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] mu mol kg(-1))> lidocaine (25.8 [24.3-27.8] mu Lmol kg(-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 (25.8 mu mol kg(-1)) and propranolol (1.7 mu mol kg(-1)) exhibited greater blockade and duration than lidocaine (25.8 mu mol kg(-1)) or propranolol (1.7 mu mol kg(-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. (C) 2012 Elsevier Ireland Ltd. All rights reserved.
