Analgesic efficacy and bioavailability of ketorolac in postoperative pain:A probability analysis

Background. The analgesic efficacy and bioavailability of 30 mg intramuscul ar ketorolac was studied in 24 patients with severe or very severe postoper ative pain. Methods. Pain and pain relief were determined by a five-point verbal rating scale and data were submitted to a probability analysis. Ketorolac plasma levels were determined by high-performance liquid chromatography. Results. Two patients chose not to finish the study; 22 patients completed the study achieving at least good pain relief. Of these 22 patients, 13 rea ched complete pain relief. Ketorolac was rapidly absorbed. Notwithstanding, pain relief increased gradually, showing considerable delay with regard to plasma concentrations. Analysis of the probability-time curves revealed th at 25% of the patients obtained moderate pain relief at 7 min after ketorol ac administration, 50% at 11 min, 75% at 29 min, and 95% at 60 min. Good pa in relief was achieved in 25, 50, and 75% of the patients at 1.1, 1.8, and 2.7 h, respectively. Complete pain relief was achieved in 25% and 50% of th e patients at 2.6 h and 3.7 h, respectively. The probability of exhibiting an acceptable pain relief in responsive patients for more than 5 h was 0.97 . No serious side effects were detected. Conclusions. Results show that 30 mg intramuscular ketorolac is an adequate treatment for postoperative pain in the Mexican population. Therefore, the use of higher doses is not justified. Due to gradual installation of analg esia, administration of additional analgesic medication before 1 h is not r ecommended. (C) 2000 IMSS, Published by Elsevier Science Inc.