[The analgesic action of new enkephalin analogs].

The enkephalin analogue peptide IKB-901 containing epsilon-ACA and cysteine with the modified S-end shows an analgetic activity in rats (1 micron, intrathecally and 5 mg/kg intravenously) and in cats (0.35 and 0.7 mg/kg intravenously). Naloxone (0.1 mg/kg) prevents the analgetic effect of peptide. The coadministration of the peptide and the enkephalinase inhibitor D-phenylalanine (0.35 and 10 mg/kg, respectively) enhances analgesia and displays an antihypertensive effect in nociceptive stimulation.