Topical diclofenac does not affect the antiplatelet properties of aspirin as compared to the intermediate effects of oral diclofenac: A prospective, randomized, complete crossover study

• Published in: Journal of clinical pharmacology Vol. 56; no. 4; p. 422
• Main Authors: Rowcliffe, M, Nezami, B, Westphal, E S, Rainka, M, Janda, M, Bates, V, Gengo, F
• Format: Journal Article
• Language: English
• Published: England 01.04.2016
• Subjects: Administration, Oral; Administration, Topical; Adolescent; Adult; Anti-Inflammatory Agents, Non-Steroidal - administration & dosage; Anti-Inflammatory Agents, Non-Steroidal - adverse effects; Aspirin - administration & dosage; Blood Platelets - drug effects; Collagen - metabolism; Cross-Over Studies; Diclofenac - administration & dosage; Diclofenac - adverse effects; Drug Interactions; Female; Humans; Male; Middle Aged; Platelet Aggregation Inhibitors - administration & dosage; Platelet Function Tests - methods; Prospective Studies; Young Adult; aspirin; drug interactions; nonsteroidal anti-inflammatory agents; diclofenac; platelet aggregation
• ISSN: 1552-4604
• DOI: 10.1002/jcph.615

Nonsteroidal anti-inflammatory drugs (NSAIDs) adversely interact with aspirin, diminishing its antiplatelet effect and potentially placing patients at an increased risk for recurrent thrombotic events. This crossover study aimed to determine whether the topical NSAID diclofenac epolamine 1.3% patch or oral diclofenac 50 mg interfered with the antiplatelet effects of aspirin 325 mg. Twelve healthy men and women aged 18-50 were included. Participants were randomized into 5 treatment arms: aspirin, diclofenac potassium 50 mg, diclofenac patch, diclofenac potassium plus ASA 325 mg, and diclofenac patch plus aspirin. Platelet responsiveness was determined using whole-blood impedance aggregation (WBA) to collagen 1 μg/mL and arachidonic acid (AA) 0.5 mM and was sampled every 2 hours. No significant difference in platelet function was observed following the diclofenac patch and aspirin vs aspirin alone. Oral diclofenac produced a mixed effect with significant reduction in platelet inhibition at hour 2 and hour 8 following aspirin administration. Topical diclofenac does not significantly interfere with the antiplatelet effects of aspirin and may be a safer alternative to the oral formulation.