A Rapid and Sensitive HPLC Method for the Analysis of Progunail and Cycloguanil in Plasma:Application to Single Dose Pharmacokinetic Studies

A simple, sensitive cost-effective and reproducible reverse phase high performance liquid chromatographic (HPLC) method was developed to quantitate plasma levels of proguanil (PGN) and its active metabolite, cycloguanil (CGN) in order to conduct single dose pharmacokinetic studies. The drug and the internal standard were a dded to plasma samples, vortexed and rendered alkaline with 2 M NaoH and the samples extracted with ether, evaporated to dryness and the residue was reconstituted in methanol, whi rlmixed before injecting an aliquot onto the HPLC system. The calibration plots were linear over the concentration range up to 4.0 μg /ml. The correlation coefficients (r) were of the order of 0.99 and above for both PGN and CGN. The ion pair method was carried out on a 5 μ reverse phase C-18 column, using perchlorate ion as the counter ion and ultra violet detection at 254 nm. The method was reproducible with coefficient of variation for P GN and CGN, being less than 4.0 %. PGN was well resolved from its active metabolite, CG N, and the internal standard, pyrimethamine. The limit of detection of PGN was 10 ng / ml and the recovery was greater than 95% in plasma. The analytical method therefore, exhi bits good precision and sensitivity in detecting and quantifying PGN and CGN and has bee n demonstrated to be suitable for the pharmacokinetic studies of proguanil. The clinic al applicability of the method was assessed by the preliminary pharmacokinetic study of PGN and CGN, in f ifteen healthy volunteers. The in vivo study was carried out according to a single dose randomized design.