Comparison of i.m. ketorolac trometamol and morphine sulphate for pain relief after cholecystectomy. I.m. ketorolac trometamol 30 mg was compared with morphine sulphate 10 mg after cholecystectomy in a double-blind, multiple dose, randomized study of 100 patients. Assessments of pain were made immediately after operation (day 1), and the next morning (day 2). Pain intensity (verbal response score and visual analogue scale) was recorded before injection and then over a 6-h period. Pain relief was assessed also. The effect of ketorolac on operative blood loss and platelet function was examined. Time to commencing oral intake and the duration of administration of i.v. fluids were recorded. Adverse events were noted. Ketorolac produced significantly less analgesia than morphine on day 1, but on day 2 the two drugs produced a similar effect. Blood loss was not increased by ketorolac, although platelet function was impaired. Repeated i.m. administration of ketorolac did not produce any serious adverse effects. 