The influence of NSAIDs on coumarin sensitivity in patients with CYP2C9 polymorphism after total hip replacement surgery.

Objective: To determine the influence of NSAIDs on the international normalized ratio (INR) in patients with cytochrome P450 (CYP)-2C9 enzyme variants starting acenocoumarol (an oral coumarin) therapy during the first 7 days after total hip replacement surgery.

Methods: In this prospective study, an age-dependent protocol was used for the initiation of the acenocoumarol dose. Low-molecular-weight heparin was given for 5 days.