NSAIDs vary in their potency, duration of action, how they are eliminated from the body, how strongly they inhibit COX-1 and their tendency to cause ulcers and promote bleeding. The more an NSAID blocks COX-1, the greater is its tendency to cause ulcers and promote bleeding. One NSAID, celecoxib (Celebrex), blocks COX-2 but has little effect on COX-1, and is therefore further classified as a selective COX-2 inhibitor. Selective COX-2 inhibitors cause less bleeding and fewer ulcers than other NSAIDs.
Aspirin is a unique NSAID, not only because of its many uses, but because it is the only NSAID that inhibits the clotting of blood for a prolonged period (4 to 7 days). This prolonged effect of aspirin makes it an ideal drug for preventing blood clots that cause heart attacks and strokes.
Most NSAIDs inhibit the clotting of blood for only a few hours. Ketorolac (Toradol) is a very potent NSAID and is used for moderately severe acute pain that usually requires narcotics. Ketorolac causes ulcers more frequently than other NSAID. Therefore, it is not used for more than five days. Although NSAIDs have a similar mechanism of action, individuals who do not respond to one NSAID may respond to another.
