HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF A POTENT ANDSELECTIVE HIV PROTEASE INHIBITOR (L-735,524) IN RAT, DOG AND MONKEY PLASMA

A high-performance liquid chromatographic method coupled with liquid-l iquid sample extraction and ultraviolet detection has been developed f or the quantification of L-735,524 (I), a potent, highly selective and orally bioavailable inhibitor of recombinant human immunodeficiency v irus (HIV) protease in rat, dog and monkey plasma. The present method is reproducible and reliable with limits of quantification of 25, 12.5 and 6.25 ng/ml, respectively for rat, dog and monkey plasma. The stan dard curve was linear over the range of 6.25-2000 ng/ml in the biologi cal fluid. The mean coefficients of variation for concentration within the range of standard curve were 7.94, 6.91 and 4.52%, respectively, for intra-day analysis and 5.58, 9.27 and 5.45%, respectively, for int er-day analysis. The recoveries of I and L-707,943 (II), an analog of I used as the internal standard, from plasma samples were all over 88% through the extraction procedure. I and II are stable in mobile phase over a 48-h period while waiting for injection at ambient temperature and over a 144-h period in rat, dog and monkey plasma while stored at -20 degrees C. Aqueous solubility of I is pH dependent, 60 mg/ml at p H 3.5 and 0.3 mg/ml at pH 4.8. The analytic procedures described in th is report have been successfully employed to quantify the concentratio n of I in rat, dog and monkey plasma and provide the kinetic informati on for toxicological and pharmacological studies.