Ropivacaine Cardiotoxicity — FRCA Primary MCQ
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Correct answer: D — It is the pure S(-)-enantiomer and has lower cardiotoxic potential
Explanation lettering: E = shown as A · A = shown as B · B = shown as E
D is correct. Ropivacaine is a long-acting amide local anaesthetic supplied as the pure S(-)-enantiomer, whereas conventional bupivacaine is racemic. Its lower lipid solubility and less marked adverse cardiac electrophysiological effects give it lower cardiotoxic potential, although severe local anaesthetic systemic toxicity remains possible. A is false because ropivacaine is licensed for epidural surgical anaesthesia and analgesia. B is false: it is an amide undergoing hepatic metabolism, not an ester hydrolysed by plasma cholinesterase. C is false because its pKa is approximately 8.07, similar to bupivacaine at approximately 8.2, rather than substantially higher. E reverses the comparison: ropivacaine is less lipid-soluble and less cardiotoxic than racemic bupivacaine and generally produces less motor block at clinically effective analgesic doses.
Reference: McClellan KJ, Faulds D. Ropivacaine: an update of its use in regional anaesthesia. Drugs. 2000;60(5):1065–1093. https://pubmed.ncbi.nlm.nih.gov/11129123/