Summary and Recommendations Aspirin in an effective antithrombotic agent in doses of 100 mg/dav to 1.2 g/day. There is no evidence that low doses (160 to 325 mg/day) are either more effective or less effective than high doses (900 to 1500 mg/dav); however, the lower doses produce fewer gastric side effects. The results of biochemical […]

As well as being studied in cerebrovascular disease, the effects of aspirin have been evaluated in several randomized trials in cardiovascular disease (unstable angina and long-term following MI). There is convincing evidence from an overview analysis of all these trials that aspirin reduces the risk of nonfatal stroke (42 ±5%; p<0.0001), nonfatal MI (31 ±5%; […]

Antithrombotic effects of aspirin have been reported with doses that have varied between 100 mg/day to over 1.5 g/day. Low doses of aspirin (100 mg/day) significantly reduced thrombosis of aortocoronary bypass grafts and of arterial venous shunts in patients undergoing long-term hemodialysis (160 mg/day) and significantly reduced MI in patients with unstable angina (325 mg/day). […]

Reports by Chesebro et al showed that dipyridamole, 225 mg/day, plus aspirin, 975 mg/day, improved the patency of coronary bypass grafts both at early and late follow-up (level I). The recent WA study using preoperative and early postoperative aspirin showed an impressive effect on early graft patency raising the possibility that dipyridamole adds nothing to the effects […]

Can Hemorrhagic Effects of a Combination of Aspirin and Anticoagulants be Reduced by Using a Very Low Dose of Aspirin Without Compromising the Antithrombotic Effects of Asprin? Aspirin does not cause a generalized bleeding abnormality unless it is given to patients with an underlying hemorrhagic defect (eg, hemophilia or uremia) or combined with anticoagulants. The effect of […]

Are There Effective Antithrombotic Dosage Regimens of Aspirin that Are Relatively Free of GI Side Effects? The side effects of aspirin are mainly GI and appear to be dose related, and there is now good evidence that these side effects are reduced by using low doses of aspirin (325 mg/day or less). An association between […]

Does Inhibition of Vascular Wall PGl2 Synthesis Interfere with the Antithrombotic Effects of Aspirin? The clinical relevance of inhibiting PGI2 production may have been exaggerated in the past, for there is little direct evidence that it is of much clinical importance. Experimentally, aspirin has been shown to be thrombogenic only at extremely high doses (200 mg/ kg), […]

These findings led to the acceptance of the view that low doses of aspirin may inhibit TXA2 production without inhibiting PGI2 production. An alternative explanation for the apparently selective effect of aspirin on thromboxane generation, sparing prostacyclin formation, was offered by Pedersen and Fitzgerald. They suggested that when administered in low dose, aspirin selectively inhibits thromboxane synthesis […]

Aspirin is rapidly absorbed in the stomach and upper intestine. Peak plasma levels occur 15-20 min after aspirin ingestion and inhibition of platelet function is evident by one hour. The plasma concentration of aspirin decays with a half-life of 15-20 min. Despite the rapid clearance of aspirin from the circulation, the platelet-inhibitory effect lasts for […]

Relationship Among Dose, Effectiveness, and Side Effects There is now unequivocal evidence that aspirin is an effective antithrombotic agent in patients with ischemic heart disease and cerebrovascular disease. Several important, interrelated issues related to the use of aspirin and other platelet active drugs will be discussed, including the following: (1) Is the antithrombotic effect of […]