HealthDay News — The effects of aspirin on platelet inhibition may be more potent after bariatric surgery, according to a study published online July 14 in Cardiovascular Therapeutics.

Nicholas B. Norgard, PharmD, from the University at Buffalo in New York, and colleagues administered 2 seven-day courses of 81mg aspirin in 15 patients scheduled to undergo bariatric surgery. The courses were administered before surgery and 3 months after surgery. Before and after each aspirin course, they measured platelet aggregation. The change in on-treatment aspirin reactive units (ARUs) pre- and post-surgery was measured as the primary end point. 

The researchers found that off-treatment ARU was significantly reduced post-bariatric surgery versus pre-surgery levels (602±59 versus 531±78; P=0.035). After surgery there was also a significant reduction in on-aspirin platelet reactivity (469±60 versus 432±143; P=0.03). The extent of weight loss was significantly correlated with the degree of improvement in on-aspirin platelet reactivity (r²=0.49; P=0.024). Compared with normal-weighted subjects, obese patients had significantly higher pre-surgery on-aspirin platelet reactivity (469±60 versus 419±52; P=0.016), which was reduced to baseline after surgery (432±63 versus 419±52; P=0.54).

“Aspirin-induced platelet inhibition may be more potent following bariatric surgery,” the authors write. “The mechanisms behind this improvement require further investigation.”

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