The National Cancer Institute phase I study of 2',3'-dideoxyinosine administration in adults with AIDS or AIDS-related complex: analysis of activity and toxicity profiles.

2',3'-Dideoxyinosine (didanosine; ddI) was administered to 37 adults with AIDS or AIDS-related complex in an escalating-dose phase I study. Groups of three or four patients received intravenous dosages of 0.4 mg/(kg.d) to 25.6 mg/(kg.d) divided into two or three daily doses for 2 weeks, followed by oral ddI at twice the intravenous dosages. When given with antacids, ddI was well absorbed by the oral route and penetrated into the cerebrospinal fluid. The patients had an increase in mean number of CD4+ cells from 114/mm3 at entry to 161/mm3 at week 6 (P = .00004). They also had an increase in the CD4+/CD8+ ratio and in total number of lymphocytes. Sixteen of 18 evaluable patients had a decrease in levels of human immunodeficiency virus p24 antigen by week 6 (P = .0034). Many patients reported increased energy and appetite and gained weight. Dose-limiting toxicities at high dosages were painful peripheral neuropathy and sporadic pancreatitis. However, dosages up to 9.6 mg/(kg.d) have been tolerated in patients for 11-14 months. Thus, ddI has activity against human immunodeficiency virus at dosages that can be tolerated for approximately 1 year. However, life-threatening pancreatitis is a possible complication even at low dosages, and the best ways to manage and avoid adverse effects are still under study.