HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF 9-(3-PYRIDYLMETHYL)-9-DEAZAGUANINE (BCX-34) IN BIOLOGICAL-FLUIDS

9-(3-Pyridylmethyl)-9-deazaguanine (BCX-34), a new purine nucleoside p hosphorylase inhibitor, has selective immunosuppressive activity with potential therapeutic value in T-cell-mediated diseases. We now report a sensitive, specific and reproducible method for measurement of 9-(3 -pyridylmethyl)-9-deazaguanine in biological fluids using high-perform ance liquid chromatography (HPLC). 9-(3-Pyridylmethyl)-9-deazaguanine wall extracted from plasma using perchloric acid precipitation followe d by passage through Sep-Pak C-18 cartridges (average extraction effic iency, 64.6%). Standard curves were linear over the range of interest (28-1120 ng/ml in plasma and 200-4000 ng/ml in urine, r(2)>0.999). Wit hin-day and between-day coefficients of variation were less than 8%. T he limit of quantitation was 28 ng/ml in plasma and 200 ng/ml in urine . This HPLC method should be useful in future clinical studies with th is drug.