Objectives. To obtain preliminary information on the pharmacokinetic properties, tolerance, safety, and antiviral activity of combination therapy with stavudine and didanosine in children with advanced human immunodeficiency virus (HIV) infection.
Methods. Eight children (median age, 6.6 years; range, 2.8 to 12 years) with advanced HIV disease (median CD4+ lymphocyte count at baseline, 42 cells/µL; range, 8 to 553 cells/µL) were treated with stavudine (2 mg/kg per day in two divided doses) and didanosine (180 mg/m2 per day in two divided doses) for 24 weeks. Seven children had histories of prior zidovudine therapy. All children had received stavudine alone for 19 to 33 months before the addition of didanosine to the treatment regimen. Children were assessed clinically and with laboratory studies at baseline, weekly through week 4 of combination therapy, and every 4 weeks thereafter.
Results. Analysis of stavudine and didanosine plasma half-life values, clearances, and area under the plasma concentration-versus-time curves revealed no obvious clinical pharmacokinetic interaction between the drugs through study week 12. Combination therapy was well tolerated, and there were no drug-associated clinical or laboratory adverse events. Signs and symptoms of peripheral neuropathy were not observed. All three children with baseline CD4+ lymphocyte counts greater than 50 cells/µL had greater than 20% increases in their counts within the first 12 weeks of therapy; CD4+ lymphocyte count increases were not observed in the other children. Plasma HIV RNA concentrations showed median declines of 0.88 log10 (range, -3.41 log10 to 0.31 log10) and 0.30 log10 (range, -0.63 log10 to 0.89 log10) at study weeks 12 and 24, respectively.
Conclusions. Combination therapy with stavudine and didanosine was well tolerated and safe in this small group of children with advanced HIV disease. Plasma HIV RNA concentration declines suggest a favorable effect of therapy on virus load. These findings should be confirmed, and the regimen's clinical efficacy should be examined, in controlled studies of HIV-infected children with less-advanced disease.