Pharmacokinetic drug interaction between atorvastatin and ezetimibe in healthy Korean volunteers

Atorvastatin and ezetimibe are frequently co-administered to treat patients with dyslipidemia for the purpose of low-density lipoprotein cholesterol control. However, pharmacokinetic (PK) drug interaction between atorvastatin and ezetimibe has not been evaluated in Korean population. The aim of this study was to investigate PK drug interaction between two drugs in healthy Korean volunteers. An open-label, randomized, multiple-dose, three-treatment, three-period, Williams design crossover study was conducted in 36 healthy male subjects. During each period, the subjects received one of the following three treatments for seven days: atorvastatin 40 mg, ezetimibe 10 mg, or a combination of both. Blood samples were collected up to 96 h after dosing, and PK parameters of atorvastatin, 2-hydroxyatorvastatin, total ezetimibe (free ezetimibe + ezetimibe-glucuronide), and free ezetimibe were estimated by non-compartmental analysis in 32 subjects who completed the study. Geometric mean ratios (GMRs) with 90% confidence intervals (CIs) of the maximum plasma concentration (C(max,ss)) and the area under the curve within a dosing interval at steady state (AUC(τ,ss)) of atorvastatin when administered with and without ezetimibe were 1.1087 (0.9799–1.2544) and 1.1154 (1.0079–1.2344), respectively. The corresponding values for total ezetimibe were 1.0005 (0.9227–1.0849) and 1.0176 (0.9465–1.0941). There was no clinically significant change in safety assessment related to either atorvastatin or ezetimibe. Co-administration of atorvastatin and ezetimibe showed similar PK and safety profile compared with each drug alone. The PK interaction between two drugs was not clinically significant in healthy Korean volunteers.

Pharmacokinetics and safety profiles of tadalafil/tamsulosin HCl fixed-dose combination capsule under fasted and fed condition in healthy volunteers

Co-administration of tadalafil and tamsulosin HCl in patients with benign prostate hyperplasia and erectile dysfunction is increasing in clinical settings. Development of fixed-dose combination (FDC) of tadalafil and tamsulosin HCl could contribute to improving patients' adherence and treatment efficacy. We evaluated the pharmacokinetics and safety profiles of a newly developed fixed-dose combination capsule of tadalafil 5 mg/tamsulosin HCl 0.4 mg in comparison with co-administration of each formulation in healthy volunteers under fasted and fed conditions. Two randomized, open-label, single-dose, two-way, crossover studies were completed in 29 subjects under fasted condition, and 33 subjects under fed condition. Serial blood sample collection for PK analysis was conducted up to 72 hours after dosing, and PK parameters were calculated using non-compartmental analysis. Geometric mean ratios and 90% confidence intervals of the C(max) and AUC(last) were used to evaluate comparative bioavailability. In both fasted and fed condition studies, the bioequivalence was established. The most common adverse drug reactions were orthostatic hypotension and headache with no statistical difference between treatment groups. All subjects with orthostatic hypotension recovered at follow-up test. Although changes in vital signs from baseline were statistically significant, there were no subjects with systolic blood pressure < 90 mmHg and there were no clinically meaningful signs or symptoms associated. FDC of tadalafil and tamsulosin HCl can be an alternative to co-administration of individual drugs for providing better compliance. Changes in blood pressure should be kept in mind when tadalafil and tamsulosin HCl are co-administered in clinical settings.