Disopyramide in acute myocardial infarction: problems with changing pharmacokinetics

Area of Science:

• Pharmacology
• Cardiology
• Clinical Pharmacy

Background:

• Serum disopyramide concentrations are often lower in acute myocardial infarction (MI).
• This is typically attributed to reduced oral bioavailability.
• However, intravenous (IV) administration may also be affected.

Purpose of the Study:

• To investigate disopyramide pharmacokinetics in patients with acute MI and cardiac dysrhythmias receiving IV therapy.
• To assess if drug clearance changes during the acute phase and subsequent recovery.

Main Methods:

• Routine pharmacokinetic data collection from 6 patients with acute MI and cardiac dysrhythmias.
• Initial treatment with intravenous disopyramide.
• Calculation of drug clearance during the acute phase and later time points.

Main Results:

• Consistently lower serum disopyramide concentrations than expected (average decrease of 2.6 µg/ml).
• Higher drug clearance in the acute phase (6.7 ± 1.5 L/h) compared to expected values (3-4 L/h).
• Increased drug concentrations later (average increase of 2.8 µg/ml) with lower clearance (3.1 ± 0.6 L/h).

Conclusions:

• Intravenous disopyramide therapy is subject to changing pharmacokinetic parameters in acute myocardial infarction.
• Drug clearance is significantly elevated during the acute phase post-MI.
• Dosage adjustments are crucial due to altered pharmacokinetics in MI patients.