Search

Gian Maria Pacifici Medical School, Department of Translational Research and New Technologies in Medicine and Surgery, Section of Pharmacology, University of Pisa, Pisa, Italy Objective: The objective of this study was to evaluate the extent of renal adverse effects caused by ibuprofen or indomethacin in order to choose the safer drug to administer to preterm infants. Methods: The following three parameters of renal function were taken into consideration: 1) the urine output; 2) the serum creatinine concentration; and 3) the frequency of oliguria. The bibliographic search was performed using PubMed and Embase databases as search engines. Results: Urine output ranged from 3.5±1.2 to 4.0±1.4 mL/kg/h after ibuprofen treatment, and from 2.8±1.1 to 3.6±1.4 mL/kg/h after indomethacin treatment. The values for ibuprofen are significantly (P

The binding of frusemide was studied in the plasma of 20 healthy subjects and 45 patients with liver disease. The unbound percentage (mean +/- s.d.) of frusemide was 1.64 +/- 0.21 healthy subjects) and 2.24 +/- 0.79 (patients) (P less than 0.01). By grouping the patients on the basis of plasma albuminaemia and bilirubinaemia four clusters namely: 'normal concentrations of albumin and bilirubin' (A), 'hyperbilirubinaemia and normal albumin concentration' (B), 'hypoalbuminaemia and normal bilirubin concentration' (C) and 'hypoalbuminaemia and hyperbilirubinaemia' (D) were defined. The unbound percentage of frusemide was 1.80 +/- 0.36 in (A); 2.44 +/- 1.05 in (B); 2.23 +/- 0.38 in (C); 2.76 +/- 0.77 in (D). The figure for healthy volunteers was not different from A, whereas it was significantly lower than those for B and D (P less than 0.01) and for C (P less than 0.05). A lowered binding of frusemide was associated with hypoalbuminaemia or hyperbilirubinaemia. [ABSTRACT FROM AUTHOR]

The effect of antipileptic drug valpromide (VPM) on the activity of epoxide hydrolase was studied in human adult and foetal liver, kidneys, lungs, intestine and in placenta. The activity of the epoxide hydrolase was measured with both styrene oxide and benzo(a)pyrene-4,5-oxide as substrates. VPM inhibited the epoxide hydrolase obtained from all organs studied. The degree of inhibition was independent of the substrate used. A lowering of the epoxide hydrolase activity by 50% was observed when the concentration of VPM was similar to that of the substrates. VPM competitively inhibited the activity of adult liver epoxide hydrolase with styrene oxide as substrate. [ABSTRACT FROM AUTHOR]

Morphine is an agonist of the µ and k receptors, whose activation results in analgesia. Morphine-like agonists act through the µ opioid receptors to cause pain relief, sedation, euphoria and respiratory depression. Morphine is glucuronidated and sulfated at positions 3 and 6; the plasma concentration ratios correlate positively with birth weight, which probably reflects increased liver weight with increasing birth weight. Moreover, morphine clearance correlates positively with gestational age and birth weight. Steady-state morphine plasma concentrations are achieved after 24-48 hours of infusion, but the glucuronide metabolite plasma concentrations do not reach steady state before 60 hours. The morphine-3-glucuronide metabolite has lower clearance, a shorter half-life and a smaller distribution volume compared with the morphine-6 metabolite, which is the most active morphine-like agonist. Ordinary doses cause constipation, urinary retention and respiratory depression. Neonatal pain relief may require a blood level of approximately 120 ng/ml, whereas lower levels (20-40 ng/ml) seem adequate for children. A bibliographic search was performed using the PubMed database and the keywords "morphine metabolism neonate" and "morphine pharmacokinetics neonate". The initial and final cutoff points were January 1990 and September 2015, respectively. The results indicate that morphine is extensively glucuronidated and sulfated at positions 3 and 6, and that the glucuronidation rate is lower in younger neonates compared with older infants. Although much is known about morphine in neonates, further research will be required to ensure that recommended therapeutic doses for analgesia in neonates are evidence based.

Phenobarbital is an effective and safe anticonvulsant drug introduced in clinical use in 1904. Its mechanism of action is the synaptic inhibition through an action on GABAA. The loading dose of phenobarbital is 20 mg/kg intravenously and the maintenance dose is 3 to 4 mg/kg by mouth. The serum concentration of phenobarbital is up to 40 µg/ml. Nonresponders should receive additional doses of 5 to 10 mg/kg until seizures stop. Infants with refractory seizures may have a serum concentration of phenobarbital of 100 µg/ml. Phenobarbital is metabolized in the liver by CYP2C9 with minor metabolism by CYP2C19 and CYP2E1. A quarter of the dose of phenobarbital is excreted unchanged in the urine. In adults, the half-life of phenobarbital is 100 hours and in term and preterm infants is 103 and 141 hours, respectively. The half-life of phenobarbital decreases 4.6 hours per day and it is 67 hours in infants 4 week old.

Fentanyl is a synthetic opioid that is very important in anesthetic practice because of its relatively short time to peak analgesic effect and the rapid termination of action after small bolus doses. The objective of this survey is to review the clinical pharmacology of fentanyl in preterm infants. The bibliographic search was performed using PubMed and EMBASE databases as search engines. In addition, the books Neofax: A manual of drugs used in neonatal care and Neonatal formulary were consulted. Fentanyl is N-dealkylated by CYP3A4 into the inactive norfentanyl. Fentanyl may be administered as bolus doses or as a continuous infusion. In neonates, there is a remarkable interindividual variability in the kinetic parameters. In neonates, fentanyl half-life ranges from 317 minutes to 1266 minutes and in adults it is 222 minutes. Respiratory depression occurs when fentanyl doses are >5 μg/kg. Chest wall rigidity may occur in neonates and occasionally is associated with laryngospasm. Tolerance to fentanyl may develop after prolonged use of this drug. Significant withdrawal symptoms have been reported in infants treated with continuous infusion for 5 days or longer. Fentanyl is an extremely potent analgesic and is the opioid analgesic most frequently used in the neonatal intensive care unit., (Copyright © 2014. Published by Elsevier B.V.)

Paracetamol is commonly used to control mild-to-moderate pain or to reduce opioid exposure as part of multimodal analgesia, and is the only compound recommended to treat fever in neonates. Paracetamol clearance is lower in neonates than in children and adults. After metabolic conversion, paracetamol is subsequently eliminated by the renal route. The main metabolic conversions are conjugation with glucuronic acid and with sulphate. In the urine of neonates sulphated paracetamol concentration is higher than the glucuronidated paracetamol level, suggesting that sulfation prevails over glucuronidation in neonates. A loading dose of 20 mg/kg followed by 10 mg/kg every 6 hours of intravenous paracetamol is suggested to achieve a compartment concentration of 11 mg/L in late preterm and term neonates. Aiming for the same target concentration, oral doses are similar with rectal administration of 25 to 30 mg/kg/d in preterm neonates of 30 weeks' gestation, 45 mg/kg/d in preterm infants of 34 weeks' gestation, and 60 mg/kg/d in term neonates are suggested. The above-mentioned paracetamol doses for these indications (pain, fever) are well tolerated in neonates, but do not result in a significant increase in liver enzymes, and do not affect blood pressure and have limited effects on heart rate. In contrast, the higher doses suggested in extreme preterm neonates to induce closure of the patent ductus arteriosus have not yet been sufficiently evaluated regarding efficacy or safety. Moreover, focussed pharmacovigilance to explore the potential causal association between paracetamol exposure during perinatal life and infancy and subsequent atopy is warranted.

Carbapenems are an effective tool to treat complicated bacterial infections. This review aims to summarize the available information on carbapenems in neonates to guide clinicians on drug choice and indications in neonates. Moreover, identification of knowledge gaps may stimulate researchers to design studies to further improve pharmacotherapy in neonates. To do so, a bibliographic search [infant/newborn and meropenem, imipenem, panipenem, ertapenem, doripenem or imipenem] was performed (PubMed, EMBASE) and public clinical trial registries (clinicaltrials.gov, EU registry) were searched to summarize the available information. Carbapenem clearance in neonates is low. Variability relates to maturation (weight, age) and renal function (creatinine clearance), while observations in neonates with renal failure are absent. Pharmacodynamics are almost exclusively limited to meropenem, and the available information will further increase (NeoMero-1-2, necrotizing enterocolitis, meningitis). Finally, there are also some ongoing doripenem pharmacokinetics (PK) studies in neonates. It was concluded that observations on carbapenems in neonates are limited, but studies (NeoMero, doripenem) are ongoing. Until this information becomes available, off label prescription of meropenem seems to be the most reasonable choice when a carbapenem is appropriate. Knowledge gaps relate to PK in neonates with renal failure and to the potential benefit of prolonged compared to short duration of infusion.

Midazolam is a benzodiazepine with rapid onset of action and short duration of effect. In healthy neonates the half-life (t 1/2) and the clearance (Cl) are 3.3-fold longer and 3.7-fold smaller, respectively, than in adults. The volume of distribution (Vd) is 1.1 L/kg both in neonates and adults. Midazolam is hydroxylated by CYP3A4 and CYP3A5; the activities of these enzymes surge in the liver in the first weeks of life and thus the metabolic rate of midazolam is lower in neonates than in adults. Midazolam acts as a sedative, as an antiepileptic, for those infants who are refractory to standard antiepileptic therapy, and as an anaesthetic. Information of midazolam as an anaesthetic in infants are very little. Midazolam is usually administered intravenously; when minimal sedation is required, intranasal administration of midazolam is employed. Disease affects the pharmacokinetics of midazolam in neonates; multiple organ failure reduces the Cl of midazolam and mechanical ventilation prolongs the t 1/2 of this drug. ECMO therapy increases t 1/2, Cl, and Vd of midazolam several times. The adverse effects of midazolam in neonates are scarce: pain, tenderness, and thrombophlebitis may occur. Respiratory depression and hypotension appear in a limited percentage of infants following intravenous infusion of midazolam. In conclusion, midazolam is a safe and effective drug which is employed as a sedative, as antiepileptic agent, for infants who are refractory to standard antiepileptic therapy, and as an anaesthetic.

Background: Ibuprofen and indomethacin are potent non-selective cyclo-oxygenase inhibitors and inhibit prostaglandin E2 synthesis. The patent ductus arteriosus (PDA) occurs in more than 70% of preterm infants weighing <1500 g. Prostaglandin E2 relaxes smooth muscle, tends to inhibit the closure of PDA, yields vasodilatation of the afferent renal arterioles and maintains glomerular filtration rate (GFR). Ibuprofen and indomethacin inhibiting prostaglandin E2 synthesis close PDA and reduce GFR with consequent decrease of urine output and increase of serum creatinine concentrations., Aims: The aims of this study are to give the definitive estimates of PDA closure rate following ibuprofen or indomethacin treatment and to evaluate the extent of renal side effects following the administration of these drugs to preterm infants. Other aims are to review the metabolism and the pharmacokinetics of ibuprofen and indomethacin in preterm infants with PDA., Methods: The bibliographic search was performed using PubMed and EMBASE databases as search engines, January 2013 was the cutoff point., Results: The %PDA closed by ibuprofen (n=24) and indomethacin (n=24) is 77.7±14.1 and 77.3±11.0, respectively. For ibuprofen, the gestational age of the infants included in the study ranged from 25.0 to 39.0 weeks (mean±SD=29.3±3.1 weeks). The %PDA did not correlate with the gestational age (p=0.2516). For indomethacin, the gestational age of infants included in the study ranged from 25.0 and 39.0 weeks (mean±SD=29.4±2.9 weeks). The %PDA did not correlate with the gestational age (p=0.3742). The treatment with ibuprofen reduces the urine output and increases the serum creatinine concentrations less extensively than indomethacin. The half-life (t1/2) of ibuprofen and indomethacin is lengthened and the clearance is reduced in preterm infants as compared with fullterm infants., Conclusions: Ibuprofen and indomethacin are equally effective in closing PDA. Treatment with ibuprofen decreases the risk of renal failure. Ibuprofen has the most favourable risk/benefit ratio. The rate of metabolism is reduced and t1/2 is lengthened in prematures as compared with term infants.

Recurrent apnea is common in preterm infants with consequent episodes of loss of effective breathing and the bronchodilator theophylline prevents apnea and reduces the number of apneic attacks. This drug also reduces hypoxaemic episodes. Theophylline acts on the lungs, kidneys and brain. Theophylline inhibits solute reabsorption in various segments of the nephron and a marked diuresis which occurs immediately after the administration of theophylline. This drug ameliorates kidney dysfunction and prophylaxis given early after birth, preventing vasomotor nephropathy. Theophylline reduces brain activity and reduces the spontaneous activity transients and alters the sleep-wake state in pre-term infants. Theophylline is extensively metabolized in premature infants and its major metabolic product is caffeine. The demethylation pathway occurring predominantly in adults is substituted by N-methylation to caffeine in premature infants. The halflife of theophylline is 5-fold longer in neonates than in adults and reaches the adult value at the age of 55 weeks. Theophylline may be administered trans-cutaneously by applying this drug to the back or abdomen of the infants and the mean fractional absorbance at 30 hours is 0.25. Theophylline is present in saliva and the concentration of this drug in saliva is similar to that in plasma, saliva may be used to monitor theophylline concentration. In conclusion, theophylline is a useful drug to treat apnea and ameliorate kidney dysfunction.

Indomethacin is a non-steroidal anti-inflammatory drug that is a potent inhibitor of prostaglandin E(2) synthesis. After birth, the ductus arteriosus closes spontaneously within 2-4 days in term infants. The major factor closing the ductus arteriosus is the tension of oxygen, which increases significantly after birth. Prostaglandin E(2) has the opposite effect to that of oxygen; it relaxes smooth muscle and tends to inhibit the closure of the ductus arteriosus. In preterm infants with respiratory distress syndrome, the ductus arteriosus fails to close (patent ductus arteriosus [PDA]) because the concentration of prostaglandin E2 is relatively high. PDA occurs in more than 70 % of neonates weighing less than 1,500 g at birth. The aim of this article was to review the published data on the clinical pharmacology of indomethacin in preterm infants in order to provide a critical analysis of the literature and a useful tool for physicians. The bibliographic search was performed electronically using the PubMed and EMBASE databases as search engines and February 2012 was the cutoff point. A remarkable interindividual variability was observed for the half-life (t(½)), clearance (CL), and volume of distribution (V(d)) of indomethacin. Prophylactic indomethacin consists of a continuous infusion of low levels of indomethacin and may be useful in preterm infants. Extremely preterm infants are less likely to respond to indomethacin. Infants with a postnatal age of 2 months do not respond to treatment with indomethacin. Indomethacin has several adverse effects, the most common of which is renal failure. An increase in serum creatinine of ≥0.5 % mg/dL after indomethacin was observed in about 10-15 % of the patients and creatinine returns to a normal level about 1 week after cessation of therapy. Indomethacin should be administered intravenously by syringe pump for at least 30 min to minimize adverse effects on cerebral, gastrointestinal, and renal blood flow velocities. A prolonged course of indomethacin appears to reduce the risk of severe intracranial hemorrhage and renal impairment in patients with PDA. In conclusion, indomethacin is a useful drug to treat PDA.

Furosemide is the diuretic most used in newborn infants. It blocks the Na+-K+-2Cl- symporter in the thick ascending limb of the loop of Henle increasing urinary excretion of Na+ and Cl-. This article aimed to review the published data on the clinical pharmacology of furosemide in neonates to provide a critical, comprehensive, authoritative and, updated survey on the metabolism, pharmacokinetics, pharmacodynamics and side-effects of furosemide in neonates. The bibliographic search was performed using PubMed and EMBASE databases as search engines; January 2013 was the cutoff point. Furosemide half-life (t1/2) is 6 to 20-fold longer, clearance (Cl) is 1.2 to 14-fold smaller and volume of distribution (Vd) is 1.3 to 6-fold larger than the adult values. t1/2 shortens and Cl increases as the neonatal maturation proceeds. Continuous intravenous infusion of furosemide yields more controlled diuresis than the intermittent intravenous infusion. Furosemide may be administered by inhalation to infants with chronic lung disease to improve pulmonary mechanics. Furosemide stimulates prostaglandin E2 synthesis, a potent dilator of the patent ductus arteriosus, and the administration of furosemide to any preterm infants should be carefully weighed against the risk of precipitation of a symptomatic patent ductus arteriosus. Infants with low birthweight treated with chronic furosemide are at risk for the development of intra-renal calcifications.

The loop diuretics furosemide and bumetanide are used widely for the management of fluid overload in both acute and chronic disease states. To date, most pharmacokinetic studies in neonates have been conducted with furosemide and little is known about bumetanide. The aim of this article was to review the published data on the pharmacology of furosemide and bumetanide in neonates and infants in order to provide a critical analysis of the literature, and a useful tool for physicians. The bibliographic search was performed electronically using PubMed and EMBASE databases as search engines and March 2011 was the cutoff point. The half-life (t(½)) of both furosemide and bumetanide is considerably longer in neonates than in adults and consequently the clearance (CL) of these drugs is reduced at birth. In healthy volunteers, plasma t(½) of furosemide ranges from 33 to 100 minutes, whereas in neonates it ranges from 8 to 27 hours. The volume of distribution (V(d)) of furosemide undergoes little variation during neonate maturation. The dose of furosemide, administered by intermittent intravenous infusion, is 1 mg/kg and may increase to a maximum of 2 mg/kg every 24 hours in premature infants and every 12 hours in full-term infants. Comparison of continuous infusion versus intermittent infusion of furosemide showed that the diuresis is more controlled with fewer hemodynamic and electrolytic variations during continuous infusion. The appropriate infusion rate of furosemide ranges from 0.1 to 0.2 mg/kg/h and when the diuresis is <1 mL/kg/h the infusion rate may be increased to 0.4 mg/kg/h. Treatment with theophylline before administration of furosemide results in a significant increase of urine flow rate. Bumetanide is more potent than furosemide and its dose after intermittent intravenous infusion ranges from 0.005 to 0.1 mg/kg every 24 hours. The t(½) of bumetanide in neonates ranges from 1.74 to 7.0 hours. Up to now, no data are available on the continuous infusion of bumetanide. Extracorporeal membrane oxygenation (ECMO) is used for a variety of indications including sepsis, persistent pulmonary hypertension, meconium aspiration syndrome, cardiac defects and congenital diaphragmatic hernia. There are two studies of furosemide in neonates undergoing ECMO and only one on the pharmacokinetics of bumetanide under ECMO. When ECMO was conducted for 72 hours, the total amount of furosemide administered was 7.0 mg/kg, and the urine production in the 3 days of treatment was about 6 mL/kg/h, which is the target value. The t(½) of bumetanide in neonates during ECMO was extremely variable. CL, t(½), and V(d) were 0.63 mL/min/kg, 13.2 hours, and 0.45 L/kg, respectively. Furosemide may be administered by inhalation and inhibits the bronco-constrictive effect of exercise, cold air ventilation and antigen challenge. However, inhaled furosemide is not active in infants with viral bronchiolitis and its effect on broncho-pulmonary dysplasia is still uncertain. Furosemide does not significantly increase the risk of failure of patent ductus arteriosus closure when indomethacin or ibuprofen have been co-administered. Infants with low birth weight treated long-term with furosemide are at risk for the development of intra-renal calcification. Furosemide therapy above 10 mg/kg bodyweight cumulative dose had a 48-fold increased risk of nephrocalcinosis. The use of furosemide in combination with indomethacin increased the incidence of acute renal failure. The maturation of the kidney governs the pharmacokinetics of furosemide and bumetanide in the infant. CL and t(½) are influenced by development, and this must be taken into consideration when planning a dosage regimen with these drugs.

Neonatal sepsis is common and is a major cause of morbidity and mortality. Vancomycin is the preferred treatment of several neonatal staphylococcal infections. The aim of this study was to review published data on vancomycin pharmacokinetics in neonates and to provide a critical analysis of the literature. A bibliographic search was performed using PubMed and Embase, and articles with a publication date of August 2011 or earlier were included in the analysis. Vancomycin pharmacokinetic estimates, which are different in neonates compared with adults, also exhibit extensive inter-neonatal variability. In neonates, several vancomycin dosing schedules have been proposed, mainly based on age (i.e., postmenstrual and postnatal), body weight or serum creatinine level. Other covariates [e.g., extracorporeal membrane oxygenation (ECMO), indomethacin or ibuprofen, and growth restriction] of vancomycin pharmacokinetics have been reported in neonates. Finally, vancomycin penetrates cerebrospinal fluid (range = 7-42%). Renal function drives vancomycin pharmacokinetics. Because either age or weight is the most relevant covariate of renal maturation, these covariates should be considered first in neonatal vancomycin dosing guidelines and further adjusted by renal dysfunction indicators (e.g., ECMO and ibuprofen/indomethacin). In addition to the prospective validation of available dosing guidelines, future studies should focus on the relevance of therapeutic drug monitoring and on the value of continuous vancomycin administration in neonates.

The aim of this work was to review the published data on the pharmacokinetics of cephalosporins in neonates to provide a critical analysis of the literature as a useful tool for physicians. The bibliographic search was performed for articles published up to December 3, 2010, using PubMed. In addition, the book Neofax: A Manual of Drugs Used in Neonatal Care by Young and Mangum was consulted. The cephalosporins are mainly eliminated by the kidneys, and their elimination rates are reduced at birth. As a consequence, clearance is reduced and t1/2 is more prolonged in the neonate than in more mature infants. The neonate's substantial body water content creates a large volume of distribution (Vd) of cephalosporins, as these drugs are fairly water soluble. Postnatal development is an important factor in the maturation of the neonate, and as postnatal age proceeds, the clearance of cephalosporins increases. The maturation of the kidney governs the pharmacokinetics of cephalosporins in the infant. Clearance and t1/2 are influenced by development, and this must be taken into consideration when planning a cephalosporin dosage regimen for the neonate.

Bacterial infections are common in the neonates and are a major cause of morbidity and mortality. Sixty percent of preterm infants admitted to neonatal intensive care units received at least one antibiotic during the first week of life. Penicillins, aminoglycosides and cephalosporins comprised 53, 43 and 16%, respectively. Kinetic parameters such as the half-life (t 1/2 ), clearance (Cl), and volume of distribution (Vd) change with development, so the kinetics of penicillins, cephalosporins and aminoglycosides need to be studied in order to optimise therapy with these drugs. The aim of this study is to review the pharmacokinetics of penicillins, cephalosporins and aminoglycosides in the neonate in a single article in order to provide a critical analysis of the literature and thus provide a useful tool in the hands of physicians. The bibliographic search was performed electronically using PubMed, as the search engine, until February 2 nd , 2010. Medline search terms were as follows: pharmacokinetics AND (penicillins OR cephalosporins OR aminoglycosides) AND infant, newborn, limiting to humans. Penicillins, cephalosporins and aminoglycosides are fairly water soluble and are mainly eliminated by the kidneys. The maturation of the kidneys governs the pharmacokinetics of penicillins, cephalosporins and aminoglycosides in the neonate. The renal excretory function is reduced in preterms compared to term infants and Cl of these drugs is reduced in premature infants. Gestational and postnatal ages are important factors in the maturation of the neonate and, as these ages proceed, Cl of penicillins, cephalosporins and aminoglycosides increases. Cl and t 1/2 are influenced by development and this must be taken into consideration when planning a dosage regimen with these drugs. More pharmacokinetic studies are required to ensure that the dose recommended for the treatment of sepsis in the neonate is evidence based.

Background: Sepsis is common in neonates and is a major cause of morbidity and mortality. Sixty percent of preterm neonates receive at least one antibiotic, and 43% of the antibiotics administered to these neonates are aminoglycosides. The clearance (Cl), serum half-life (t(1/2)), and volume of distribution (Vd) of aminoglycosides change during the neonatal life, and the pharmacokinetics of aminoglycosides need to be studied in neonates in order to optimise therapy with these drugs., Objective: The aim of this work is to review the published data on the pharmacokinetics of aminoglycosides in order to provide a critical analysis of the literature that can be a useful tool in the hands of physicians., Methods: The bibliographic search was performed electronically using PubMed, as the search engine, through July 11th, 2008. Firstly, a Medline search was performed with the keywords "pharmacokinetics of aminoglycosides in neonates" with the limit of "human". Other Medline searches were performed with the keywords "pharmacokinetics of ... in neonates" followed by the name of the aminoglycosides: amikacin, gentamicin, netilmicin and tobramycin. In addition, the book Neofax: A Manual of Drugs Used in Neonatal Care by Young and Mangum (Thomson Healthcare, 2007) was consulted., Results: The aminoglycosides are mainly eliminated by the kidney, and their elimination rates are reduced at birth. As a consequence Cl is reduced and t(1/2) is prolonged in the neonate as compared to more mature infants. The high body-water content of the neonate results in a large Vd of aminoglycosides as these drugs are fairly water soluble. Postnatal development is an important factor in the maturation of the neonate, and as postnatal age proceeds, Cl of aminoglycosides increases., Conclusion: The maturation of the kidney governs the pharmacokinetics of aminoglycosides in the infant. Cl and t(1/2) are influenced by development, and this must be taken into consideration when planning a dosage regimen with aminoglycosides in the neonate. Aminoglycosides are fairly water soluble, and the larger water content of neonates yields a larger Vd in these patients.

Background: Sepsis is common in neonates and a major cause of morbidity and mortality. Sixty percent of preterm neonates receive at least one antibiotic during the first week of life, with penicillins being the most frequently administered antibiotics. The clearance (Cl), serum half-life (t((1/2))) and volume of distribution (Vd) of penicillins are different in the neonate than in the adult. As such, the pharmacokinetics of penicillins need be studied in neonates in order to optimise therapy in this age class with these drugs., Objectives: The aim of this study was to review the published data on the pharmacokinetics of penicillins in the neonate in order to provide a critical analysis of the literature and, consequently, a useful tool in the hands of the physician., Methods: The bibliographic search was performed electronically using the PubMed and EMBASE databases as search engines. An initial search was performed with the keywords "pharmacokinetics", "penicillins" and "neonates". Secondly, other searches were performed using the keywords "pharmacokinetics" and "neonates", followed by the name of a single antibiotic. The search included articles up to 2007., Results: There have been few pharmacokinetic studies on the use of penicillins in neonates. The results from those few studies that have been carried out suggest that the Cl is reduced and t((1/2)) prolonged in the neonate as compared with the more mature infant. There is little variation in Vd during the first week of life. In the premature neonate, Cl is reduced compared to the full-term infant. As postnatal age proceeds, the Cl of penicillins increases., Conclusions: More pharmacokinetic studies are required to provide a sound scientific basis for planning a dosage regimen with penicillins in the neonate.

Background: About 1000 neonates with HIV infection are born every day worldwide. The antiviral therapy for newborn infants is a real necessity. Pharmacokinetics is an important contribution to therapy and no review has been published on the pharmacokinetics of antivirals in neonates up to now., Aims: This article provides a review on the pharmacokinetics of antivirals in the neonate. The pharmacokinetic parameters in the neonate are compared with those of the adult, and when possible, the pharmacokinetic parameters were compared in neonates of different ages., Results: Zidovudine is the antiviral with the largest amount of information on its pharmacokinetics. The clearance (Cl; l/h/kg) of zidovudine is 0.15 (premature), 0.34 (1 day), 0.69 (7 days), 0.65 (< or =14 days), 1.14 (>14 days) and 1.56 (adult). t(1/2) (h) of zidovudine is 7.2 (premature), 4.2 (1 day), 4.0 (7 days), 3.1 (< or =14 days), 1.9 (>14 days) and 1.1 (adult). Zidovudine is mainly eliminated by conjugation with glucuronic acid and glucuronosyl transferase develops postnatally. Cl of lamivudine is 0.19 (1 day), 0.32 (7 days) and 0.30 (adult) and the Cl (l/h/m2) of didanosine is 65 (1 day) and 271 (7 days). A greater volume of distribution (Vd) has been observed in the neonate compared with the adult for nelfinavir, nevirapine and pleconaril., Conclusions: The pharmacokinetic parameters of antivirals differ in the neonate and in the adult. The Cl is reduced and t(1/2) is increased in the neonate compared with the adult for zidovudine, lamivudine and ganciclovir. t(max) is generally greater in the neonate than in the adult due to reduced absorption rate in the neonate. The Vd of nelfinavir, nevirapine and pleconaril is greater in the newborn than in the adult. The neonate is a developing organism and the pharmacokinetic parameters of antivirals vary during the first weeks of life.

Background: Viruses cross the placenta and infect the fetus. Antivirals are administered to pregnant women to protect them and the fetus against the viruses. It is necessary to know which antivirals cross the placenta and reach the fetal circulation in pharmacologically significant concentrations in order to plan antiviral therapy., Aims: This article reviews the literature on the placental transfer of antivirals against HIV. The review considers also the placental transfer of acyclovir and ganciclovir, which are used against the herpes simplex virus and the cytomegalovirus, respectively., Study Design: Firstly, a medline was performed with the following key words "placental transfer of antivirals". Secondly, a medline was performed with the key words "placenta transfer of..." followed by the name of a single antiviral and it was repeated for 20 antivirals. Thirdly, another medline was performed using the following key words "pharmacokinetics of antiviral in newborn" in order to collect those articles which describe in vivo transfer of antivirals. The literature was critically read and a written note was produced., Results: The literature on the placental transfer of antivirals includes studies in vitro perfusing the human placenta and studies performed in vivo in which the cord and maternal antiviral plasma concentrations are compared. Both the results obtained in vitro and in vivo show that the protease inhibitors poorly transfer the placenta because of their great molecular weight. With the exception of didanosine, the nucleoside reverse transcriptase inhibitors and nelfinavir, a non-nucleoside reverse transcriptase inhibitor, cross the placenta and the cord, and maternal plasma concentrations equilibrate., Conclusions: In vitro and in vivo results are consistent with the view that the nucleoside reverse transcriptase inhibitors cross the human placenta and produce significant pharmacological concentrations in the fetal circulation. Nevirapine, the only studied non-nucleoside reverse transcriptase inhibitor, reach the equilibrium between the fetal and maternal concentration, whereas the protease inhibitors have a poor transfer across the human placenta.

Background: Sulfotransferase is an important enzyme family that catalyses the transfer of a sulfate group from a donor substrate, 3'-phosphoadenosine-5'-phosphosulphate (PAPS), to an acceptor substrate which may be a drug, a hormone or a neurotransmitter that possesses a hydroxy or an amine group. Drugs and hormones are sulfated in human fetal tissues but a review on this topic has not yet been published., Aims: The aim of this article is to review the literature on the sulfation of drugs and hormones in human fetus and, when possible, to compare the rate of sulfation in fetal and adult human tissues., Study Design: A medline search was performed by using the following key words: "fetal sulfotransferase" and "sulfotransferase in fetus" with the limit of "human". The literature was collected, critically read and a written note was produced., Subjects: The majority of studies were conducted with mid-gestation human fetuses and limited studies include younger and older fetuses., Results: The sulfation rate of dopamine (SULT1A3) was 3-fold higher in fetal than adult liver whereas the sulfation rate of 4-nitrophenol (SULT1A1) was one order of magnitude lower in fetal than adult liver. Ritodrine is sulfated at a higher rate in the fetal than adult liver. The sulfation rates of dopamine, 4-nitrophenol and ritodrine varied considerably in the fetal liver and did not correlate with the gestation age. 3,3'-T2 was sulfated in human placenta and the sulfation rate of 3,3'-T2 correlated with SULT1A1 activity. Dehydroepiandrosterone sulfotransferase activity is 6-fold higher in the fetal than adult adrenal., Discussion: Sulfotransferase activity develops early in the human fetal liver and is subjected to a remarkable interindividual variability. Because of this variability, the examined enzyme activities did not correlate with the gestation age. Hormones are extensively sulfated in human fetal liver and other tissues. Sulfated hormones may serve as circulating or intracellular stores from which the free hormone can be regenerated by the action of the sulfatases.

Human sulfotransferases catalyze sulfate conjugation and 2 polymorphic genes, SULT1A1 and SULT1A2 in this family of transferases have been identified, encoding for 2 isoenzymes with very similar properties and substrate specificities. In order to test the hypothesis that variability in sulfation is due to genetic polymorphism in SULT1A1, the sulfation rate of 4-nitrophenol, a diagnostic substrate, was measured in 50 human liver samples and the genotype at the SULT1A1 locus was analyzed. The rate of 4-nitrophenol sulfation varied from 473 - 1,405 pmol/min/mg between the 5th and 95th percentiles, with a median and a mean +/- SD of 757 and 807 +/- 292 pmol/min/mg, respectively. The activities detected among the SULT1A1*2/*2 homozygotes (5 cases) were significantly lower than those of the other 2 genotypes, SULTA1*11/*1 and SULT1A1*1/*2 (5 and 40 cases, respectively), whereas there was no significant difference found between the SULT1A1*1/*1 and SULT1A1*1/*2 genotypes. To evaluate the possible influence of SULT1A2 polymorphism, genotype assays were also performed for this locus. No SULT1A2*2/*2 carrier, 26 SULT1A2*1/*1 and 24 SULT1A2*1/*2 were detected in the population sample under study. However, no correlation between the rate of 4-nitrophenol sulfation and the SULT1A2 genotype was detected. These results confirm that the variation in the rate of 4-nitrophenol sulfation in human liver is mainly due to SULT1A. Since SULT1A1*1/*2 polymorphism accounts for no more than 10% of the phenotypic variation seen in this cohort, other factors must also contribute to the variability in the rate of 4-nitrophenol sulfation in human liver. However, on the basis of the data obtained, variations in age, gender and liver function as possible causative factors can be excluded. The IC50 of quercetin, a potent inhibitor of 4-nitrophenol sulfation, was measured in the liver samples and ranged from 4.6 to 17.3 nM between the 5th and 95th percentiles. The median and the mean +/- SD were 7.7 nM and 8.3 +/- 2.5 nM, respectively. There was a weak but significant correlation between the IC50 value and age of the liver donors (r = 0.283, p = 0.046). The observed variation did not correlate with the genotypes at the SULT1A1 and SULT1A2 loci.

Sulfotransferase catalyzes the transfer of sulfate, donated by 3'-phosphoadenosine-5'-phosphosulfate, to an acceptor substrate that may be a hydroxy group or an amine group. Man is exposed daily to drugs and dietary chemicals that can inhibit sulfotransferase activity. The aim of this study was to review the literature concerning the inhibition of sulfotransferases by drugs and dietary chemicals in the human liver and duodenum. The IC50 value of mefenamic acid for human liver phenol sulfotransferase (SULT 1A1) was 0.02 microM and for human liver catechol sulfotransferase (SULT1A3) 76 microM with a SULT 1A3/SULT1A1 ratio for the IC50 of 3,800. Mefenamic acid is therefore a potent and selective inhibitor of human liver SULT1A1. The IC50 values of mefenamic acid for the sulfation rates of (-)-salbutamol and (-)-apomorphine were 4 orders of magnitude greater in the human duodenum than in the liver. Salicylic acid inhibited the sulfation of (-)-apomorphine in human liver with an IC50 of 54 gM but did not inhibit the sulfation of (-)-apomorphine in human duodenum. Quercetin, a flavonoid present in edible fruit, vegetable and wine, was a potent inhibitor of human liver SULT1A1 and estrogen sulfotransferase (EST) activities and the sulfation of resveratrol. Quercetin inhibited the sulfation of dopamine, (-)-salbutamol, minoxidil and paracetamol and the IC50 values were 1 - 2 orders of magnitude greater in human duodenum than in the liver. In conclusion, mefenamic acid, salicylic acid and quercetin inhibit SULT1A1 whereas SULT1A3 is relatively resistant to the inhibition by these compounds. Under particular circumstances, human duodenum sulfotransferase is more resistant than liver sulfotransferase to the inhibition by mefenamic acid, salicylic acid and quercetin.

1. Curcumin has anti-carcinogen effects and is under clinical evaluation as a potential colon cancer chemopreventive agent. The first aim was to see whether curcumin inhibited phenol sulfotransferase (SULT1A1) and, if so, to study the variability of the IC(50) of curcumin for SULT1A1 in 50 human liver samples. For comparative purposes, the inhibition of catechol sulfotransferase (SULT1A3) in five human liver specimens was studied. The second aim was to measure the IC(50) of curcumin against SULT1A1 in five samples of human duodenum, colon, kidney and lung. 2. Curcumin was a potent inhibitor of SULT1A1 in human liver; the mean +/- SD and median of IC(50) were 14.1 +/- 7.3 nM and 12.8 nM, respectively. The IC(50) ranged from 6.2 to 30.6 nM between the 5th and 95th percentiles and the fold of variation was 4.9. The distribution of IC(50) was positively skewed (skewness 1.2) and deviated from normality (p = 0.0004). 3. Curcumin inhibited human SULT1A3, and the inhibition was studied in five liver specimens with an IC(50) of 4324 +/- 1026 nM. This inhibition was greater than the IC(50) of curcumin for SULT1A1 (p < 0.0001). 4. In the extrahepatic tissues, the IC(50) of curcumin for SULT1A1 was 25.9 +/- 4.8 nM (duodenum), 25.4 +/- 6.8 nM (colon), 23.4 +/- 2.2 nM (kidney) and 25.6 +/- 5.6 nM (lung). Inhibition in these tissues is greater than that of curcumin for SULT1A1 in human liver (p < 0.0001). 5. In conclusion, curcumin is a potent inhibitor of SULT1A1 in human liver, duodenum, colon, kidney and lung. The IC(50) of curcumin for SULT1A1 varied 4.9-fold in human liver. The comparison of the present data with those of the literature revealed that the IC(50) of curcumin in the liver and extrahepatic tissues is one order of magnitude lower that the peak serum concentration of curcumin after therapeutic doses of 4 g to humans.

The first aim of this investigation was to study the sulfation of R(-)-apomorphine in human brain. The second aim was to investigate the inhibition of R(-)-apomorphine sulfation by quercetin in human brain. R(-)-apomorphine is hereafter referred to as apomorphine. Apomorphine sulfation was measured in 5 brain specimens; 3 derived from the frontal cortex and 2 derived from the temporal cortex. The rate of apomorphine sulfation was 5.6 +/- 4.3 pmol/min/mg. The activities of SULT1A1 and SULT1A3, which were also measured in these samples, were 11 +/- 9.1 and 2.6 +/- 1.7 pmol/min/mg, respectively. The rate of apomorphine sulfation correlated with the activity of SULT1A1 (r = 0.989; p = 0.002) and SULT1A3 (r = 0.973; p = 0.005). Apomorphine sulfotransferase followed Michaelis-Menten kinetics, the Km (mean +/- SD) and Vmax values (mean +/- SD) of which, measured in 5 brain samples, were 32 +/- 7.3 microM and 8.9 +/- 7.9 pmol/min/mg, respectively. Quercetin was a potent inhibitor of apomorphine sulfation with an IC50 value, measured in 5 brain samples, of 16 +/- 2.3 nM. The inhibition mechanism of quercetin using apomorphine sulfation in 5 brain samples was mixed, non-competitive with a Ki and Kies (mean +/- SD) of 16 +/- 4.1 and 87 +/- 37 nM, respectively (p = 0.008). The intrinsic clearance value of apomorphine (mean +/- SD) was 247 +/- 170 ml/min/mg(-1) and was decreased to 100 +/- 85 ml/min/mg(-1) (p < 0.01) in the presence of 25 nM quercetin. In conclusion, apomorphine is sulfated in human brain. Sulfation might reduce the level of apomorphine in human brain and be a factor limiting the effect of this drug. Quercetin is a potent inhibitor of apomorphine sulfation and may inhibit the sulfation of apomorphine in human brain in vivo.

1. The aim of this investigation was to see whether 7-OH-flavone, 5-OH-flavone and 3-OH-flavone, which are present in edible vegetables, fruit and wine, are substrates or inhibitors of human liver and duodenum sulfotransferase. 2. An assay was set up to study the sulfation of 7-OH-flavone, and using this assay, it was observed that 7-OH-flavone was sulfated and the rate of sulfation (mean +/- SD) was 324 +/- 87 pmol min(-1) mg(-1) (liver) and 584 +/- 164 pmol min(-1) mg(-1) (duodenum; p < 0.0001). 3. 7-OH-flavone sulfotransferase followed Michaelis-Menten kinetics and the K(m) (mean +/- SD) was 0.2 +/- 0.04 microM (liver) and 1.1 +/- 0.3 microM (duodenum; p = 0.008). V(max) (mean +/- SD) was 392 +/- 134 pmol min(-1) mg(-1) (liver) and 815 +/- 233 pmol min(-1) mg(-1) (duodenum; p = 0.016). 4. 5-OH-flavone and 3-OH-flavone were not sulfated and were inhibitors of human liver and duodenum SULT1A1 activity and 7-OH-flavone sulfation rate. 5. The IC50 of 5-OH-flavone for SULT1A1 was 0.3 +/- 0.06 microM (liver) and 0.3 +/- 0.1 microM (duodenum; n.s.) and those of 3-OH-flavone were 1.0 +/- 0.1 microM (liver) and 1.6 +/- 0.03 microM (duodenum; p = 0.0006). 6. There was inhibition of 7-OH-flavone sulfation rate by 5-OH-flavone and 3-OH-flavone. The IC(50) of 5-OH-flavone for the sulfation rate of 7-OH-flavone was 3.5 +/- 0.5 microM (liver) and 69 +/- 18 microM (duodenum; p < 0.0001) and for 3-OH-flavone it was 18 +/- 3.4 microM (liver) and 213 +/- 47 microM (duodenum; p < 0.0001). 7. The position of the hydroxy group confers to the molecules of OH-flavones the quality of substrate or inhibitor of sulfotransferase.

1. The aims were to study the sulfation of R-(-)-apomorphine (hereafter apomorphine) in the human liver and duodenum, and to study the rate of inhibition of apomorphine sulphation by mefenamic acid, salicylic acid and quercetin also in the human liver and duodenum. 2. A rapid and sensitive method was developed to measure the sulfation rate of apomorphine in the human liver and duodenum. The method was based on the use of 0.4 micro M 3'-phosphoadenosine-5'-phosphosulfate-[(35)S] (PAPS) and 50 micro M apomorphine. The unreacted PAPS was precipitated with barium hydroxide, barium acetate and zinc sulfate. 3. The rate of apomorphine sulfation (mean +/- SD and median) was 261 +/- 82 and 242 pmol min(-1) mg(-1), respectively (liver), and 433 +/- 157 and 443 pmol min(-1) mg(-1), respectively (duodenum). The apomorphine sulfation rate was higher in the duodenum than in the liver (p = 0.0005). 4. Apomorphine sulfation was correlated with SULT1A1 activity in the liver (r(2) = 0.363, p = 0.005) and duodenum (r(2) = 0.494, p = 0.0005), but it did not correlate with SULT1A3 activity both in the liver and duodenum. 5. The K(m) estimate of apomorphine sulfation rate was 20 +/- 3.6 (liver) and 6.5 +/- 0.2 microM (duodenum, p = 0.024), and the V(max) estimate was 248 +/- 99 (liver) and 636 +/- 104 pmol min(-1) mg(-1) (duodenum, p = 0.018). 6. Mefenamic acid, salicylic acid and quercetin were potent inhibitors of apomorphine sulfation rate in the liver, and the IC(50) estimates were 16 +/- 0.2 nM, 54 +/- 8.6 microM and 18 +/- 2.8 nM, respectively. These compounds were poor inhibitors of apomorphine sulfation in the duodenum. 7. Apomorphine is sulfated by the human liver and duodenum, the highest activity being associated with the duodenum. The K(m) of apomorphine sulfotransferase is in the order of micro M both in the liver and duodenum. The non-steroidal anti-inflammatory drug mefenamic acid and the natural flavonoid quercetin inhibit the hepatic sulfation of apomorphine with an IC(50) in the order of nM.

Objectives: The first aim of this investigation was to study the variability of mycophenolic acid (MPA) glucuronidation rate in human liver. The second aim was to study the inhibition type of niflumic acid (NA) for MPA glucuronidation in human liver. The third aim was to study the variability of the IC(50) value of NA for MPA glucuronidation in human liver., Methods: The rate of MPA glucuronidation was measured by employing an assay based on uridine 5'-diphosphate-[U-(14)C]-glucuronic acid (UDPGA), and MPA glucuronide was isolated by means of thin-layer chromatography. The necessary concentration for UDPGA and MPA was 1 mM. The rate of MPA glucuronidation was measured in 50 human liver samples. The inhibition type of NA for MPA glucuronidation was studied in 5 human liver samples. The NA IC(50) value was measured in 27 human liver samples using six concentrations of NA ranging from 1.05 microM to 34 microM., Results: MPA glucuronidation rate was positively skewed, was not gender regulated and did not correlate with the liver donor's age. The rate of MPA glucuronidation varied 4.8-fold within the 5th and 95th percentiles, with a mean+/-SD and a median of 2.8+/-1.0 nmol/min/mg and 2.5 nmol/min/mg, respectively. The inhibition type of NA for MPA glucuronidation was mixed non-competitive. The Ki value of NA (mean+/-SD) was 15+/-10 microM and, in non-inhibited samples, the K(m) value for MPA was 0.41+/-0.06 mM. The distribution of NA IC(50) value varied 3.3-fold within the 5th and 95th percentiles with a mean+/-SD and a median of 5.6+/-2.1 microM and 5.2 microM, respectively. The distribution of NA IC(50) value did not deviate significantly from normality., Conclusion: The range of hepatic rate of MPA glucuronidation is narrow relative to those of ethinyloestradiol, testosterone and zidovudine glucuronidation obtained from literature. The Ki value of NA is one order of magnitude lower than the K(m) for MPA in non-inhibited samples. This indicates that the inhibitor affinity for glucuronosyl transferase is greater than that of the substrate. The range of variation of NA IC(50) values is narrow.

The aim of this investigation was to study the methylation of quercetin and fisetin, 2 chemically related flavonoids, in human liver and to this purpose, an assay was set-up to measure the rates of quercetin and fisetin methylation in human liver. The methylation rates (pmol/min/mg) of quercetin and fisetin were measured in 10 liver samples and the mean +/- SD and the median were 170+/-30 and 177 (quercetin) and 183+/-15 and 178 (fisetin). The rates of quercetin and fisetin methylation were not different (p = 0.283). The fold of variation among samples was 2 (quercetin) and 1.3 (fisetin). Methyltransferase towards quercetin and fisetin followed Michaelis-Menten kinetics, and the Km values were 2.6+/-0.3 (quercetin) and 8.6+/-0.7 microM (fisetin, p = 0.009) and the Vmax values were 187+/-20 (quercetin) and 276+/-33 pmol/min/mg (fisetin, p = 0.009). Two, 4 and 8 microl of red Chianti wine added to the incubation mixture reduced the rate of quercetin methylation to 75+/-4%, 65+/-9% and 59+/-9%, respectively, and that of fisetin methylation to 62+/-3%, 51+/-3% and 44+/-4%, respectively. In conclusion, quercetin and fisetin are methylated in human liver and their rates of methylation have a limited variation among subjects.

1. Quercetin is one of the most abundant flavonoids in edible vegetables, fruit and wine. The aim was to study the type of inhibition of SULT1A1 by quercetin in the human adult and foetal livers. 2. The activity of SULT1A1 was measured with 4 microM 4-nitrophenol and 0.4 microM 3'-phosphoadenosine-5'-phosphosulphate-[(35)S], and its mean (+/-SD) and median were 769 +/- 311 and 740 pmol min(-1) mg(-1), respectively (adult liver, n = 10), and 185 +/- 98 and 201 pmol min(-1) mg(-1), respectively (foetal liver, n = 8, p < 0.0001). 3. In non-inhibited samples, K(m) for SULT1A1 (mean +/- SD) was 0.31 +/- 0.14 microM (adult liver) and 0.49 +/- 0.17 microM (foetal liver, n.s.). V(max) for SULT1A1 (mean +/- SD) was 885 +/- 135 pmol min(-1) mg(-1) (adult liver) and 267 +/- 93 pmol min(-1) mg(-1) (foetal liver, p = 0.007). 4. The IC(50) of quercetin for SULT1A1 was measured in three samples of adult and foetal livers and was 13 +/- 2.1 and 12 +/- 1.4 nM, respectively. 5. The type of inhibition was mixed non-competitive in adult and foetal livers and K(i) was 4.7 +/- 2.5 nM (adult liver) and 4.8 +/- 1.6 nM (foetal liver). 6. In the adult liver, the intrinsic clearance (mean +/- SD) was 3.3 +/- 1.5 ml min(-1) mg(-1) (non-inhibited samples), 0.9 +/- 0.4 ml min(-1) mg(-1) (12.5 nM quercetin) and 0.5 +/- 0.06 ml min(-1) mg(-1) (25 nM quercetin). In the foetal liver, the intrinsic clearance (mean +/- SD) was 0.5 +/- 0.2 ml min(-1) mg(-1) (non-inhibited samples), 0.12 +/- 0.01 ml min(-1) mg(-1) (12.5 nM quercetin) and 0.2 +/- 0.09 ml min(-1) mg(-1) (25 nM quercetin). 7. In conclusion, quercetin is a potent inhibitor of human adult and foetal liver SULT1A1. It reduces the sulphation rate and intrinsic clearance of 4-nitrophenol in both human adult and foetal livers. This suggests that quercetin may inhibit the sulfation rate of those drugs sulphated by SULT1A1. The inhibition of SULT1A1 is complex and not due solely to competition at the catalytic site of SULT1A1.

1. Quercetin is a natural flavonoid present in vegetables, fruit and wine, and is known to inhibit sulphotransferase. Drugs are often taken orally and the intestinal mucosa is an early site of drug metabolism. The aims of this investigation were to study the inhibition of dopamine, (-)-salbutamol, minoxidil and paracetamol sulphation by quercetin in the duodenal mucosa and liver and to compare the IC50 in these tissues. 2. The rates (pmol min(-1) mg(-1)) of sulphation of 4-nitrophenol were 343+/-92 (liver) and 164+/-22 (duodenum; p = 0.031), of dopamine were 15+/-11 (liver) and 656+/-516 (duodenum; p = 0.049), of (-)-salbutamol 153+/-31 (liver) and 654+/-277 (duodenum; p = 0.018), of minoxidil were 156+/-47 (liver) and 105+/-7 (duodenum; n.s.), and of paracetamol were 229+/-86 (liver) and 328+/-187 (duodenum; n.s.). 3. The IC50 of quercetin for 4-nitrophenol was 48+/-11 nM (liver) and 56+/-1 nM (duodenum, n.s.), for dopamine was 5.7+/-0.7 microM (liver) and 170+/-12 microM (duodenum, p < 0.0001), for (-)-salbutamol was 54+/-4 nM (liver) and 16+/-8 microM (duodenum; p = 0.025), for minoxidil was 134+/-22 nM (liver) and 3+/-0.3 microM (duodenum, p = 0.013), and for paracetamol was 57+/-7 nM (liver) and 35+/-1 microM (duodenum; p = 0.0002). 4. Quercetin inhibited the sulphation of 4-nitrophenol, dopamine, (-)-salbutamol, minoxidil and paracetamol both in liver and duodenum. With dopamine, (-)-salbutamol, minoxidil and paracetamol as substrates, quercetin was a more potent inhibitor in the liver than the duodenum. Such a difference may reflect the different composition of sulphotransferase forms in the liver and duodenum.

Objective: The aim of the present study was to estimate the concordance rate between erythrocyte thiopurine methyltransferase (TPMT) activity and genotype at the TPMT locus in an Italian population sample., Methods: The TPMT phenotype and genotype were determined in an unrelated population of 103 Italian healthy blood donors. Erythrocyte TPMT activity was measured with a radiochemical assay using 12.5 microM S-adenosyl-L-(methyl-14C)-methionine and 4 mM 6-mercaptopurine. The genotyping assay was based on restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR) and allele-specific oligonucleotide polymerase chain reaction (ASO-PCR) methods., Results: All subjects had detectable TPMT activity. The activity of TPMT varied 2.8-fold between the 5th and 95th percentile. This variation was neither age (P = 0.63) nor gender (P = 0.44) regulated and the frequency distribution of TPMT activity is compatible with a polymorphic distribution. The presence of the four most common defective alleles, i.e. TPMT*2, TPMT*3A, TPMT*3B and TPMT*3C, was examined through the entire phenotyped population. Ninety-two subjects did not carry any of the tested mutations. Eleven individuals were heterozygous for one of the mutant alleles and had a TPMT activity lower than 30 pmol/min/mg. Eight subjects were TPMT*1/TPMT*3A, two TPMT*1/TPMT*3C and one was TPMT*1/TPMT*2. The TPMT*3B allele was not detected in the samples analysed., Conclusion: There was a concordance of 97% between genotype and phenotype. All the heterozygotes had an intermediate phenotype. However, the wide variation range in TPMT activity detected in the wild-type homozygotes indicates that other genetic or epigenetic factors influence the TPMT phenotype.

Objective: The aims of this investigation were to study the glucuronidation of mycophenolic acid (MPA) in human liver and kidney and to search for a compound that inhibits MPA glucuronidation among the non-steroidal anti-inflammatory drugs (NSAIDs)., Methods: A sensitive and reproducible radiometric assay was developed to measure the rate of MPA glucuronidation in human liver and kidney microsomes. The assay employed uridine 5'-diphosphate-[U-14C]-glucuronic acid (UDPGA) and MPA-glucuronide was isolated by TLC. The final concentrations of UDPGA and MPA necessary were 1 mM (liver), and MPA concentration was 0.5 mM (kidney). The inhibition of MPA glucuronidation was studied with 18 NSAIDs and tacrolimus., Results: Glucuronosyl transferase activity followed Michaelis-Menten kinetics and the Km (mean +/- SD; mM) was 0.31+/-0.06 (liver; n = 5) and 0.28+/-0.07 (kidney; n = 5; P = 0.555); the Vmax (mean SD; nmol/mg per minute) was 5.2+/-1.4 (liver; n = 5) and 10.5+/-1.2 (kidney; n = 5; P = 0.0005). The MPA glucuronidation rates (mean +/- SD; nmol/min/mg) were 3.3+/-0.9 (liver; n = 10) and 7.8+/-1.5 (kidney; n = 10; P = 0.0002). The rate of MPA glucuronidation ranged between 2.0 and 5.1 nmol/ mg per minute with a 2.5-fold variation (liver) and between 5.7 and 9.8 nmol/mg per minute with a 1.7-fold variation (kidney). The inhibition study was performed in liver and revealed that the percentage of control ranged from 8%+/-3% (niflumic acid) to 119%+/-16% (Ketoralac). The inhibition curves for MPA glucuronidation rate were determined with the four most effective inhibitors: niflumic acid, flufenamic acid, mefenamic acid and diflunisal. Their IC50 estimates (microM) were 8+/-1, 19+/-9, 63+/-8 and 109+/-15, respectively (liver), and 8+/-2, 13+/-2, 49+/-4 and 122+/-18, respectively (kidney). The IC50 estimate for niflumic acid was eightfold lower than the peak plasma levels after a single oral dose of 250 mg of this drug., Conclusion: The human liver and kidney are important sites of MPA glucuronidation. MPA glucuronidation was inhibited to various extents by different NSAIDs and the four most effective inhibitors were niflumic acid, flufenamic acid, mefenamic acid and diflunisal. These drugs have similar molecular structures consisting of two aromatic rings bearing a carboxylic group.

1. Resveratrol, a polyphenolic compound present in grape and wine, has beneficial effects against cancer and protective effects on the cardiovascular system. It has been shown that the compound is sulphated in human liver and the aims of the present investigation were to study resveratrol glucuronidation in human liver microsomes and to determine whether flavonoids inhibit resveratrol glucuronidation. 2. A simple and reproducible radiometric assay for resveratrol glucuronidation was developed. The assay employed uridine-5'-diphosphoglucuronic acid-[14C] and unlabelled resveratrol. Resveratrol-glucuronide was isolated by TLC. The intra- and interassays variabilities were 1 and 1.5%, respectively. 3. The rate of resveratrol glucuronidation was measured in 10 liver samples. The mean +/- SD and median of resveratrol glucuronidation rate were 0.69 +/- 0.34 and 0.80 nmol/min/mg, respectively. Resveratrol glucuronosyl transferase followed Michaelis-Menten kinetics and the Km and Vmax (mean +/- SD; n = 5) were 0.15 +/- 0.09 mM and 1.3 +/- 0.3 nmol/min/mg, respectively. The intrinsic clearance was 11 +/- 4 x 10(-3) ml/min.mg. 4. The flavonoid quercetin inhibited resveratrol glucuronidation and its IC50 (mean +/- SD; n = 3) was 10 +/- 1 microM. Myricetin, catechin, kaempferol, fisetin and apigenin (all at 20 microM) inhibited resveratrol glucuronidation and the percent of control ranged between 46% (catechin) to 72% (apigenin). 5. The present results show that resveratrol is glucuronated in the human liver. Glucuronidation may reduce the bioavailability of this compound however, flavonoids inhibit resveratrol glucuronidation and such an inhibition might improve the bioavailability of resveratrol.

Objective: The aim of this investigation was to determine whether mefenamic acid and salicylic acid inhibit the sulfation of (-)-salbutamol and minoxidil in the human liver and duodenum, and if so, to ascertain whether the 50% inhibitory concentration (IC50) estimates are different in the two tissues., Methods: Sulfotransferase activities were measured for 10 mM (-)-salbutamol and 5 mM minoxidil, and the concentration of 3'-phosphoadenosine-5'-phosphosulphate-[35S] was 0.4 microM., Results: The IC50 estimates for (-)-salbutamol and minoxidil sulfation of mefenamic acid were 72 +/- 5.4 nM and 1.5 +/- 0.6 microM (liver), respectively, and 161 + 23 microM and 420 +/- 18 microM (duodenum), respectively. The figures for the liver were significantly lower (P < 0.0001) than those for the duodenum. The IC50 estimates for (-)-salbutamol sulfation of salicylic acid were 93 +/- 11 microM (liver) and 705 +/- 19 microM (duodenum, P < 0.0001). Salicylic acid was a poor inhibitor of minoxidil sulfation., Conclusion: The IC50 estimates for (-)-salbutamol sulfation of mefenamic acid and salicylic acid are lower than their unbound plasma concentrations after standard dosing, suggesting that mefenamic acid and salicylic acid should inhibit the hepatic sulfation of (-)-salbutamol in vivo.

1. Resveratrol, a polyphenolic compound present in grape and wine, has beneficial effects against cancer and protective effects on the cardiovascular system. Resveratrol is sulphated, and the hepatic and duodenal sulphation might limit the bioavailability of this compound. The aim of this study was to see whether natural flavonoids present in wine, fruits and vegetables inhibit the sulphation of resveratrol in the human liver and duodenum. 2. In the liver, IC50 for the inhibition of resveratrol sulphation was 12+/-2 pM (quercetin), 1.0+/-0.04 microM (fisetin), 1.4+/-0.1 microM (myricetin), 2.2+/-0.1 microM (kaempferol) and 2.8+/-0.2 microM (apigenin). Similarly, in the duodenum, IC50 was 15+/-2 pM (quercetin), 1.3+/-0.1 microM (apigenin), 1.3+/-0.5 microM (fisetin), 2.3+/-0.1 microM (kaempferol) and 2.5+/-0.3 microM (myricetin). 3. The type of inhibition of quercetin on resveratrol sulphation was studied in three liver samples and was determined to be non-competitive and mixed in nature. Km (mean+/-SD; microM) was 0.23+/-0.07 (control), 0.40+/-0.08 (5 pM quercetin) and 0.56+/-0.09 (10 pM quercetin). Vmax (mean+/-SD; pmol min(-1) x mg(-1)) was 99+/-11 (control), 73+/-15 (5 pM quercetin) and 57 +/- 10 (10 pM quercetin). Kj and Kies estimates (mean+/-SD) were 3.7+/-1.8 pM and 12.1+/-1.7 pM respectively (p = 0.010). 4. Chrysin was a substrate for the sulphotransferase(s) and an assay was developed for measuring the chrysin sulphation rate in human liver. The enzyme followed Michaelis-Menten kinetics and Km and Vmax (mean+/-SD) measured in four livers were 0.29+/-0.07 microM and 43.1+/-1.9 pmol x min(-1) x mg(-1) respectively. 5. Catechin was neither an inhibitor of resveratrol sulphation nor a substrate of sulphotransferase. 6. These results are consistent with the view that many, but not all, flavonoids inhibit the hepatic and duodenal sulphation of resveratrol, and such inhibition might improve the bioavailability of this compound.

The endogenous concentration of uridine 5'-diphosphoglucoronic acid (UDPGLcUA), the endogenus substrate of UDP-glucuronosyltransferase, was measured in the human fetal and adult liver and kidney and in the placenta. The concentrations (mumol/Kg wet weight) of UDPGLcUA were 59.4 +/- 11.3 (fetal liver), 301 +/- 119 (adult liver), 11.9 +/- 3.2 (fetal kidney), 17.4 +/- 3.0 (adult kidney), 17.8 +/- 1.8 (mid-term placenta) and 17.0 +/- 1.7 (term placenta). UDPGLcUA is present in the human fetal liver at a concentration 5-fold lower than in the adult liver indicating a potential limiting factor for glucuronidation ind the human fetus.