CHLOROQUINE BIOASSAY OF PLASMA SPECIMENS OBTAINED FROM SOLDIERS ON CHLOROQUINE PLUS DOXYCYCLINE FOR MALARIA PROPHYLAXIS

In this study we describe the application of a bioassay for measuring chloroquine equivalent concentrations in plasma samples obtained from soldiers on chloroquine (300 mg weekly) and doxycycline (50 or 100 mg daily) for malaria prophylaxis. Chloroquine, its principal metabolite monodesethylchloroquine and doxycycline were also measured by high per formance liquid chromatography (HPLC). Physiological concentrations of doxycycline did not interfere with the measurement of chloroquine equ ivalent concentrations. The correlation between bioassay and HPLC was r(s)=0.88, with a median bioassay/HPLC chloroquine concentration ratio of 1.1 (range 0.6-2.4, n=26). The bioassay is a valuable method, part icularly under field conditions, for measuring chloroquine concentrati ons and can be very helpful in distinguishing drug failures from eithe r poor compliance or inadequate drug absorption. Copyright (C) 1996 Au stralian Society for Parasitology. Published by Elsevier Science Ltd.