POSSIBLE INHIBITION OF HEPATIC-METABOLISM OF QUINIDINE BY ERYTHROMYCIN

Objective: To present and analyze a patient case illustrating a possib le drug interaction between quinidine and erythromycin. Methods: This is a case report of one hospitalized patient, The setting for this ana lysis was a university hospital. Through a MEDLINE search of all Engli sh medical literature (1966 to 1994) documenting possible interactions between quinidine and erythromycin, retrospective patient chart revie w, and analysis of the relationship between serum quinidine concentrat ions and significant clinical events, deduce the possibility of a quin idine and erythromycin pharmacokinetic and pharmacodynamic interaction in this particular patient case. Results: This case demonstrated a pr obable erythromycin-quinidine pharmacokinetic interaction that led to a decrease in quinidine apparent clearance, an increase in quinidine s erum concentrations, and a possible quinidine toxicity. Conclusion: Se rum quinidine concentrations, electrocardiograms, and other factors th at may predispose patients to torsades de pointes, such as hypokalemia and hypomagnesemia, should be monitored closely if quinidine is coadm inistered with erythromycin.