Key result
Naproxen shows no effect on warfarin concentrations or prothrombin times despite increased warfarin-free fraction.
Why the study?
Does naproxen alter the steady-state serum concentration and anticoagulant activity of warfarin in healthy adults?
Does naproxen alter the steady-state serum concentration and anticoagulant activity of warfarin in healthy adults?
Concomitant administration of naproxen and warfarin does not significantly alter warfarin's steady-state concentration or anticoagulant activity.
No apparent interaction in healthy volunteers; leaves open relevance to patients on chronic anticoagulation.
The purpose of this investigation was to determine whether the anti-inflammatory drug naproxen interacts with warfarin during prolonged administration of both drugs. Healthy adults received oral doses of warfarin daily for 26 days. Naproxen, 375 mg twice daily, was given from the eleventh through the twentieth days. Naproxen administration had no apparent effect on the steady-state concentrations of free and total (free and protein-bound) warfarin in serum, despite a small but statistically significant increase of the warfarin-free fraction in serum. There was no apparent difference between the prothrombin times (at a constant daily dose of warfarin) observed before, during, and after administration of naproxen.
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Jain et al. (1979) studied Healthy adults. Naproxen vs. Warfarin alone (before and after naproxen administration) was evaluated on Steady-state concentrations of free and total warfarin in serum and prothrombin times. Naproxen administration had no apparent effect on steady-state serum concentrations of warfarin or prothrombin times in healthy adults, despite a small increase in the warfarin-free fraction.
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