Duration and Dose-Response Relationship of the Analgesic Action of the Tetrapeptide H-Tyr-D-Arg-Phe-Gly-NH2 (Taphalgin), a Synthetic Derivative of Dermorphine, in Comparison with Morphine Hydrochloride

The effect of the tetrapeptide H-Tyr-D-Arg-Phe-Gly-NH2 (Taphalgin), a synthetic derivative of dermorphine, was evaluated in the tail-flick test in mice after a single subcutaneous (s.c.) injection. Taphalgin significantly prolongs the tail-flick latency when administered in the dose range 0.01 - 5 mg/kg. The analgesic effect of a single s.c. injection of Taphalgin at 1 mg/kg exceeds the effect of morphine hydrochloride at the same dose. The effect of Taphalgin at 0.5 mg/kg is comparable to that of morphine hydrochloride at 1 mg/kg. The magnitude and duration of the analgesic effect grow as the dose of Taphalgin increases from 0.5 to 1.5 and 4.5 mg/kg. The maximum 4-h duration of the analgesic effect is observed at doses of 1.5 and 4.5 mg/kg.

Automated summary

The tetrapeptide H-Tyr-D-Arg-Phe-Gly-NH2 (Taphalgin) was found to significantly prolong the tail-flick latency in mice within the dose range of 0.01-5 mg/kg. The analgesic effect of a single injection of Taphalgin at 1 mg/kg surpasses that of morphine hydrochloride at the same dose. The magnitude and duration of the analgesic effect of Taphalgin increase as the dose is raised from 0.5 to 1.5 and 4.5 mg/kg, with the maximum duration observed at 1.5 and 4.5 mg/kg.