Safety and Efficacy of Didanosine Enteric-Coated Capsule in Patients with HIV-1 Infection

Didanosine (ddI) has been used to treat HIV infection, in combination with other anti-retroviral drugs, for over 15 years. However, the use of the original formulation of ddI was limited by serious gastro-intestinal adverse effects, which were mainly attributable to the buffer used to protect ddI from the effect of gastric pH. Didanosine enteric-coated capsule (ddI-EC), a more recently introduced formulation, is less likely to cause gastrointestinal intolerance and its absorption might not be compromised by food intake. In this review we discuss efficacy of ddI-EC-containing anti-retroviral combinations (cART) both in naive and previously treated patients. Because of its favorable resistance profile, ddI-EC has been shown to be potentially efficacious in rescuing patients in virological failure, even if they have nucleoside reverse transcriptase inhibitors (NRTI)-associated resistance mutations. However, ddI has been shown as a potent inducer of mitochondrial dysfunction. Peripheral neuropathy, severe hyperlactatemia and pancreatitis have all been described in patients exposed to ddI. Close monitoring of patients on ddI-EC-containing cART and low threshold for treatment modifications are required to prevent major complications. In the context of once daily cART, ddI-EC is a valid option, particularly when other agents are not available, or when other medical conditions preclude the use of drugs such as tenofovir or abacavir. The role of ddI-EC in second line cART may be even more important in resource-limited settings where additional options are lacking.