BACKGROUND AND OBJECTIVES: A bupivacaine formulation containing 25% of R(+) and 75% of S(-) isomer has been used because its anesthetic properties with less toxicity than the racemic bupivacaine. This study aimed at evaluating the racemic bupivacaine as compared to B25/75 in epidural anesthesia. METHODS: Participated in this study 44 patients who were distributed in two groups (n = 22), namely Bupivacaine and S75-R25. Patients were premedicated with intravenous midazolam. Epidural anesthesia was induced at L3-L4 or L2-L3 interspace with 16 to 24 ml of the anesthetic solution. Group Bupivacaine received 0.5% bupivacaine with vasoconstrictor. Group S75-R25 received the enantiomeric mixture of 0.5% bupivacaine with vasoconstrictor. The following parameters were evaluated: lower limb temperature before and after epidural block, blockade onset, type of sensation referred by the patient, possible sensory failures, metameric sensory level and motor block level. Time for first analgesic request in the PACU was also recorded. RESULTS: Forty-one patients completed the study. Groups were demographically similar. Perioperative midazolam dose, epidural anesthetic volume, blockade onset, sensory failures at pinprick, lower limb temperature in different moments, type of paresthesia sensation and anesthetic depth in dermatomes were similar between groups. Motor block was less intense in group S75-R25 (p = 0.0117) as compared to group Bupivacaine. Time to first postoperative analgesic dose was longer for group S75-R25 as compared to group Bupivacaine (596 ± 436 min versus 463 ± 270 min, respectively; p= 0.04572). The incidence of adverse effects was similar between groups. CONCLUSIONS: Enantiomeric bupivacaine (S75-R25) resulted in longer analgesia and less intense motor block as compared to racemic bupivacaine.
ANESTHETICS; ANESTHETICS; ANESTHETIC TECHNIQUES; ANESTHETIC TECHNIQUES
