MIRTAZAPINE PHARMACOKINETICS IN HEALTHY THAI VOLUNTEERS

Mirtazapine (MZP) is a third-generation antidepressant with a dual mode of action. To investigate the pharmacokinetic profile of MZP in 22 healthy Thai volunteers (12 males, 10 females), each volunteer received a single 30mg oral dose of MZP in the form of conventional tablets, in the fasting state. Serial blood samples were taken and MZP plasma concentrations were measured from 0 to 72 h by a HPLC-UV spectrometry validated method. Pharmacokinetic parameters were calculated and statistically analyzed from MZP plasma levels. Means +/- standard deviations of the pharmacokinetic parameters were as follows: The rate of absorption, as measured by peak level (C-max) and peak time (t(max)) were 169.9 +/- 31.5 ng ml(-1) and 0.6 +/- 0.2 h, respectively. The extent of absorption, as measured by area under the curve from zero time to the last measurable sampling time (AUC(0-last)), and total area under the curve from time zero to infinity (AUC(0-inf)), were 564.4 +/- 241.6 ng ml(-1) h and 678.6 +/- 283.9 ng ml(-1) h, respectively. Elimination rate, characterized by termination half-life (t(1/2)), was 10.4 +/- 5.6 h. A comparison with published pharmacokinetic studies on MZP demonstrated a significantly greater absorption rate and elimination in Thai subjects. Meanwhile, the total extent of absorption (AUC(0-inf)) of MZP was not different (p> 0.05).