Comparison of long-term safety of ketorolac tromethamine and aspirin in the treatment of chronic pain.

A double-blind, randomized trail was conducted in 823 patients who required long-term analgesic therapy for chronic pain such as that caused by osteoarthritis, fibromyopathies or fibromyalgias, other nonarticular chronic soft tissue pain syndromes, or headaches. The safety and analgesic efficacy of ketorolac tromethamine 10 mg 4 times a day as needed was compared with that of aspirin 650 mg 4 times a day as needed. The primary emphasis of this 52-week study was on evaluating the safety of the drugs. Patients returned to the clinics at 2, 5, 10, 15, 20, 28, 36, 44, and 52 weeks for assessments of safety and efficacy. Both patients' and investigators' evaluations of overall efficacy and safety favored ketorolac over aspirin. The probability of early withdrawal from the study was significantly higher with aspirin than with ketorolac, primarily because of lack of efficacy. Early withdrawal for safety-related reasons alone was similar for those taking aspirin and ketorolac.