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Drug interactions with clinafloxacin.
E J Randinitis1, C W Alvey, J R Koup
1Clinical Pharmacokinetics and Pharmacodynamics Department, Pfizer Global Research and Development, Ann Arbor, Michigan 48105, USA. Edward.Randinitis@pfizer.com
Antimicrobial Agents and Chemotherapy
|August 15, 2001
Summary
Clinafloxacin significantly impacts drug metabolism, reducing clearance for theophylline and caffeine, and altering warfarin levels. It also slightly decreases phenytoin clearance, highlighting potential drug interaction risks.
Area of Science:
- Pharmacology
- Drug Metabolism
- Drug Interactions
Background:
- Fluoroquinolone antibiotics, like clinafloxacin, can inhibit cytochrome P450 enzymes.
- This inhibition can lead to significant drug-drug interactions when co-administered with other medications.
Purpose of the Study:
- To investigate the pharmacokinetic interactions between clinafloxacin and theophylline, caffeine, warfarin, and phenytoin.
- To assess the impact of phenytoin on clinafloxacin pharmacokinetics.
Main Methods:
- Pharmacokinetic studies involving the administration of clinafloxacin with theophylline, caffeine, warfarin, and phenytoin.
- Analysis of plasma concentrations and clearance rates of the involved drugs.
Main Results:
- Clinafloxacin (200-400 mg) reduced theophylline clearance by 50-70% and caffeine clearance by 84%.
- (R)-warfarin plasma concentrations increased by 32% during clinafloxacin treatment; (S)-warfarin concentrations were unchanged.
- Phenytoin clearance was reduced by 15% during clinafloxacin administration, while clinafloxacin pharmacokinetics were unaffected by phenytoin.
Conclusions:
- Clinafloxacin significantly alters the pharmacokinetics of theophylline, caffeine, and warfarin, indicating a high potential for drug interactions.
- Clinafloxacin may also affect phenytoin clearance, and gut flora changes might contribute to observed pharmacodynamic effects.