Aspirin: old drug, new uses and challenges

Salicylates have been used since antiquity to relieve pain and inflammation. However, it has been only in the last half century that evidence has emerged that aspirin causes reproducible acute and superficial injury to the gastric and duodenal mucosa, and is an important cause of complicated and uncomplicated peptic ulcer. Superficial damage to the mucosa occurs rapidly and reproducibly and acid and pepsin then produce a second wave of deeper injury. Most of the time this heals rapidly, but some focal deeper mucosal lesions (erosions) occur frequently and the point prevalence of frank ulcers in low dose aspirin users is around 10%. It is even more recently that aspirin's unique antiplatelet action has been recognized, with long-lasting inhibition of platelet aggregation due to irreversible inactivation of the cyclooxygenase-1 mediated production of thromboxane. It has now become the mainstay of pharmacological reduction of thrombotic risk in patients with cardiovascular diseases. In addition, evidence is accumulating about the cancer-reducing effects of blocking cyclooxygenase in a number of tissues. For example, recent data indicate that even at a 75-mg/day dose, it may reduce colorectal cancer risk after a lag of a year or so. Because of its widespread use for cardiovascular protection, aspirin is now one of the most frequently prescribed drugs-and gastroenterologists regularly need to deal with its ulcerative complications along the whole length of the gastrointestinal tract. Strategies that can be used to reduce these risks include using the lowest effective aspirin dose and co-prescribing acid suppressants.