Anaes · Local anaesthetic pharmacology

Local anaesthetic agents compared

Also known as Lidocaine bupivacaine ropivacaine comparison · Amide local anaesthetic head-to-head · Levobupivacaine and ropivacaine (safer S-enantiomers) · Local anaesthetic cardiotoxicity ranking

The amide local anaesthetics differ in onset, duration, potency and cardiotoxicity, and these four properties drive every exam answer on agent selection. Lidocaine (lignocaine) is the fast-onset, intermediate-duration versatile all-rounder and also a class Ib antiarrhythmic, validated as a benchmark topical and infiltration agent by Shao et al. (2026) and Majewska et al. (2026). Bupivacaine is long-acting and potent but is the MOST CARDIOTOXIC amide, with a racemic formulation whose R(+)-enantiomer drives refractory ventricular arrhythmia (Robinson et al., 2026). Levobupivacaine and ropivacaine are the pure S-enantiomer alternatives that retain long duration with less cardiotoxicity, and ropivacaine additionally produces less motor block at low concentration, valued in labour epidural analgesia (Stojanovic et al., 2026; Cao et al., 2026; Grelowska et al., 2026). Prilocaine is short-acting and the least toxic per unit potency but causes methaemoglobinaemia via its o-toluidine metabolite, treated with methylene blue (Shao, Majewska). The cardiotoxicity ranking is bupivacaine greater than levobupivacaine or ropivacaine greater than lidocaine or prilocaine.