Anaes · Local anaesthetic pharmacology
Local anaesthetic pharmacology
Also known as Local anaesthetics · Lidocaine · Bupivacaine · Ropivacaine · LAST · Lipid rescue
Local anaesthetics produce reversible blockade of nerve conduction by binding the voltage-gated sodium channel from inside the axon, preventing the action potential. The framework rests on four exam-critical ideas: the agents are classified as amides or esters by their linking bond (which determines their metabolism — hepatic for amides, plasma-cholinesterase for esters); their onset, potency and duration are governed by their pKa, lipid solubility and protein binding respectively; their systemic toxicity (LAST) progresses from CNS excitation to seizures to cardiovascular collapse, with bupivacaine uniquely cardiotoxic; and the specific antidote for severe LAST is intravenous lipid emulsion, which acts as a lipid sink absorbing the drug. Built on the ASRA LAST checklist (Neal 2021), the lipid-resuscitation mechanism review (Fettiplace & Weinberg 2018), the bupivacaine reference (McAllister 2026), the LAST emergency protocols (Meral 2026), and the geriatric LA toxicity review (Waldinger 2020).
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20 MCQs with explanations
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Red flags
Meet the patient
A 70-year-old man is having an epidural for a total knee replacement. Halfway through injecting he tells you his lips are tingling and he feels strange, and the monitor throws up a run of multifocal ventricular ectopics. That is the opening chord of local-anaesthetic systemic toxicity — stop the injection, call for help, and have the lipid drawn up before the drug reaches the heart.[1]
Two questions decide every local-anaesthetic stem: did you calculate the dose in milligrams per kilogram before drawing up the syringe? and is a bag of 20 percent lipid in the room? Hold those two and the whole topic organises itself around them.[1]
You have read the opening of this topic. The complete unit — every section and its primary-source references — is part of the Anaesthesia fellowship atlas.
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- [1]Neal JM, Neal EJ, Weinberg GL. American Society of Regional Anesthesia and Pain Medicine Local Anesthetic Systemic Toxicity checklist: 2020 version Reg Anesth Pain Med, 2021.PMID 33148630
- [2]Fettiplace MR, Weinberg G. The Mechanisms Underlying Lipid Resuscitation Therapy Reg Anesth Pain Med, 2018.PMID 29356774
- [3]McAllister RK, Patel P. Bupivacaine 2026.PMID 30422478
- [4]Meral RM, Nagpal AS, Wasserman R. International Pain and Spine Intervention Society Emergency Protocols: Local Anesthetic Systemic Toxicity (LAST) Interv Pain Med, 2026.PMID 42325878
- [5]Waldinger R, Weinberg G, Gitman M Local Anesthetic Toxicity in the Geriatric Population Drugs Aging, 2020.PMID 31598909