Safety profile of antiviral medications: A pharmacovigilance study using the Italian spontaneous-reporting database

Purpose. The results of an analysis of suspected antiviral-associated adverse drug reactions (ADRs) in Italy over a 22-year period are presented. Methods. A case/non-case analysis was conducted using ADR reports compiled in the nationwide spontaneous-reporting database through September 2010. All reported events included in the analysis were evaluated and coded by drug safety experts; causality assessments were performed according to the algorithm of Naranjo et al. The association between an adverse reaction and antiviral use was assessed by estimating the reporting odds ratio (ROR), with 95% confidence interval (Cl), as a measure of disproportionality. Results. Overall, 863 reports of suspected ADRs involving antivirals and 42,430 reports of adverse reactions to other drugs were identified; of those events, 3.3% and 64.3% were determined to be definite or probable ADRs, respectively, and an additional 32.4% were deemed possibly drug related. Several ADRs were disproportionately associated with antivirals relative to other drugs: renal colic (ROR, 25.5; 95% CI, 13.3-49.0), lactic acidosis (ROR, 18.6; 95% Cl, 9.2-37.7), depression (ROR, 18.0; 95% CI, 11.6-27.9), anemia (ROR, 15.9; 95% CI, 12.3-20.4), hallucination (ROR, 4.3; 95% Cl, 2.7-7.1), neutropenia (ROR, 4.1; 95% Cl, 2.9-5.8), acute renal failure (ROR, 3.9; 95% Cl, 2.3-6.4), fever (ROR, 3.8; 95% Cl, 2.8-5.1), hyperpyrexia (ROR, 2.9; 95% Cl, 1.7-4.9), and asthenia (ROR, 1.8; 95% Cl, 1.2-2.8). Conclusion. Analysis of data from a large Italian database showed that, among antiviral agents, the ribavirin-interferon combination, acyclovir, valacyclovir, indinavir, and zidovudine accounted for the most serious hematologic, neuropsychiatric, and renal ADRs.