Twice-weekly dapsone for primary prophylaxis against Pneumocystis carinii pneumonia in HIV-1 infection: Efficacy, safety and pharmacokinetic data

Objectives: In this study we evaluated the pharmacokinetics, efficacy and safety of dapsone given 100 mg twice weekly as primary prophylaxis against Pneumocystis carinii pneumonia (PCP) in patients with HIV-1 infection. Methods: This was a prospective open trial, evaluating a total of 55 HIV-1-infected patients with CD4 cell counts below 200/mm³ and without previous episodes of PCP. Plasma concentrations of dapsone were determined with high-performance liquid chromatography (HPLC). After a mean follow-up of 471 days, the PCP rates per year of observation were 6.79%. Discontinuation of treatment as a result of severe side effects was required in four patients (7.5%). At steady state, mean plasma concentrations 24, 72, 96 and 144 h following the administration of dapsone were 1.46±0.8, 0.28±0.20, 0.30±0.21 and 0.37±0.27 mg/L, respectively. Dapsone plasma levels showed a high interpatient variability. The values for the pharmacokinetic parameters were comparable to those described for healthy volunteers. Conclusions: The administration of 100 mg twice weekly of dapsone seems appropriate to maintain effective plasma concentrations of the drug and to prevent PCP with good safety in patients with HIV-1-related immunodeficiency.