931-112 A Low-dose Intravenous Aspirin, Bolus Injection, Effectively Inhibits Platelet Aggregation

Prompt inhibition of platelet aggregation is important in acute coronary syndrome and before an intervention procedure. To determine whether a single low dose of iv aspirin inhibits platelet aggregation, twenty-seven healthy volunteers (7 F and 20 M), mean age 43.5 years, were randomized double-blind to a single iv low dose of aspirin DL-Iysine (L-ASA) equivalent to 2 mg/kg of aspirin, high dose (H-ASA) equivalent to 10 mg/kg, or placebo (PI). Platelet aggregation were performed before and 1 hand 24 h after drug administration, in whole blood (WB) using electrical impedance and in platelet-rich plasma (PRP) by optical light transmittance. Baseline WB platelet aggregation (Col 3 μg/mI) was the same with L-ASA, H-ASA and PI (24 ± 5, 23 ± 3 and 24 ± 4rl respectively) and decreased significantly more with L-ASA and H-ASA than with PI after 1 h.(17 ± 6, 15 ± 7 and 21 ± 5Ω p l 0.0l)and 24 h(17 ± 7, 16 ± 6 and 25 ± 4Ω P l 0.01). Results in PRP were similar: PR Poptical aggregation (%) Before AfterASA 1 h. 24 h ADP (5/LM): L-ASA 73 ± 21 50 ± 14 * 45 ± 15 * H-ASA 65 ± 23 54 ± 17 * 52 ± 16 * PI 69 × 18 72 ± 22 69 ± 14 Col (3 /Lg/ml): L-ASA 64 ± 19 33 ± 13 * 36 ± 18 * H-ASA 60 ± 16 32 ± 17 * 34 ± 14 * PI 55 ± 13 56 ± 18 57 ± 14 * p l 0.001 (ANOVA test) respect to PI and the baseline values No differences in response were observed between the two doses of aspirin and no significant changes occurred between 1 and 24 hours in any group. Effective inhibition of platelet aggregation is thus achieved within 1 hour after the administration of low-dose 2 mg/kg of ivaspirin.