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Enhanced pirmenol elimination by rifampin
K A Stringer1, A B Cetnarowski, A Goldfarb
1Clinical Pharmacokinetics Laboratory, Millard Fillmore Hospital, Buffalo, New York 14209.
Journal of Clinical Pharmacology
|December 1, 1988
Summary
Rifampin significantly reduces pirmenol levels in the body, requiring dosage adjustments for patients taking both drugs. This interaction highlights the impact of hepatic enzyme inducers on antiarrhythmic drug metabolism.
Area of Science:
- Pharmacology
- Drug Metabolism
- Clinical Pharmacology
Background:
- Pirmenol is an antiarrhythmic drug that undergoes extensive metabolism.
- Rifampin is a potent inducer of hepatic drug-metabolizing enzymes.
- Drug-drug interactions involving enzyme inducers can alter drug pharmacokinetics.
Purpose of the Study:
- To evaluate the potential drug-drug interaction between pirmenol and rifampin.
- To assess the effect of rifampin on pirmenol pharmacokinetics in healthy adults.
Main Methods:
- A pharmacokinetic study was conducted in 12 healthy adults.
- Pirmenol was administered orally as a single dose before and during rifampin treatment.
- Plasma and urine concentrations of pirmenol were measured over 72 hours postdose.
Main Results:
- Coadministration of rifampin with pirmenol led to significant changes in pirmenol pharmacokinetics.
- Pirmenol area under the curve (AUC) decreased sixfold, and apparent plasma clearance increased sevenfold.
- The elimination half-life of pirmenol decreased more than twofold.
Conclusions:
- Dosage adjustment of pirmenol is necessary when coadministered with rifampin.
- The findings suggest that other hepatic enzyme-inducing agents may also accelerate pirmenol clearance.