Unlicensed intravenous lidocaine for postoperative pain: always a safer 'licence to stop' than to start

Population Pharmacokinetics of Intravenous Lidocaine in Adults: A Systematic Review

BACKGROUND

The establishment of optimal dosing regimens for intravenous (IV) lidocaine in the perioperative setting, aiming to balance effective pain relief with minimisation of potential side effects, is a topic of ongoing debate. This discussion stems from the significant variability in lidocaine's pharmacokinetic (PK) parameters and its relatively narrow safety margin. Population pharmacokinetic (popPK) modelling has emerged as a valuable tool for understanding the factors contributing to this observed variability in drug kinetics.

OBJECTIVES

This systematic review compiles the existing knowledge on lidocaine's PK properties and published popPK models, with a focus on significant covariates.

METHODS

A systematic search on Cochrane CENTRAL, Medline, and EMBASE was performed from inception to June 2023. Original clinical studies that administered IV lidocaine to adults and performed PK analyses using a nonlinear mixed effects modelling approach were included. The quality of the included studies was assessed by compliance with the Clinical Pharmacokinetics (ClinPK) statement checklist.

RESULTS

Seven studies were included, which involved a diverse adult population, including both volunteers and patients with various comorbidities. Lidocaine PK was primarily characterised by a two- or three-compartment model. The volume of distribution at steady state ranged from 66 to 194 L, and the total clearance ranged from 22 to 49 L/h. Despite adjusting for significant covariates like heart failure status, alpha-1-acid glycoprotein, duration of lidocaine infusion, and body weight, each study revealed substantial variability in PK parameters. The potential impact of hepatic or renal function biomarkers on these PK parameters calls for further investigation. Incomplete reporting of key aspects of developed models may hinder the models' reliability and clinical application.

CONCLUSION

The findings emphasise the importance of tailoring drug dosage to ensure the safe and effective use of intravenous lidocaine. Optimal design methodologies may be incorporated for a more efficient identification of important covariates. Utilising contemporary model evaluation methods like visual predictive checks and bootstrapping would enhance the robustness of popPK models and the reliability of their predictions. This comprehensive review advances our understanding of lidocaine's pharmacokinetics and lays the groundwork for further research in this critical area of perioperative pain management. Review protocol registered on 25 August 2023 in PROSPERO (CRD42023441113). This work was supported by the Fundamental Research Grant Scheme, the Ministry of Higher Education, Malaysia (FRGS/1/2020/SKK01/UM/02/2).

PROcedure-SPECific postoperative pain management guideline for laparoscopic colorectal surgery: A systematic review with recommendations for postoperative pain management

Colorectal cancer is the second most common cancer diagnosed in women and third most common in men. Laparoscopic resection has become the standard surgical technique worldwide given its notable benefits, mainly the shorter length of stay and less postoperative pain. The aim of this systematic review was to evaluate the current literature on postoperative pain management following laparoscopic colorectal surgery and update previous procedure-specific pain management recommendations. The primary outcomes were postoperative pain scores and opioid requirements. We also considered study quality, clinical relevance of trial design, and a comprehensive risk-benefit assessment of the analgesic intervention. We performed a literature search to identify randomised controlled studies (RCTs) published before January 2022. Seventy-two studies were included in the present analysis. Through the established PROSPECT process, we recommend basic analgesia (paracetamol for rectal surgery, and paracetamol with either a nonsteroidal anti-inflammatory drug or cyclo-oxygenase-2-specific inhibitor for colonic surgery) and wound infiltration as first-line interventions. No consensus could be achieved either for the use of intrathecal morphine or intravenous lidocaine; no recommendation can be made for these interventions. However, intravenous lidocaine may be considered when basic analgesia cannot be provided.

Serum lidocaine (lignocaine) concentrations during prolonged perioperative infusion in patients undergoing breast cancer surgery: A secondary analysis of a randomised controlled trial

Perioperative lidocaine (lignocaine) infusions are being employed with increasing frequency. The determinants of systemic lidocaine concentrations during prolonged administration are unclear. In the Long-term Outcomes after Lidocaine Infusions for PostOperative Pain (LOLIPOP) pilot trial, the impact of infusion duration and body size metrics on serum lidocaine concentrations was examined with regression models in 48 women undergoing breast cancer surgery. Lidocaine was delivered as an intravenous bolus (1.5 mg/kg) and infusion (2 mg/kg per h) intraoperatively, followed by a 12-h subcutaneous infusion (1.33 mg/kg per h) postoperatively. Dosing was based on total body weight. Wound infiltration with other long-acting local anaesthetics was permitted. Protein binding and pharmacogenomic data were also collected. Lidocaine concentrations (median (interquartile range) (range)) during prolonged administration were in the safe and potentially therapeutic range: post-anaesthesia care unit 2.16 (1.73-2.82) (1.12-6.06) µg/ml; ward 1.41 (1.22-1.75) (0.64-2.81) µg/ml. Concentrations increased non-linearly during the early intravenous phase of administration (mean rise 1.21 µg/ml per hour of infusion, P = 0.007) but reached a pseudo steady-state during the later subcutaneous phase. Higher dose rates received per kilogram of lean (P = 0.004), adjusted (P = 0.006) and ideal body weight (P = 0.009) were associated with higher steady-state concentrations. The lidocaine free fraction was unaffected by the presence of ropivacaine, and phenotypes linked to slow metabolism were infrequent. Serum lidocaine concentrations reached a pseudo steady-state during a 12-h postoperative infusion. Greater precision in steady-state concentrations can be achieved by dosing on lean body weight versus adjusted or ideal body weight (equivalent lean body weight doses: intravenous bolus 2.5 mg/kg; intravenous infusion 3.33 mg/kg per h; subcutaneous infusion 2.22 mg/kg per h.

Preventive Effect of Local Lidocaine Administration on the Formation of Traumatic Neuroma

BACKGROUND

Traumatic neuroma is a common sequela of peripheral nerve injury or amputation, which often leads to severe neuropathic pain. The present study investigated the effect of local lidocaine administration on preventing the formation of traumatic neuroma.

METHODS

Forty-eight male Sprague-Dawley rats were randomly assigned to two groups. The lidocaine group underwent sciatic nerve transection, followed by an injection of lidocaine (0.5%) around the proximal of a severed sciatic nerve under ultrasound-guidance 2-7 days after neurectomy. In the control group, rats received an injection of saline following neurectomy. The autotomy score, mechanical allodynia, thermal hyperalgesia, histological assessment, expression of neuroma, and pain-related markers were detected.

RESULTS

Lidocaine treatment reduced the autotomy score and attenuated mechanical allodynia and thermal hyperalgesia. The mRNA expression of α-SMA, NGF, TNF-α, and IL-1β all significantly decreased in the lidocaine group in comparison to those in the saline control group. The histological results showed nerve fibers, demyelination, and collagen hyperplasia in the proximal nerve stump in the saline control group, which were significantly inhibited in the lidocaine group.

CONCLUSIONS

The present study demonstrated that local lidocaine administration could inhibit the formation of painful neuroma due to traumatic nerve injury.

Effect of intravenous lidocaine on pain after head and neck cancer surgery (ELICO trial): A randomised controlled trial

BACKGROUND

Treatment of postoperative pain after ear, nose and throat (ENT) cancer surgery is mainly morphine administration. Additional systemic lidocaine has shown promising results in some surgical procedures.

OBJECTIVE

The main objective was to evaluate morphine consumption in the first 48 postoperative hours after intra-operative lidocaine infusion during major ENT cancer surgery.

DESIGN

A randomised, double-blind, placebo-controlled trial.

SETTING

Bicentric study including a university hospital and a major cancer centre, conducted from December 2016 to December 2019.

PATIENTS

A total of 144 patients undergoing major ENT cancer surgery were included.

INTERVENTION

The patients were randomly assigned to receive intravenous lidocaine or placebo during surgery and in the recovery room.

MAIN OUTCOME MEASURES

Endpoints were postoperative morphine consumption in the first 24 and 48 h postoperatively, intra-operative remifentanil consumption, adverse events occurrence and assessment 3 to 6 months after surgery with the McGill pain questionnaire.

RESULTS

A total of 118 patients were included (lidocaine n  = 57; placebo n  = 61, 26 patients were excluded). There was no significant difference in morphine consumption during the first 48 postoperative hours in the lidocaine group compared with the placebo group with a median [IQR] of 0.60 [0.30 to 1.03] mg kg -1 vs. 0.57 [0.37 to 0.96] mg kg -1 , total dose 44 [21 to 73.3] mg vs. 38 [23.3 to 56.5] mg, P  = 0.92.There was no significant difference between the two groups in any of the other endpoints, including at follow up 3 to 6 months after surgery.

CONCLUSION

Intravenous lidocaine in ENT cancer surgery did not show any additional analgesic or morphine-sparing effect 48 h after surgery. Three to six months after surgery, there was no significant difference in pain scores or consumption of analgesics. Patients treated pre-operatively with opioids were not evaluated in the study.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT02894710 and EUDRACT number 2015-005799-90.

The Use of Intravenous Lidocaine in Perioperative Medicine: Anaesthetic, Analgesic and Immune-Modulatory Aspects

This narrative review provides an update on the applied pharmacology of lidocaine, its clinical scope in anaesthesia, novel concepts of analgesic and immune-modulatory effects as well as the current controversy around its use in perioperative opioid-sparing multi-modal strategies. Potential benefits of intravenous lidocaine in the context of cancer, inflammation and chronic pain are discussed against concerns of safety, toxicity and medico-legal constraints.

The ALLEGRO trial: a placebo controlled randomised trial of intravenous lidocaine in accelerating gastrointestinal recovery after colorectal surgery

Background

Return of gastrointestinal (GI) function is fundamental to patient recovery after colorectal surgery and is required before patients can be discharged from hospital safely. Up to 40% of patients suffer delayed return of GI function after colorectal surgery, causing nausea, vomiting and abdominal discomfort, resulting in longer hospital stay. Small, randomised studies have suggested perioperative intravenous (IV) lidocaine, which has analgesic and anti-inflammatory effects, may accelerate return of GI function after colorectal surgery. The ALLEGRO trial is a pragmatic effectiveness study to assess the benefit of perioperative IV lidocaine in improving return of GI function after elective minimally invasive (laparoscopic or robotic) colorectal surgery.

Methods

United Kingdom (UK) multi-centre double blind placebo-controlled randomised controlled trial in 562 patients undergoing elective minimally invasive colorectal resection. IV lidocaine or placebo will be infused for 6–12 h commencing at the start of surgery as an adjunct to usual analgesic/anaesthetic technique. The primary outcome will be return of GI function.

Discussion

A 6–12-h perioperative intravenous infusion of 2% lidocaine is a cheap addition to usual anaesthetic/analgesic practice in elective colorectal surgery with a low incidence of adverse side-effects. If successful in achieving quicker return of gut function for more patients, it would reduce the rate of postoperative ileus and reduce the duration of inpatient recovery, resulting in reduced pain and discomfort with faster recovery and discharge from hospital. Since colorectal surgery is a common procedure undertaken in every acute hospital in the UK, a reduced length of stay and reduced rate of postoperative ileus would accrue significant cost savings for the National Health Service (NHS).

Trial registration

EudraCT Number 2017-003835-12; REC Number 17/WS/0210 the trial was prospectively registered (ISRCTN Number: ISRCTN52352431); date of registration 13 June 2018; date of enrolment of first participant 14 August 2018.

Evaluating the Safety of Continuous Infusion Lidocaine for Postoperative Pain

OBJECTIVES

The aim was to evaluate the safety of intravenous lidocaine for postoperative pain and the impact on opioid requirements and pain scores.

MATERIALS AND METHODS

This was a single-center, retrospective, single-arm analysis of adult patients who received intravenous lidocaine for postoperative pain from January 2016 to December 2019. Patients were excluded if they received lidocaine for any indication other than pain or if lidocaine was only given intraoperatively. The primary outcome of this analysis was to determine the incidence of adverse effects (AEs) and the reason for discontinuation of lidocaine. Secondary outcomes included median daily pain scores (visual analog scale and Critical-Care Pain Observation Tool) and opioid consumption (daily morphine milligram equivalents) 24 hours before infusion and during day 1.

RESULTS

A total of 452 patients were evaluated of which 298 (65.9%) patients met inclusion criteria. Of the 154 patients excluded, 153 did not receive lidocaine postoperatively. The median duration of infusion was 34 [20:48] hours with a median initial and maintenance rate of 1 mg/kg/h dosed on ideal body weight. In our analysis, 174 (58.4%) patients had a documented AE during infusion and 38 (12.8%) had lidocaine discontinued because of an AE. The most common AE was nausea in 62 (20.8%) patients and the most common reason for discontinuation was confusion in 8 (2.7%) patients. Daily morphine milligram equivalents (P<0.001) and visual analog scale (P<0.001) significantly decreased when comparing 24 hours before infusion and day 1.

CONCLUSION

Although a majority of patients receiving lidocaine for postoperative pain experienced an AE, this did not result in discontinuation in most patients.

Perioperative Intravenous Lidocaine and Metastatic Cancer Recurrence - A Narrative Review

Cancer is a major global health problem and the second leading cause of death worldwide. When detected early, surgery provides a potentially curative intervention for many solid organ tumours. Unfortunately, cancer frequently recurs postoperatively. Evidence from laboratory and retrospective clinical studies suggests that the choice of anaesthetic and analgesic agents used perioperatively may influence the activity of residual cancer cells and thus affect subsequent recurrence risk. The amide local anaesthetic lidocaine has a well-established role in perioperative therapeutics, whether used systemically as an analgesic agent or in the provision of regional anaesthesia. Under laboratory conditions, lidocaine has been shown to inhibit cancer cell behaviour and exerts beneficial effects on components of the inflammatory and immune responses which are known to affect cancer biology. These findings raise the possibility that lidocaine administered perioperatively as a safe and inexpensive intravenous infusion may provide significant benefits in terms of long term cancer outcomes. However, despite the volume of promising laboratory data, robust prospective clinical evidence supporting beneficial anti-cancer effects of perioperative lidocaine treatment is lacking, although trials are planned to address this. This review provides a state of the art summary of the current knowledge base and recent advances regarding perioperative lidocaine therapy, its biological effects and influence on postoperative cancer outcomes.

Anesthetic technique and cancer surgery outcomes

PURPOSE OF REVIEW

Surgery remains integral to treating solid cancers. However, the surgical stress response, characterized by physiologic perturbation of the adrenergic, inflammatory, and immune systems, may promote procancerous pathways. Anesthetic technique per se may attenuate/enhance these pathways and thereby could be implicated in long-term cancer outcomes.

RECENT FINDINGS

To date, clinical studies have predominantly been retrospective and underpowered and, thus limit meaningful conclusions. More recently, prospective studies of regional anesthesia for breast and colorectal cancer surgery have failed to demonstrate long-term cancer outcome benefit. However, based on the consistent observation of protumorigenic effects of surgical stress and that of volatile anesthesia in preclinical studies, supported by in vivo models of tumor progression and metastasis, we await robust prospective clinical studies exploring the role of propofol-based total intravenous anesthesia (cf. inhalational volatiles). Additionally, anti-adrenergic/anti-inflammatory adjuncts, such as lidocaine, nonsteroidal anti-inflammatory drugs and the anti-adrenergic propranolol warrant ongoing research.

SUMMARY

The biologic perturbation of the perioperative period, compounded by the effects of anesthetic agents, renders patients with cancer particularly vulnerable to enhanced viability of minimal residual disease, with long-term outcome consequences. However, low level and often conflicting clinical evidence equipoise currently exists with regards to optimal oncoanesthesia techniques. Large, prospective, randomized control trials are urgently needed to inform evidence-based clinical practice guidelines.

A pilot multicentre randomised controlled trial of lidocaine infusion in women undergoing breast cancer surgery

Chronic postoperative pain is common after breast cancer surgery. Peri-operative lidocaine infusion may prevent the development of chronic postoperative pain, but a large-scale trial is required to test this hypothesis. It is unclear whether a pragmatic, multicentre trial design that is consistent with expert guidance, addresses the limitations of previous studies, and overcomes existing translational barriers is safe, effective and feasible. We conducted a double-blind, randomised controlled pilot study in 150 patients undergoing breast cancer surgery across three hospitals in Western Australia. Patients received lidocaine, or equivalent volumes of saline, as an intravenous bolus (1.5 mg.kg^-1 ) and infusion (2 mg.kg^-1 .h^-1 ) intra-operatively, and a subcutaneous infusion (1.33 mg.kg^-1 .h^-1 ) postoperatively for up to 12 h on a standard surgical ward, with novel safety monitoring tools in place. The co-primary outcomes were: in-hospital safety events; serum levels of lidocaine during intravenous and subcutaneous infusion; and annualised enrolment rates per site with long-term data capture. In-hospital safety events were rare, and similar in the placebo and lidocaine arms (3% vs. 1%). Median (IQR [range]) serum lidocaine levels during intravenous (2.16 (1.74-2.83 [1.12-6.06]) µg.ml^-1 , n = 41) and subcutaneous (1.52 (1.28-1.83 [0.64-2.85]) µg.ml^-1 , n = 48) infusion were comparable with previous trials reporting improved pain outcomes. Annualised enrolment approximated 50 patients per site per year, with high levels of protocol adherence and ≥ 99% capture of outcomes at 3 and 6 months. The adjusted odds ratio (95%CI) for postoperative pain at 6 months in the lidocaine arm was 0.790 (0.370-1.684). We conclude that this trial, as designed, is safe, effective and feasible in patients undergoing breast cancer surgery, and a larger-scale trial is planned.