Relationship between ketorolac pharmacokinetics and analgesic effect in postoperative pain Article uri icon

abstract

  • 22 patients with postoperative pain received a single 30 mg dose of ketorolac tromethamine, im. Ketorolac plasma concentration and analgesic effect were determined simultaneously. Pain relief was evaluated by a five-point verbal rating scale. All patients reported an analgesic effect. However, the appearance of the effect was delayed with regard to plasma concentration. Effect against plasma concentration curves exhibited a counterclockwise hysteresis loop, showing that there is no direct relationship. Hence, the effect was related to drug concentration in an effect compartment by pharmacokinetic-pharmacodynamic modelling. Drug transfer from the central to the effect compartment was described by a k of 3.42xlO~4 h. Additionally, effect compartment concentrations were related to the probability of observing a moderate, sufficient and total pain relief by logistic analysis, a good correlation being obtained in the three cases. Results show a very good analgesic efficacy for ketorolac. The probabilities of obtaining a sufficient and a total pain relief with the effect compartment concentrations achieved with the 30 mg (im) dose were about 100%25 and 70%25 respectively.

publication date

  • 1996-01-01