Ropivacaine: a pharmacological review

Ropivacaine (Naropin, AstraZeneca) a new long-acting amide local anaesthetic agent, is a pure S-enantiomer, with a high pKa and relatively low-lipid solubility. Since its clinical introduction in 1996, it has been the focus of intense interest because of its increased CNS and cardiovascular safety compared with bupivacaine. This article reviews the pharmacology of ropivacaine with particular emphasis placed on toxicological issues. Compared with bupivacaine (the drug of choice for many years), ropivacaine is equally effective for subcutaneous infiltration, epidural, intrathecal and peripheral nerve block surgery, and obstetrics and postoperative analgesia. Ropivacaine is virtually identical to bupivacaine in terms of onset, quality and duration of sensory block, but seems to produce less motor block. The lesser toxicity of ropivacaine compared with bupivacaine has been confirmed in numerous animal experiments as well as human studies, including studies considering the presumed lower potency of ropivacaine. In fact, the reduced cardiovascular toxicity compared with bupivacaine may be a distinct feature of ropivacaine. So far, the increased cost of ropivacaine compared with bupivacaine has limited its wider clinical use -- in spite of the improved safety profile. During the last few years, cost differences between bupivacaine and ropivacaine have been minimized, thus making pharmacoeconomical speculations a much lesser concern when choosing a local anaesthetic drug. In conclusion, ropivacaine appears to be a safer local anaesthetic agent than bupivacaine. It seems particularly indicated for major peripheral nerve blocks and obstetrics. Ropivacaine should be considered when regional blocks are used in neonates and young infants. With the current trend in the cost development, ropivacaine will most likely be used increasingly in the future.