PROLONGED QUINIDINE HALF-LIFE WITH ASSOCIATED TOXICITY IN A PATIENT WITH HEPATIC-FAILURE

A markedly prolonged quinidine elimination half-life due to hepatic fa ilure and resultant quinidine toxicity occurred in a 57-year-old man w ith a history of atrial fibrillation. A prolonged QT interval, develop ment of torsades de pointes, and a serum quinidine concentration of 3. 1 mu g/ml contributed to a decision favoring permanent pacemaker impla ntation. The apparent quinidine half-life ranged from 66-99 hours and was associated with QT prolongation and persistent U waves. On discont inuing quinidine, all signs associated with toxicity resolved as serum quinidine concentrations decreased, which resulted in reversal of the decision to implant a permanent pacemaker. This case reports an extre mely long quinidine elimination half-life and reillustrates the import ance of drug pharmacokinetics in patient care.