GasGasGas - Anaesthetic Science for Anaesthesia! GasGasGas - Bupivacaine and Friends
Jul 8, 2025
Explore the fascinating world of bupivacaine, an essential local anesthetic, and learn about its formulations and clinical uses. Delve into the science behind sodium channel blockade and the differences between neuronal and cardiac action potentials. Discover the implications of combining additives with bupivacaine and the potential toxicity involved. Uncover the advantages of levobupivacaine, including its reduced cardiotoxicity and sensory-sparing effects. Tune in for crucial insights into dosing, mechanisms, and practical applications in anesthesia!
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Bupivacaine Basics And Mechanism
- Bupivacaine is an amide local anaesthetic provided as a racemic mixture of R and S enantiomers in common concentrations of 0.25% and 0.5%.
- Its mechanism is sodium channel blockade and pharmacologic properties (pKa, lipid solubility, protein binding) determine onset and duration.
Use-Dependent Sodium Channel Block
- Local anaesthetics prefer the open state of neuronal sodium channels causing use-dependent (phasic) block.
- The unionized fraction enters the nerve then re-dissociates; the ionized form blocks the channel.
Neuron Action Potential Outline
- Neuronal action potentials have four phases without a plateau and show an overshoot/hyperpolarization on repolarisation.
- Voltage-gated sodium influx causes depolarization and potassium efflux causes repolarization.