Oral Administration of Sustained Release Niacin Inhibits Platelet Aggregation

Background: Previous studies have suggested that niacin may have antiplatelet properties, however the effects of niacin on the platelet activity are not well defined. Objective: The purpose of this trial was to investigate whether the oral administration of niacin inhibits platelet aggregation. Method: This study was run in three segments measuring the inhibitory effect of niacin: 1) 3 mmol/L niacin in vitro, 2) one hour after 1-gram sustained-release (SR) niacin administration, 3) twelve hours after 2-gram SR niacin administration. Platelet aggregation was measured using the VerifyNow-Aspirin and whole blood impedance aggregometry. Results: Preincubation with niacin resulted in a significant inhibition of platelet aggregation. Significant inhibition of platelet aggregation was found one hour following the oral administration of 1 gram of SR niacin while the oral administration of a 2 gram dose of SR niacin did not produce significant platelet inhibition when platelet aggregation was measured 12 hours after the dose. Conclusion: Niacin has a small, direct effect on platelet aggregation. Niacin platelet inhibition is transient and may dissipate as it is converted into metabolites. The clinical significance is unknown.