A review of the mechanism of the central analgesic effect of lidocaine

Anesthetic Mechanisms: Synergistic Interactions With Lipid Rafts and Voltage-Gated Sodium Channels

Despite successfully utilizing anesthetics for over 150 years, the mechanism of action remains relatively unknown. Recent studies have shown promising results, but due to the complex interactions between anesthetics and their targets, there remains a clear need for further mechanistic research. We know that lipophilicity is directly connected to anesthetic potency since lipid solubility relates to anesthetic partition into the membrane. However, clinically relevant concentrations of anesthetics do not significantly affect lipid bilayers but continue to influence various molecular targets. Lipid rafts are derived from liquid-ordered phases of the plasma membrane that contain increased concentrations of cholesterol and sphingomyelin and act as staging platforms for membrane proteins, including ion channels. Although anesthetics do not perturb membranes at clinically relevant concentrations, they have recently been shown to target lipid rafts. In this review, we summarize current research on how different types of anesthetics-local, inhalational, and intravenous-bind and affect both lipid rafts and voltage-gated sodium channels, one of their major targets, and how those effects synergize to cause anesthesia and analgesia. Local anesthetics block voltage-gated sodium channel pores while also disrupting lipid packing in ordered membranes. Inhalational anesthetics bind to the channel pore and the voltage-sensing domain while causing an increase in the number, size, and diameter of lipid rafts. Intravenous anesthetics bind to the channel primarily at the voltage-sensing domain and the selectivity filter, while causing lipid raft perturbation. These changes in lipid nanodomain structure possibly give proteins access to substrates that have translocated as a result of these structural alterations, resulting in lipid-driven anesthesia. Overall, anesthetics can impact channel activity either through direct interaction with the channel, indirectly through the lipid raft, or both. Together, these result in decreased sodium ion flux into the cell, disrupting action potentials and producing anesthetic effects. However, more research is needed to elucidate the indirect mechanisms associated with channel disruption through the lipid raft, as not much is known about anionic lipid products and their influence over voltage-gated sodium channels. Anesthetics' effect on S-palmitoylation, a promising mechanism for direct and indirect influence over voltage-gated sodium channels, is another auspicious avenue of research. Understanding the mechanisms of different types of anesthetics will allow anesthesiologists greater flexibility and more specificity when treating patients.

A randomised controlled trial of the effect of intra-articular lidocaine on pain scores in inflammatory arthritis

ABSTRACT

Chronic pain in inflammatory arthritis (IA) reflects a complex interplay between active disease in a peripheral joint and central pronociceptive mechanisms. Because intra-articular lidocaine may be used to abolish joint-specific peripheral input to the central nervous system, we aimed to validate its use as a clinical tool to identify those patients with IA whose pain likely incorporates centrally mediated mechanisms. We began by investigating whether there was a placebo response of intra-articular injection in patients with IA 1:1 randomised to receive intra-articular lidocaine or control (0.9% saline). After, in a larger patient cohort not randomized to placebo vs lidocaine groups, we tested whether patients with IA could be stratified into 2 cohorts based on their response to intra-articular lidocaine according to markers of centrally mediated pain. To this end, we evaluated postlidocaine pain numerical rating scale (NRS) scores alongside baseline painDETECT, fibromyalgia criteria fulfillment, and quantitative sensory testing outcomes. Numerical rating scale scores were collected at baseline and 3-, 5-, and 10-minutes postinjection. Firstly, the placebo effect of intra-articular injection was low: compared to baseline, the mean pain NRS score 5-minutes postinjection was reduced by 3.5 points in the lidocaine group vs 1.2 points in the control group. Secondly, postlidocaine NRS scores were significantly higher in those with a high (>18) baseline painDETECT score, fibromyalgia, and low-pressure pain threshold at the trapezius (P = 0.002, P = 0.001, P = 0.005, respectively). Persistent high pain after intra-articular lidocaine injection could be used as an indicator of pronociceptive mechanisms that are centrally mediated, informing centrally targeted analgesic strategies.

An extract of phase II and III trials on recent developments in managing neuropathic pain syndromes: diabetic peripheral neuropathy, trigeminal neuralgia, and postherpetic neuralgia

INTRODUCTION

Neuropathic pain (NP) conditions involve lesions to the somatosensory nervous system leading to chronic and debilitating pain. Many patients suffering from NP utilize pharmacological treatments with various drugs that seek to reduce pathologic neuronal states. However, many of these drugs show poor efficacy as well as cause significant adverse effects. Because of this, there is a major need for the development of safer and more efficacious drugs to treat NP.

AREAS COVERED

In this review, we analyzed current treatments being developed for a variety of NP conditions. Specifically, we sought drugs in phase II/III clinical trials with indications for NP conditions. Various databases were searched including Google Scholar, PubMed, and clinicaltrials.gov.

EXPERT OPINION

All the mentioned targets for treatments of NP seem to be promising alternatives for existing treatments that often possess poor side effect profiles for patients. However, gene therapy potentially offers the unique ability to inject a plasmid containing growth factors leading to nerve growth and repair. Because of this, gene therapy appears to be the most intriguing new treatment for NP.

Long-term pain outcomes after serial lidocaine infusion in participants with recent onset of peripheral neuropathic pain: A pilot double-blind, randomized, placebo-controlled trial

BACKGROUND

This study investigated the outcomes up to 12 weeks after serial lidocaine infusion for early-onset peripheral neuropathic pain.

METHODS

This pilot double-blind, randomized, 2-arm placebo-controlled trial recruited 50 participants with onset of peripheral neuropathic pain within the past 6 months and randomized them to either receive lidocaine (3 mg/kg) in normal saline (50 mL) intravenous infusion over 1 hour (lidocaine group) once a week for 4 weeks or 50 mL of normal saline infusion (placebo group) once a week for 4 weeks. Twenty-nine participants completed the protocol; 15 participants were assigned to the lidocaine group and 14 to the placebo group. The outcomes were pain intensity assessed using a numerical rating scale (NRS), quality of life assessed using EuroQol-Five Dimensions-Five Levels questionnaire (EQ-5D-5L), psychological function using the Thai version of the 21-item Depression Anxiety Stress Scales (DASS-21), pain medication use, and adverse effects, all assessed at baseline (BL) and again at 4, 8, and 12 weeks following randomization.

RESULTS

The reported tramadol use at 8 and 12 weeks following the first infusion was significantly lower in the lidocaine group (P = .023). No other significant between-group differences were observed at any time point or for any other outcome, and no serious adverse events were observed.

CONCLUSION

Multiple lidocaine infusions of 3 mg/kg once a week for 4 weeks in participants with recent onset of peripheral neuropathic pain demonstrated no significant benefits in pain intensity, quality of life, or psychological outcomes. At most, this treatment may result in less tramadol use.

Mechanisms and Preventative Strategies for Persistent Pain following Knee and Hip Joint Replacement Surgery: A Narrative Review

Chronic postsurgical pain (CPSP) following total knee arthroplasty (TKA) and total hip arthroplasty (THA) is a prevalent complication of joint replacement surgery which has the potential to decrease patient satisfaction, increase financial burden, and lead to long-term disability. The identification of risk factors for CPSP following TKA and THA is challenging but essential for targeted preventative therapy. Recent meta-analyses and individual studies highlight associations between elevated state anxiety, depression scores, preoperative pain, diabetes, sleep disturbances, and various other factors with an increased risk of CPSP, with differences observed in prevalence between TKA and THA. While the etiology of CPSP is not fully understood, several factors such as chronic inflammation and preoperative central sensitization have been identified. Other potential mechanisms include genetic factors (e.g., catechol-O-methyltransferase (COMT) and potassium inwardly rectifying channel subfamily J member 6 (KCNJ6) genes), lipid markers, and psychological risk factors (anxiety and depression). With regards to therapeutics and prevention, multimodal pharmacological analgesia, emphasizing nonopioid analgesics like acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs), has gained prominence over epidural analgesia. Nerve blocks and local infiltrative anesthesia have shown mixed results in preventing CPSP. Ketamine, an N-methyl-D-aspartate (NMDA)-receptor antagonist, exhibits antihyperalgesic properties, but its efficacy in reducing CPSP is inconclusive. Lidocaine, an amide-type local anesthetic, shows tentative positive effects on CPSP. Selective serotonin reuptake inhibitors (SSRIs) and serotonin norepinephrine reuptake inhibitors (SNRIs) have mixed results, while gabapentinoids, like gabapentin and pregabalin, present hopeful data but require further research, especially in the context of TKA and THA, to justify their use for CPSP prevention.

Lidocaine Inhibits Rat Prostate Cancer Cell Invasiveness and Voltage-Gated Sodium Channel Expression in Plasma Membrane

There is increasing evidence, mostly from breast cancer, that use of local anaesthetics during surgery can inhibit disease recurrence by suppressing the motility of the cancer cells dependent on inherent voltage-gated sodium channels (VGSCs). Here, the possibility that lidocaine could affect cellular behaviours associated with metastasis was tested using the Dunning cell model of rat prostate cancer. Mostly, the strongly metastatic (VGSC-expressing) Mat-LyLu cells were used under both normoxic and hypoxic conditions. The weakly metastatic AT-2 cells served for comparison in some experiments. Lidocaine (1-500 μM) had no effect on cell viability or growth but suppressed Matrigel invasion dose dependently in both normoxia and hypoxia. Used as a control, tetrodotoxin produced similar effects. Exposure to hypoxia increased Nav1.7 mRNA expression but VGSCα protein level in plasma membrane was reduced. Lidocaine under both normoxia and hypoxia had no effect on Nav1.7 mRNA expression. VGSCα protein expression was suppressed by lidocaine under normoxia but no effect was seen in hypoxia. It is concluded that lidocaine can suppress prostate cancer invasiveness without effecting cellular growth or viability. Extended to the clinic, the results would suggest that use of lidocaine, and possibly other local anaesthetics, during surgery can suppress any tendency for post-operative progression of prostate cancer.

Topical anesthesia versus topical and subconjunctival anesthesia combined in diabetic retinopathy photocoagulation

PURPOSE

comparison between two anesthetic techniques on the ability to reduce pain during panretinal photocoagulation (PRP) treatment.

METHODS

Observational retrospective single center study. Medical charts of patients who underwent PRP for proliferative diabetic retinopathy were revised. Patients were included if they had the first eye treated with oxybuprocaine hydrochloride drops, and in case of severe pain, the fellow eye received topical anesthesia in combination with 2% subconjunctival lidocaine. The groups were compared for pain perception using an analog visual scale (VAS), number of laser spots, number of interruptions, and laser session duration.

RESULTS

Forty-two eyes of 21 patients (mean age: 58.3 ± 7.6 years) were analyzed. The mean number of laser spots was significantly higher under combined anesthesia (+84.2 ± 155.9 spots, p = 0.01), with a reduced time for laser execution (-2.5 ± 3.12, p = 0.0008). The use of combined anesthesia significantly decreased the number of interruptions (-40.8%, p < 0.0001) into a single session. On the pain grading scale, the pain perception was significantly lower in the combined anesthesia group (p < 0.0001). In eyes receiving topical anesthesia the treatment was stopped for pain in 5 eyes (23.8%), while 5 eyes under combined anesthesia presented subconjunctival hemorrhage (23.8%).

CONCLUSION

Using combined anesthesia in patients subjected to PRP appeared to reduce pain perception limiting the treatment duration and the interruptions for pain without significant complications. Further studies on a larger scale would be desirable to replicate such findings and standardize the analgesic procedures in ophthalmology.

Elucidating molecular mechanisms of protoxin-II state-specific binding to the human NaV1.7 channel

Human voltage-gated sodium (hNaV) channels are responsible for initiating and propagating action potentials in excitable cells, and mutations have been associated with numerous cardiac and neurological disorders. hNaV1.7 channels are expressed in peripheral neurons and are promising targets for pain therapy. The tarantula venom peptide protoxin-II (PTx2) has high selectivity for hNaV1.7 and is a valuable scaffold for designing novel therapeutics to treat pain. Here, we used computational modeling to study the molecular mechanisms of the state-dependent binding of PTx2 to hNaV1.7 voltage-sensing domains (VSDs). Using Rosetta structural modeling methods, we constructed atomistic models of the hNaV1.7 VSD II and IV in the activated and deactivated states with docked PTx2. We then performed microsecond-long all-atom molecular dynamics (MD) simulations of the systems in hydrated lipid bilayers. Our simulations revealed that PTx2 binds most favorably to the deactivated VSD II and activated VSD IV. These state-specific interactions are mediated primarily by PTx2's residues R22, K26, K27, K28, and W30 with VSD and the surrounding membrane lipids. Our work revealed important protein-protein and protein-lipid contacts that contribute to high-affinity state-dependent toxin interaction with the channel. The workflow presented will prove useful for designing novel peptides with improved selectivity and potency for more effective and safe treatment of pain.

Impact of anesthesia choice in cutaneous melanoma surgery

Invasive cutaneous melanoma is the most lethal skin cancer, but fortunately, the vast majority can be surgically treated with wide local excision, and sometimes additionally with sentinel or index lymph node biopsy for prognostication. Melanomas are particularly immunogenic malignancies, and preclinical studies have demonstrated that use of volatile anesthetics and opioids, unlike local agents, can suppress the immune system during the perioperative period. Immunosuppression has implications for creating a potentially favorable microenvironment for the survival and propagation of residual melanoma cells or micro-metastases, which could lead to disease relapse, both in the local tumor bed and distally. Results from observational clinical studies are mixed, but the literature would suggest that patients are at risk of decreased melanoma-specific survival after undergoing general anesthesia compared to regional anesthesia and spinal blocks. With the safety of close observation now established rather than automatic completion or total lymph node dissection for patients with either a positive sentinel lymph node biopsy or significant clinical response to neoadjuvant immunotherapy after index node sampling, the indications for definitive surgery with local or regional anesthesia have increased tremendously in recent years. Therefore, cutaneous melanoma patients might benefit from avoidance of general anesthesia and other perioperative drugs that suppress cell-mediated immunity if the option to circumvent systemic anesthesia agents is feasible.

Assessment of the Pharmacokinetics and Pharmacodynamics of Injectable Lidocaine and a Lidocaine-Impregnated Latex Band for Castration and Tail Docking in Lambs

The objectives of this study were to assess the pharmacokinetics and pharmacodynamics of the current standard-of-care for pain mitigation in lambs during castration and tail docking (injectable lidocaine) and assess the ability of Lidocaine-Loaded Bands (LLBs) to deliver therapeutic concentrations into the contacted tissues over time. The study was comprised of four different trials: (1) investigation of in vitro release of lidocaine from LLBs; (2) pharmacokinetics and pharmacodynamics of injectable lidocaine in scrotal and tail tissue; (3) pharmacokinetics and pharmacodynamics of in vivo delivery of lidocaine with LLBs placed on the tail and scrotum of lambs; and (4) a "proof-of-concept" study comparing the sensation of control- versus LLB-banded tail tissue over time. The use of injectable lidocaine provides effective short-term anesthesia for 120 to 180 min following the injection; however, additional strategies are needed to manage long-term pain. The use of an LLB could provide an alternative where tissue lidocaine concentrations meet or exceed the EC50 for at least 21-28 days and, based on electrostimulation data, provides local anesthesia for at least 3 days when compared to a control band. Further studies are needed to compare the use of an injectable local anesthetic to the LLBs.

Comparing the Efficacy of Diluted Lidocaine Solution and Placebo in Reducing Pain Perception During Burn Wound Dressing Change

The aim of this study was to evaluate the effectiveness of 0.08% diluted lidocaine solution during and after wound dressing procedures for patients with burn injuries. Fifty burn patients aged 18-60 years, with burns ranging from 30% to 60%, were divided into intervention and control groups. The intervention group received dressings diluted with 0.08% lidocaine solution, while the control group received a placebo. Vital signs were continuously monitored before, during, and after the application of new dressings. Pain was assessed using the Visual Analog Scale (VAS) checklist before and after the dressing change in both groups. The study included 25 participants in the intervention group with a mean age of 40.2 ± 6.5 and 25 participants in the control group with a mean age of 39.1 ± 6.8. The groups were comparable in terms of baseline characteristics, including gender, age, weight, height, body mass index, percentage and degree of burns, as well as average morphine intake. No significant differences were observed in vital signs or pain scores before and after dressing changes between the 2 groups. However, the intervention group reported significantly lower pain scores during the dressing change compared to the control group (P < .001). Diluted lidocaine solution during wound dressing procedures can reduce pain in burn patients. Further research with larger sample sizes is needed to establish the safety and efficacy of this technique. This study suggests that lidocaine can be a useful tool in the management of pain during dressing changes for burn patients.

Lidocaine-Liposomes-A Promising Frontier for Transdermal Pain Management

(1) Background: We aim to develop novel gel formulations for transdermal drug delivery systems in acute and inflammatory pain therapy. (2) Methods: We induced inflammation by the injection of λ-carrageenan on the hind paw of 80 Wistar male rats. The animals were randomized into eight groups of 10 rats each: C (placebo gel), E (EMLATM), L (lidocaine 2%), L-CD (lidocaine + cyclodextrin 2.5%), L-LP (lidocaine + liposomes 1.7%), L-CS (lidocaine + chitosan 4%), L-CSh (lidocaine + chitosan hydrochloride), and L-CS-LP (lidocaine + chitosan + liposomes). The behavior response was determined with a hot plate, cold plate, and algesimeter, each being performed at 30, 60, 120, 180, and 240 min after pain induction. At the end of the experiment, tissue samples were collected for histological assessment. (3) Results: L-LP had the greatest anesthetic effects, which was proven on the cold plate test compared to placebo and EMLATM (all p ≤ 0.001). L-CS-LP had a significant effect on cold plate evaluation compared to placebo (p ≤ 0.001) and on hot plate evaluation compared to EMLATM (p = 0.018). (4) Conclusions: L-LP is a new substance with a substantial analgesic effect demonstrated by the cold plate in the first 120 min. Further studies with more animals are needed to determine the maximum doses that can be applied for a better analgesia with minimum side effects.

The Pharmacological Treatment of Neuropathic Pain in Children

The International Association for the Study of Pain (IASP) defines neuropathic pain as pain caused by a lesion or disease of the somatosensory nervous system. It is characterized as a clinical condition in which diagnostic studies reveal an underlying cause of an abnormality in the peripheral or central nervous system. Many common causes of neuropathic pain in adults are rare in children. The purpose of this focused narrative review is, to 1) provide an overview of neuropathic pain in children, 2) highlight unique considerations related to the diagnosis and mechanisms of neuropathic pain in children, and 3) perform a comprehensive analysis of the pharmacological treatments available. We emphasize that data for routine use of pharmacological agents in children with neuropathic pain are largely inferred from adult literature with little research performed on pediatric populations, yet have clear evidence of harms to pediatric patients. Based on these findings, we propose risk mitigation strategies such as utilizing topical treatments whenever possible, assessing pain phenotyping to guide drug class choice, and considering pharmaceuticals in the broader context of the multidisciplinary treatment of pediatric pain. Furthermore, we highlight important directions for future research on pediatric neuropathic pain treatment.

Adverse Events of the Long-Term Use of Opioids for Chronic Non-cancer Pain: A Narrative Review

BACKGROUND

The long-term use of opioids for chronic non-cancer pain (CNCP) has drawn more attention and debate. Although opioids are frequently used to treat chronic pain, their effectiveness and safety over extended periods are still unknown.

OBJECTIVES

The purpose of this review is to provide an overview of what is currently known about the adverse events of long-term use of opioids in CNCP. It also delivers patient-centered strategies designed to mitigate these risks.

METHODS

We conducted a literature search in PubMed, MEDLINE, EMBASE, and Web of Science databases. Search terms included CNCP, pain pathophysiology, opioid pharmacodynamics, opioid prescribing trends, guidelines for opioid use, and opioid side effects.  Results: Our review highlights that while opioids may provide short-term relief from CNCP, their effectiveness diminishes over time due to the development of opioid tolerance. This tolerance often leads to increased dosages, which can subsequently result in opioid dependence. Additionally, long-term opioid therapy is associated with a spectrum of adverse effects, including constipation, drowsiness, respiratory depression, and potential for drug interactions. Furthermore, our review indicates that alternative pain management strategies play a crucial role in controlling CNCP. They offer significant benefits with fewer adverse events. These strategies include non-opioid medications, physical therapy, cognitive-behavioral therapy (CBT), various interventional procedures, injection therapy, and acupuncture.

CONCLUSION

Using opioids to manage CNCP presents several challenges. Given these challenges, alternative treatments are being considered as viable options. Moreover, it is crucial to customize treatment plans to align with the patients' specific health requirements, existing conditions, and potential risks to ensure the best possible outcomes.

A Review of the Lidocaine in the Perioperative Period

This review analyzes the controversies surrounding lidocaine (LIDO), a widely recognized local anesthetic, by exploring its multifaceted effects on pain control in the perioperative setting. The article critically analyzes debates about lidocaine's efficacy, safety, and optimal administration methods. While acknowledging its well-documented analgesic attributes, the text highlights the ongoing controversies in its application. The goal is to provide clinicians with a comprehensive understanding of the current discourse, enabling informed decisions about incorporating lidocaine into perioperative protocols. On the other hand, emphasizes the common uses of lidocaine and its potential role in personalized medicine. It discusses the medication's versatility, including its application in anesthesia, chronic pain, and cardiovascular diseases. The text recognizes lidocaine's widespread use in medical practice and its ability to be combined with other drugs, showcasing its adaptability for individualized treatments. Additionally, it explores the incorporation of lidocaine into hyaluronic acid injections and its impact on pharmacokinetics, signaling innovative approaches. The discussion centers on how lidocaine, within the realm of personalized medicine, can offer safer and more comfortable experiences for patients through tailored treatments.

Lidocaine aerosol preoperative application for improving the comfort of pediatric patients undergoing tonsillectomy and adenoidectomy: A prospective randomized controlled trial

Background and Aims

The use of lidocaine aerosol for pediatric tonsil and adenoidectomy has been reported less frequently. We hope to improve the perioperative comfort of pediatric patients undergoing these procedures by applying lidocaine aerosol.

Methods

A total of 122 pediatric patients receiving tonsil and adenoidectomy were randomly divided into a lidocaine aerosol group (Group L) and a saline group (Group C), with 61 patients in each group; 2.4% alkaline lidocaine aerosol and saline were sprayed in the pharynx before induction. Our primary outcome were the incidence and rate ratio (RR) of postoperative pharyngeal complications (oropharyngeal dryness, dysphagia, hoarseness, and sore throat) and the pharyngeal comfort score, the latter of which was assessed by the occurrence of the above complications (yes = 0 point, none = 1 point). The secondary outcomes included preoperative and intraoperative blood pressure and heart rate, the incidence of choking during the induction period, the intraoperative opioid dosage, and the pain level and depth of sedation at 2, 6, and 24 h postoperatively. Statistical software used in this study included PASS15.0, SPSS 26.0, and GraphPad Prism 9.3.1, and statistical methods used included the t-test, the χ² test, the Mann-Whitney U test, and the repeated measures analysis of variance.

Results

The incidence and RR of postoperative pharyngeal complications such as oropharyngeal dryness (RR: 0.667, 95% confidence interval [CI]: 0.458-0.970, p = 0.03), dysphagia (RR: 0.333, 95% CI: 0.114-0.976, p = 0.03), hoarseness (RR: 0.647, 95% CI: 0.433-0.967, p = 0.03), and sore throat (RR: 0.727, 95% CI: 0.547-0.967, p = 0.03) were significantly lower in Group L than in Group C at 2 h postoperatively, and the incidence and RR of postoperative sore throat was significantly lower in Group L than in Group C at 6 h postoperatively (RR: 0.717, 95% CI: 0.547-0.942, p = 0.01). The postoperative pharyngeal comfort scores were significantly higher in Group L than in Group C at all postoperative time points (p < 0.05). The Ramsay sedation score was significantly higher (p < 0.01) and FLACC (face, legs, activity, crying, and consolability) score was significantly lower (p < 0.01) in Group L than in Group C at 2 h postoperatively. In Group C, the blood pressure and heart rate significantly faster at all time points immediately after intubation and afterward, except at the end of surgery (p < 0.05).

Conclusions

In pediatric tonsil and adenoidectomy, the application of lidocaine aerosol before induction can reduce the incidence of postoperative pharyngeal complications, improve the child's postoperative pharyngeal comfort, and better realize perioperative "comfort medical treatment."

How long to wait after local infiltration anaesthesia: systematic review

BACKGROUND

Conflicting evidence exists regarding the optimal waiting time for stable analgesic and vasoconstrictive effects after local infiltration of lidocaine with epinephrine. An objective review is needed to dispel surgical dogma.

METHODS

This systematic review (PROSPERO ID: CRD42022362414) included RCTs and prospective cohort studies. Primary outcomes were (1) onset of analgesia and (2) onset of stable hypoperfusion, assessed directly, or measured indirectly using perfusion imaging. Other data extracted include waiting strategies, means of outcome assessment, anaesthetic concentrations, volume/endpoint of infiltration, and injection sites. Methodological quality was evaluated using the Cochrane risk-of-bias tool for randomized trials. Articles describing waiting strategies were critically appraised by the Joanna Briggs Institute tools.

RESULTS

Twenty-four articles were analysed, comprising 1013 participants. Ten investigated analgesia onset. Their pooled mean was 2.1 min (range 0.4-9.0 min). This varied with anatomic site and targeted nerve diameter. Fourteen articles investigated onset of stable hypoperfusion. Four observed bleeding intraoperatively, finding the minimum time to hypoperfusion at 7.0 min in the eyelid skin and 25.0 min in the upper limb. The ten remaining studies used perfusion imaging, reporting a wide range of results (0.0-30.0 min) due to differences in anatomic sites and depth, resolution and artefacts. Studies using near-infrared reflectance spectroscopy and hyperspectral imaging correlated with clinical observations. Thirteen articles discussed waiting strategies, seven relating to large-volume tumescent local infiltration anaesthesia. Different waiting strategies exist for emergency, arthroscopic and cosmetic surgeries, according to the degree of hypoperfusion required. In tumescent liposuction, waiting 10.0-60.0 min is the norm.

CONCLUSION

Current literature suggests that around 2 min are required for most patients to achieve complete analgesia in all sites and with all anaesthesia concentrations. Waiting around 7 min in eyelids and at least 25 min in other regions results in optimal hypoperfusion. The strategies discussed inform decisions of when and how long to wait.

Simultaneous application of lidocaine and ketamine during ambulatory infusion therapy: a retrospective analysis

Background: Infusions with lidocaine or ketamine have been separately established in the treatment of chronic pain. This study aims to retrospectively evaluate the effect of combined infusions of lidocaine and ketamine. Materials & methods: Patient records were screened for receipt of combined ambulatory infusions of lidocaine and ketamine from 2012 through 2021. A scoring system was designed to assess pain response retrospectively. Results: A total of 319 patients were included. Median pain reduction in days was 10.00 (interquartile range: 13.25). Side effects were limited to the acute phase of infusions. A total of 41.4% of patients who received concomitant pain medication reported a dose reduction. Conclusion: Our data support combined infusions as a safe therapy option, with good short-, medium- and long-term reductions in pain and great heterogeneity in treatment response. Clinical trial registration: ClinicalTrials.gov (NCT05103319).

Anesthetic Effect of 2% Amitriptyline Versus 2% Lidocaine: A Comparative Evaluation

Introduction A common dental problem is the fear of pain during needle prick for giving local anesthesia (LA). The needle prick pain during dental procedures often varies with sex and age. Perception of pain depends on various factors, which can be psychological and biological. This perception of pain may change the behavior of patients toward dental treatments. Traditionally, lidocaine gel formulation was utilized before the parenteral dosage form. The lidocaine gel formulation is considered the drug of choice for LA in dental surgery. Currently, amitriptyline has been utilized in dental practice because of its beneficial pharmacology. Hence, the present study has been undertaken to compare the anesthetic ability of amitriptyline as an intraoral topical anesthetic agent with lidocaine gel. Methods This study was a comparative clinical study between two medications' anesthetic properties. This study included 120 patients indicated for bilateral orthodontics (the subdivision of dentistry that emphasizes identifying necessary interventions for the malocclusion of teeth) procedures. All the subjects were divided into amitriptyline and lidocaine groups. Both anesthetic gels were applied at separate sites before the injection of LA. The time of the onset of anesthesia was noted and analyzed. Patients were selected on the basis of inclusion and exclusion criteria. Individuals aged 18 to 30 years who were systemically healthy and orthodontically indicated for bilateral premolar extraction were included in this study. Again, patients with a history of neurological disorders and allergies to amitriptyline and lidocaine were excluded from the current study. Results Significant differences emerged between groups at five and 10 minutes, with amitriptyline-induced partial numbness (36.7% and 6.7%). At 40 and 45 minutes, both groups showed varied partial and complete numbness, with amitriptyline leading to partial recovery (23.3% and 73.3% complete numbness, 23.3% partial recovery) and lidocaine resulting in partial recovery (81.7%). When comparing the visual analog scale (VAS) scores, both groups exhibited a similar simultaneous effect at 15 minutes. Nonetheless, amitriptyline displayed significantly lower scores at 25 and 35 minutes (p < 0.001) in comparison to lidocaine. Similar observations were made when controlling for pain intensity. Conclusion It was concluded that amitriptyline holds both anesthetic and analgesic properties. Nevertheless, this study was unable to generalize the study findings because of the small sample size and being a single-center study. However, the VAS scores of anesthetic and analgesic pharmacodynamics properties of amitriptyline were statistically significantly lower than lidocaine, particularly at 25 and 35 minutes. Additionally, amitriptyline-induced anesthetic and analgesic pharmacology, especially pharmacokinetics properties, depends on the location and pattern of pain.

A Hematoma Block in the Wrist for a Displaced Distal Radius Fracture Induces Systemic Neurological Symptoms: A Case Report

Hematoma blocks are considered a relatively simple, safe, and effective technique in the acute setting to provide sufficient anesthesia and allow for closed reduction of displaced distal radius fractures. Complications associated with the utilization of local anesthetics in this setting are rare. We present the case of a patient who had a hematoma block in the wrist and developed short-term systemic neurologic complications likely secondary to systemic absorption of 20 mL of 1% lidocaine without epinephrine via the cancellous bone channels.

Elucidating Molecular Mechanisms of Protoxin-2 State-specific Binding to the Human NaV1.7 Channel

Human voltage-gated sodium (hNaV) channels are responsible for initiating and propagating action potentials in excitable cells and mutations have been associated with numerous cardiac and neurological disorders. hNaV1.7 channels are expressed in peripheral neurons and are promising targets for pain therapy. The tarantula venom peptide protoxin-2 (PTx2) has high selectivity for hNaV1.7 and serves as a valuable scaffold to design novel therapeutics to treat pain. Here, we used computational modeling to study the molecular mechanisms of the state-dependent binding of PTx2 to hNaV1.7 voltage-sensing domains (VSDs). Using Rosetta structural modeling methods, we constructed atomistic models of the hNaV1.7 VSD II and IV in the activated and deactivated states with docked PTx2. We then performed microsecond-long all-atom molecular dynamics (MD) simulations of the systems in hydrated lipid bilayers. Our simulations revealed that PTx2 binds most favorably to the deactivated VSD II and activated VSD IV. These state-specific interactions are mediated primarily by PTx2's residues R22, K26, K27, K28, and W30 with VSD as well as the surrounding membrane lipids. Our work revealed important protein-protein and protein-lipid contacts that contribute to high-affinity state-dependent toxin interaction with the channel. The workflow presented will prove useful for designing novel peptides with improved selectivity and potency for more effective and safe treatment of pain.

Therapeutic Perspectives for Inflammation and Senescence in Osteoarthritis Using Mesenchymal Stem Cells, Mesenchymal Stem Cell-Derived Extracellular Vesicles and Senolytic Agents

Osteoarthritis (OA) is the most common cause of disability worldwide among the elderly. Alarmingly, the incidence of OA in individuals less than 40 years of age is rising, likely due to the increase in obesity and post-traumatic osteoarthritis (PTOA). In recent years, due to a better understanding of the underlying pathophysiology of OA, several potential therapeutic approaches targeting specific molecular pathways have been identified. In particular, the role of inflammation and the immune system has been increasingly recognized as important in a variety of musculoskeletal diseases, including OA. Similarly, higher levels of host cellular senescence, characterized by cessation of cell division and the secretion of a senescence-associated secretory phenotype (SASP) within the local tissue microenvironments, have also been linked to OA and its progression. New advances in the field, including stem cell therapies and senolytics, are emerging with the goal of slowing disease progression. Mesenchymal stem/stromal cells (MSCs) are a subset of multipotent adult stem cells that have demonstrated the potential to modulate unchecked inflammation, reverse fibrosis, attenuate pain, and potentially treat patients with OA. Numerous studies have demonstrated the potential of MSC extracellular vesicles (EVs) as cell-free treatments that comply with FDA regulations. EVs, including exosomes and microvesicles, are released by numerous cell types and are increasingly recognized as playing a critical role in cell-cell communication in age-related diseases, including OA. Treatment strategies for OA are being developed that target senescent cells and the paracrine and autocrine secretions of SASP. This article highlights the encouraging potential for MSC or MSC-derived products alone or in combination with senolytics to control patient symptoms and potentially mitigate the progression of OA. We will also explore the application of genomic principles to the study of OA and the potential for the discovery of OA phenotypes that can motivate more precise patient-driven treatments.

Efficacy of intraoperative intravenous lidocaine infusion on postoperative opioid consumption after laparoscopic cholecystectomy: a randomized controlled trial

PURPOSE

We designed this study to evaluate the impact of intraoperative intravenous lidocaine infusion on postoperative opioid consumption after laparoscopic cholecystectomy.

METHODS

In total, 98 patients scheduled for elective laparoscopic cholecystectomy were included and randomized. In the experimental group, intravenous lidocaine (bolus 1.5 mg/kg and continuous infusion 2 mg/kg/h) was administered intraoperatively additionally to the standard analgesia, whereas the control group received a matching placebo. Blinding existed at the level of both the patient and the investigator.

RESULTS

Our study failed to confirm any benefit in opioid consumption, during the postoperative period. Lidocaine resulted to reduced intraoperative systolic, diastolic, and mean arterial pressure. Lidocaine administration did not change postoperative pain scores or the incidence of shoulder pain, at any time endpoint. Moreover, we did not identify any difference in terms of postoperative sedation levels and nausea rates.

CONCLUSION

Overall, lidocaine did not have any effect on postoperative analgesia after laparoscopic cholecystectomy.

Pharmacotherapy optimization for rapid sequence intubation in the emergency department

PURPOSE

Rapid-sequence intubation (RSI) is the process of administering a sedative and neuromuscular blocking agent (NMBA) in rapid succession to facilitate endotracheal intubation. It is the most common and preferred method for intubation of patients presenting to the emergency department (ED). The selection and use of medications to facilitate RSI is critical for success. The purpose of this review is to describe pharmacotherapies used during the RSI process, discuss current clinical controversies in RSI medication selection, and review pharmacotherapy considerations for alternative intubation methods.

SUMMARY

There are several steps to the intubation process requiring medication considerations, including pretreatment, induction, paralysis, and post-intubation sedation and analgesia. Pretreatment medications include atropine, lidocaine, and fentanyl; but use of these agents in clinical practice has fallen out of favor as there is limited evidence for their use outside of select clinical scenarios. There are several options for induction agents, though etomidate and ketamine are the most used due to their more favorable hemodynamic profiles. Currently there is retrospective evidence that etomidate may produce less hypotension than ketamine in patients presenting with shock or sepsis. Succinylcholine and rocuronium are the preferred neuromuscular blocking agents, and the literature suggests minimal differences between succinylcholine and high dose rocuronium in first-pass success rates. Selection between the two is based on patient specific factors, half-life and adverse effect profiles. Finally, medication-assisted preoxygenation and awake intubation are less common methods for intubation in the ED but require different considerations for medication use.

AREAS FOR FUTURE RESEARCH

The optimal selection, dosing, and administration of RSI medications is complicated, and further research is needed in several areas. Additional prospective studies are needed to determine optimal induction agent selection and dosing in patients presenting with shock or sepsis. Controversy exists over optimal medication administration order (paralytic first vs induction first) and medication dosing in obese patients, but there is insufficient evidence to significantly alter current practices regarding medication dosing and administration. Further research examining awareness with paralysis during RSI is needed before definitive and widespread practice changes to medication use during RSI can be made.

Efficacy of Lidocaine Infusion in High-Risk Vascular Surgery—A Randomized, Double-Blind, Placebo-Controlled Single-Center Clinical Trial

Background: In perioperative pain control, adjuvants such as lidocaine can reduce opioid consumption in a specific type of surgery. The aim of this single-center prospective double-blinded randomized controlled trial was to determine opioid consumption in the perioperative period in patients receiving continuous lidocaine infusion. Methods: Patients undergoing elective abdominal aorta and/or iliac arteries open surgery were randomized into two groups to receive 1% lidocaine or placebo at the same infusion rate based on ideal body weight (bolus of 0.15 mL/kg during the induction of anesthesia followed by continuous infusion of 0.2 mL/kg/h during surgery; postoperatively 0.1 mL/kg/h for 24 h) additionally to standard opioid analgesia. Results: Total opioid consumption within 24 h after surgery was 89.2 mg (95%CI 80.9–97.4) in the lidocaine and 113.1 mg (95%CI 102.5–123.6) in the placebo group (p = 0.0007). Similar findings were observed in opioid consumption intraoperatively (26.7 mg (95%CI 22.2–31.3) vs. 35.1 mg (95%CI 29.1–41.2), respectively, p = 0.029) and six hours postoperatively (47.5 mg (IQR 37.5–59.5) vs. 60 mg (IQR 44–83), respectively, p = 0.01). Conclusions: In high-risk vascular surgery, lidocaine infusion as an adjunct to standard perioperative analgesia is effective. It may decrease opioid consumption by more than 20% during the first 24 h after surgery, with no serious adverse effects noted during the study period.

Lidocaine inhibits osteogenic differentiation of human dental pulp stem cells in vitro

OBJECTIVE

Lidocaine is an amide local anaesthetic commonly used for pain control, however, few studies have investigated the effect of lidocaine on the osteogenic differentiation of human dental pulp stem cells (HDPSCs). The present study aimed to determine the effect of lidocaine on HDPSC viability and osteogenic differentiation.

METHODS

HDPSCs were incubated with 0, 0.05, 0.2, 0.5, and 1 mM lidocaine for 24, 48 and 72 h, after which, MTT assays were performed. HDPSCs cultured with the above lidocaine concentrations and osteogenic differentiation medium for 7 and 14 days were stained for alkaline phosphatase (ALP). Protein and mRNA levels of relevant osteogenic factors (bone morphogenetic protein-2 [BMP-2] and runt-related transcription factor 2 [RUNX2]) were examined using western blotting and real-time reverse-transcription polymerase chain reaction, respectively.

RESULTS

Lidocaine did not affect the viability of HDPSCs, however, lidocaine reduced ALP activity in HDPSCs. Levels of ALP, BMP-2, and RUNX2 mRNA were reduced with lidocaine, and levels of BMP-2 and RUNX2 proteins were decreased, versus controls.

CONCLUSIONS

Lidocaine inhibits osteogenic differentiation markers in HDPSCs in vitro, even at low concentrations, without cytotoxicity. This study suggests that lidocaine may inhibit osteogenic differentiation in HDPSC-mediated regenerative medicine, including pulp regeneration and repair.

Research progress of p38 as a new therapeutic target against morphine tolerance and the current status of therapy of morphine tolerance

With the development of the medical industry, new painkillers continue to appear in people's field of vision, but so far no painkiller can replace morphine. While morphine has a strong analgesic effect, it is also easy to produce pain sensitivity and tolerance. Due to the great inter-individual differences in patient responses, there are few clear instructions on how to optimise morphine administration regimens, which complicates clinicians' treatment strategies and limits the effectiveness of morphine in long-term pain therapy. P38MAPK is a key member of the MAPK family. Across recent years, it has been discovered that p38MAPK rises dramatically in a wide range of morphine tolerance animal models. Morphine tolerance can be reduced or reversed by inhibiting p38MAPK. However, the role and specific mechanism of p38MAPK are not clear. In this review, we synthesise the relevant findings, highlight the function and potential mechanism of p38MAPK in morphine tolerance, as well as the present status and efficacy of morphine tolerance therapy, and underline the future promise of p38MAPK targeted morphine tolerance treatment.

Enhancing Intradermal Delivery of Lidocaine by Dissolving Microneedles: Comparison between Hyaluronic Acid and Poly(Vinyl Pyrrolidone) Backbone Polymers

Lidocaine hydrochloride (LiH), an amide-type local anesthetic agent, is commonly used in dermatological procedures. LiH is categorized as a BCS (biopharmaceutics classification system) class III group, which has high solubility and poor permeability. It should be noted that, in this context, LiH is intended as a local anesthetic, so the level of LiH in systemic circulation should be minimized to avoid toxicity and unwanted side effects such as hypotension and bradycardia. This study aimed to formulate and evaluate LiH-loaded dissolving microneedles (DMNs) with different polymer bases. Moreover, an in vitro permeation study using Franz diffusion cells and in vivo study were also performed. LiH-loaded DMNs were prepared using polymer groups of poly(vinyl pyrrolidone) (PVP-K30) and hyaluronic acid (HA). DMNs were created using the micro-molding method with centrifugation. The formulations selected based on the evaluation were F3 (HA 10%) and F5 (PVP-K30 25%). Based on the in vitro permeation study, the amount of drug permeated and deposited in the skin at F3 (HA 10%) was 247.1 ± 41.85 and 98.35 ± 12.86 μg, respectively. On the other hand, the amount of drug permeated and deposited in the skin at F5 (PVP-K30 25%) was 277.7 ± 55.88 and 59.46 ± 9.25 μg, respectively. Our in vivo drug-permeation study showed that only one rat from the PVP-K30 polymer group-with a concentration of 150.32 ng/mL-was detected on rat plasma. Therefore, LiH can be formulated into a DMN and can be deposited in the skin with a safe concentration of the drug permeating into systemic circulation.

Systemic Lidocaine Infusions for Pediatric Patients with Cancer-Related Pain

Pediatric patients with cancer experience significant distress from both treatment and cancer-related pain. Careful selection of an analgesic regimen should be based upon individual patient factors, including the level of pain, response to therapy, and physiologic profile. Refractory pain is a therapeutic dilemma frequently encountered in the pediatric cancer setting. Systemic lidocaine infusions have been described as both safe and efficacious, as prior studies show patients reporting decreased pain scores and improved quality of life after lidocaine treatment. Given the favorable side effect profile of lidocaine, it has the potential to be considered for analgesia in the setting of refractory pain. This review discusses the use of systemic lidocaine infusions for analgesia in pediatric oncology patients with cancer-related pain.

In Vitro Drug Screening Using iPSC-Derived Cardiomyocytes of a Long QT-Syndrome Patient Carrying KCNQ1 & TRPM4 Dual Mutation: An Experimental Personalized Treatment

Congenital long QT syndrome is a type of inherited cardiovascular disorder characterized by prolonged QT interval. Patient often suffer from syncopal episodes, electrocardiographic abnormalities and life-threatening arrhythmia. Given the complexity of the root cause of the disease, a combination of clinical diagnosis and drug screening using patient-derived cardiomyocytes represents a more effective way to identify potential cures. We identified a long QT syndrome patient carrying a heterozygous KCNQ1 c.656G>A mutation and a heterozygous TRPM4 c.479C>T mutation. Implantation of implantable cardioverter defibrillator in combination with conventional medication demonstrated limited success in ameliorating long-QT-syndrome-related symptoms. Frequent defibrillator discharge also caused deterioration of patient quality of life. Aiming to identify better therapeutic agents and treatment strategy, we established a patient-specific iPSC line carrying the dual mutations and differentiated these patient-specific iPSCs into cardiomyocytes. We discovered that both verapamil and lidocaine substantially shortened the QT interval of the long QT syndrome patient-specific cardiomyocytes. Verapamil treatment was successful in reducing defibrillator discharge frequency of the KCNQ1/TRPM4 dual mutation patient. These results suggested that verapamil and lidocaine could be alternative therapeutic agents for long QT syndrome patients that do not respond well to conventional treatments. In conclusion, our approach indicated the usefulness of the in vitro disease model based on patient-specific iPSCs in identifying pharmacological mechanisms and drug screening. The long QT patient-specific iPSC line carrying KCNQ1/TRPM4 dual mutations also represents a tool for further understanding long QT syndrome pathogenesis.

Drug Repurposing: The Mechanisms and Signaling Pathways of Anti-Cancer Effects of Anesthetics

Cancer is one of the leading causes of death worldwide. There are only limited treatment strategies that can be applied to treat cancer, including surgical resection, chemotherapy, and radiotherapy, but these have only limited effectiveness. Developing a new drug for cancer therapy is protracted, costly, and inefficient. Recently, drug repurposing has become a rising research field to provide new meaning for an old drug. By searching a drug repurposing database ReDO_DB, a brief list of anesthetic/sedative drugs, such as haloperidol, ketamine, lidocaine, midazolam, propofol, and valproic acid, are shown to possess anti-cancer properties. Therefore, in the current review, we will provide a general overview of the anti-cancer mechanisms of these anesthetic/sedative drugs and explore the potential underlying signaling pathways and clinical application of these drugs applied individually or in combination with other anti-cancer agents.

Lidocaine Suppresses Gastric Cancer Development Through Circ_ANO5/miR-21-5p/LIFR Axis

BACKGROUND

Lidocaine has been manifested to exert anti-tumor role in gastric cancer (GC) progression. However, the action mechanism by which Lidocaine functions in GC has not been fully elucidated.

AIM

The study aimed to reveal the molecular mechanism of Lidocaine in GC progression.

METHODS

Cell clonogenicity and viability were assessed by colony formation and methyl thiazolyl tetrazolium assays, respectively. Transwell assay was employed to detect cell migration and invasion. Flow cytometry was implemented to monitor cell apoptosis. Relative expression of circular RNA ANO5 (circ_ANO5), microRNA (miR)-21-5p and Leukemia inhibitory factor receptor (LIFR) was examined by quantitative reverse transcription-polymerase chain reaction. Western blot assay was performed to analyze the levels of LIFR and cell metastasis-related proteins. The target relationship between miR-21-5p and circ_ANO5 or LIFR was confirmed by dual-luciferase reporter assay. In addition, xenograft model was established to explore the role of Lidocaine in vivo.

RESULTS

Lidocaine inhibited cell proliferation, migration and invasion, while promoted apoptosis of GC cells. Lidocaine upregulated circ_ANO5 and LIFR expression, but downregulated miR-21-5p expression in GC cells. Additionally, expression of circ_ANO5 and LIFR was decreased, while miR-21-5p expression was increased in GC cells. Circ_ANO5 depletion or miR-21-5p overexpression attenuated Lidocaine-induced anti-proliferative and anti-metastatic effects on GC cells. Circ_ANO5 could sponge miR-21-5p, and miR-21-5p targeted LIFR. Moreover, Lidocaine suppressed the tumor growth in vivo.

CONCLUSION

Lidocaine might GC cell malignancy by modulating circ_ANO5/miR-21-5p/LIFR axis, highlighting a novel insight for GC treatment.

Central Neuropathic Pain Syndromes: Current and Emerging Pharmacological Strategies

Central neuropathic pain is caused by a disease or lesion of the brain or spinal cord. It is difficult to predict which patients will develop central pain syndromes after a central nervous system injury, but depending on the etiology, lifetime prevalence may be greater than 50%. The resulting pain is often highly distressing and difficult to treat, with no specific treatment guidelines currently available. This narrative review discusses mechanisms contributing to central neuropathic pain, and focuses on pharmacological approaches for managing common central neuropathic pain conditions such as central post-stroke pain, spinal cord injury-related pain, and multiple sclerosis-related neuropathic pain. Tricyclic antidepressants, serotonin-norepinephrine reuptake inhibitors, and gabapentinoids have some evidence for efficacy in central neuropathic pain. Medications from other pharmacologic classes may also provide pain relief, but current evidence is limited. Certain non-pharmacologic approaches, neuromodulation in particular, may be helpful in refractory cases. Emerging data suggest that modulating the primary afferent input may open new horizons for the treatment of central neuropathic pain. For most patients, effective treatment will likely require a multimodal therapy approach.

Continuous infusion of lidocaine in pediatric colonoscopy: A randomized double-blind placebo-controlled study

BACKGROUND

Propofol is commonly used for providing procedural sedation during pediatric colonoscopy. Intravenous (i.v.) lidocaine can mitigate visceral pain and reduce propofol requirements during surgery. The aim of this study is to investigate the effect of i.v. lidocaine on perioperative propofol and sufentanil dose, pulse oxygen saturation, postoperative pain score, and recovery time during pediatric colonoscopy.

METHODS

We designed a randomized, double-blind, placebo-controlled study and enrolled 40 children aged from 3 to 10 years who underwent colonoscopy. After titration of propofol to achieve unconsciousness, the patients were given i.v. lidocaine (1.5 mg/kg later 2 mg/kg^/hour) or the same volume of saline. Sedation was standardized and combined propofol with sufentanil. The primary outcome variables were intraoperative propofol and sufentanil requirements, and the number of oxygen desaturation episodes. Secondary outcome variables were recovery time after colonoscopy and post-colonoscopy pain.

RESULTS

Lidocaine infusion resulted in a significant reduction in propofol requirements: (median (quartile) 1.8 (1.5-2.0) vs. 3.0 (2.8-3.3) mg/kg respectively; P < 0.001) and sufentanil requirements: (median (quartile) 0.06 (0.05-0.08) vs. 0.1 (0.1-0.1) μg/kg respectively; P < 0.001). The number of subjects who experienced oxygen desaturation below 95% in the lidocaine group was also significantly less than that in the control group: 1 vs. 6 (P = 0.04). The mean (SD) recovery time was significantly shorter in the lidocaine group: (19.2 (2.6) vs. 13.3 (2.6) min respectively; P < 0.001). There was no significant difference in post-colonoscopy pain.

CONCLUSION

Continuous infusion of lidocaine resulted in reduction of propofol and sufentanil requirements, recovery time, and risk of hypoxemia during pediatric colonoscopy.

Dexmedetomidine Co-Administered with Lidocaine Decreases Nociceptive Responses and Trigeminal Fos Expression without Motor Dysfunction and Hypotension in a Murine Orofacial Formalin Model

Administration of dexmedetomidine significantly induces sedation and anti-nociception in several nociceptive models, but clinical trials are restricted due to adverse side effects, including lethargy, hypotension, and bradycardia. Herein, we investigated whether intraperitoneal inoculation of dexmedetomidine reduced the orofacial nociceptive response and affected motor coordination and blood pressure and examined whether a lower dose of dexmedetomidine in combination with 0.5% lidocaine produced an antinociceptive effect without any adverse side events in a murine model. To perform the experiment, 5% formalin (10 µL) was subcutaneously inoculated into the right upper lip, and the rubbing responses were counted for 45 min. Different doses of dexmedetomidine combined with 0.5% lidocaine were administered 10 and 30 min before formalin injection, respectively. Dexmedetomidine (10 μg/kg) significantly reduced orofacial nociceptive responses during the second phase of the formalin test and decreased the expression of Fos in trigeminal nucleus caudalis (TNC). Besides, a high dose of dexmedetomidine (30 μg/kg) induced lessening physical ability and significantly reduced systolic pressure and heart rate. When 0.5% lidocaine was injected subcutaneously, nociceptive responses were reduced only in the first phase. Interestingly, although a low dose of dexmedetomidine (3 μg/kg) alone did not show an antinociceptive effect, its co-administration with lidocaine significantly reduced the nociceptive response in both phases and decreased TNC Fos expression without motor dysfunction and hypotension. This finding suggests that the combination of a low-dose of systemic dexmedetomidine with lidocaine may be a safe medicinal approach for acute inflammatory pain management in the orofacial region, particularly mucogingival pain.

Continuous infusion of lidocaine in pediatric colonoscopy: A randomized double-blind placebo-controlled study

BACKGROUND

Propofol is commonly used for providing procedural sedation during pediatric colonoscopy. Intravenous (i.v.) lidocaine can mitigate visceral pain and reduce propofol requirements during surgery. The aim of this study is to investigate the effect of i.v. lidocaine on perioperative propofol and sufentanil dose, pulse oxygen saturation, postoperative pain score, and recovery time during pediatric colonoscopy.

METHODS

We designed a randomized, double-blind, placebo-controlled study and enrolled 40 children aged from 3 to 10 years who underwent colonoscopy. After titration of propofol to achieve unconsciousness, the patients were given i.v. lidocaine (1.5 mg/kg later 2 mg/kg^/hour) or the same volume of saline. Sedation was standardized and combined propofol with sufentanil. The primary outcome variables were intraoperative propofol and sufentanil requirements, and the number of oxygen desaturation episodes. Secondary outcome variables were recovery time after colonoscopy and post-colonoscopy pain.

RESULTS

Lidocaine infusion resulted in a significant reduction in propofol requirements: (median (quartile) 1.8 (1.5-2.0) vs. 3.0 (2.8-3.3) mg/kg respectively; P < 0.001) and sufentanil requirements: (median (quartile) 0.06 (0.05-0.08) vs. 0.1 (0.1-0.1) μg/kg respectively; P < 0.001). The number of subjects who experienced oxygen desaturation below 95% in the lidocaine group was also significantly less than that in the control group: 1 vs. 6 (P = 0.04). The mean (SD) recovery time was significantly shorter in the lidocaine group: (19.2 (2.6) vs. 13.3 (2.6) min respectively; P < 0.001). There was no significant difference in post-colonoscopy pain.

CONCLUSION

Continuous infusion of lidocaine resulted in reduction of propofol and sufentanil requirements, recovery time, and risk of hypoxemia during pediatric colonoscopy.

Role of Intravenous Lidocaine Infusion in the Treatment of Peripheral Neuropathy

Purpose of Review

This is a comprehensive review of the literature regarding intravenous lidocaine infusion to treat peripheral neuropathy. The clinical symptoms of peripheral neuropathy occur on a broad spectrum and stem from many etiologies resulting in complex treatment approaches. This review presents the background, evidence, and indications for the use of intravenous lidocaine infusions as a treatment option for this condition.

Recent Findings

The clinical range of peripheral neuropathy symptoms includes pain, numbness, muscle weakness, paresthesia, balance difficulty, and autonomic dysfunction. However, severe neuropathic pain remains one of the most debilitating symptoms that significantly affects the quality of life. Current treatment options include antidepressants, anticonvulsants, and, in some cases, opiates, but these are often ineffective, creating the need for other therapeutic approaches.The pathophysiology of neuropathic pain involves sodium channels which create abnormal pain responses. Intravenous lidocaine primarily functions by inhibiting membrane sodium channels which desensitize peripheral nociceptors, thus creating an analgesic effect. The research in using intravenous lidocaine for neuropathic pain is not fully complete and requires further evaluation.

Summary

Peripheral neuropathy is a manifestation commonly resulting from diabetes, alcohol abuse, vitamin deficiencies, and chemotherapy, among other causes. One of the most significant complications is neuropathic pain which is often resistant to multi-modal therapeutic regimens. Intravenous lidocaine infusions are a newer treatment option for neuropathic pain, which have additional anti-inflammatory effects with a minimal side effect profile. Studies have concluded it effectively treats neuropathic pain for weeks after administration, but results are variable depending on specific procedures. Further research, including additional direct comparison studies, should be conducted to fully evaluate this drug's usefulness.

Postoperative pain: a review of emerging therapeutic options

INTRODUCTION

Postoperative pain is often managed by opioid medications, even though they carry a risk of adverse effects such as vomiting, constipation, sedation, respiratory depression and physical dependence. Furthermore, opioid use in the healthcare setting has likely contributed to the epidemic. However, the mismanagement of postoperative pain can result in delayed recovery time, impaired physical function, increased risk of morbidity and mortality, chronic pain, and higher healthcare costs.

AREAS COVERED

This review explores emerging therapeutic options and strategies in the management of acute postoperative pain and focuses on opioid-sparing, multimodal analgesia. This includes regional anesthetic techniques, non opioid pharmacotherapy, novel opioids and non-pharmacologic therapy. We have also discussed examples of novel analgesics and formulations which have potential benefits in reducing postoperative pain and opioid use after surgery.

EXPERT OPINION

The development of novel regional anesthesia techniques allows for opioid minimization in increasing number of surgical procedures. This synergizes with the availability of novel non-opioid analgesic adjucts. In addition, several novel opioid drugs have been developed which may be pathway selective and associated with less adverse effect than conventional opioids.

Lidocaine has antitumor effect on hepatocellular carcinoma via the circ_DYNC1H1/miR-520a-3p/USP14 axis

Lidocaine can inhibit the malignant development of various human cancers. Circular RNA (circRNA) dynein 1 heavy chain gene (circ_DYNC1H1) acted as a pro-cancer molecule in hepatocellular carcinoma (HCC). This study aimed to explore whether the function of lidocaine was related to the oncogenic circ_DYNC1H1 in HCC. Colony formation assay and 3-(4,5-dimethylthiazol-2-y1)-2, 5-diphenyl tetrazolium bromide (MTT) assay were used for proliferation detection. Cell apoptosis was assessed by flow cytometry, and migration or invasion was determined by the transwell assay. The levels of circ_DYNC1H1, microRNA-520a-3p (miR-520a-3p), and ubiquitin-specific protease 14 (USP14) were examined using the quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Protein levels were measured using western blot. The binding between miR-520a-3p and circ_DYNC1H1 or USP14 was confirmed by the dual-luciferase reporter assay. In vivo assay was conducted by a xenograft model in mice. Lidocaine reduced proliferation, migration, and invasion but promoted apoptosis in HCC cells. The circ_DYNC1H1 expression was downregulated in lidocaine-treated HCC cells. The inhibitory effect of lidocaine on HCC progression was weakened after circ_DYNC1H1 overexpression. miR-520a-3p was a target of circ_DYNC1H1, and the function of lidocaine was related to the regulation of circ_DYNC1H1/miR-520a-3p axis. USP14 served as a target for miR-520a-3p, and circ_DYNC1H1 could sponge miR-520a-3p to regulate the USP14 expression. The lidocaine-induced suppression of HCC development was also achieved by mediating the miR-520a-3p/USP14 axis. In vivo assay revealed that lidocaine suppressed the tumor growth of HCC by reducing the expression of circ_DYNC1H1 to affect the levels of miR-520a-3p and USP14. Our results clarified that lidocaine impeded tumor progression via targeting the circ_DYNC1H1/miR-520a-3p/USP14 axis in HCC cells.

Lidocaine Infusions for Pain Management in Pediatrics

Lidocaine is an amino amide with a well-established role as a local anesthetic agent. Systemic intravenous administration expands its clinical use to include acute and chronic pain circumstances, such as postoperative pain, neuropathic pain, postherpetic neuralgia, hyperalgesia, visceral pain, and centrally mediated pain. For refractory pain that has not responded to conventional therapy or if further escalation of treatment is prevented by contraindications or side effects to standard therapies, a continuous infusion of lidocaine may be considered as a single intervention or as a sequence of infusions. Here, we review and evaluate published data reflecting the use of lidocaine continuous infusions for pain management in the pediatric population.

Intravenous Infusion of Lidocaine Can Accelerate Postoperative Early Recovery in Patients Undergoing Surgery for Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is defined by intermittent and recurrent episodes of partial or complete obstruction of the upper airway during sleep. Intermittent and recurrent hypoxia/reoxygenation is the main pathophysiological mechanism of OSA. Its consequences include systemic inflammation, activation of the sympathetic nervous system, and release of oxygen free radicals. Infusion of intravenous (IV) lidocaine has anti-inflammatory, antihyperalgesic, and analgesic properties, supporting its use as an anesthetic adjuvant. Lidocaine can reduce nociception and/or cardiovascular responses to surgical stress, as well as postoperative pain and/or analgesic requirements. Because of the high prevalence of OSA in obese patients, the use of opioids to manage postoperative pain in that population is often accompanied by the development of adverse respiratory events, such as hypoventilation and hypoxemia. IV infusion of lidocaine has been shown to enhance the quality of early recovery after laparoscopic bariatric and upper airway surgery. However, limited evidence exists regarding its use in patients undergoing surgery for OSA. In addition, whether IV infusion of lidocaine can improve postoperative early recovery in patients undergoing surgery for OSA remains unknown. Therefore, we hypothesized that IV infusion of lidocaine can improve postoperative early recovery in patients undergoing surgery for OSA. Perioperative infusion also may be a promising analgesic adjunct to enhanced recovery after surgery (ERAS) protocols.

Utilization of Intravenous Lidocaine Infusion for the Treatment of Refractory Chronic Pain

Context

Chronic pain accounts for one of the most common reasons patients seek medical care. The financial burden of chronic pain on health care is seen by direct financial cost and resource utilization. Many risk factors may contribute to chronic pain, but there is no definite risk. Managing chronic pain is a balance between maximally alleviating symptoms by utilizing a therapeutic regimen that is safe for long-term use. Currently, non-opioid analgesics, NSAIDs, and opioids are some of the medical treatment options, but these have numerous adverse effects and may not be the best option for long-term use. However, Lidocaine can achieve both central and peripheral analgesic effects with relatively few side effects, which may be an ideal compound for managing chronic pain.

Evidence Acquisition

This is a Narrative Review.

Results

Infusion of lidocaine (2-(diethylamino)-N-(2,6-dimethylphenyl)acetamide), an amino-amide compound, is emerging as a promising option to fill the therapeutic void for treatment of chronic pain. Numerous studies have outlined dosing protocols for lidocaine infusion for the management of perioperative pain, outlined below. While there are slight variations in these different protocols, they all center around a similar dosing regimen to administer a bolus to reach a rapid steady state, followed by infusion for up to 72 hours to maintain the therapeutic analgesic effects.

Conclusions

Lidocaine may be a promising pharmacologic solution with a low side effect profile that provides central and peripheral analgesia. Even though the multifaceted mechanism is not entirely understood yet, lidocaine may be a promising novel remedy in treating chronic pain in various conditions.