Spinal anesthesia: bupivacaine compared with tetracaine.

A solution of 0.75% bupivacaine (Marcaine) in 8.25% dextrose was compared with a similar solution of tetracaine (Pontocaine), the drug most used for spinal anesthesia in the USA. The study employed a randomized double-blind method and a standardized technique for spinal anesthesia in 435 patients. For perineal and lower extremity surgery, 7.5 mg of the local anesthetic was injected, and for intra-abdominal gynecologic surgery, 12 mg was administered. With the 7.5-mg dose, in only one of 121 patients was anesthesia unsatisfactory when bupivacaine was used; anesthesia was unsatisfactory in 19 of 114 patients when tetracaine was used. With the 12-mg dose, 12 patients given bupivacaine and 14 given tetracaine had unsatisfactory analgesia. With both doses, the motor blockade lasted significantly longer with tetracaine. Epinephrine added to the local anesthetic solution significantly increased the duration of action of both drugs. It also prolonged the duration of postoperative analgesia of tetracaine significantly more than the duration of bupivacaine. Bupivacaine 0.75% in 8.25% dextrose is a safe, reliable local anesthetic solution for spinal anesthesia.