Relative potencies of bupivacaine and ropivacaine for analgesia in labour

Abstract

We have used the technique of randomized, double-blind sequential allocation to compare the minimum local analgesic concentrations (MLAC) of epidural bupivacaine and ropivacaine for women in the first stage of labour. The test bolus was 20 ml of local anaesthetic solution. The concentration was determined by the response of the previous woman to a higher or lower concentration of local anaesthetic, according to up-down sequential allocation. Efficacy was assessed using a 100-mm visual analogue pain score (VAPS). The test solution had to achieve a VAPS of 10 mm or less to be judged effective. For bupivacaine, MLAC was 0.093 (95% CI 0.076-0.110)% w/v, and for ropivacaine, 0.156 (95% CI 0.136-0.176)%w/v (P < 0.0001, 95% CI difference 0.036-0.090). The analgesic potency of ropivacaine was 0.60 (0.47-0.75) relative to bupivacaine. Claims for reduced toxicity and motor block must be considered with differences in analgesic potency in mind.

Ropivacaine and bupivacaine in obstetric analgesia

“…Studies of the minimum local analgesic concentration with respect to the relative analgesic potencies of ropivacaine and bupivacaine for epidural analgesia in labour have found ropivacaine to be 40% less potent than bupivacaine [8,9]. These results are in agreement with a study that compared the intrathecal administration of the two local anaesthetics [10].…”

The posterior lumbar plexus (psoas compartment) block and the three-in-one femoral nerve block provide similar postoperative analgesia after total knee replacement

“…2 Although the local anesthetic used in the present study (ropivacaine 0.2% at 12 mL·hr -1 ) differed from the one used by Singelyn et al (bupivacaine 0.125% at 10 mL·hr -1 ), both regimens were roughly equivalent, considering a two-third potency for ropivacaine compared to bupivacaine. 2,20 In their study, Singelyn et al added clonidine 1 µg·mL -1 (or 240 µg·day -1 ) and sufentanil (0.1 µg·mL -1 or 24 µg·day -1 ) to their local anesthetic infusion. When added to a peripheral nerve block, clonidine, a pure specific α 2 -agonist, reduces the onset time of sensory blockade, extends the field of adequate analgesia, decreases the use of supplementary iv anesthetic agents during surgery, and produces a dose-dependent prolongation of postoperative analgesia.…”

The effect of low concentrations versus high concentrations of local anesthetics for labour analgesia on obstetric and anesthetic outcomes: a meta-analysis

“…Low concentrations were defined as B 0.1% bupivacaine or an equipotent concentration of ropivacaine (B 0.17%). 16,17 There is no universally accepted concentration that is regarded as a low concentration. We decided to use [ 0.1% bupivacaine as our cut-off value for high concentration because this value is utilized in many randomized controlled studies, including the largest trial (COMET) to represent HCs of epidural solution.…”