GasGasGas - The FRCA Primary Exam Podcast GasGasGas - Prilocaine (+Ampres) for the FRCA Primary
Jul 24, 2025
This episode dives into the benefits of prilocaine, a local anaesthetic that's often overlooked in favor of bupivacaine. Discover why it's preferred for spinals due to lower risks associated with lidocaine. Learn about prilocaine's chemistry, its unique mechanisms for nerve blocks, and dosing limits. The discussion also covers the potential risks of methemoglobinemia and management strategies. Dr Gas highlights faster recovery times and practical advice for using prilocaine effectively in day-case procedures.
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Prilocaine Beats Lidocaine For TNS Risk
- Prilocaine is a viable alternative to lidocaine for spinal anaesthesia due to much lower TNS risk.
- A Cochrane review found non-lidocaine agents cut TNS risk by ~82–90% versus lidocaine.
Prilocaine Formulation And Presentation
- Prilocaine is an amide local anaesthetic presented as racemic prilocaine hydrochloride in 1–3% solutions.
- It is commonly available as heavy (hyperbaric) prilocaine for spinals.
How Local Anaesthetics Reach Sodium Channels
- Local anaesthetics must be unionised to cross the neuronal membrane and ionised inside to block sodium channels.
- Lipophilicity and the fraction unionised determine onset and effectiveness.
