Does 5 aminosalicylic acid (5-ASA) have a clinically relevant anticoagulant effect?/nThe question c

Fråga: Does 5 aminosalicylic acid (5-ASA) have a clinically relevant anticoagulant effect?

The question concerns a woman with ulcerative colitis, treated with 5-ASA (Asacol) 400 mg 2x2. Now she has been diagnosed with a persistent atrial fibrillation and minor stroke. Warfarin is deemed contraindicated due to the ulcerative colitis, and treatment with acetylsalicylic acid (ASA) 320 mg x1 is planned. The question of whether 5-ASA has intrinsic platelet activity, has arisen.

Sammanfattning: Weighing the evidence, a clinically relevant antiplatelet effect of 5-ASA is not implied. ASA should not be withheld, if indicated, in patients treated with 5-ASA.

Svar: There are no clinical trials demonstrating or attempting to demonstrate an antithrombotic effect of 5-ASA.

Two ex vivo studies have been published addressing the issue. Carty et al assessed spontaneous or thrombin induced-platelet activation in samples from patients with inflammatory bowel disease with or without 5-ASA treatment, and detected a statistically significant inhibition of in vitro platelet activation in patients treated with 5-ASA 1-4 g/day (1). Winther et al used a different methodology, studying adenosine diphosphate-induced platelet aggregation in inflammatory bowel disease patients on and off mesalazine 500 mg x3. No difference in platelet aggregation could be seen when patients were treated with mesalazine. However, a significant effect was seen in controls treated with aspirin (2).

Medications containing 5-ASA do not appear to be associated with hemorrhagic side effects (3,4). In this respect they differ from ASA. From this fact it could be inferred that a clinically relevant inhibition of platelet aggregation may be absent. Carty E, Macey M, Rampton DS. Inhibition of platelet activation by 5-aminosalicylic acid in inflammatory bowel disease. Aliment Pharmacol Ther 2000;14:1169-79. Winther K, Bondesen S, Hansen SH, Hvidberg EF. Lack of effect of 5-aminosalicylic acid on platelet aggregation and fibrinolytic activity in vivo and in vitro. Eur J Clin Pharmacol 1987;33:419-22. Fass (The Swedish catalogue of aproved medical products) 2004 SWEDIS (cited 2005-01-20)