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Background: Intravenous salbutamol is used to treat children with refractory status asthmaticus, however insufficient pharmacokinetic data are available to guide initial and subsequent dosing recommendations for its intravenous use. The pharmacologic activity of salbutamol resides predominantly in the (R)-enantiomer, with little or no activity and even concerns of adverse reactions attributed to the (S)-enantiomer., Objective: Our aim was to develop a population pharmacokinetic model to characterize the pharmacokinetic profile for intravenous salbutamol in children with status asthmaticus admitted to the pediatric intensive care unit (PICU), and to use this model to study the effect of different dosing schemes with and without a loading dose., Methods: From 19 children (median age 4.9 years [range 9 months-15.3 years], median weight 18 kg [range 7.8-70 kg]) treated with continuous intravenous salbutamol at the PICU, plasma samples for R- and S-salbutamol concentrations (111 samples), as well as asthma scores, were collected prospectively at the same time points. Possible adverse reactions and patients' clinical data (age, sex, weight, drug doses, liver and kidney function) were recorded. With these data, a population pharmacokinetic model was developed using NONMEM 7.2. After validation, the model was used for simulations to evaluate the effect of different dosing regimens with or without a loading dose., Results: A two-compartment model with separate clearance for R- and S-salbutamol (16.3 L/h and 8.8 L/h, respectively) best described the data. Weight was found to be a significant covariate for clearance and volume of distribution. No other covariates were identified. Simulations showed that a loading dose can result in higher R-salbutamol concentrations in the early phase after the start of infusion therapy, preventing accumulation of S-salbutamol., Conclusions: The pharmacokinetic model of intravenous R- and S-salbutamol described the data well and showed that a loading dose should be considered in children. This model can be used to evaluate the pharmacokinetic-pharmacodynamic relationship of intravenous salbutamol in children, and, as a next step, the effectiveness and tolerability of intravenous salbutamol in children with severe asthma.

While studies have demonstrated substantial differences in beta 2 -adrenergic agonist enantiomer pharmacology, enantioselective disposition of long-acting beta 2 -adrenergic ligand racemic (rac)-formoterol in blood is inadequately explored after inhaled therapy given analytical challenges. Furthermore, information on enantioselective disposition and partitioning of beta 2 -adrenergic agonist in skeletal muscle is absent despite its promising data on muscle anabolism in humans. Using a sensitive ultra-high performance liquid chromatography-mass spectrometry (UPLC-MS/MS) assay, we determined disposition of (R,R)-formoterol and (S,S)-formoterol in plasma and skeletal muscle samples from 11 non-asthmatic men who had inhaled rac-formoterol at therapeutic doses (2 × 27 μg). Mean (SD) concentrations of (R,R)- and (S,S)-formoterol in plasma and in muscle biopsies of the vastus lateralis 1 hour after inhalation of formoterol were 31 (15) and 45 (18) pg × mL -1 for (R,R)-formoterol and (S,S)-formoterol, respectively, in plasma, and 0.56 (0.32) and 0.51 (0.29) pg × mg wet wt -1 , respectively, in muscle. Formoterol exhibited different enantioselective disposition in plasma and muscle (p < 0.0001). In plasma, mean log (R,R):(S,S)-formoterol ratio was lower than 0 [-0.17(0.07), p < 0.0001], whereas in muscle, mean log (R,R):(S,S)-formoterol ratio was slightly higher than 0 [0.04(0.07), p < 0.05]. Log (R,R):(S,S)-formoterol ratio in muscle was related to muscle fiber-type composition. Furthermore, formoterol induced an approximately two-fold increase in muscle p-PKA Ser/thr phosphorylation (p < 0.01), indicating a substantial beta 2 -adrenergic response. Collectively, these findings suggest that formoterol exhibits modest enantioselective disposition in plasma after inhaled therapy in humans, which appear related to a greater (R,R)-enantiomer disposition in skeletal muscle that may be dependent on fiber-type composition., (© 2019 John Wiley & Sons, Ltd.)

Background: Predicting local lung tissue pharmacodynamic (PD) responses of inhaled drugs is a longstanding challenge related to the lack of experimental techniques to determine local free drug concentrations. This has prompted the use of physiologically based pharmacokinetic (PBPK) modeling to potentially predict local concentration and response. A unique opportunity for PBPK model evaluation is provided by the clinical PD data for salbutamol, which in its inhaled dosage form (400 μg), produces a higher bronchodilatory effect than in its oral dosage form (2 mg) despite lower drug concentrations in blood. The present study aimed at evaluating whether inhalation PBPK model predictions of free drug in tissue would be predictive of these observations., Methods: A PBPK model, including 24 airway generations, was parameterized to describe lung, plasma, and epithelial lining fluid concentrations of salbutamol administered intratracheally and intravenously to rats (100 nmol/kg). Plasma and lung tissue concentrations of unbound (R)-salbutamol, the active enantiomer, were predicted with a humanized version of the model and related to effect in terms of forced expiratory volume in 1 second (FEV 1 )., Results: In contrast to oral dosing, the model predicted inhalation to result in spatial heterogeneity in the target site concentrations (subepithelium) with higher free drug concentrations in the lung as compared with the plasma. FEV 1 of inhaled salbutamol was accurately predicted from the PK/PD relationship derived from oral salbutamol and PBPK predictions of free concentration in airway tissue of high resistance (e.g., 6th generation)., Conclusion: An inhalation PBPK-PD model was developed and shown predictive of local pharmacology of inhaled salbutamol, thus conceptually demonstrating the validity of PBPK model predictions of free drug concentrations in lung tissue. This achievement unlocks the power of inhalation PBPK modeling to interrogate local pharmacology and guide optimization and development of inhaled drugs and their formulations.

Objectives: The aim of the study was to investigate the pharmacokinetics and tolerability of salbutamol/ambroxol fixed-dose combination granules following single and multiple dosing in healthy Chinese subjects., Materials and Methods: This was a randomized, open-label, two-period, one-sequence study (n = 12). Each subject received a single oral dose in period 1 and multiple doses in period 2. Plasma concentrations of these two components were determined using a validated LC-MS/MS method. Adverse events (AEs) were documented throughout the study. Investigators evaluated AEs in terms of frequency, duration, intensity, seriousness, outcome, and relationship to study drugs., Results: Following single dosing, C max values were 8.07 ± 1.31 ng/mL and 25.7 ± 6.5 ng/mL for salbutamol and ambroxol, respectively. The corresponding T 1/2 values were 8.15 ± 3.13 hours and 9.31 ± 2.27 hours, respectively. Moreover, no statistical differences in the pharmacokinetics of salbutamol and ambroxol in subjects receiving single or multiple dosage were observed. Single- and multiple-dose oral administration of fixed-dose combination granules were safe and well tolerated in healthy Chinese subjects. Drug hypersensitivity syndrome did not occur during our study., Conclusion: The pharmacokinetics of salbutamol and ambroxol in the fixed-dose combination granules were not affected by dosing duration, and gender differences seemed to have no effect on the pharmacokinetics of salbutamol and ambroxol after a single dose and multiple doses of the medication.
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Background: Cardiac dysfunction is associated with a higher mortality in exacerbations of chronic obstructive pulmonary disease (COPD). It is unknown how the heart responds to treatment of COPD exacerbations. We followed cardiac biomarker levels during hospital admissions for exacerbations of COPD and hypothesised that these biochemical markers of cardiac dysfunction might be affected the severity and treatment of exacerbations of COPD., Methods: N-terminal pro-B-type natriuretic peptide (NT-proBNP) and troponin T were measured at admission, 12 h, 72 h, and clinical stability in 176 patients. In a second cohort (n = 93), associations between blood salbutamol concentrations and biomarker changes at 12 h were analysed., Results: NT-proBNP increased from a geometric mean of 43 pmol/L at admission to 56 pmol/L at 12 h (p < 0.001), 53 pmol/L at 72 h (p = 0.045), and decreased to 25 pmol/L (p < 0.001) at stability. Troponin T levels decreased at 12 h (p < 0.001), but 15/174 (9%) patients had a clinically significant rise. Nebulised bronchodilator treatment and blood salbutamol concentrations were associated with greater increases in NT-proBNP rise at 12 h independently of baseline COPD or exacerbation severity and other treatments (p < 0.05). Nebulised bronchodilator and blood salbutamol concentrations also predicted rises in troponin T in univariate analyses (p < 0.05)., Conclusions: NT-proBNP continues to rise after admission to hospital for COPD exacerbations and a minority of patients have clinically significant rises in cardiac troponins. These rises were associated with nebulised beta 2 -agonist treatment. These findings suggest that high doses of beta 2 -agonists may exacerbate cardiac dysfunction in COPD., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Objectives: The aims of the study were to investigate the potential drug-drug interaction between salbutamol and ambroxol, the bioequivalence of the new fixed-dose combination containing salbutamol and ambroxol compared with co-administration of the two separate formulations, and to describe the safety and tolerability of the fixed-dose combination formulation in healthy Chinese volunteers., Materials and Methods: An open-label, single-dose, four-treatment, four-period crossover study for evaluation of drug-drug interaction and bioequivalence (n = 24) was performed. Each participant received salbutamol 4 mg, ambroxol 15 mg, salbutamol 4 mg co-administered with ambroxol 15 mg or fixed-dose combination formulation (salbutamol 4 mg and ambroxol 15 mg). Plasma concentrations of two analytes were determined with the use of validated LC-MS/MS method. Safety and tolerability were assessed by recording adverse events., Results: Co-administration of salbutamol and ambroxol was not associated with a significant influence on single salbutamol or ambroxol pharmacokinetics. After statistical comparisons of log-transformed C max and AUC of salbutamol and ambroxol between fixed-dose combination and concomitant treatments, all 90% confidence intervals of geometric mean ratios were within the predefined equivalence range of 80 - 125%. No serious adverse events were reported, and all treatments were safe and well tolerated in Chinese healthy subjects., Conclusion: There were no significant drug-drug pharmacokinetic interactions between salbutamol and ambroxol after oral administration. The new formulation was bioequivalent to the co-administration of two drugs in separate dosage forms.
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Purpose: The efficacy and tolerability of GFF MDI (Bevespi Aerosphere ® ), a fixed-dose combination of glycopyrronium (GP)/formoterol fumarate dihydrate (FF) 14.4/10 μg (equivalent to glycopyrrolate/formoterol fumarate 18/9.6 μg) delivered by metered dose inhaler (MDI) using innovative co-suspension delivery technology, has been investigated in a Phase III clinical trial program (NCT01854645, NCT01854658, NCT01970878) in patients with COPD. Here, we present findings from a pharmacokinetic (PK) sub-study of NCT01854645 (PINNACLE-1)., Methods: PINNACLE-1 was a multicenter, randomized, double-blind, parallel-group, 24 wk chronic-dosing, placebo- and active-controlled study. The PK sub-study assessed the systemic accumulation of glycopyrronium and formoterol following administration of GFF MDI 14.4/10 μg, GP MDI 14.4 μg, or FF MDI 10 μg (all BID) for 12 wks. Plasma for PK analysis was collected for up to 12 h after dosing, on Day 1 and Week 12., Results: Of 2,103 patients randomized in PINNACLE-1, 292 participated in the PK sub-study. The plasma concentration-time profiles of glycopyrronium were similar following treatment with GFF MDI or GP MDI, both after single dosing and at Week 12. Accumulation at Week 12 relative to Day 1 was up to 2.30-fold for glycopyrronium. The plasma concentration-time profiles of formoterol were similar following treatment with GFF MDI or FF MDI, both after single dosing and at Week 12. Accumulation at Week 12 relative to Day 1 was up to 1.62-fold for formoterol., Conclusion: Overall, the results have characterized the accumulation of glycopyrronium and formoterol associated with GFF MDI, GP MDI, and FF MDI, and indicated that there were no meaningful PK interactions, whether drug-drug or due to formulation, between glycopyrronium and formoterol following treatment with GFF MDI formulated using co-suspension delivery technology., Competing Interests: Disclosure GTF reports grants and personal fees from AstraZeneca, Boehringer Ingelheim, Novartis, Pearl – A member of the AstraZeneca Group, Sunovion, and Theravance. He has also received grants from Forest and personal fees from GlaxoSmithKline, Meda, Mylan, and Verona. RRR has received personal fees from AstraZeneca, Boehringer Ingelheim, Pearl – A member of the AstraZeneca Group, TEVA, Menarini, and Novartis; and grants/research support from Menarini. CR is an employee of AstraZeneca and Chief Executive Officer of Pearl – A member of the AstraZeneca Group. AM is an employee of Pearl – A member of the AstraZeneca Group. SS and UJM are employees of Astra-Zeneca. The authors report no other conflicts of interest in this work.

Salmeterol (SAL) is a long-acting β2-adrenergic agonist, which is widely used in the therapy of asthma. The aim of this study was to investigate the pharmacokinetics (PK) of inhaled salmeterol in asthma patients using two different dry powder inhalers. This analysis was based on data from 45 subjects who participated in a two-sequence, four-period crossover bioequivalence (BE) study after single administration of the test (T) and reference (R) products. In order to mimic more closely the real treatment conditions, activated charcoal was not co-administered. Plasma concentration-time (C-t) data were initially analysed using classic non-compartmental PK approaches, while the main objective of the study was to apply population PK modeling. The relative fraction of the dose absorbed via the lungs (R L ) was set as a parameter in the structural model. The plasma C-t profiles of salmeterol showed a biphasic time course indicating a parallel pulmonary and gastrointestinal (GI) absorption. A two-compartment disposition model with first order absorption from the GI and very rapid absorption from lungs (like an i.v. bolus) was found to describe successfully the C-t profiles of salmeterol. The estimated R L value was 13% suggesting a high gut deposition of inhaled salmeterol. Women were found to exert less capability to eliminate salmeterol than men, while body weight (in allometric form) was found to be an important covariate on the peripheral volume of distribution., (Copyright © 2017 John Wiley & Sons, Ltd.)

Enantioseparation of four commonly used β-adrenolytics (bisoprolol, salbutamol, and carvedilol, marketed as racemic mixtures) has been achieved by both TLC and RPHPLC via an indirect approach. A new chiral reagent, (S)-naproxen benzotriazole ester, was synthesized and it was characterized by UV, IR, 1 HNMR, elemental analysis and polarimetry. It was used to synthesize diastereomeric derivatives of the three β-adrenolytics under microwave irradiation. TLC separation of diastereomeric derivatives was achieved which were then isolated by preparative approach; these were characterized and were used as standard reference for determining absolute configuration of diastereomeric derivatives and for establishing validated HPLC method for enantioseparation and sensitive detection of the three β-adrenolytics in human plasma. Mobile phase in gradient mode containing methanol and aqueous triethylaminephosphate (TEAP) was successful for HPLC separation; conditions with respect to pH, flow rate, and buffer concentration were optimized. The method is capable to accurately quantitate β-adrenolytics in human plasma with minimal sample clean-up and rapid separation by TLC and RPHPLC. The limit of detection values were 0.97 and 0.87ng/mL for diastereomeric derivatives of (S)- and (R)-bisoprolol, respectively, which are very low in comparison to literature reports., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Most contemporary methods of screening and quantitating controlled substances and therapeutic drugs in biofluids typically require laborious, time-consuming, and expensive analytical workflows. In recent years, our group has worked toward developing microextraction (μe)-mass spectrometry (MS) technologies that merge all of the tedious steps of the classical methods into a simple, efficient, and low-cost methodology. Unquestionably, the automation of these technologies allows for faster sample throughput, greater reproducibility, and radically reduced analysis times. Coated blade spray (CBS) is a μe technology engineered for extracting/enriching analytes of interest in complex matrices, and it can be directly coupled with MS instruments to achieve efficient screening and quantitative analysis. In this study, we introduced CBS as a technology that can be arranged to perform either rapid diagnostics (single vial) or the high-throughput (96-well plate) analysis of biofluids. Furthermore, we demonstrate that performing 96-CBS extractions at the same time allows the total analysis time to be reduced to less than 55 s per sample. Aiming to validate the versatility of CBS, substances comprising a broad range of molecular weights, moieties, protein binding, and polarities were selected. Thus, the high-throughput (HT)-CBS technology was used for the concomitant quantitation of 18 compounds (mixture of anabolics, β-2 agonists, diuretics, stimulants, narcotics, and β-blockers) spiked in human urine and plasma samples. Excellent precision (∼2.5%), accuracy (≥90%), and linearity (R 2 ≥ 0.99) were attained for all the studied compounds, and the limits of quantitation (LOQs) were within the range of 0.1 to 10 ng·mL -1 for plasma and 0.25 to 10 ng·mL -1 for urine. The results reported in this paper confirm CBS's great potential for achieving subsixty-second analyses of target compounds in a broad range of fields such as those related to clinical diagnosis, food, the environment, and forensics.

Salbutamol, a selective β 2 -agonist, endangers the safety of animal products because of its illegal use in food animals. In this work, residues of salbutamol and its metabolites were investigated to select appropriate targets and marker residues for monitoring the illegal use of salbutamol. Ten metabolites of salbutamol were identified from plasma, urine, liver, and kidney samples; of these, six were newly identified. There were significant differences (P < 0.01) between the parent (nonconjugated) and total (conjugated + nonconjugated) salbutamol concentrations in plasma, urine, liver, and kidney tissues. Salbutamol residues in urine were relatively higher than those in plasma and other internal tissues during the dosing period and were rapidly eliminated from plasma, heart, spleen, and kidney tissues during the withdrawal time. Total salbutamol was identified as more preferable than parent salbutamol as a marker residue, and urine and eye tissues were found to be more suitable as targets for preslaughter and postslaughter monitoring of the illegal use of salbutamol in beef cattle.

Veterinary drugs usually have rapid clearance rates in the liver and kidney, hampering their detection in conventional matrices such as the liver or urine. Pharmacological principles such as esterification may be applied to facilitate the administration of veterinary drugs and increase drug half-life. Prednisolone, whose therapeutic administration is regulated for food producing animals in the EU, is available in its acetate form as well as nandrolone, a banned anabolic steroid, which may be obtained as nandrolone phenylpropionate and estradiol as a benzoyl ester. While the distribution and accumulation of lipophilic and hydrophilic substances in human teeth have been well documented, studies on residues in bovine teeth are lacking. We hypothesised that analysis of bovine teeth could be used to detect both regulated and banned veterinary drugs. Steroids may be illegally used as growth promoters in food producing animals, alone or combined with β2-agonists; therefore, we developed, and validated, in accordance with the Commission Decision 2002/657/EC, two analytical confirmatory LC-MS/MS methods to detect these classes of compounds following a unique liquid extraction procedure. Finally, we analysed teeth from three male Friesian veal calves treated with intramuscular estradiol benzoate, oral prednisolone acetate or intramuscular nandrolone phenylpropionate in combination with oral ractopamine, respectively, and from seven bovines from the food chain. Teeth from treated animals were positive for their respective drugs, with the exception of nandrolone phenylpropionate. One sample from a food chain bovine was positive for isoxsuprine, one of the seven β2-agonists studied. Non-esterified forms of the steroids were not found. These results demonstrate that bovine teeth are a suitable matrix for the determination of pseudoendogenous substances or illicit administration of veterinary drugs.

Background and Objectives: Previous pharmacokinetic studies of the inhaled corticosteroid, fluticasone furoate (FF), and the long-acting, beta2-receptor agonist, vilanterol (VI) have been performed in relatively small populations using non-compartmental pharmacokinetic methods and censored data (due to low drug exposure relative to assay sensitivity). This paper presents a population pharmacokinetic analysis, utilizing pooled concentration-time data from clinical studies in healthy subjects and from global trials in patients with chronic obstructive pulmonary disease (COPD). The objective of this analysis was to characterize the population pharmacokinetics of FF and VI following once-daily inhalation dosing of FF/VI or the individual components (FF and VI) and to identify significant covariates that impact systemic exposure to FF and VI in this population., Methods: Population pharmacokinetic methods that maximize the likelihood of all data were developed to describe systemic exposure to FF and VI following once-daily FF/VI, FF, or VI, and to identify significant covariates that impact the pharmacokinetics. COPD patients (N = 1225 for the FF analysis and N = 1091 for the VI analysis; 94 and 93 % of total data, respectively) and healthy subjects contributed to the analysis., Results: FF data were described by a two-compartment model with first-order absorption and elimination. The population grouping "race" was a significant covariate on inhaled clearance (CL/F). The area under the curve over 24 h (AUC 0-24 ) for FF was higher for East Asian, Japanese, and South East Asian (average 23-30 %) and Asian Central, White Arabic, American Indian/Native Alaskan, and 'other' (10-26 %) subjects compared with White/Caucasians. VI pharmacokinetics were described by a three-compartment model with zero-order absorption and first-order elimination. Significant demographic covariates identified to affect pharmacokinetics of VI were age [on CL/F and central volume (V 1 /F)], bodyweight (on CL/F), sex and smoking (on V 1 /F)., Conclusions: While significant effects of the covariates were observed in this study, the magnitude of these effects on systemic exposure is not large enough to warrant FF/VI dosage adjustment in patients with COPD., Competing Interests: Compliance with Ethical Standards Funding All of the studies used in this analysis were funded by GSK. Conflict of interest Sarah Siederer and Shuying Yang are employed by and hold shares in GSK. Ann Allen was an employee of GSK at the time of these analyses. Ethical approval All procedures were carried out in accordance with the International Conference on Harmonisation E6 guidelines for Good Clinical Practice and the principles of the Declaration of Helsinki. The studies described in this paper were approved by independent institutional review boards and ethics committees at all study sites. A full list of approving bodies is included in Appendix 1. Informed consent Written informed consent was obtained from each subject prior to the performance of any study-specific procedures.

Background: The Mini Spacer has been developed for use with Ventolin(®) metered dose inhalers (MDIs) to improve accessibility to affordable spacers in developing countries. To ensure patient safety is not compromised if the Mini Spacer is used off-label with fluticasone propionate (FP) or salmeterol/FP combination (SFC) MDIs (currently not recommended), this study compared the systemic exposure of FP and salmeterol following delivery of FP and SFC MDIs with the Mini Spacer and the Aerochamber Plus(®) spacer (Aerochamber)., Methods: This was an open-label, randomized, single dose, crossover study in healthy subjects that evaluated four treatments: i) FP 250 μg MDI with Mini Spacer; ii) FP 250 μg MDI with Aerochamber; iii) SFC 25/250 μg with Mini Spacer; iv) SFC 25/250 μg with Aerochamber. There was a minimum 7 day washout between treatments. Pharmacokinetic samples were collected over 24 hours post-dose. The co-primary endpoints were FP area under the concentration-time curve from time zero to 24 h [FP AUC(0-24)] and salmeterol maximum plasma concentration [Cmax]., Results: FP systemic exposure in terms of AUC(0-24) was lower following inhalation with the Mini Spacer compared with the Aerochamber for both FP 250 μg (Mini Spacer/Aerochamber Ratio 0.76 [90% CI: 0.57-1.01]) and SFC 25/250 μg (Ratio 0.74 [90% CI: 0.56-0.99]). Salmeterol systemic exposure was also lower following SFC 25/250 μg with Mini Spacer compared with Aerochamber (Cmax Ratio 0.90 [90% CI 0.48-1.66]). The incidence of adverse events was low and similar with each treatment., Conclusions: In the event of use of the Mini Spacer with FP and SFC MDIs, which is not recommended, FP and salmeterol systemic exposure is unlikely to be higher than if MDIs were to be used with the Aerochamber. However, these data do not indicate that the Mini Spacer and Aerochamber are interchangeable.

The present study investigated the influence of exercise and dehydration on the urine concentrations of salbutamol after inhalation of that maximal permitted (1600 µg) on the 2015 World Anti-Doping Agency (WADA) prohibited list. Thirteen healthy males participated in the study. Urine concentrations of salbutamol were measured during three conditions: exercise (EX), exercise+dehydration (EXD), and rest (R). Exercise consisted of 75 min cycling at 60% of VO2max and a 20-km time-trial. Fluid intake was 2300, 270, and 1100 mL during EX, EXD, and R, respectively. Urine samples of salbutamol were collected 0-24 h after drug administration. Adjustment of urine concentrations of salbutamol to a specific gravity (USG) of 1.020 g/mL was compared with no adjustment. The 2015 WADA decision limit (1200 ng/mL) for salbutamol was exceeded in 23, 31, and 10% of the urine samples during EX, EXD, and R, respectively, when unadjusted for USG. When adjusted for USG, the corresponding percentages fell to 21, 15, and 8%. During EXD, mean urine concentrations of salbutamol exceeded (1325±599 ng/mL) the decision limit 4 h after administration when unadjusted for USG. Serum salbutamol Cmax was lower (P<0.01) for R(3.0±0.7 ng/mL) than EX(3.8±0.8 ng/mL) and EXD(3.6±0.8 ng/mL). AUC was lower for R (14.1±2.8 ng/mL·∙h) than EX (16.9±2.9 ng/mL·∙h)(P<0.01) and EXD (16.1±3.2 ng/mL·∙h)(P<0.05). In conclusion, exercise and dehydration affect urine concentrations of salbutamol and increase the risk of Adverse Analytical Findings in samples collected after inhalation of that maximal permitted (1600 µg) for salbutamol. This should be taken into account when evaluating doping cases of salbutamol. Copyright © 2015 John Wiley & Sons, Ltd., (Copyright © 2015 John Wiley & Sons, Ltd.)

The long-acting muscarinic antagonist umeclidinium (UMEC) is approved as a once-daily monotherapy and in combination with the long-acting β2 agonist vilanterol (VI) for chronic obstructive pulmonary disease. The objective of this analysis was to assess the relationship between observed plasma UMEC and/or VI concentrations and QT interval corrected using Fridericia's correction (QTcF). 103 subjects were enrolled and 86 (83 %) completed the study. Subjects were randomized to 4 of 5 repeat-dose treatments (days 1-10: n = 77 subjects received placebo, n = 76 UMEC 500 µg, n = 78 UMEC/VI 125/25 µg, or n = 76 UMEC/VI 500/100 µg; day 10: n = 74 oral tablet moxifloxacin 400 mg [positive control]). The concentration-QTcF interval relationship was examined using nonlinear mixed-effects methods. For UMEC, predicted QTcF interval prolongation (at observed geometric mean of maximum plasma concentrations) was -2.38 ms (90 % prediction interval [PI] -3.82, -0.85) with UMEC 500 µg and -0.50 ms (90 % PI -0.80, -0.18) and -2.01 ms (90 % PI -3.22, -0.72) with UMEC/VI 125/25 µg and 500/100 µg, respectively. For VI, estimates were 5.89 ms (90 % PI 4.89, 6.91) and 7.23 ms (90 % PI 5.88, 8.55) with UMEC/VI 125/25 µg and 500/100 µg, respectively. Combined additive mean effects were estimated for UMEC/VI 125/25 µg (5.39 ms [90 % PI 4.40, 6.47]) and 500/100 µg (5.22 ms [90 % PI 3.72, 6.80]). The model-predicted decrease with UMEC and increase with UMEC/VI combination in QTcF interval suggest that the QT effect is likely attributable to VI. These model-predicted results support those of previously-published traditional statistical analyses.

Aims: Olodaterol, a novel β2-adrenergic receptor agonist, is a long-acting, once-daily inhaled bronchodilator approved for the treatment of chronic obstructive pulmonary disease. The aim of the present study was to describe the plasma and urine pharmacokinetics of olodaterol after intravenous administration and oral inhalation in healthy volunteers by population pharmacokinetic modelling and thereby to infer its pulmonary fate., Methods: Plasma and urine data after intravenous administration (0.5-25 μg) and oral inhalation (2.5-70 μg via the Respimat® inhaler) were available from a total of 148 healthy volunteers (single and multiple dosing). A stepwise model building approach was applied, using population pharmacokinetic modelling. Systemic disposition parameters were fixed to estimates obtained from intravenous data when modelling data after inhalation., Results: A pharmacokinetic model, including three depot compartments with associated parallel first-order absorption processes (pulmonary model) on top of a four-compartment body model (systemic disposition model), was found to describe the data the best. The dose reaching the lung (pulmonary bioavailable fraction) was estimated to be 49.4% [95% confidence interval (CI) 46.1, 52.7%] of the dose released from the device. A large proportion of the pulmonary bioavailable fraction [70.1% (95% CI 66.8, 73.3%)] was absorbed with a half-life of 21.8 h (95% CI 19.7, 24.4 h)., Conclusions: The plasma and urine pharmacokinetics of olodaterol after intravenous administration and oral inhalation in healthy volunteers were adequately described. The key finding was that a high proportion of the pulmonary bioavailable fraction had an extended pulmonary residence time. This finding was not expected based on the physicochemical properties of olodaterol., (© 2015 The British Pharmacological Society.)

Tulobuterol is a β2-adrenergic agonist that was the first bronchodilator approved as a transdermal patch for humans. Previous studies have examined the pharmacokinetics of tulobuterol in humans but not in the veterinary species. In this study, the pharmacokinetics of tulobuterol was examined in healthy Beagle dogs after transdermal and intravenous administration. The Cmax was 2.09 ng/mL at 16.0 h for a 0.2 mg/kg patch and 4.85 ng/mL at 13.6 h for a 0.4 mg/kg patch. The effective blood level in humans is 1-3 ng/mL, a concentration achieved using the 0.2 mg/kg patch in dogs. In conclusion, application of a 0.2 mg/kg tulobuterol patch to healthy dogs led to an apparently effective blood concentration for 24 h., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

GSK961081 (batefenterol) is a novel bifunctional molecule composed of a muscarinic antagonist and a β2-agonist. The aims of this substudy were (1) to characterize the population pharmacokinetics (PK) and pharmacodynamics (PD) of GSK961081 in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD); and (2) to investigate the relationship between systemic exposure to GSK961081 and key cardiac-related safety parameters. Three once-daily doses (100, 400, and 800 μg) and three twice-daily doses (100, 200, and 400 μg) of GSK961081 DISKUS were investigated. A two-compartment disposition PK model with first-order absorption adequately described the plasma GSK961081 concentration-time data. An empirical maximum-effects PD model adequately described the forced expiratory volume in 1 s (FEV1) response relationship with the covariate baseline FEV1 on day 1. No clear relationships between GSK961081 plasma drug levels and cardiac-related safety parameters were apparent. The PK and PD models will be used to guide the dose selection and development of GSK961081 in patients with COPD.

Background: Olodaterol is a novel long-acting β2-agonist with proven ≥24-hour duration of action in preclinical and clinical studies., Objective: This randomized, double-blind, placebo-controlled, parallel-group study evaluated the dose response of once-daily (QD) olodaterol based on bronchodilator efficacy, safety, and pharmacokinetics over 4 weeks in Japanese patients with chronic obstructive pulmonary disease (COPD)., Methods: All eligible patients were randomized to receive 2 µg, 5 µg, or 10 µg of olodaterol or placebo for 4 weeks via the Respimat Soft Mist inhaler. The primary end point was the change from baseline in trough forced expiratory volume in 1 second (FEV1) after 4 weeks of olodaterol treatment. Secondary end points included trough FEV1 after 1 week and 2 weeks of treatment, FEV1 area under the curve from 0 hour to 3 hours (AUC(0-3)), peak FEV1 from 0 hour to 3 hours (peak FEV1), and corresponding forced vital capacity (FVC) responses. Rescue medication use, COPD symptoms, physician global evaluation, pharmacokinetics, and safety were also assessed., Results: A total of 328 patients with COPD were randomized to receive treatment. All olodaterol doses assessed in the study showed statistically significant increases in trough FEV1 compared to placebo at Day 29 (P<0.0001). Mean increases in peak FEV1 and FEV1 AUC(0-3) compared to placebo were also significant (P<0.0001). A clear dose-response relationship was observed across all treatment groups. FVC responses (trough and FVC AUC(0-3)) supported FEV1 outcomes. All doses of olodaterol were well tolerated, and no safety concerns were identified., Conclusion: QD olodaterol demonstrated 24-hour bronchodilator efficacy and was well tolerated in Japanese patients with COPD., Trial Registration: ClinicalTrials.gov: NCT00824382.

Objective: Budesonide formoterol (BF) Spiromax® is a breath-actuated dry-powder inhaler designed to deliver similar combinations of budesonide and formoterol as Symbicort® Turbohaler®. We performed two studies to demonstrate pharmacokinetic (PK) equivalence of BF Spiromax with BF Turbohaler., Materials and Methods: Two single-center, open-label, randomized, 5-period crossover studies were performed. The first study compared BF Spiromax 160/4.5 μg with BF Turbohaler 200/6 μg, while the second study compared BF Spiromax 320/9 μg with BF Turbohaler 400/12 μg. All treatments were administered with and without charcoal. PK parameters were calculated by measuring plasma drug concentrations from blood samples taken pre-dose and up to 24 hours post-dose., Results: In each study, 90 healthy volunteers were randomized. Bioequivalence of BF Spiromax with BF Turbohaler was demonstrated for budesonide and formoterol (AUC0-t and Cmax (90% confidence intervals of the geometric mean between-device ratios for both parameters were within the predefined range of 0.80-1.25 in both studies)). Equivalence was observed without use of charcoal (overall absorption post-inhalation) and with charcoal (pulmonary absorption). There were no major differences between treatments in tmax for either budesonide or formoterol. All study treatments were well tolerated (one treatment-emergent adverse event (TEAE) in the medium-dose study and four TEAEs in the high-dose study)., Conclusions: These studies indicate that BF Spiromax (±charcoal block) is bioequivalent to BF Turbohaler with respect to the PK parameters assessed. Single doses of BF Spiromax were well tolerated; the overall safety profile of BF Spiromax and BF Turbohaler was similar.

Purpose: To investigate the potential for systemic pharmacokinetic (PK) and pharmacodynamic (PD) interactions between inhaled fluticasone furoate (FF) and vilanterol (VI) when delivered simultaneously via the ELLIPTA™ dry powder inhaler (DPI)., Methods: Randomized, double-blind, placebo-controlled, crossover study. Healthy subjects (n = 16) received single doses of FF (800 mcg), VI (100 mcg), FF/VI (800/100 mcg), and placebo. Endpoints measured were systemic PD (FF: serum cortisol; VI: heart rate), FF and VI plasma PK (0-48 hours), pharyngometry, inhalation and breath hold profiles and safety assessments., Results: Treatment differences [90% confidence interval (CI)] in weighted mean serum cortisol (0-24 hours) were 12.3% [4.4, 20.9] (FF/VI vs. FF) and for maximum heart rate (0-4 hours) were -1.2 bpm [-4.6, 2.1] (FF/VI vs. VI). When delivered simultaneously, FF and VI systemic exposures were slightly lower (<20%) versus delivery of either agent alone (although this was not a formal bioequivalence study). In vitro simulation of selected inhalation profiles and modeling supported the PK and PD findings. FF/VI, FF and VI were well tolerated with an AE incidence comparable to placebo., Conclusions: These results suggest there was a slight PK interaction and no PD interactions of concern between inhaled FF and VI when delivered simultaneously via the ELLIPTA DPI in healthy subjects., (© 2014, The American College of Clinical Pharmacology.)

Background: Formoterol fumarate (FF) is a well-established long-acting β2-agonist. This represents the first clinical study of FF in a metered-dose inhaler (FF MDI) based on proprietary lipid-based porous-particle engineering technology., Methods: In this randomized, double-blind, 5-period, crossover study (NCT00880490), subjects received 2.4, 4.8, and 9.6 μg of FF MDI, open-label Foradil(®) Aerolizer(®) (FA) 12 μg, and placebo. Spirometry was performed at baseline, 15 and 30 min, and 1, 2, 4, 6, 8, 10, 11.5, and 12 h post-dose., Results: Thirty-four subjects were enrolled. Improvement in forced expiratory volume in 1 s (FEV1) was similar between FF MDI 9.6 μg and FA. Change in FEV1 area under the curve for 0-12 h (AUC0-12) for each FF MDI dose demonstrated superior efficacy versus placebo (P < .001 for all 3 doses). Over 12 h and at each time point, FF MDI 9.6 μg was non-inferior to FA for FEV1 AUC0-12 with the 95% CI's supporting a maximum difference of approximately 45 mL. Peak and trough FEV1, forced vital capacity, peak expiratory flow rate, peak inspiratory capacity, and pharmacokinetics confirmed the primary endpoint, with dose ordering of the FF MDI 2.4, 4.8, and 9.6 μg, and comparability of FF MDI 9.6 μg to FA. All 3 doses of FF MDI were safe and well-tolerated, with a safety profile similar to that of placebo and FA., Conclusions: The efficacy and pharmacokinetic profile of FF MDI 9.6 μg were comparable to FA 12 μg and with similar safety to placebo and FA., Trial Registration: This clinical trial was registered on ClinicalTrials.gov, Identifier: NCT NCT00880490., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Background: The object of this study was to assess whether a capsule-based and multidose dry powder inhaler containing salmeterol (as xinafoate salt) 50 μg plus fluticasone propionate (FP) 250 μg [combination (SFC 50/250)] could be equivalent in terms of in vivo drug delivery and systemic exposure., Methods: This was a randomized, double-blind, double-dummy, replicate treatment design comparative bioavailability study of SFC 50/250 delivered in a capsule-based inhaler (Rotahaler®) and a multidose dry powder inhaler (Diskus®). Subjects with asthma or chronic obstructive pulmonary (COPD) disease (n=60) were randomized to receive twice-daily SFC 50/250 via a Rotahaler and via Diskus each for two 10-day treatment periods (GlaxoSmithKline Protocol ASR114334)., Results: For FP and salmeterol, the in vitro aerodynamic particle size profiles were within±15% of Diskus for the fine particle mass (FPM) and emitted dose (ED) using the Andersen Cascade Impactor, and ED, mass median aerodynamic diameter, and geometric standard deviation using the New Generation Impactor (NGI). This was also the case for FP but not salmeterol for FPM and fine particle dose using the NGI. For the combined asthma and COPD subjects, the plasma AUC and Cmax for FP and salmeterol were higher for Rotahaler:Rotahaler/Diskus geometric mean ratios (90% confidence intervals) for FP AUC0-τ of 1.52 (1.37-1.67) and Cmax of 1.94 (1.75-2.10) and salmeterol AUC0-τ of 1.15 (1.09-1.21) and Cmax of 1.56 (1.42-1.67). Corresponding values for the primary pharmacodynamic endpoint, weighted mean (0-12 hr) serum cortisol, were 0.928 (0.886-0.971). Inhaled FP/salmeterol via both inhalers was well-tolerated. One serious adverse event, considered possibly related to study medication, resulted in subject withdrawal from the study., Conclusions: The in vitro tests and systemic pharmacodynamic endpoints revealed no major differences between the two inhalers, but lacked predictive power and sensitivity to guide in vivo drug delivery performance and systemic exposure. Based on pharmacokinetic endpoints, the inhalers were not considered bioequivalent in terms of systemic exposure. Further studies to refine the Rotahaler performance are ongoing.

Ritodrine hydrochloride (RD-HCl) tablets containing alginate (AL) and lactose (LC) with or without microcrystalline cellulose (MC) as excipients were produced as a buccal dosage form. The RD-HCl (2 mg) tablets with AL/LC but no MC swelled and dissolved gradually in the in vitro dissolution test. The tablet showing the fastest dissolution and highest drug release rate, called Tablet A1, was selected as a tablet to show rapid and prolonged absorption. However, in the in vivo buccal absorption test using rats, it could not give a plasma concentration over the human minimal effective level (15 ng/mL). The modified tablet containing AL, LC, MC and RD-HCl (4 mg), named Tablet B/MC, showed better hardness and faster drug release. Tablet B/MC gave a plasma concentration over the human effective level within 15 min, and the plasma concentration was maintained at >15 ng/mL over 4 h. Moreover, the deconvolution analyses demonstrated that a prolonged high absorption rate could be achieved in vivo best with Tablet B/MC. Tablet B/MC improved the pharmacokinetic profile in comparison with Tablet A1 and the solution dosage form. The RD-HCl buccal tablets with AL, LC and MC as excipients are suggested to be possibly useful for the treatment of premature labor., (Copyright © 2014 Elsevier B.V. All rights reserved.)

The fast, visual discrimination of β2-agonist drugs is needed for the on-site screening of various types of β2-agonists in blood and urine samples. We developed a simple, rapid, one-step colorimetric method to detect phenolic β2-agonists by use of a tyrosinase catalytic reaction, which involved the oxidation of the phenol group on the benzene rings of β2-agonists. The enzymatic oxidation products of β2-agonists with phenolic groups exhibited different color transitions based on the different substituent groups on the aromatic ring, whereas β2-agonists with the aniline group or the resorcinol group remained colorless. This visual color discrepancy has been used to intuitively and conveniently differentiate the phenolic group β2-agonists, such as ractopamine, isoxsuprine, ritodrine, and fenoterol. The oxidation products of these compounds have been identified using mass spectrometry, and the possible reaction mechanisms between β2-agonists and tyrosinase have been deduced. The parameters that govern the analytical performance of the reaction product, including the pH of the buffer solution, the concentration of tyrosinase, and the incubation time, have been studied and optimized using ultraviolet-visible (UV-vis) spectroscopy and electrochemical methods. Under the optimal experimental conditions, the absorbance intensity and electrochemical signal were found to increase proportionally to the concentrations of the phenolic group β2-agonists, which gave a quantitative description of the β2-agonists in solution.

Purpose: In healthy individuals upwards of 90 % of an injected dose of terbutaline is excreted in the urine. The purpose of this study is to determine the pharmacokinetic properties of terbutaline in patients with severe renal impairment as defined by a glomerular filtration rate (GFR) below 30 mL/min., Methods: Ten patients were included in the study. GFR was measured with Cr-EDTA clearance. They were given an intravenous injection of 0.500 mg of terbutaline. Blood samples were collected at intervals for 60 h and urine samples were collected for 96 h. The concentration of terbutaline in the blood and in the urine was used to calculate pharmacokinetic parameters., Results: In patients with normal renal function the total clearance of terbutaline is 2.23-3 mL/min/kg. In our population the total clearance of terbutaline was found to be 1.72 (SD: 0.49) mL/min/kg of which approximately 15 % (0.25 mL/min/kg) was renal clearance. We calculated a distribution volume at steady state of 0.74 (SD: 0.22) L/kg with a terminal half-life of 7.93 (SD: 4.06) hours. The mean residence time (MRT) was 8.35 (SD: 4.93) hours., Conclusions: In healthy individuals the excretion of terbutaline is foremost renal but this study shows that severe renal impairment does not lower the total clearance of terbutaline to a degree that might be expected from the Cr-EDTA clearance. However, more research is needed to determine if dosage adjustment is warranted in patients with CKD.

Background: Although ritodrine (RD)-hydrochloride (HCl), named RD-HCl, is widely used in the treatment of premature labor by intravenous prolonged infusion or frequent oral dosing of tablets, those administrations often lower patients' quality of life (QOL) or cause undesirable side effects, such as tachycardia; therefore, in this study, the potential usefulness of buccal administration as a novel administration method was examined in vivo., Method: First, the HPLC method was assessed for the determination of plasma RD concentration. Then, after RD-HCl solution in saline was administered intravenously (1 mg/kg), intragastrically (10 mg/kg) or buccally (10 mg/kg) in rats, the plasma concentration-time profiles were investigated, and the absorption extent and rate compared., Results: The present modified determination method by HPLC with fluorescence detection (Ex. 278 nm, Em. 306 nm) was suitable to analyze the plasma level at 8-200 ng/mL. Buccal administration gave the best plasma concentration-time profile for maintenance of an effective plasma level and fewer side effects. Absorption rates calculated by deconvolution also supported better sustained absorption in buccal dosing., Conclusion: Buccal application of RD-HCl was demonstrated to be a potentially useful dosing method in the treatment of premature labor with RD-HCl.

Background and Objectives: PF-00610355 is an orally inhaled long-acting β2-adrenoreceptor agonist that is being developed for the once-daily treatment of chronic obstructive pulmonary disease (COPD). The pharmacological effect is exerted in the lungs. However, systemic exposure of PF-00610355 is expected to be responsible for certain drug-related adverse effects. This analysis characterizes PF-00610355 using an integrated analysis of systemic exposure, across trials and patient populations., Methods: A total of 6,107 samples of PF-00610355 plasma concentration, collected in 264 subjects from eight studies in healthy volunteers, asthma, and COPD patients, were analyzed using non-linear mixed-effects models. Model-based mean (95 % CI) exposure profiles for a range of PF-00610355 doses in COPD patients were simulated., Results: PF-00610355 exposure profiles were described by a three-compartment disposition model with first-order absorption through a transit compartment. Patient status, inhalation device, and demographic factors were found to influence systemic drug exposure. Relative fine particle dose had a minor effect, whereas no effect of baseline lung function on the systemic exposure was found. An implicit method to address pharmacokinetic variability between occasions of drug intake yielded similar results as the established explicit method, yet in a much more efficient way., Conclusion: The estimated systemic pre-dose and maximum PF-00610355 plasma concentration was 23 and 38 % in COPD patients compared to healthy volunteers, respectively. The analysis illustrated the value of an integrated pharmacokinetic analysis to address specific challenges in the clinical development of long-/ultra-long-acting β2-agonists and inhaled compounds in general, both in relation to selecting a safe starting dose in patients, but also in understanding exposure and systemic safety information across different patient populations and different inhalation devices/formulations.

Introduction: We examined urinary and serum concentrations of formoterol in asthmatic and healthy individuals after a single dose of 18 μg inhaled formoterol and after repeated inhaled doses in healthy individuals. Results were evaluated using the World Anti-Doping Agency (WADA) 2012 threshold for formoterol., Methods: On the day of this open-label, crossover study, 10 asthmatic subjects who regularly used beta2-agonists and 10 healthy participants with no previous use of beta2-agonists received a single dose of 18 μg formoterol. Further, 10 nonasthmatic participants inhaled 18 μg formoterol every second hour until obtaining a total of 72 μg, which is twice the maximum daily dose (36 μg formoterol) permitted by the WADA. Blood samples were collected at baseline, 30 min, 1, 2, 3, 4, and 6 h after the first inhalation. Urine samples were collected at baseline, 0-4, 4-8, and 8-12 h after the first inhalation., Results: Median urine concentration, corrected for specific gravity, after the single-dose administration peaked during 0-4 h after inhalation at a maximum of 7.4 ng·mL(-1) in asthmatic subjects and 7.9 ng·mL(-1) in healthy subjects. Median urine concentration after repeated doses peaked during 4-8 h after inhalation of a total of 72 μg formoterol at a maximum of 16.8 ng·mL(-1) in healthy participants. The maximum individual concentration of 25.6 ng·mL(-1) was found after inhalation of a total of 72 μg formoterol., Conclusions: We found no significant differences in urinary and serum concentrations of formoterol between asthmatic and healthy subjects. We found high interindividual variability in the concentrations in all groups. Our data support the WADA 2012 urinary threshold of 30 ng·mL(-1) formoterol as being an adverse analytical finding.

Background: The combination of umeclidinium (UMEC), a long-acting muscarinic receptor antagonist, and vilanterol (VI), a selective long-acting β₂ agonist, is in development for the treatment of chronic obstructive pulmonary disease (COPD). This study evaluated the pharmacokinetics, safety and tolerability, and pharmacodynamics of once-daily, inhaled UMEC and UMEC/VI when co-administered with oral verapamil, a moderate P-glycoprotein transporter and moderate cytochrome P450 3A4 (CYP3A4) inhibitor frequently used by patients with COPD and cardiovascular comorbidities., Methods: Subjects were randomized to one of two 13-day treatment regimens: UMEC 500 μg or UMEC 500 μg/VI 25 μg. All subjects received a single tablet containing 240 mg verapamil on each of days 9-13., Results: Repeat doses of UMEC and UMEC/VI in combination with and without verapamil were safe and well tolerated. There was no increase in systemic exposure of UMEC when administered in combination with VI compared to UMEC alone. UMEC maximum concentration was similar with or without verapamil; a moderate increase in UMEC area under the curve (approximately 1.4-fold) was observed with verapamil. Verapamil did not increase systemic exposure to VI following administration of the UMEC/VI combination., Conclusion: Administration of UMEC and UMEC/VI combination was well tolerated and did not show clinically relevant increases in systemic exposure for either drug. The UMEC/VI combination is unlikely to have a clinically meaningful drug-drug interaction with moderate P-glycoprotein transporter and CYP3A4 inhibitor drugs.

The metabolism, pharmacokinetics, and excretion of [(14)C]indacaterol were investigated in healthy male subjects. Although indacaterol is administered to patients via inhalation, the dose in this study was administered orally. This was done to avoid the complications and concerns associated with the administration of a radiolabeled compound via the inhalation route. The submilligram doses administered in this study made metabolite identification and structural elucidation by mass spectrometry especially challenging. In serum, the mean t(max), C(max), and AUC(0-last) values were 1.75 h, 0.47 ng/ml, and 1.81 ng · h/ml for indacaterol and 2.5 h, 1.4 ngEq/ml, and 27.2 ngEq · h/ml for total radioactivity. Unmodified indacaterol was the most abundant drug-related compound in the serum, contributing 30% to the total radioactivity in the AUC(0-24h) pools, whereas monohydroxylated indacaterol (P26.9), the glucuronide conjugate of P26.9 (P19), and the 8-O-glucuronide conjugate of indacaterol (P37) were the most abundant metabolites, with each contributing 4 to 13%. In addition, the N-glucuronide (2-amino) conjugate (P37.7) and two metabolites (P38.2 and P39) that resulted from the cleavage about the aminoethanol group linking the hydroxyquinolinone and diethylindane moieties had a combined contribution of 12.5%. For all four subjects in the study, ≥90% of the radioactivity dose was recovered in the excreta (85% in feces and 10% in urine, mean values). In feces, unmodified indacaterol and metabolite P26.9 were the most abundant drug-related compounds (54 and 17% of the dose, respectively). In urine, unmodified indacaterol accounted for ∼0.3% of the dose, with no single metabolite accounting for >1.3%.

Objective: Data on pharmacokinetics of inhaled and oral salbutamol in elite athletes with asthma are needed to differentiate between therapeutic use and doping in doping control., Design: An interventional open-label crossover., Setting: Respiratory Research Unit, Copenhagen University Hospital, Bispebjerg., Participants: Eight elite athletes with asthma and 10 nonasthmatic subjects aged 18 to 33 years., Intervention: Administration of 0.8 mg of inhaled salbutamol and 8 mg of oral salbutamol separated by 14 days., Main Outcome Measures: Urine concentration of free salbutamol., Results: Maximum urine concentrations peaked in the period of 0 to 4 hours after the administration of inhaled and oral salbutamol in both groups. Median concentrations after inhaled salbutamol and oral salbutamol were 401.6 and 2108.1 ng/mL in healthy subjects and 334.9 and 2975.2 ng/mL in elite athletes with asthma. There were no significant statistical differences between the groups. One sample exceeded the World Anti-Doping Agency threshold value of 1000 ng/mL with a urinary salbutamol concentration of 1057 ng/mL 4 hours after inhalation, when no correction for urine specific gravity was done. When this sample was corrected for urine specific gravity, the result was 661 ng/mL., Conclusions: We found no significant difference in pharmacokinetic profile of inhaled and oral salbutamol between elite athletes with asthma and nonasthmatic subjects. Our results indicate that urine salbutamol concentrations should be corrected for urine specific gravity when evaluating doping cases.