Conversion from intravenous procainamide to oral sustained release tablets in cardiac patients.

There is as yet no established method for converting from intravenous to oral sustained release procainamide (Procan SR; Parke-Davis Canada Inc). The pharmacokinetics of simultaneous discontinuation of intravenous procainamide and administration of oral sustained release procainamide was studied in six patients with ventricular tachyarrhythmias. Patients were converted after ensuring that steady-state concentrations were achieved with intravenous procainamide. Serum procainamide levels were obtained at the time of conversion and 0.5, 1.0, 1.5, 2.0, 3.0, 4.0 and 6.0 h after conversion. The mean steady-state concentration (23.7 +/- 8.9 mumols/L) and the adjusted mean serum procainamide concentration with Procan SR (25.3 +/- 7.9 mumols/L) were not significantly different. This indicated that the serum procainamide concentration obtained with the intravenous infusion was not compromised when the patients were switched to oral therapy. Although mean percentage serum procainamide concentration fluctuation was 102.6 +/- 92.5, all patients tolerated the conversion well. Therefore, the method used in this study is an acceptable method of conversion.

Calcium-channel blockers in acute myocardial infarction.

The calcium-channel blockers are useful in treating a variety of cardiovascular disorders. Due to their antiischemic and spasmolytic properties, these agents have been studied in the prophylaxis and treatment of acute myocardial infarction. This article reviews this application with respect to reduction of mortality, infarct size, and reinfarction rate. Of the agents currently available for clinical use, nifedipine has been studied most extensively. This agent shows no beneficial effects in this setting and its use may in fact be harmful. Of the few trials that have been conducted with verapamil, none have shown decreased mortality. Verapamil may reduce infarct size although further confirmation is required. Diltiazem is the only agent that has been shown to have short- and long-term benefits in the patient with acute myocardial infarction. Proper patient selection is of utmost importance in ensuring successful therapy. In particular, those patients with non-Q-wave infarctions and/or normal left ventricular function can be expected to derive the most benefit in terms of reducing mortality and reinfarction rate associated with the acute event.