Disopyramide pharmacokinetics in patients with acute myocardial infarction

Effects of cardiovascular disease on pharmacokinetics

The pathophysiologic changes occurring in cardiovascular disease can affect the kinetics of drugs in several different ways. The present review examines these modifications and the underlying mechanisms. The kinetics of specific agents, such as antiarrhythmic, antihypertensive, cardiotonic, and other drugs are considered, and the clinical implications are outlined. The clinician should be aware of these modifications, because they require an adjustment of the dosage regimen. A rational basis for a correct therapeutic choice can be provided by adequate knowledge of these modifications.

Conversion from intravenous to oral slow-release disopyramide in acute myocardial infarction

Twelve patients with acute myocardial infarction were given 1.5 mg/kg/5 min bolus +0.4 mg/kg/hr 6 hr IV infusion of disopyramide followed by 250 mg twice daily of a slow-release oral formulation of this drug. Plasma concentrations of total disopyramide rapidly reached steady-state within the therapeutic margins. The plasma steady-state concentrations of the major metabolite mono-N-dealkyl-disopyramide (MND) showed large intra-individual variations. There was no correlation between plasma levels of either disopyramide or MND and the occurrence of anticholinergic side effects. The drug had no significant effect on mean blood pressure, heart rate, or ECG intervals. This therapeutic regimen, including conversion from the IV form to oral slow-release tablets, could be recommended in myocardial infarction.

Disopyramide in acute myocardial infarction: problems with changing pharmacokinetics

In the acute phase of myocardial infarction it is recognized that serum disopyramide concentrations may be lower than expected. This has generally been attributed to reduced oral bioavailability. This report describes data obtained routinely from 6 patients with acute myocardial infarction and cardiac dysrhythmias treated initially with intravenous disopyramide. Serum disopyramide concentrations were consistently lower than expected, on average by 2.6 micrograms/ml. This was interpreted as being due to relatively high drug clearance, calculated as 6.7 +/- 1.5 l/h, compared to expected values of 3-4 l/h. Dosage schedules determined on the basis of the acute phase pharmacokinetics subsequently produced higher than predicted concentrations at later times on average by 2.8 micrograms/ml. Clearance at this time was calculated to be 3.1 +/- 0.6 l/h. Thus even with intravenous disopyramide therapy there are problems with changing pharmacokinetic parameters after myocardial infarction.