The aim of this study was to investigate infiltrative cutaneous anesthesia of 2-adamantanamine and rimantadine. After subcutaneous injections of drugs in rats, the blockade of cutaneous trunci muscle reflex by 2-adamantanamine and rimantadine was evaluated. Lidocaine, a common local anesthetic, was used as control. We showed that rimantadine and 2-adamantanamine as well as the local anesthetic lidocaine produced infiltrative anesthesia of skin in a dose-dependent fashion. Saline (vehicle) group displayed no cutaneous anesthesia. The relative potency of these drugs was rimantadine [23.8 (21.1-26.8)]=lidocaine [26.4 (22.7-30.6)]>2-adamantanamine [64.6 (55.0-75.9)] (P<0.01). On an equianesthetic basis [25% effective dose (ED25), ED50, and ED75], rimantadine and 2-adamantanamine had longer duration of action than lidocaine (P<0.05). Neither local injection of saline nor intraperitoneal administration of a large dose of drugs elicited cutaneous anesthesia (data not shown). These data demonstrated for the first time that rimantadine had a similar potent and longer duration of skin infiltrative anesthesia than did lidocaine, whereas 2-adamantanamine had a less potency but longer duration of cutaneous anesthesia than did lidocaine.
Fundamental & Clinical Pharmacology, v.28 n.2, pp.199-204