Beschreibung
Ranitidine can modestly increase warfarin plasma levels and INR by inhibiting CYP2C9-mediated warfarin metabolism, though the magnitude is smaller than with cimetidine.
Mechanismus
Ranitidine weakly inhibits CYP2C9, the primary enzyme responsible for S-warfarin hydroxylation; reduced clearance leads to higher warfarin concentrations and elevated INR.
Klinische Bedeutung
Case reports and pharmacokinetic studies show modest but clinically relevant INR elevations; the interaction is less pronounced than the well-established cimetidine-warfarin interaction.
Maßnahmen
Monitor INR when starting or stopping ranitidine in patients on warfarin; adjust warfarin dose if INR rises above therapeutic range; consider switching to a PPI with less CYP interaction (e.g., pantoprazole).
Medizinischer Haftungsausschluss
This content is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making medication decisions.