High Rate of Didanosine-Related Mitochondrial Toxicity in HIV/HCV-Coinfected Patients Receiving Ribavirin

Background Nucleoside analogues may induce mitochondrial toxicity, particularly didanosine. Ribavirin increases didanosine exposure, which might be clinically relevant when coadministered in HIV/HCV-coinfected patients.Objective To evaluate, among 89 patients receiving highly active antiretroviral therapy (HAART) and therapy for chronic hepatitis C, clinically relevant mitochondrial toxicity in those treated with concomitant ribavirin and didanosine (n=35, 39%).Methods From January 2000 to July 2002 longitudinal analysis of the incidence and clinical course of didanosine-related hyperamylasaemia, pancreatitis, hyperlactataemia/lactic acidosis or neuropathy. Risk factors were evaluated using univariate and multivariate Cox's proportional hazards model.Results Among 35 patients who received concomitant didanosine (400 mg/day in 86%) and ribavirin (=10 mg/kg/day in 91%), 20 (57%) developed one or more adverse events after a mean of 87 days. Most frequent laboratory abnormalities were hyperamylasaemia (18 patients, 51%) and hyperlactataemia (eight patients, 23%). Acute pancreatitis and symptomatic hyperlactataemia developed in 10 (28%) and six (17%) patients, respectively. Two patients (6%) with pancreatitis and severe lactic acidosis died; the other patients recovered uneventfully despite continuation of anti-HCV therapy in 83% after didanosine withdrawal in 40%. In the Cox's model higher baseline amylase levels (HR: 1.04, 95% CI: 1.02–1.06, P=0.001) and three nucleoside reverse transcriptase inhibitor-based HAART (HR: 5.3, 95% CI: 1.73–16.24, P=0.003) were significantly associated to toxicity.Conclusions The coadministration of didanosine and ribavirin should be avoided in HIV/HCV-coinfected patients, due to a high rate of clinically significant toxicity, particularly in triple nucleoside-based HAART. Amylase levels should be strictly monitored, especially if elevated at baseline.