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In vitro amiodarone protein binding and its interaction with warfarin.
Experientia
|March 15, 1985
Summary
Amiodarone binds extensively to human plasma protein (96.3%). Amiodarone and warfarin exhibit distinct binding sites on bovine serum albumin, suggesting noncompetitive inhibition and potential metabolite interference.
Area of Science:
- Pharmacology
- Biochemistry
- Analytical Chemistry
Background:
- Amiodarone is a widely used antiarrhythmic drug.
- Understanding amiodarone's protein binding is crucial for its efficacy and safety.
- Drug interactions, particularly with anticoagulants like warfarin, require detailed investigation.
Purpose of the Study:
- To quantify amiodarone binding to human plasma protein and bovine serum albumin.
- To investigate the binding site specificity of amiodarone and warfarin on bovine serum albumin.
- To elucidate the mechanism underlying the interaction between amiodarone and warfarin.
Main Methods:
- Protein binding was assessed using ultracentrifugation, equilibrium dialysis, and fluorescence spectroscopy.
- Binding site interactions were analyzed using 1-anilino-naphthalene-8-sulfonate as a probe.
- Inhibition studies were conducted with amiodarone and warfarin as independent inhibitors.
Main Results:
- A high fraction (96.3%) of amiodarone was found to be bound to human plasma protein.
- Amiodarone and warfarin bind to distinct sites on bovine serum albumin, indicating a noncompetitive inhibition mechanism.
- Metabolite interference may contribute to the enhanced pharmacological action of warfarin when co-administered with amiodarone.
Conclusions:
- Amiodarone exhibits significant binding to plasma proteins.
- The distinct binding sites of amiodarone and warfarin suggest complex drug-drug interactions.
- Metabolite interactions are a plausible explanation for the observed potentiation of warfarin's effects by amiodarone.