Ketorolac: a parenteral nonsteroidal antiinflammatory drug

Ketorolac tromethamine is a pyrrolo-pyrrole nonsteroidal antiinflammatory drug (NSAID) with potent analgesic effects when administered intramuscularly for the treatment of acute pain. Ketorolac is well absorbed and has a rapid onset of action. Maximum plasma concentrations are achieved in 45-50 minutes and peak analgesic effects in about one to two hours following intramuscular injection. Ketorolac is more than 99 percent bound to plasma proteins and has a mean apparent volume of distribution of 0.11-0.25 L/kg. About 91 percent of a dose is excreted in urine, mostly as inactive metabolites, and approximately 6 percent is eliminated in feces. The elimination half-life, approximately four to six hours, increases in elderly patients and those with renal impairment. Its analgesic effectiveness was similar or superior to that of morphine, meperidine, or pentazocine in single-dose studies of patients with postoperative pain or renal colic and greater than that of placebo in patients with chronic cancer pain. The adverse effects are generally mild to moderate, self-limiting, and similar to those seen with other prostaglandin inhibitors. Ketorolac has a reversible inhibitory effect on platelet aggregation. It can cause dose-related gastric ulcerations, even when administered parenterally. Ketorolac is a promising parenteral alternative to oral NSAIDs and a nonnarcotic alternative to opioid analgesics. Additional multiple-dose studies are needed to more clearly define its place in therapy.