The aims of the study were to evaluate the spinal anesthetic effect of caramiphen and also assess spinal anesthetic interactions of caramiphen with lidocaine. Lidocaine, a common local anesthetic, was used as control. Dose-dependent responses of intrathecal caramiphen on spinal anesthesia were compared with lidocaine in rats. The interactions of caramiphen with lidocaine were evaluated via an isobolographic analysis. Caramiphen and lidocaine produced a dose-dependent local anesthetic effect as spinal anesthesia. On a 50% effective dose (ED(50)) basis, the spinal anesthetic effect of caramiphen was more potent than lidocaine (P<0.01 for each comparison). Co-administration of caramiphen with lidocaine produced an additive effect. Caramiphen and lidocaine are known to have local anesthetic effects as spinal anesthesia in rats. The spinal anesthetic effects of adding caramiphen to lidocaine are similar to the combinations of other anesthetics with lidocaine.
