A large, 832-patient, multicenter, international study10 recently confirmed the increased efficacy of combination therapy using interferon and ribavirin. In this study, previously untreated patients received 3 million U interferon alfa-2b 3 times a week combined with 1 to 1.2 mg ribavirin for 6 or 12 months. A control group of patients received the same dose of interferon and a placebo for 12 months. Thirteen percent of those receiving monotherapy discontinued treatment. In another US multicenter study, Davis et al 12 evaluated 345 patients who had previously been treated with interferon but had relapsed following an initial response.
Most side effects improve rapidly with dosage reduction.
The major side effect of ribavirin is reversible hemolytic anemia. The anemia becomes manifest early in the course of treatment and, at times, may be severe enough to result in discontinuation of therapy. Patients with significant cardiac disease may be at risk because of an occasional rapid fall in hemoglobin. The other significant side effect is the teratogenicity of ribavirin. Thus, this agent must be used with caution in men and women capable of reproduction.