Pharmacokinetics of pirmenol in young and elderly subjects

Analysis of the variability of the pharmacokinetics of multiple drugs in young adult and elderly subjects and its implications for acceptable daily exposures and cleaning validation limits

The elderly constitute a significant, potentially sensitive, subpopulation within the general population, which must be taken into account when performing risk assessments including determining an acceptable daily exposure (ADE) for the purpose of a cleaning validation. Known differences in the pharmacokinetics of drugs between young adults (who are typically the subjects recruited into clinical trials) and the elderly are potential contributors affecting the interindividual uncertainty factor (UF_H) component of the ADE calculation. The UF_H values were calculated for 206 drugs for young adult and elderly groups separately and combined (with the elderly assumed to be a sensitive subpopulation) from published studies where the pharmacokinetics of the young adult and elderly groups were directly compared. Based on the analysis presented here, it is recommended to use a default UF_H value of 10 for worker populations (which are assumed to be approximately equivalent to the young adult groups) where no supporting pharmacokinetic data exist, while it is recommended to use a default UF_H value of 15 for the general population, to take the elderly into consideration when calculating ADE values. The underlying reasons for the large differences between the exposures in the young adult and elderly subjects for the 10 compounds which show the greatest separation are different in almost every case, involving the OCT2 transporter, glucuronidation, hydrolysis, CYP1A2, CYP2A6, CYP2C19, CYP2D6, CYP3A4 or CYP3A5. Therefore, there is no consistent underlying mechanism which appears responsible for the largest differences in pharmacokinetic parameters between young adult and elderly subjects.

Pharmacokinetics of multiple-dose oral cilostazol in middle-age and elderly men and women

Cilostazol is being developed for the treatment of intermittent claudication due to peripheral arterial disease (PAD). This study was conducted to investigate the effects of age and gender on the pharmacokinetics of cilostazol after multiple-dose administration. It was an open label, multiple-dose study of cilostazol administered to male and female subjects 50 years of age and older at a dose of 100 mg (oral tablet) twice daily for 7 days. Equal numbers of healthy male and female (7 per group), nonsmoking subjects stratified into age groups of 50 to 59 years, 60 to 69 years, and 70 years or older were enrolled. Serial plasma samples were obtained. Data were analyzed by model-independent methods. Cilostazol was absorbed at a moderate rate, with peak plasma concentrations occurring at an overall mean of 2.4 hours after administration. Cilostazol is extensively bound (95%), primarily to albumin. A trend toward increasing cilostazol free fraction with age was observed in the male subjects, which was explained by a decrease in plasma albumin concentration with age. Differences in plasma protein binding between age and gender groups (less than 15%) are not expected to have any clinical significance. Plasma cilostazol concentrations reached steady state by day 4. The pharmacokinetic characteristics of cilostazol were not affected by age or gender.