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Apparent reduced absorption of gemfibrozil when given with colestipol
S C Forland1, Y Feng, R E Cutler
1Clinical Pharmacology Section, Loma Linda University Medical School, CA.
Journal of Clinical Pharmacology
|January 1, 1990
Summary
Colestipol reduces gemfibrozil absorption when taken together, decreasing its bioavailability. To avoid this drug interaction and ensure effective cholesterol and triglyceride lowering, separate administration by at least two hours.
Area of Science:
- Pharmacology
- Clinical Pharmacy
- Drug Interactions
Background:
- Colestipol and gemfibrozil are used to manage hyperlipidemia.
- Colestipol is known to bind to certain anionic drugs.
- Potential interactions between colestipol and gemfibrozil require investigation.
Purpose of the Study:
- To investigate the pharmacokinetic effects of colestipol on gemfibrozil absorption.
- To determine if co-administration alters gemfibrozil bioavailability.
- To provide guidance on managing concomitant use of these lipid-lowering agents.
Main Methods:
- A pharmacokinetic study involving 10 patients with hyperlipidemia.
- Administration of 600 mg gemfibrozil alone or with/before/after 5g colestipol.
- Measurement of serum gemfibrozil concentrations over time, including Cmax, tmax, AUC, and t1/2.
Main Results:
- Co-administration of colestipol with gemfibrozil significantly decreased gemfibrozil's area under the curve (AUC), indicating reduced bioavailability.
- Peak gemfibrozil concentration (Cmax) and elimination half-life (t1/2) were not significantly altered.
- Serum gemfibrozil concentrations were significantly lower at early time points (0.5, 1.0, 1.5 hours) when taken concurrently with colestipol.
Conclusions:
- Concomitant administration of colestipol reduces gemfibrozil bioavailability.
- Separating the intake of colestipol and gemfibrozil by at least two hours can prevent this interaction.
- This finding is crucial for optimizing lipid-lowering therapy when both drugs are prescribed.