Analgesic efficacy of ketorolac and morphine in neonatal rats

Ketorolac is a potent nonsteroidal antiinflammatory drug (NSAID). In adult humans and animals, its analgesic efficacy can be comparable to opiates. However, it has not been studied in neonatal animals. We conducted a blinded, controlled study comparing the effects of ketorolac and morphine in neonatal rats using the formalin model. Animals were given intraperitoneal (i.p.) injections of ketorolac or morphine at 3 or 21 days of age. Ketorolac had an analgesic and antiinflammatory effect in 21-day-old pups, but not in the 3-day-olds. Morphine had a significant analgesic, but no antiinflammatory effect at both ages. These results indicate that ketorolac is an effective analgesic agent in preweaning, but not neonatal rats. Opiates may be more appropriate analgesics in neonates.