Stability and preliminary pharmacokinetic studies of 1-(2-chloroethyl)-3-[1-(5'-paranitrobenzoyl-2',3'-isopropylidene)-alpha, beta-D-ribofuranosyl]-1-nitrosourea (RFCNU), a nonimmunosuppressive nitrosourea.

Using high-performance liquid chromatography, the stability of RFCNU was monitored as a function of pH in aqueous buffers at 37 degrees C and as a function of temperature in plasma. The kinetics of degradation of RFCNU are apparently first-order. The log kappa-pH profile demonstrated the hydroxyl ion-catalyzed solvolysis and a maximum stability around pH 3.0. This analytic assay was reliable for quantitating intact RFCNU in biologic fluids. After administration of 400 mg of RFCNU orally to a female patient, no intact drug was excreted in the urine and plasma levels were very low.