A double-blind clinical trial to determine if an interaction exists between diclofenac sodium and the oral anticoagulant acenocoumarol (nicoumalone).

A double-blind crossover trial between diclofenac sodium and placebo was carried out in 32 hospitalized patients who were thought to be stabilized on concurrent anticoagulant therapy with acenocoumarol. The object of the trial was to investigate any possible interaction between diclofenac and anticoagulant by monitoring prothrombin times daily through the four week period. No statistically significant difference between placebo and diclofenac could be shown and some problems of accurately monitoring prothrombin times are discussed.