Pharmacodynamic Comparison of Two Aspirin Formulations in the Caribbean: The ARC Study

This prospective, single-arm, crossover pharmacodynamic study assessed the effect of Bayer^® low-dose enteric-coated aspirin 81 mg tablets (LD EC-ASA) (Bayer AG, Leverkusen, North Rhine-Westphalia, Germany) compared to Vazalore^® low-dose phospholipid-aspirin liquid-filled 81 mg capsules (LD PL-ASA) (PLx Pharma Inc., Sparta, NJ, USA) on platelet reactivity with respect to aspirin reaction units (ARU).

Forty-seven healthy volunteers were recruited. Platelet function was evaluated with the VerifyNow™ ARU assay (Werfen, Bedford, MA, USA) and assessed post-initiation of Bayer^® LD EC-ASA daily for 14 days, with a washout period of 28 days, followed by Vazalore^® LD PL-ASA daily for 14 days, again followed by ARU testing.

Participants on LD EC-ASA had a mean ARU score of 426, with 19.1% of participants having an ARU > 550; patients on LD PL-ASA derived a mean ARU score of 435, with 14.9% achieving an ARU > 550. There were no significant differences in aspirin resistance (ARU > 550) according to the formulation (Bayer^® LD EC-ASA vs. Vazalore^® LD PL-ASA) used. Aspirin resistance was independent of ethnicity regardless of the formulation used. In addition, there were no significant associations between body surface area (BSA) and Bayer^® LD EC-ASA ARU value (p value 0.788) or Vazalore^® LD PL-ASA ARU value (p value 0.477). No patients experienced any serious adverse events or treatment-emergent adverse events.

There were no significant differences in aspirin resistance between Bayer^® LD EC-ASA and Vazalore^® LD PL-ASA. This dedicated pharmacodynamic study could potentially be informative and applicable for Trinidadian patients on dual antiplatelet therapy (DAPT). Further studies are required to confirm these exploratory findings.

ClinicalTrials.gov identifier, NCT06228820, prospectively registered 1/18/2024.