Adverse reactions to quinidine in hospitalized patients: findings based on data from the Boston Collaborative Drug Surveillance Program.

This study systematically analyzed the incidence and variety of adverse reactions to quinidine sulfate in 652 consecutively monitored hospitalized patients. Fourteen percent of the patients sustained adverse reactions of sufficient severity to warrant discontinuation of the drug. These reactions include GI intolerance, cardiac arrhythmias, fever with and without associated hepatic dysfunction or leukopenia, cinchonism, and hemolytic anemia. Cardiac arrhythmias were infrequent and, when present, generally occurred within 3 days of institution of quinidine therapy. There were no quinidine-related fatalities in this study group.