrolled; 2 discontinued prior to receiving telaprevir. The minimum plasma concentration in the dosing interval (C(min)), the maximum plasma concentration (Cmax), and the area under the plasma concentration-time curve from h 0 (time of administration) to 24 h postdose (AUC(0-24)) for R-methadone were reduced by 31%, 29%, and 29%, respectively, in the presence of telaprevir. The AUC0-24 ratio of S-methadone/R-methadone was not altered. The median unbound percentage of R-methadone increased by 26% in the presence of telaprevir. The R-methadone median (absolute) unbound C(min) values in the absence (10.63 ng/ml) and presence (10.45 ng/ml) of telaprevir were similar. There were no symptoms of opioid withdrawal and no discontinuations due to adverse events. In summary, exposure to total R-methadone was reduced by approximately 30% in the presence of telaprevir, while the exposure to unbound R-methadone was unchanged. No symptoms of opioid withdrawal were observed. These results suggest that dose adjustment of methadone is not required when initiating telaprevir treatment. (This study has been registered at ClinicalTrials.gov under registration no. NCT00933283.).

Opiates continue to be used at high rates in East and Southeast Asia. Hair analysis for drugs of abuse has been developed into a powerful and widely used tool in forensic and clinical toxicology. Specifically, testing the proximal segment of scalp hair to confirm morphine (MOR) positive urine samples could solve the poppy seed problem. Human scalp hair grows approximately 1cm per month and can therefore reflect a retrospective timeline of drug exposure. This study is the first to investigate the disappearance of 6-acetylmorphine (6-AM), MOR and codeine (COD) from human scalp hair after the discontinuation of drug use. Thirty-two healthy women (ages 21-51 years) with a known history of heroin abuse, who went to a rehabilitation centre and ceased consuming heroin (for 4-5 months), were recruited into the study. A pharmacokinetic analysis in seven individual hair segments was performed using a first-order kinetic. Assuming a rate of hair growth of 1cm/month, the mean hair elimination half-lives of 6-AM, MOR and COD were 0.88 months (95% CI, 0.74-1.03), 0.73 months (95% CI, 0.64-0.81), and 0.61 months (95% CI, 0.54-0.69), respectively. Our results suggest that to evaluate the discontinuation of opiate abuse after a 6-month period of abstinence, the results from a 3-cm proximal hair segment should be free of 6-AM at the proposed 0.2 ng/mg cutoff level. This finding should become the basis for the interpretation of results from segmental hair analyses in the evaluation of drug abstinence., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

The presence of cocaine (COC) in fluids or tissues does not prove that death was due to drug consumption and the interpretation of postmortem concentrations is more complex than attempts at making such correlations in the living. The purpose of this study was to investigate the distribution of cocaine and its metabolite benzoylecgonine in brain and compare with whole blood and vitreous humour. The distribution in three brain structures (prefrontal cortex, basal ganglia and cerebellum) was homogeneous. There is a strong correlation for cocaine concentrations between vitreous humour and brain, vitreous humour and whole blood, and whole blood and brain in overdose cases. In addition, the comparison of COC/benzoylecgonine (BE) ratios in different experimental specimens proved to be more appropriate for evaluating cocaine-related death than individual drug values. These findings suggest that the comparison of cocaine levels in different compartments is essential to assess the cause of death., (Copyright © 2012 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.)

Body fluids and tissues in 16 methadone (MTD)-associated fatalities were investigated to find out whether analysis of MTD and its metabolite 2-ethylidine-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) following enantioselective separation of both compounds may assist in the interpretation of MTD findings. Individual case histories were shortly described. R- and S-MTD as well as R- and S-EDDP concentrations were determined by chiral LC-MS/MS. In all cases under investigation total MTD was present in sufficient quantities to kill or to contribute to death; concentrations were highest in lungs (MTD) and kidneys (EDDP). It appears that both MTD and EDDP undergo postmortem redistribution. In three cases, only the pharmacologically active R-MTD isomer was present. R-MTD mainly contributing to the drug's pharmacological effects, the enantiomeric ratio of MTD and EDDP may indicate whether MTD intoxication might have contributed to death or not. Further, it may be helpful to establish whether racemic MTD or enantiomerically pure R-MTD has been administered last, especially if R/S-ratios of MTD and EDDP significantly differ. It could be shown, that in vivo racemization occurs for neither MTD nor EDDP in any body fluid or tissue sample. Significantly higher MTD R/S-ratios in femoral and heart blood were present in individuals having participated in a MTD maintenance program. Overall, R/S-ratios of MTD and EDDP allow a more detailed interpretation of analytical results in MTD-associated deaths. Thus, determination of MTD and EDDP by enantioselective methods and calculation of their R/S-ratios should be favored., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Biochemical diagnostics of fatal opium intoxication remains a topical problem in forensic medical science and practice. We investigated materials obtained in the course of forensic medical expertise of the cases of fatal opium intoxication. The study revealed significant differences between myoglobin levels in blood, urine, myocardium, and skeletal muscles. The proposed approach to biochemical diagnostics of fatal opium intoxication enhances the accuracy and the level of evidence of expert conclusions.

Butorphanol is a narcotic analgesic commonly used in horses. Currently, any detectable concentration of butorphanol in biological samples collected from performance horses is considered a violation. The primary goal of the study reported here was to update the pharmacokinetics of butorphanol following intravenous administration, utilizing a highly sensitive liquid chromatography-mass spectrometry (LC-MS) assay that is currently employed in many drug-testing laboratories. An additional objective was to characterize behavioral and cardiac effects following administration of butorphanol. Ten exercised adult horses received a single intravenous dose of 0.1 mg/kg butorphanol. Blood and urine samples were collected at time 0 and at various times for up to 120 h and analyzed using LC-MS. Mean±SD systemic clearance, steady-state volume of distribution, and terminal elimination half-life were 11.5±2.5 mL/min/kg, 1.4±0.3 L/kg, and 5.9±1.5 h, respectively. Butorphanol plasma concentrations were below the limit of detection (LOD) (0.01 ng/mL) by 48 h post administration. Urine butorphanol concentrations were below the LOD (0.05 ng/mL) of the assay in seven of 10 horses by 120 h post drug administration. Following administration, horses appeared excited as noted by an increase in heart rate and locomotion. Gastrointestinal sounds were markedly decreased for up to 24 h., (© 2012 Blackwell Publishing Ltd.)

Growing interest in pharmacological resting state fMRI (RSfMRI) necessitates developing standardized and robust analytical approaches that are insensitive to spurious correlated physiological signals. However, in pharmacological experiments physiological variations constitute an important aspect of the pharmacodynamic/pharmacokinetic profile of drug action; therefore retrospective corrective methods that discard physiological signals as noise may not be suitable. Previously, we have shown that template-based dual regression analysis is a sensitive method for model-free and objective detection of drug-specific effects on functional brain connectivity. In the current study, the robustness of this standard approach to physiological variations in a placebo controlled, repeated measures pharmacological RSfMRI study of morphine and alcohol in 12 healthy young men is tested. The impact of physiology-related variations on statistical inferences has been studied by: 1) modeling average physiological rates in higher level group analysis; 2) Regressing out the instantaneous respiration variation (RV); 3) applying retrospective image correction (RETROICOR) in the preprocessing stage; and 4) performing combined RV and heart rate correction (RVHRCOR) by regressing out physiological pulses convolved with canonical respiratory and cardiac hemodynamic response functions. Results indicate regional sensitivity of the BOLD signal to physiological variations, especially in the vicinity of large vessels, plus certain brain structures that are reported to be involved in physiological regulation, such as posterior cingulate, precuneus, medial prefrontal and insular cortices, as well as the thalamus, cerebellum and the brainstem. The largest impact of "correction" on final statistical test outcomes resulted from including the average respiration frequency and heart rate in the higher-level group analysis. Overall, the template-based dual regression method seems robust against physical noise that is corrected by RV regression or RETROICOR. However, convolving the RV and HR with canonical hemodynamic response functions caused a notable change in the BOLD signal variance, and in resting state connectivity estimates. The impact of RVHRCOR on statistical tests was limited to elimination of both morphine and alcohol effects related to the somatosensory network that consists of insula and cingulate cortex-important structures for autonomic regulation. Although our data do not warrant speculations about neuronal or vascular origins of these effects, these observations raise caution about the implications of physiological 'noise' and the risks of introducing false positives (e.g. increased white matter connectivity) by using generalized physiological correction methods in pharmacological studies. The obvious sensitivity of the posterior part of the default mode network to different correction schemes, underlines the importance of controlling for physiological fluctuations in seed-based functional connectivity analyses., (Copyright © 2012 Elsevier Inc. All rights reserved.)

High blood-brain permeability and effective delivery of morphine to the brain have been considered as explanations for the high potency of heroin. Results from Andersen et al. indicate that 6-monoacetylmorphine (6-MAM), and not morphine, is the active metabolite responsible for the acute effects observed for heroin. Here, we use pharmacokinetic modeling on data from the aforementioned study to calculate parameters of the distribution of heroin, 6-MAM and morphine in blood and brain tissue after subcutaneous heroin administration in mice. The estimated pharmacokinetic parameters imply that the very low heroin and the high 6-MAM levels observed both in blood and brain in the original experiment are likely to be caused by a very high metabolic rate of heroin in blood. The estimated metabolic rate of heroin in brain was much lower and cannot account for the low heroin and high 6-MAM levels in the brain, which would primarily reflect the concentrations of these compounds in blood. The very different metabolic rates for heroin in blood and brain calculated by the model were confirmed by in vitro experiments. These results show that heroin's fast metabolism in blood renders high concentrations of 6-MAM which, due to its relatively good blood-brain permeability, results in high levels of this metabolite in the brain. Thus, it is the high blood metabolism rate of heroin and the blood-brain permeability to 6-MAM, and not to heroin, which could account for the highly efficient delivery of active metabolites to the brain after heroin administration., (© 2010 The Authors, Addiction Biology © 2010 Society for the Study of Addiction.)