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Theophylline and warfarin interaction studies with grepafloxacin
C Efthymiopoulos1, S L Bramer, A Maroli
1Glaxo Wellcome R&D, Greenford, Middlesex, England.
Clinical Pharmacokinetics
|January 1, 1997
Summary
Grepafloxacin significantly increases theophylline levels, requiring a 50% dose reduction and monitoring. However, grepafloxacin does not interact with warfarin, necessitating no dose adjustments for either drug.
Area of Science:
- Pharmacology
- Drug Interactions
- Clinical Trials
Background:
- Grepafloxacin is a fluoroquinolone antibiotic.
- Potential interactions with theophylline and warfarin require investigation.
Purpose of the Study:
- To assess pharmacokinetic and pharmacodynamic interactions between grepafloxacin and theophylline.
- To evaluate interactions between grepafloxacin and warfarin.
Main Methods:
- Phase I clinical trials with healthy adult volunteers.
- Administration of grepafloxacin with maintenance doses of theophylline or warfarin.
- Pharmacokinetic parameter determination and pharmacodynamic assessments.
Main Results:
- Grepafloxacin increased theophylline peak concentrations and AUC by approximately 50%, reducing its clearance.
- Theophylline did not affect grepafloxacin pharmacokinetics.
- No significant changes in warfarin pharmacodynamics or pharmacokinetics were observed with grepafloxacin coadministration.
Conclusions:
- Theophylline maintenance doses should be reduced by 50% and serum concentrations monitored during grepafloxacin treatment.
- No dose adjustments are needed for grepafloxacin when coadministered with theophylline or warfarin.