Pharmacokinetics of loratadine and its active metabolite descarboethoxyloratadine in healthy Chinese subjects.

AIM

To investigate the pharmacokinetics of loratadine (LOR) and its active metabolite descarboethoxyloratadine (DCL) in healthy Chinese subjects.

METHODS

Twenty healthy Chinese male subjects received a single oral dose of LOR 20 mg. A sensitive liquid chromatography-tandem mass spectrometry method (LC/MS/MS) was used for the determination of LOR and DCL in plasma.

RESULTS

Mean maximum concentration (C(max)) was found (17+/-14) microg/L for LOR at 1.2 h and (16+/-9) microg/L for DCL at 1.5 h. Mean area under the plasma concentration-time curve from zero to infinity (AUC(0-infinity)) was (47+/-49) microg x h x L(-1) for LOR and (181+/-122) microg x h x L(-1) for DCL, respectively. The apparent elimination half-life (T1/2) of LOR was (6+/-4) h, and that of DCL was (13.4+/-2.6) h. The ratios of AUC(DCL)/AUCLOR ranged from 0.36 to 54.5.

CONCLUSION

LOR was rapidly absorbed and transformed to DCL. AUC of the parent drug was extremely variable, while AUC of the active metabolite DCL was moderately variable after an oral dose of LOR to Chinese subjects.