To investigate pharmacokinetic and pharmacodynamic differences of zolpidem between males and females and their causes, including CYP3A4 activity. A single oral dose of zolpidem (10 mg) was administered to 15 male and 15 female healthy subjects. Blood samples were collected up to 12 h post-dose to determine plasma zolpidem concentrations. Pharmacokinetic parameters were obtained using non-compartmental analysis. Digit symbol substitution test, choice reaction time, and visual analog scale of sleepiness were used to evaluate pharmacodynamics. We measured CYP3A4 activity using 4β-hydroxycholesterol, an endogenous metabolite. Mean maximum plasma concentration and area under the plasma concentration–time curve were higher for females than for males (9.9% and 32.5%, respectively); other pharmacokinetic parameters showed no significant differences. Pharmacodynamic scores for females showed delayed recovery compared with that for males. CYP3A4 activity was higher in females than in males (p = 0.030). There was no serious adverse event, and adverse event incidence was not different between the sexes. Zolpidem exposure was about 30% higher in females than in males. Delayed pharmacodynamic score recovery in females could be related to higher zolpidem concentrations. Although apparent clearance was lower in females, systemic clearance might not be the cause of the different exposures to zolpidem.

SummaryBackgroundDWP14012 (fexuprazan), a novel potassium‐competitive acid blocker, is under development for the treatment of acid‐related disorders.AimsTo compare the pharmacodynamics (PDs), pharmacokinetics (PKs) and safety of DWP14012 among healthy subjects of Korean, Caucasian and Japanese descent.MethodsA randomised, double‐blind, placebo‐controlled, single‐ and multiple‐dose study was conducted. Ten subjects in each dose group (40, 60 or 80 mg for Koreans; 40 or 80 mg for Caucasians; 20, 40 or 80 mg for Japanese) were randomly assigned to DWP14012 or a placebo. Twenty‐four‐hour intragastric pH measurements and serial blood samples were collected for PK/PD evaluation. The PK/PD parameters were compared between each ethnicity.ResultsThe extent of gastric acid suppression was similar among the ethnicities; the mean percentages of time that the intragastric pH was above 4 after multiple doses of 40 mg in the Korean, Caucasian and Japanese subjects were 64.3%, 62.8% and 70.3%, respectively, and the corresponding values for the 80 mg dose were 94.8%, 90.6% and 90.6% respectively. The changes in serum gastrin were not clinically significant between all three ethnicities. The systemic exposure of DWP14012 was similar between the three ethnicities after the 40 mg doses but slightly lower in Caucasian and Japanese subjects after the 80 mg doses. Gastric acid suppression by DWP14012 showed a clear exposure‐response relationship in the three ethnicities.ConclusionsGastric acid suppression by DWP14012 was similar among the Korean, Caucasian and Japanese subjects in this study, and the PK, PK‐PD relationships and safety were also similar among the three ethnicities. DWP14012 could be used without consideration of ethnicity.

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Omeprazole blocks the gastric H + /K + adenosine triphosphatase, thus inhibiting gastric acid secretion, and is metabolized by cytochrome P450 (CYP) 2C19. Due to the physiological changes in the elderly, there are different pharmacokinetic consequences compared to young people. The aim of this study was to evaluate the pharmacokinetic profiles of omeprazole in 15 elderly participants according to the CYP2C19 genotype. The concentration-time profiles of omeprazole and its metabolites, 5-hydroxy (5-OH) omeprazole and omeprazole sulfone, were similar between the CYP2C19 extensive metabolizer (EM) and intermediate metabolizer groups. In contrast, when comparing the EM group and CYP2C19 poor metabolizer (PM) group, the EM/PM geometric mean ratio (95% confidence interval) of area under the plasma concentration-time curve from time of dosing to the last measurable concentration was 0.52 (0.27-1.01) and that of the IM group was 0.71 (0.32-1.59), indicating that the exposure of omeprazole in the PM group was increased. The exposure of 5-OH omeprazole was significantly decreased in the PM group when compared to the EM group, with an EM/PM geometric mean ratio (95% confidence interval) of 2. 20 (1.50-3.22). In conclusion, the tendency of drug exposure according to the CYP2C19 genotype in the elderly and young adults was similar in that the exposure level was highest in the PM group. However, when compared to young adults, the difference between the genotype groups was smaller in the elderly.

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