The boosting of didanosine by allopurinol permits a halving of the didanosine dosage

The pharmacokinetic boosting of didanosine by allopurinol was studied in four HIV-1-positive patients taking didanosine, hydroxyurea and chloroquine, in whom the didanosine dosage was halved and allopurinol was added at 300 mg/day. Didanosine plasma levels and HIV-1-RNA levels remained unchanged after 4 and 17-20 months, respectively. Halving the didanosine dosage with allopurinol reduces treatment costs, and may lend itself to once-daily combination therapies, which are of particular interest for HIV therapy in resource-poor countries.