EN
Cenajek, D., Szczawińska, K., Chodera, A. and Nowakowska, E.: Development of tolerance to pethidine in rats, pretreated or not, with ß-naphtoflavone or SKF 525 A. Acta physiol, pol., 1988, 39 (4): 281-287. Tolerance to the analgesic effect of pethidine (PD) in rats, treated with a dose of 15 mg/kg of the compound twice daily at 12 h intervals for 1-3 weeks, was assessed using both, heat and current irritating stitnuli, (Tolerance could be detected earlier by the current irritating method, .than by the hot plate technique. Pretreatment with β -naphtoflavone did only slightly affect the development of tolerance to the antinofciceptive effect of (PD. In contrast after one week of treatment with SKF 525 А PD retained its1 analgesic effect. The prolonged pretreatment with SKF 525 A did not prevent the development of tolerance to the analgesic effect of PD.