The Antiviral Effect of Zidovudine and Ribavirin in Clinical Trials and the Use of p24 Antigen Levels as a Virologic Marker

Abstract

The inhibition of viremia and p24 core antigenemia in patients infected with human immunodeficiency virus (HIV) was evaluated in separate multicenter, double-blind, placebo-controlled trials of zidovudine and ribavirin. Of 29 patients (14 with AIDS and 15 with AIDS-related complex [ARC]) enrolled in the zidovudine study, 16 received 250 mg of zidovudine every 4 h and 13 received placebo. No difference in HIV isolation from peripheral blood was observed at 20 w in treated versus placebo groups (79% vs. 82%). In patients tolerating zidovudine, mean p24 antigen levels dropped to 8.2% ± 8.1% of their baseline values, whereas in placebo recipients mean p24 antigen levels declined to 61.3% ± 40.8% of their baseline values (P < .005). In the ribavirin study, patients with ARC treated with either 800 mg or 600 mg of ribavirin daily or with placebo showed no consistent reduction in p24 antigenemia or decrease in HIV isolation. These data indicate that decline in p24 antigenemia can be a useful virologic marker in evaluation of new antiretroviral drugs.