PUBLIC LECTURE: Aspirin: how long can this old dog surprise us with new tricks?

Aspirin has been used to relieve pain and discomfort for thousands of years and has been commercially available for more than 100 years. Today it is one of the most widely used drugs globally and can be obtained without prescription from most supermarket and corner stores.

Scientific discoveries detailing the mechanism of action and the benefits of aspirin for patients are detailed in thousands of research papers published over the past century. People were aware of aspirin’s analgesic and anti-inflammatory properties long before any research was performed, but it was not until scientists found that it reduced blood clotting that aspirin transformed the management of patients with cardiovascular disease. Aspirin’s cardiovascular benefits are explained by its unique pharmacology. When taken at low doses, aspirin is cleared from the circulation within an hour. It takes only minutes for aspirin to permanently block the blood platelets that cause heart attack and stroke, and its rapid clearance limits the potentially harmful effects of aspirin on the walls of blood vessels when it is given in higher doses.

Recent discoveries have further refined our understanding of the cardiovascular benefits of aspirin. The evidence supporting its use for the treatment of heart attack and stroke is overwhelming, but we are now less certain of its benefits for “primary” prevention in persons without a history of cardiovascular disease, and aspirin may even be harmful when used for this reason in older persons. Possibly balancing this concern is the unexpected finding that continued use of aspirin for more than a decade prevents the onset of cancer.

Current aspirin research focuses on the evaluation of aspirin for new indications, optimizing its benefits with alternative dosing regimens, and reducing the risks of bleeding. Aspirin does not fully protect against the risk of a further heart attack or stroke, and trials currently underway are exploring whether its use in combination with other treatments is more effective. Efforts to replace aspirin with potentially more effective and safer new designer drugs have so far proven unsuccessful, and in the meantime new aspirin discoveries continue unabated.

How long can this old dog continue to surprise us with new tricks?

John Eikelboom, MBBS, MSc, FRCPC is Associate Professor in the Department of Medicine, McMaster University, and haematologist in the Thrombosis Service, Hamilton General Hospital, Ontario, Canada. He originally trained in Internal Medicine and Haematology in Perth, Australia and subsequently moved to Hamilton to take up a Tier II Canada Research Chair in Cardiovascular Medicine. Dr Eikelboom has co-authored more than 500 articles in peer-reviewed journals. His current research, supported by the Canadian Institutes for Health Research, the Heart and Stroke Foundation and the National Health and Medical Research Council of Australia, focuses on the efficacy and safety of antithrombotic therapies, outcomes after blood transfusion and bleeding, and the mechanisms of variable response to antiplatelet drugs.