Pharmacokinetics of tramadol in a diverse healthy Chinese population

Drug disposition may show ethnicity and gender differences. The objective of this study is to assess whether there are gender and ethnic differences in the pharmacokinetics of tramadol.

Fifty healthy volunteers from five different ethnic Chinese groups (Han, Mongolian, Korean, Uygur and Hui) were recruited, and blood samples were obtained for up to 36 h after oral administration of a single 100 mg capsule of tramadol. The plasma concentration-time course of tramadol was measured by high-performance liquid chromatography and the pharmacokinetic estimated.

The mean maximum plasma concentration (C(max)) of tramadol was different between Chinese males and females. There were also statistically significant differences between Hui and the other ethnic groups in tramadol's clearance (CL/F), volume of distribution (V(d) /F), C(max) and area under the plasma concentration time curve (AUC(0-∞)) (P < 0·05).

The pharmacokinetics of tramadol was different in Hui subjects compared to the other Chinese ethnic groups. Tramadol CL/F may also show gender differences.