Journal of Clinical Pharmacology最新文献

Amitriptyline is a tricyclic antidepressant that is metabolized mainly by CYP2C19 and CYP2D6 enzymes. Higher plasma levels of amitriptyline and its active metabolite, nortriptyline, are associated with an increased risk of adverse events including anticholinergic effects. The aim of this study was to evaluate the effects of CYP2C19 and CYP2D6 genetic polymorphisms on amitriptyline and nortriptyline pharmacokinetics. Twenty-four Korean healthy adult male volunteers were enrolled in the study after stratification by their CYP2C19 and CYP2D6 genotypes. Serial blood draws for pharmacokinetic analysis were made after a single oral 25-mg dose of amitriptyline was administered. Plasma amitriptyline and nortriptyline concentrations were measured by a validated liquid chromatography with tandem mass spectrometry. Population pharmacokinetic modeling analysis was conducted using NONMEM, which evaluated the effects of CYP2C19 and CYP2D6 genotypes on amitriptyline and nortriptyline pharmacokinetics. The biotransformation of amitriptyline into nortriptyline was significantly different between subjects with the CYP2C19*2/*2, *2/*3, and *3/*3 genotypes and those with the other genotypes, with an estimated metabolic clearance of 17 and 61.5 L/h, respectively. Clearance of amitriptyline through pathways other than biotransformation into nortriptyline was estimated as 18.8 and 30.6 L/h for subjects with the CYP2D6*10/*10 and *10/*5 genotypes and those with the other genotypes, respectively. This study demonstrated a quantitative effect of the CYP2C19 and CYP2D6 genotypes on amitriptyline and nortriptyline pharmacokinetics. Production of nortriptyline from amitriptyline was associated with CYP2C19 genotypes, and clearance of amitriptyline through pathways other than biotransformation into nortriptyline was associated with CYP2D6 genotypes. These observations may be useful in developing individualized, optimal therapy with amitriptyline.

The combination regimen of daclatasvir, asunaprevir, and beclabuvir has been developed for the treatment of hepatitis C virus infection. The objectives of this analysis were to characterize the relationship between the exposures of the daclatasvir, asunaprevir, and beclabuvir regimen and liver-related laboratory elevations (Grade 3 or 4 alanine aminotransferase [ALT] and total bilirubin [Tbili]), and to evaluate the impact of selected covariates on the exposure-response relationships. The exposure-response analysis was performed with data from 1 phase 2 and 3 phase 3 studies in hepatitis C virus-infected subjects. The probability of liver-related laboratory elevations were modeled using linear logistic regression. Selected covariates were tested using a forward-addition and backward-elimination approach. The final model for ALT elevation included Asian race, body weight in non-Asian subjects, and asunaprevir exposure. The final model for Tbili elevation included Asian race, fibrosis score (F0-F3 or F4) and asupanprevir exposure. Asian subjects had greater the Grade 3 or 4 ALT and Tbili elevation rates than non-Asians. The Grade 3 or 4 ALT elevation rate increased with decreasing body weight in non-Asian subjects. Subjects with F4 fibrosis score had a higher rate of Grade 3 or 4 Tbili elevation compared to subjects with F0 to F3 fibrosis score. Higher asunaprevir exposure was associated with increases in Grade 3 or 4 ALT and Tbili elevation rates; however, the impact on the ALT elevation was not clinically relevant and the effect on Tbili elevation was smaller than the other significant covariates.

Extraparenchymal neurocysticercosis is the most severe form of cysticercosis, and response to treatment is suboptimal. We sought to determine how demographic and clinical characteristics and albendazole sulfoxide concentrations were related to cysticidal treatment response. We conducted a longitudinal study of 31 participants with extraparenchymal vesicular parasites who received the same treatment, albendazole 30 mg/kg/day for 10 days with dexamethasone 0.4 mg/kg/day for 13 days, followed by a prednisone taper. Response to treatment was determined by parasite volumes before and 6 months after treatment. Eight participants (25.8%) had a complete treatment response, 16 (51.6%) had a treatment response > 50% but < 100%, and 7 (22.6%) had a treatment response < 50%. Complete treatment response was significantly associated with higher concentrations of albendazole sulfoxide (P = .032), younger age (P = .032), fewer cysts (P = .049) and lower pretreatment parasite volume (P = .037). Higher number of previous cysticidal treatment courses was associated with a noncomplete treatment response (P = .023). Although the large proportion of participants with less than a complete response emphasizes the need to develop more efficacious pharmacologic regimens, the association of albendazole sulfoxide concentrations with treatment response highlights the importance of optimizing existing therapeutic regimens. In addition, the association of treatment response with parasite volume emphasizes the importance of early diagnosis.

The aim of the present study is to establish a population pharmacokinetic (PPK) model of mycophenolic acid (MPA) and limited sampling strategy models for the estimation of MPA exposure in Chinese adult renal allograft recipients following oral administration of enteric coated mycophenolate sodium (EC-MPS). A total of 74 sets of full pharmacokinetic profiles and 47 sets of MPA-sparing samples were collected from 102 renal transplant recipients who received oral EC-MPS. The MPA concentration was determined by an enzyme-multiplied immunoassay technique, and the pathophysiologic data were recorded. The PPK model was constructed using nonlinear mixed-effects modeling, and the limited sampling strategy models for MPA were established by using multiple regression analysis and the maximum a posteriori Bayesian assay based on 2 to 4 sampling time points following EC-MPS administration. The pharmacokinetics of MPA were best described by a 2-compartment model with a first-order absorption process and a lag time of absorption. The clearance of MPA was 12.3 ± 1.14 L/h. Comedicating with cyclosporine A was found to have a significant impact on the clearance/bioavailability of MPA (P < .01). Sampling strategies consisted of plasma concentration at 1.5, 2, 4 (C1.5-C2-C4) hours and 1.5, 2, 4, 6 (C1.5-C2-C4-C6) hours after EC-MPS administration were shown to be suitable for the estimation of the MPA area under the concentration-time curve in these patients. The PPK model was acceptable and can describe the pharmacokinetics of MPA in Chinese renal transplant recipients administered EC-MPS. The area under the concentration-time curve of MPA in Chinese renal transplant recipients could be estimated through a limited sampling strategy method, based on which individualized immunosuppressive regimens could be designed.

Upadacitinib is a novel selective oral Janus kinase 1 (JAK) inhibitor being developed for treatment of several inflammatory diseases. Oral contraceptives are anticipated to be a common concomitant medication in the target patient populations. This study was designed to evaluate the effect of multiple doses of upadacitinib on the pharmacokinetics of ethinylestradiol and levonorgestrel in healthy female subjects. This phase I, single-center, open-label, 2-period crossover study evaluated the effect of multiple doses of 30 mg once daily extended-release upadacitinib on the pharmacokinetics of a single oral dose of ethinylestradiol/levonorgestrel (0.03/0.15 mg; administered alone in period 1 and on day 12 of a 14-day regimen of upadacitinib in period 2) in 22 healthy female subjects. The ratios (90% confidence intervals) for maximum plasma concentration and area under the plasma drug concentration-time curve from time zero to infinity following administration of ethinylestradiol/levonorgestrel with upadacitinib compared with administration of ethinylestradiol/ levonorgestrel alone were 0.96 (0.89-1.02) and 1.1 (1.04-1.19), respectively, for ethinylestradiol, and 0.96 (0.87-1.06) and 0.96 (0.85-1.07), respectively, for levonorgestrel. The harmonic mean terminal half-life for ethinylestradiol (7.7 vs 7.0 hours) and levonorgestrel (37.1 vs 33.1 hours) was similar in the presence and absence of upadacitinib. Ethinylestradiol and levonorgestrel were bioequivalent in the presence and absence of upadacitinib. Therefore, upadacitinib can be administered concomitantly with oral contraceptives containing ethinylestradiol or levonorgestrel.

The accurate prediction of pharmacokinetics (PK) is fundamental to underwriting safety and efficacy in pediatric clinical trials; age-dependent PK may be observed with pediatrics because of the growth and maturation processes that occur during development. Understanding the ontogeny of drug-metabolizing enzymes is a critical enabler for pediatric PK prediction, as enzyme expression or activity may change with age. Although ontogeny functions for the cytochrome P450s (CYPs) have been developed, disconnects between ontogeny functions for the same CYP may exist, depending on whether the functions were derived from in vitro or in vivo data. This report describes the development of ontogeny functions for all the major hepatic CYPs based on in vitro or in vivo data; these ontogeny functions were subsequently incorporated into a physiologically based pharmacokinetic model and evaluated. Pediatric PK predictions based on in vivo-derived ontogeny functions performed markedly better than those developed from in vitro data for intravenous (100% versus 51% within 2-fold, respectively) and oral (98% versus 67%, respectively) dosing. The verified models were then applied to complex pediatric scenarios involving active metabolites, CYP polymorphisms and physiological changes because of critical illness; the models reasonably explained the observed age-dependent changes in pediatric PK.

The integrated glucose-insulin (IGI) model is a previously published semimechanistic model that describes plasma glucose and insulin concentrations after glucose challenges. The aim of this work was to use knowledge of physiology to improve the IGI model's description of glucose absorption and gastric emptying after tests with varying glucose doses. The developed model's performance was compared to empirical models. To develop our model, data from oral and intravenous glucose challenges in patients with type 2 diabetes and healthy control subjects were used together with present knowledge of small intestinal transit time, glucose inhibition of gastric emptying, and saturable absorption of glucose over the epithelium to improve the description of gastric emptying and glucose absorption in the IGI model. Duodenal glucose was found to inhibit gastric emptying. The performance of the saturable glucose absorption was superior to linear absorption regardless of the gastric emptying model applied. The semiphysiological model developed performed better than previously published empirical models and allows better understanding of the mechanisms underlying glucose absorption. In conclusion, our new model provides a better description and improves the understanding of dynamic glucose tests involving oral glucose.

Pradigastat, a novel diacylglycerol acyltransferase-1 inhibitor, has activity in common metabolic diseases associated with abnormal accumulation of triglycerides. In vitro studies suggest that glucuronidation is the predominant metabolism pathway for elimination of pradigastat in humans and confirmed the role of uridine 5'-diphosphoglucuronosyltransferase (UGT) enzymes, UGT1A1, -1A3, and -2B7. The in vitro studies using atazanavir as a selective inhibitor of UGT1A1 and -1A3 indicated that these enzymes contribute ∼55% toward the overall glucuronidation pathway. Therefore, a clinical study was conducted to assess the potential for drug interaction between pradigastat and probenecid (purported general UGT inhibitor) or atazanavir (selective UGT1A1, -1A3 inhibitor). The study included 2 parallel cohorts, each with 3 sequential treatment periods and 22 healthy subjects per cohort. The 90%CI of the geometric mean ratios for Cmax,ss and AUCτ,ss of pradigastat were within 0.80-1.25 when administered in combination with probenecid. However, the Cmax,ss and AUCτ,ss of pradigastat decreased by 31% (90%CI: 0.62-0.78) and 26% (0.67-0.82), respectively, when administered in combination with atazanavir. This magnitude of decrease in pradigastat steady-state exposure is not considered clinically relevant. Pradigastat was well tolerated by all subjects, either alone or in combination with atazanavir or probenecid.

This multicenter, randomized, open-label, parallel-group, phase-1 study assessed the pharmacokinetics (PK), safety, and tolerability of the investigational intramuscular paliperidone palmitate 3-month (PP3M) formulation in patients with schizophrenia or schizoaffective disorder. A total of 328 patients (men or women, aged 18-65 years) were enrolled in 1 of 4 separately conducted panels (A to D). Each panel had 2 single-dose treatment periods (period 1, 1 mg intramuscular paliperidone immediate release [IR]; period 2, intramuscular PP3M 75-525 mg eq) separated by a washout of 7-21 days. Overall, 245 of 308 (79.5%) PP3M-dosed patients completed the study. Because the PK studies of panels A and C were compromised by incomplete injection in some patients, PK data from only panels B and D are presented. Safety data from all panels are presented. Peak paliperidone plasma concentration was achieved between 23 and 34 days, and apparent half-life was ∼2-4 months. Mean plasma AUC∞ and Cmax of paliperidone appeared to be dose-proportional. Relative bioavailability in comparison with paliperidone was ∼100% independent of the dose and injection site. Headache and nasopharyngitis were the most common (>7%) treatment-emergent adverse events. Overall, safety and tolerability were similar to those of the 1-month formulation. Results support a once-every-3-months dosing interval in patients with schizophrenia or schizoaffective disorder.

Meropenem is frequently prescribed in critically ill children receiving continuous renal replacement therapy (CRRT). We previously used clinical trial simulations to evaluate dosing regimens of meropenem in this population and reported that a dose of 20 mg/kg every 12 hours optimizes target attainment. Meropenem pharmacokinetics were investigated in this prospective, open-label study to validate our previous in silico predictions. Seven patients received meropenem (13.8-22 mg/kg) administered intravenously every 12 hours as part of standard care. A mean dose of 18.6 mg/kg of meropenem was administered, resulting in a mean peak concentration of 80.1 μg/mL. Meropenem volume of distribution was 0.35 ± 0.085 L/kg. CRRT clearance was 40.2 ± 6.6 mL/(min · 1.73 m(2) ) and accounted for 63.4% of the total clearance of 74.8 ± 36.9 mL/(min · 1.73 m(2) ). Simulations demonstrated that a dose of 20 mg/kg every 12 hours resulted in a time above the minimum inhibitory concentration (%fT > MIC) of 100% in 5 out of 7 subjects, with a %fT > MIC of 93% and 43% in the remaining 2 subjects. We conclude that CRRT contributed significantly to the total clearance of meropenem. A dosing regimen of 20 mg/kg achieved good target attainment in critically ill children receiving CRRT, which is consistent with our previously published in silico predictions.