Propranolol elicits cutaneous analgesia against skin nociceptive stimuli in rats.

The purpose of this study was to investigate the cutaneous analgesic effect of propranolol and compare with a local anesthetic lidocaine. The potencies and equipotent doses were determined for infiltrative cutaneous analgesia on the rat back by determination of dose-response curves for propranolol and lidocaine. Propranolol as well as lidocaine elicited dose-dependent cutaneous analgesia. On a 50% effective dose (ED(50)) basis, the relative potency was propranolol (10.3 [8.9-11.9]μmolkg(-1))>lidocaine (25.8 [24.3-27.8]μmolkg(-1)) (P<0.01). On equianalgesic doses (ED(25), ED(50), ED(75)), propranolol produced longer action of infiltrative cutaneous analgesia than lidocaine (P<0.01). Coadministration of lidocaine (25.8μmolkg(-1)) and propranolol (1.7μmolkg(-1)) exhibited greater blockade and duration than lidocaine (25.8μmolkg(-1)) or propranolol (1.7μmolkg(-1)) alone. Propranolol displayed more potent and longer duration of action than lidocaine at producing cutaneous analgesia. Furthermore, propranolol may prove useful as an adjuvant for lidocaine in producing cutaneous analgesia.
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