Optimising peri-operative intravenous lidocaine dosing regimens

Abstract

We thank Dr Hansel for his interest and comments [1] related to our publication [2]. This discussion highlights the ongoing debate regarding dosing of intravenous lidocaine infusions and ongoing concerns with the lack of safety data. The aim of our observational pharmacokinetic study and dosing simulations was to improve the understanding of intravenous lidocaine pharmacokinetics and, ultimately, to improve safety and efficacy of dosing of this commonly used (albeit ‘off-label’) peri-operative drug.

We acknowledge this is a simulated regimen that requires external validation and evaluation in the clinical setting for safety and efficacy. Our proposed simulated dose regimen is specific to our studied population, carefully considers covariates and body weight metrics, and shows (simulated) concentrations < 5 μg.ml^-1. Our proposed dosing aligns with other regimens used clinically, with infusions ranging from 1–5 mg.kg^-1.h^-1 [3, 4]. Importantly, in patients with obesity, dosing should be adjusted based on lean body weight. We have not examined infusions > 3 h and have not made any comments regarding postoperative dosing and administration.

The use of intravenous lidocaine for peri-operative pain management is common in Australia and parts of the UK. We agree that it requires careful individual patient assessment of risk vs. benefit, should consider the clinical context, and close monitoring is required to pick up adverse events. Consensus statements, such as that published by Foo et al. [5] and focused on postoperative lidocaine infusions, can be a useful guide for clinicians. Ensuring patient safety is paramount and, with intra-operative administration, intravenous lidocaine can be delivered carefully and monitored by the anaesthetist. Large anaesthesia incident reporting systems, such as WebAIRS in Australia, remain important in identifying safety data related to infrequent anaesthesia-related events, but are limited by reliance on self-reporting.

We agree with Hansel and others [6] that robust evidence is needed through large clinical trials with carefully considered safety and outcome measures. We believe dosing strategies such as those proposed in this study may help enable optimal peri-operative use of intravenous lidocaine infusions and look forward to prospective evaluation.