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 (ED50) 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 (ED25, ED50, ED75), 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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