Single-dose Pharmacokinetics of Desloratadine in Healthy Korean Volunteers

건강한 한국인 자원자에서 Desloratadine 단회투여에 의한 약동학적 특성 연구

Background: Desloratadine, a nonsedating histamine $H_1$ receptor antagonist, is an orally active major metabolite of loratadine. We investigated the pharmacokinetic (PK) characteristics of a single oral dose of desloratadine in healthy Korean male volunteers. Methods: A parallel group, rising single dose (5, 10 and 20 mg), block (dose) randomized, double-blind, placebo-controlled study was conducted in 36 healthy male volunteers. Subjects were randomized into each dose group (placebo: active drug= 2: 10 subjects). Plasma concentrations of deslorataine and its major metabolite, 3-OH desloratadine were measured till 168 hours after drug administration. The results were compared to Caucasian data from a previous study. Results: The mean $AUC_{inf}$ were 37.9, 81.8, 172.2 ${\mu}g*h/L$ and $C_{max}$ were 2.4, 5.0, 9.9 ${\mu}g/L$ in 5, 10 and 20 mg dose groups, respectively. The range of mean metabolic ratio by dose groups was $0.67{\sim}0.75$. $C_{max}$ and $AUC_{inf}$ of desloratadine and 3-OH desloratadine exhibited linear properties over a dose range of 5 to 20 mg. Mean terminal elimination half-life ($t_{1/2}$) was 25 hours for desloratadine, and 38 hours for 3-OH desloratadine. The geometric mean ratios(90% confidence interval) for Koreans to Caucasians were 1.3 (1.06-1.60) for dose-normalized $AUC_{inf}$ and 1.3 (1.11-1.51) for dose-normalized $C_{max}$; PK parameters of desloratadine in Koreans showed statistically significant differences with the PK parameters in Caucasians. However, desloratadine has a wide safety margin and flat dose-response relationship, so approximately 1.3 times higher exposure is not thought to be clinically significant. Conclusions: The PK parameters of desloratadine in Koreans were linear according to dose increments. Comparison of the $AUC_{inf}$ and $C_{max}$ values between Koreans and Caucasians indicates no clinically relevant difference that requires dosage adjustment for desloratadine in Koreans.