Specific radioimmunoassays for the measurement of stavudine in human plasma and urine.

Sensitive and specific radioimmunoassays (RIAs) have been developed and validated for the determination of stavudine, a nucleoside analog possessing anti-human immunodeficiency virus (HIV) activity, in human plasma and urine. The hemisuccinate of stavudine was conjugated with histamine and radioiodinated to yield the radiotracer. Antisera were produced by injecting the immunogen, stavudine-hemisuccinate-bovine thyroglobulin, into rabbits. The antisera exhibited high specificity for stavudine as the structurally related analogs and other anti-HIV agents did not interfere in the assays. The methods could reliably quantitate stavudine in plasma from 2.5-100 ng ml-1 and in urine from 5.0-1000 ng ml-1 (after 2.5-fold dilution) with good accuracy and precision. The lower limits of quantitation were 2.5 ng ml-1 in human plasma and 5.0 ng ml-1 in urine (after 2.5-fold dilution). The RIA methods were applied to the analysis of stavudine in plasma and urine obtained from HIV-infected patients receiving the drug in clinical trials.