Quantification of (+)-calanolide A, a novel and naturally occurring anti-HIV agent, by high-performance liquid chromatography in plasma from rat, dogand human

A HPLC method was validated for quantification of (+)-calanolide A (1), a n ovel anti-HIV agent, in rat, dog and human plasma. The synthetic intermedia te (+/-)-12-oxocalanolide A (2) was found to be a suitable internal standar d. Compounds were extracted from plasma using a solid-phase C-18 cartridge and quantified over the assay range of 12.5 to 800 ng/ml. The method was ut ilized to determine (+)-calanolide A pharmacokinetics in rats, dogs and hum ans. This is the first report of a validated HPLC assay for determination o f (+)-calanolide A concentrations in rat and dog plasma as well as human pl asma obtained from clinical trials. There was no evidence of in vivo epimer ization of (+)-calanolide A to its inactive epimer (+)-calanolide B (3). (C ) 2000 Elsevier Science B.V. All rights reserved.