Investigation of the Differences in the Pharmacokinetics of CYP2D6 Substrates, Desipramine, and Dextromethorphan in Healthy African Subjects Carrying the Allelic Variants CYP2D6*17 and CYP2D6*29, When Compared with Normal Metabolizers.

This study investigated the differences in the pharmacokinetics (PK) of dextromethorphan and desipramine in healthy African volunteers to understand the effect of allelic variants of the human cytochrome P450 2D6 (CYP2D6) enzyme, namely the diplotypes of CYP2D6*1/*2 (*1*1, *1*2, *2*2) and the genotypes of CYP2D6*17*17 and CYP2D6*29*29. Overall, 28 adults were included and split into 3 cohorts after genotype screening: CYP2D6*1/*2 (n = 12), CYP2D6*17*17 (n = 12), and CYP2D6*29*29 (n = 4). Each subject received a single oral dose of dextromethorphan 30 mg syrup on day 1 and desipramine 50 mg tablet on day 8. The PK parameters of area under the plasma concentration-time curve from time of dosing to time of last quantifiable concentration (AUClast ), and extrapolated to infinity (AUCinf ), and the maximum plasma concentration (Cmax ) were determined. For both dextromethorphan and desipramine, AUCinf and Cmax were higher in subjects of the CYP2D6*29*29 and CYP2D6*17*17 cohorts, as compared with subjects in the CYP2D6*1/*2 diplotype cohort and with normal metabolizers from the literature. All PK parameters, including AUCinf , Cmax , and the elimination half-life, followed a similar trend: CYP2D6*17*17 > CYP2D6*29*29 > CYP2D6*1/*2. The plasma and urinary drug/metabolite exposure ratios of both drugs were higher in subjects of the CYP2D6*17*17 and CYP2D6*29*29 cohorts, when compared with subjects in the CYP2D6*1/*2 diplotype cohort. All adverse events were mild, except in 1 subject with CYP2D6*17*17 who had moderately severe headache with desipramine. These results indicate that subjects with CYP2D6*17*17 and CYP2D6*29*29 genotypes were 5-10 times slower metabolizers than those with CYP2D6*1/*2 diplotypes. These findings suggest that dose optimization may be required when administering CYP2D6 substrate drugs in African patients. Larger studies can further validate these findings.

Evaluating the Acceptability, Swallowability, and Palatability of Film-Coated Mini-Tablet Formulation in Young Children: Results from an Open-Label, Single-Dose, Cross-Over Study.

Mini-tablets are advantageous over liquid formulations in overcoming challenges related to stability, taste, and dosage. This open-label, single-dose, cross-over study investigated the acceptability and safety of drug-free, film-coated mini-tablets in children aged 1 month-6 years (stratified: 4-6 years, 2-<4 years, 1-<2 years, 6-<12 months, and 1-<6 months), and their preference for swallowing either a high quantity of 2.0 mm or a low quantity of 2.5 mm diameter mini-tablets. The primary endpoint was acceptability derived from swallowability. The secondary endpoints were investigator-observed palatability, acceptability as a composite endpoint derived from both swallowability and palatability, and safety. Of 320 children randomized, 319 completed the study. Across all tablet sizes, quantities and age groups, acceptability rates based on swallowability were high (at least 87%). Palatability was rated as "pleasant/neutral" in 96.6% of children. The acceptability rates as per the composite endpoint were at least 77% and 86% for the 2.0 mm and 2.5 mm film-coated mini-tablets, respectively. No adverse events or deaths were reported. Recruitment in the 1-<6-months group was stopped early due to coughing-evaluated as "choked on" in three children. Both 2.0 mm and 2.5 mm film-coated mini-tablets are suitable formulations for young children.

The Bioequivalence Between Valsartan Oral Solution and Suspension Formulations Developed for Pediatric Use.

The bioequivalence of valsartan 160 mg oral solution compared to suspension was assessed in a single-dose, open-label, randomized, 2-period, 2-way crossover study in 82 healthy adults. The participants were randomly assigned (1:1) to receive a single dose of the solution or suspension formulation in each of the two treatment periods. Serial blood samples for pharmacokinetic evaluation were collected up to 48 hours post-dose. The pharmacokinetic parameters were estimated by noncompartmental methods and analyzed as per bioequivalence criteria of statistical analysis. The peak plasma concentration of valsartan was reached with median time of 1 and 3 hours with solution and suspension formulation, respectively. Compared to suspension formulation, the mean peak plasma concentration with solution formulation was higher by 32% (90%CI, 1.27-1.38) while the geometric mean ratios (1.09) and the associated 90%CIs (1.05-1.13) of both the areas under the concentration time-curves (from time zero to the last quantifiable concentration and from time zero to infinity) were contained in the required range of 0.80 to 1.25. No new safety signals were observed with either of the formulations.

Drug-Drug Interaction Studies With Oral Contraceptives: Pharmacokinetic/Pharmacodynamic and Study Design Considerations.

Oral contraceptives (OCs) are the most widely used form of birth control among women of childbearing potential. Knowledge of potential drug-drug interactions (DDIs) with OCs becomes imperative to provide information on the medication to women of childbearing potential and enable their inclusion in clinical trials, especially if the new molecular entity is a teratogen. Although a number of DDI guidance documents are available, they do not provide recommendations for the design and conduct of OC DDI studies. The evaluation of DDI potential of a new molecular entity and OCs is particularly challenging because of the availability of a wide variety of combinations of hormonal contraceptives, different doses of the ethinyl estradiol, and different metabolic profiles of the progestin component. The aim of this review is to comprehensively discuss factors to be considered such as pharmacokinetics (PK), pharmacodynamics (PD), choice of OC, and study population for the conduct of in vivo OC DDI studies. In this context, metabolic pathways of OCs, the effect of enzyme inhibitors and inducers, the role of sex hormone-binding globulin in the PK of progestins, current evidence on OC DDIs, and the interpretation of PD end points are reviewed. With the emergence of new tools like physiologically based PK modeling, the decision to conduct an in vivo study can be made with much more confidence. This review provides a comprehensive overview of various factors that need to be considered in designing OC DDI studies and recommends PK-based DDI studies with PK end points as adequate measures to establish clinical drug interaction and measurement of PD end points when there is basis for PD interaction.

Effect of mavoglurant (AFQ056), a selective mGluR5 antagonist, on the pharmacokinetics of a combined oral contraceptive containing ethinyl estradiol and levonorgestrel in healthy women.

OBJECTIVE: To compare the pharmacokinetics (PKs) of a combination oral contraceptive (OC) when given alone or concomitantly with the selective metabotropic glutamate receptor 5 antagonist mavoglurant (AFQ056). METHODS: This open-label, fixed-sequence, two-period study included 30 healthy female subjects aged 18-40 years. In period 1, a single oral dose of an OC containing 30 µg ethinyl estradiol (EE)/150 µg levonorgestrel (LNG) was administered alone. In period 2, the OC was administered with a clinically relevant multiple dose of mavoglurant 100 mg b.i.d. under steady-state conditions. Plasma concentrations of EE and LNG were measured up to 72 hours post administration, and the PK parameters Cmax and AUClast were estimated using noncompartmental methods. RESULTS: The geometric mean ratios of EE Cmax and AUClast obtained with and without mavoglurant were 0.97 (90% confidence interval (CI): 0.90-1.06) and 0.94 (90% CI: 0.86-1.03), respectively. The corresponding Cmax and AUClast for LNG were 0.81 (90% CI: 0.75-0.87) and 0.68 (90% CI: 0.63-0.73), respectively. CONCLUSIONS: In conclusion, EE PK was unchanged, whereas Cmax and AUClast of LNG were 19% and 32% lower, respectively, when given with mavoglurant Further investigation regarding the impact on contraceptive efficacy is warranted.