Systemic lidocaine for neuropathic pain relief

Procoagulant, antibacterial and antioxidant high-strength porous hydrogel adhesives in situ formed via self-gelling hemostatic microsheets for emergency hemostasis and wound repair

Procoagulant, antibacterial and analgesic hemostatic hydrogel dressing with high wet tissue adhesion, ultra-high burst pressure, and easy preparation shows huge promising for rapid hemostasis in emergencies, yet it remains a challenge. Herein, we propose hemostatic microsheets based on quaternized chitosan-g-gallic acid (QCS-GA) and oxidized hyaluronic acid (OHA), which merge the benefits of sponges, hydrogels, and powders for rapid hemostasis and efficient wound healing. Specifically, they exhibit a large specific surface area and excellent hydrophilicity, rapidly absorbing blood and self-gelling through electrostatic interaction and Schiff base crosslinking. And this results in dense, porous hydrogel adhesives with superior mechanical properties, adhesion strength, and ultra-high burst pressure. Furthermore, the microsheets are biocompatible, biodegradable, and possess procoagulant, antibacterial, and antioxidant properties. In mouse and rat liver hemorrhage models, the optimized formulation (QCS-GA + OHA4) demonstrated superior hemostatic effects compared to Celox. In particular, QCS-GA + OHA4 microsheets could stop bleeding quickly from rat femoral artery transection and deliver lidocaine to provide analgesia during emergency treatment. Additionally, they promoted wound healing in mouse full-thickness skin defect wound. These easy-to-manufacture hemostatic microsheets are adaptable to irregular wounds, providing a novel solution for rapid hemostasis and wound healing.

Voltage-gated sodium channels in excitable cells as drug targets

Excitable cells - including neurons, muscle cells and cardiac myocytes - are unique in expressing high densities of voltage-gated sodium (NaV) channels. This molecular adaptation enables these cells to produce action potentials, and is essential to their function. With the advent of the molecular revolution, the concept of 'the' sodium channel has been supplanted by understanding that excitable cells in mammals can express any of nine different forms of sodium channels (NaV1.1-NaV1.9). Selective expression in particular types of cells, together with a key role in controlling action potential firing, makes some of these NaV subtypes especially attractive molecular targets for drug development. Although these different channel subtypes display a common overall structure, differences in their amino acid sequences have provided a basis for the development of subtype-specific drugs. This approach has resulted in exciting progress in the development of drugs for epilepsy, cardiac disorders and pain. In this Review, we discuss recent progress in the development of drugs that selectively target each of the sodium channel subtypes.

Middle meningeal artery embolization in migraine: From concept to reality

Migraine is a common neurological disorder that primarily affects young adults. Despite the availability of multiple therapeutic options for patients with intractable migraine, a significant proportion of these patients remain refractory to treatment, highlighting the importance for novel therapies. In this study, we comprehensively assessed the role of the middle meningeal artery (MMA) in the management of intractable migraine. Although the exact pathophysiology of migraine remains a subject of debate, the neurovascular theory of migraine has gained attention recently following multiple studies assessing the role of the MMA in migraine pathophysiology. In addition, the successful utilization of lidocaine both through intravenous injection and directly into the MMA, as well as favorable results observed in the form of headache relief following MMA embolization (MMAE) in patients with chronic subdural hematoma, has further substantiated the neurovascular theory hypothesis. In this study, we evaluated the current evidence, potential trends, role of other injection medications, as well as risks and limitations of MMAE in the management of patients with refractory migraine. Intractable migraine is a complex condition that often requires multimodal management. MMAE has emerged as a promising, novel therapeutic technique that may help reduce pain and minimize the need for additional treatments. However, further prospective and randomized trials are still necessary for further validation.

The role of lidocaine in cancer progression and patient survival

Since its development in 1943, lidocaine has been one of the most commonly used local anesthesia agents for surgical procedures. Lidocaine alters neuronal signal transmission by prolonging the inactivation of fast voltage-gated sodium channels in the cell membrane of neurons, which are responsible for action potential propagation. Recently, it has attracted attention due to emerging evidence suggesting its potential antitumor properties, particularly in the in vitro setting. Further, local administration of lidocaine around the tumor immediately prior to surgical removal has been shown to improve overall survival in breast cancer patients. However, the exact mechanisms driving these antitumor effects remain largely unclear. In this article, we will review the existing literature on the mechanism of lidocaine as a local anesthetic, its effects on the cancer cells and the tumor microenvironment, involved pathways, and cancer progression. Additionally, we will explore recent reports highlighting its impact on clinical outcomes in cancer patients. Taken together, there remains significant ambiguity surrounding lidocaine's functions and roles in cancer biology, particularly in perioperative setting.

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.

Prevention of persistent pain with lidocaine infusions in breast cancer surgery (PLAN): study protocol for a multicenter randomized controlled trial

BACKGROUND

Persistent pain is a common yet debilitating complication after breast cancer surgery. Given the pervasive effects of this pain disorder on the patient and healthcare system, post-mastectomy pain syndrome (PMPS) is becoming a larger population health problem, especially as the prognosis and survivorship of breast cancer increases. Interventions that prevent persistent pain after breast surgery are needed to improve the quality of life of breast cancer survivors. An intraoperative intravenous lidocaine infusion has emerged as a potential intervention to decrease the incidence of PMPS. We aim to determine the definitive effects of this intervention in patients undergoing breast cancer surgery.

METHODS

PLAN will be a multicenter, parallel-group, blinded, 1:1 randomized, placebo-controlled trial of 1,602 patients undergoing breast cancer surgery. Adult patients scheduled for a lumpectomy or mastectomy will be randomized to receive an intravenous 2% lidocaine bolus of 1.5 mg/kg with induction of anesthesia, followed by a 2.0 mg/kg/h infusion until the end of surgery, or placebo solution (normal saline) at the same volume. The primary outcome will be the incidence of persistent pain at 3 months. Secondary outcomes include the incidence of pain and opioid consumption at 1 h, 1-3 days, and 12 months after surgery, as well as emotional, physical, and functional parameters, and cost-effectiveness.

DISCUSSION

This trial aims to provide definitive evidence on an intervention that could potentially prevent persistent pain after breast cancer surgery. If this trial is successful, lidocaine infusion would be integrated as standard of care in breast cancer management. This inexpensive, widely available, and easily administered intervention has the potential to reduce pain and suffering in an already afflicted patient population, decrease the substantial costs of chronic pain management, potentially decrease opioid use, and improve the quality of life in patients.

TRIAL REGISTRATION

This trial has been registered on clinicaltrials.gov (NCT04874038, Dr. James Khan. Date of registration: May 5, 2021).

Sedation and Analgesia for Toxic Epidermal Necrolysis in the Intensive Care Unit: Few Certainties, Many Questions Ahead

Toxic epidermal necrolysis (TEN) is a rare, acute mucocutaneous life-threatening disease. Although research has focused on the pathophysiological and therapeutic aspects of the disease, there is a paucity of data in the literature regarding pain management and sedation in the intensive care unit (ICU). Most therapies have been extrapolated from other situations and/or the general ICU population. These patients present unique challenges during the progression of the disease and could end up requiring invasive mechanical ventilation due to inadequate pain management, which is potentially avoidable through a comprehensive treatment approach. In this review, we will present clinical and pathophysiological aspects of TEN, analyze pain pathways and relevant pharmacology, and propose therapeutic alternatives based on a rational and multimodal approach.

Hazard and health risk assessment of exposure to pharmaceutical active compounds via toxicological evaluation by zebrafish

The uncontrolled or continuous release of effluents from wastewater treatment plants leads to the omnipresence of pharmaceutical active compounds (PhACs) in the aquatic media. Today, this is a confirmed problem becoming a main subject of twin public and scientific concerns. However, still little information is available about the long-term impacts of these PhACs on aquatic organisms. In this review, efforts were made to reveal correlation between the occurrence in the environment, ecotoxicological and health risks of different PhACs via toxicological evaluation by zebrafish (Danio rerio). This animal model served as a bioindicator for any health impacts after the exposure to these contaminants and to better understand the responses in relation to human diseases. This review paper focused on the calculation of Risk Quotients (RQs) of 34 PhACs based on environmental and ecotoxicological data available in the literature and prediction from the ECOSAR V2.2 software. To the best of the authors' knowledge, this is the first report on the risk assessment of PhACs by the two different methods as mentioned above. RQs showed greater difference in potential environmental risks of the PhACs. These differences in risk values underline the importance of environmental and experimental factors in exposure conditions and the interpretation of RQ values. While the results showed high risk to Danio rerio of the majority of PhACs, risk qualification of the others varied between moderate to insignifiant. Further research is needed to assess pharmaceutical hazards when present in wastewater before discharge and monitor the effectiveness of treatment processes. The recent new advances in the morphological assessment of toxicant-exposed zebrafish larvae for the determination of test compounds effects on the developmental endpoints were also discussed. This review emphasizes the need for strict regulations on the release of PhACs into environmental media in order to minimize their toxicity to aquatic organisms.

Inflammation and subsequent nociceptor sensitization in the bone marrow are involved in an animal model of osteoarthritis pain

AIMS

This study aimed to determine whether pathological changes in the bone marrow cause Osteoarthritis (OA) pain based on magnetic resonance imaging (MRI), immunohistochemistry, and electrophysiology.

MAIN METHODS

Adjuvant-induced arthritis (AIA) was achieved by injecting 150 μL of complete Freund's adjuvant into the right knee joints of male Sprague-Dawley rats. AIA rats were compared with saline-injected rats.

KEY FINDINGS

AIA significantly induced mechanical hyperalgesia and spontaneous pain in the right hind paw 1-14 days after induction. Intratibial injection of 50 μL of 1 % lidocaine significantly suppressed AIA-induced mechanical hyperalgesia (p = 0.0001) and spontaneous pain (p = 0.0006) 3 days after induction. In T2-weighted MRI, AIA induced high-signal intensity within the proximal tibial metaphysis, and the mean T2 values in this area significantly increased on days 3 (p = 0.0043) and 14 (p = 0.0012) after induction. AIA induced intraosseous edema and significantly increased the number of intraosseous granulocytes on days 3 (p < 0.0001) and 14 (p < 0.0001) after induction. The electrophysiological study on days 3-7 after induction showed significantly increased spontaneous firing rates (p = 0.0166) and evoked responses to cutaneous stimuli (brush, p < 0.0001; pinching, p = 0.0359) in the right hind paw plantar surface and intratibial stimuli (p = 0.0002) in wide-dynamic-range neurons of the spinal dorsal horn.

SIGNIFICANCE

Intraosseous changes caused by OA induce hypersensitivity in the sensory afferents innervating bone marrow may be involved in OA pain. Novel bone marrow-targeted therapies could be beneficial for treating OA pain.

Mussel-Inspired Adhesive Hydrogels Based on Laponite-Confined Dopamine Polymerization as a Transdermal Patch

Transdermal patch for local drug delivery has attained huge attention as an attractive alternative to existing drug delivery techniques as it is painless and user-friendly. However, most adhesive hydrogels either do not have adequate adhesion with the skin or cause discomfort while being removed from the skin surface due to excessive adhesion. To address this challenge, we developed an adhesive hydrogel based on laponite-confined dopamine polymerization as a transdermal patch. Laponite RDS nanoclay was used to control the hydrogel's viscous behavior and dopamine polymerization. The laponite polymerized polydopamine (l-PDA) was incorporated into poly(vinyl alcohol) (PVA) to make the PVA-l-PDA hydrogel. The laponite-confined polymerization improved the hydrogels' water contact angle and adhesion strength. The adhesion strength of the PVA-l-PDA hydrogel was adequate to adhere to the evaluated goat skin, glass, and polypropylene surfaces. Notably, the PVA-l-PDA hydrogel was easy to peel off from the skin. Further, we evaluated the drug release profile in goat skin using lidocaine as a model drug. We observed the controlled release of lidocaine from the PVA-l-PDA hydrogel compared to the PVA-PDA hydrogel. In addition, the nanoclay-confined adhesive hydrogel did not show any cytotoxic effect in fibroblasts. Altogether, PVA-l-PDA hydrogels offer appropriate adhesive strength, toughness, and biocompatibility. Thus, the PVA-l-PDA hydrogel has the potential to be an efficient transdermal patch.

Lidocaine inhibits influenza a virus replication by up-regulating IFNα4 via TBK1-IRF7 and JNK-AP1 signaling pathways

Influenza A viruses (IAV), significant respiratory pathogenic agents, cause seasonal epidemics and global pandemics in intra- and interannual cycles. Despite effective therapies targeting viral proteins, the continuous generation of drug-resistant IAV strains is challenging. Therefore, exploring novel host-specific antiviral treatment strategies is urgently needed. Here, we found that lidocaine, widely used for local anesthesia and sedation, significantly inhibited H1N1(PR8) replication in macrophages. Interestingly, its antiviral effect did not depend on the inhibition of voltage-gated sodium channels (VGSC), the main target of lidocaine for anesthesia. Lidocaine significantly upregulated early IFN-I, interferon α4 (IFNα4) mRNA, and protein levels, but not those of early IFNβ in mouse RAW 264.7 cell line and human THP-1 derived macrophages. Knocking out IFNα4 by CRISPR-Cas9 partly reversed lidocaine's inhibition of PR8 replication in macrophages. Mechanistically, lidocaine upregulated IFNα4 by activating TANK-binding kinase 1 (TBK1)-IRF7 and JNK-AP1 signaling pathways. These findings indicate that lidocaine has an incredible antiviral potential by enhancing IFN-I signaling in macrophages. In conclusion, our results indicate the potential auxiliary role of lidocaine for anti-influenza A virus therapy and even for anti-SARS-CoV-2 virus therapy, especially in the absence of a specific medicine.

A case report of an 18-year-old receiving nebulized lidocaine for treatment of COVID-19 cough

An 18-year-old girl presenting with respiratory and gastrointestinal symptoms was found to have COVID-19 pneumonia and severe acute respiratory distress syndrome (ARDS). She was transferred to our pediatric intensive care unit (PICU) for ongoing mechanical ventilation and initiation of venovenous extracorporeal membrane oxygenation (VV-ECMO) for management of progressive hypoxic respiratory failure. She developed a worsening cough with associated life-threatening desaturation events that impaired ECMO flow and required deep sedation. Despite multiple sedative agents, our patient continued to have frequent coughing episodes with associated tachycardia, hypertension, and hypoxemia. The PICU team started nebulized lidocaine 1% 4 mL (40 mg) every 6 hours with albuterol pretreatment, gabapentin, and scheduled ipratropium. Lidocaine levels were <1 mcg/mL throughout the treatment duration. Nebulized lidocaine was stopped after 18 days given improvement in coughing episode severity. Our patient is one of the first reports of an adolescent patient receiving nebulized lidocaine for COVID-19 associated cough. Administration of nebulized lidocaine was well tolerated in this patient without adverse effects and was associated with decreased sedation needs. Given the widespread impact of the COVID-19 pandemic and its sequelae in pediatric, adolescent, and adult patients, additional research is warranted to explore options for management of COVID-19 associated cough.

Case Report: Angiostrongylus cantonensis Infection Presenting as Small Fiber Neuropathy

Angiostrongylus cantonensis is an emerging parasite that is the most common cause of eosinophilic meningitis worldwide. Human infection typically presents with headache, neck stiffness, and paresthesia. We report a case of a woman with PCR positive A. cantonensis infection who presented with symptoms of small fiber neuropathy (SFN) but no headache. SFN was confirmed by skin biopsy. After failing standard medications for neuropathy, she was treated with intravenous lidocaine with considerable improvement. However, she required medications for 1 year to treat her chronic neuropathy. Infection by A. cantonensis should be added to the list of causes of SFN, and its potential to cause chronic sequelae should be appreciated.

Evaluation of lung function and clinical features of interlaminar cervical epidural steroid injections: a randomized controlled trial

OBJECTIVE

Interlaminar cervical epidural steroid injections (ICESIs) are commonly used to treat axial neck pain and cervical radicular pain. However, local anesthetics can spread to and block the phrenic nerve and upper segments of the thoracic spinal cord where the sympathetic innervation of the lungs emerges. Therefore, changes in lung function may occur following ICESIs.

METHODS

The primary outcome measure was the pulmonary function test (PFT) result 30 minutes before and after ICESI with ropivacaine (0.1875% or 0.25%). The secondary outcome measure was the comparison of the pain scores and functional disability between the two concentrations of ropivacaine 4 weeks after the ICESIs.

RESULTS

Fifty patients were randomly assigned to either the R1 (0.1875% ropivacaine) or R2 (0.25% ropivacaine) group. No significant difference was observed between the pre-ICESI and 30-minute post-ICESI PFT results within each group, and no difference was observed between the two groups. After 4 weeks of treatment, both groups showed a significant decrease in pain scores and functional disability; however, no significant differences were observed between the two groups.

CONCLUSIONS

This study showed no significant change in lung function after ICESIs in either group and no local anesthetic concentration-based difference in the clinical efficacy of the ICESIs.

Lidocaine ameliorates chronic constriction injury-induced neuropathic pain through regulating M1/M2 microglia polarization

This study is intended to explore the mechanism that lidocaine ameliorates chronic constriction injury (CCI)-induced neuropathic pain (NP) related to the polarization of M1 and M2 microglia. CCI rats were established by surgery to induce NP. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) of rats were determined. Microglial line HAPI cells were polarized into M1 or M2 cells using lipopolysaccharide (LPS) or interleukin (IL)-4, respectively. Immunofluorescence staining was performed to determine the Iba1/CD86- and Iba1/CD206-positive cells. Markers of M1 and M2 microglia were assessed using flow cytometry. Real-time polymerase chain reaction and enzyme-linked immunosorbent assay were performed to detect the level of mRNA and inflammatory factors. Lidocaine ameliorates CCI-induced NP, evidenced by the markedly increased values of MWT and TWL in NP rats. Lidocaine inhibited M1 microglia polarization but promoted M2 microglia polarization in a rat model of CCI-induced NP. Besides, in the in vitro experiment, lidocaine regulated M1/M2 polarization in LPS- or IL-4-treated HAPI microglia. Lidocaine ameliorates CCI-induced NP by regulating M1/M2 microglia polarization. This study investigated the biological role of lidocaine in regulating NP in rats, which may be helpful for revealing the pathogenic mechanisms of NP and provide a potential therapeutic factor.

Effects of Local Anesthetics With or Without Steroids in High-Volume Transforaminal Epidural Blocks for Lumbar Disc Herniation: A Randomized, Double-Blind, Controlled Trial

BACKGROUND

Lumbar transforaminal epidural block (TFEB) is an effective treatment modality for radicular pain due to lumbar disc herniation (LDH). The addition of steroids is more effective than local anesthetic alone in TFEBs for patients with LDH. Moreover, the efficacy of TFEBs has been reported to be positively correlated with the volume of injectate. We hypothesized that high-volume TFEBs without steroids effectively alleviate axial back and radicular pain associated with LDH. This study compared the efficacy of high-volume TFEBs with vs. without steroids for the management of the axial and radicular pain caused by LDH.

METHODS

A total of 54 patients were randomly assigned to either group L or group D. Patients in group L received 8-mL injections of 0.33% lidocaine only. Patients in group D received 8-mL injections of 0.33% lidocaine with 5 mg of dexamethasone. The primary outcomes were pain intensity at baseline and 4 weeks after the procedure. The secondary outcomes included the change of functional disability between baseline and 4 weeks after the procedure, pain scores during injection, and adverse effects.

RESULTS

Both groups showed a significant reduction in axial and radicular pain and improvement in the functional status at the outpatient visit 4 weeks after TFEB. However, there were no significant differences between the groups in terms of changes in back pain (10.00 [20.00] vs. 10.00 [22.50]; P = 0.896) or radicular pain (5.00 [20.00] vs. 10.00 [12.50]; P = 0.871).

CONCLUSION

High-volume TFEBs with and without steroid administration yielded similar significant pain reductions and functional improvements among LDH patients 4 weeks after the procedure.

Intermolecular Dynamics and Structure in Aqueous Lidocaine Hydrochloride Solutions

We investigated the intermolecular dynamics and static structure in the aqueous solutions of lidocaine hydrochloride (LDHCl) in the concentration range of [LDHCl] = 0-2.00 M using femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES), small- and wide-angle X-ray scattering (SWAXS), and dynamic light scattering (DLS). For the fs-RIKES experiments, the concentration dependence of the difference low-frequency spectra of the aqueous LDHCl solutions relative to the neat water, which was mainly due to the intermolecular vibrations, was characterized using an exponential function with a characteristic concentration of ∼1 M. For the SWAXS experiments, we observed a manifestation of an excess scattering component centered within a range of 8-10 nm^-1 in the aqueous LDHCl solutions. The results of Fourier inversion and further deconvolution analyses unambiguously demonstrated that lidocaines assemble into a nanometer-sized micelle-like structure with the innermost core (∼0.3 nm) and outer shell (∼0.5 nm), respectively. The DLS experiments also found nanometer-sized aggregates and further indicated evidence of the clusters of the aggregates. The results of viscosities, densities, and surface tensions of the solutions and the quantum chemistry calculations supported the unique features of the microscopic intermolecular interaction and the micelle-like aggregation.

iPSCs and DRGs: stepping stones to new pain therapies

There is a pressing need for more effective nonaddictive treatment options for pain. Pain signals are transmitted from the periphery into the spinal cord via dorsal root ganglion (DRG) neurons, whose excitability is driven by voltage-gated sodium (NaV) channels. Three NaV channels (NaV1.7, NaV1.8, and NaV1.9), preferentially expressed in DRG neurons, play important roles in pain signaling in humans. Blockade of these channels may provide a novel approach to the treatment of pain, but clinical translation of preclinical results has been challenging, in part due to differences between rodent and human DRG neurons. Human DRG neurons and iPSC-derived sensory neurons (iPSC-SNs) provide new preclinical platforms that may facilitate the development of novel pain therapeutics.

Prediction of Individual Analgesic Response to Intravenous Lidocaine in Painful Diabetic Peripheral Neuropathy: A Randomized, Placebo-controlled, Crossover Trial

OBJECTIVES

Intravenous lidocaine can alleviate painful diabetic peripheral neuropathy (DPN) in some patients. Whether quantitative sensory testing (QST) can identify treatment responders has not been prospectively tested.

MATERIALS AND METHODS

This was a prospective, randomized, double-blind, crossover, placebo-controlled trial comparing intravenous lidocaine to normal saline (placebo) for painful DPN. Thirty-four participants with painful DPN were enrolled and administered intravenous lidocaine (5 mg/kg ideal body weight) or placebo as a 40-minute infusion, after a battery of QST parameters were tested on the dorsal foot, with a 3-week washout period between infusions.

RESULTS

Thirty-one participants completed both study sessions and were included in the final analysis. Lidocaine resulted in a 51% pain reduction 60 to 120 minutes after infusion initiation, as assessed on a 0 to 10 numerical rating scale, while placebo resulted in a 33.5% pain reduction (difference=17.6%, 95% confidence interval [CI], 1.9%-33.3%, P=0.03). Neither mechanical pain threshold, heat pain threshold, or any of the other measured QST parameters predicted the response to treatment. Lidocaine administration reduced mean Neuropathic Pain Symptom Inventory paresthesia/dysesthesia scores when compared with placebo by 1.29 points (95% CI, -2.03 to -0.55, P=0.001), and paroxysmal pain scores by 0.84 points (95% CI, -1.62 to -0.56, P=0.04), without significant changes in burning, pressing or evoked pain subscores.

DISCUSSION

While some participants reported therapeutic benefit from lidocaine administration, QST measures alone were not predictive of response to treatment. Further studies, powered to test more complex phenotypic interactions, are required to identify reliable predictors of response to pharmacotherapy in patients with DPN.

Intra-arterial injection of lidocaine into middle meningeal artery to treat intractable headaches and severe migraine

BACKGROUND AND PURPOSE

We report the results of intra-arterial injection of lidocaine in the middle meningeal artery in patients with intractable headache or status migrainosus.

METHODS

We treated four patients with intra-arterial lidocaine (2 mg/ml) in doses up to 50 mg in each middle meningeal artery via a microcatheter bilaterally (except in one patient). In two patients with intractable headache, the daily maximum intensity of headache (graded by 11-point numeric rating scale) was recorded for 7 days postprocedure. In two patients with status migrainosus, migraine-related disability 3 months prior and after treatment using MIDAS (Migraine Disability Assessment) questionnaire was recorded.

RESULTS

Intra-arterial lidocaine reduced the headache intensity from 8/10 and 10/10 to 0/10 in the two patients with intractable headaches for 2 days (day 0 and day 1) postprocedure. Despite recurrence of headache on day 2, the intensity was less than preprocedure intensity up to the last day recorded (by 3 and 2 points on day 7). In the two patients with status migrainosus, there was immediate reduction in headache intensity following intra-arterial lidocaine. The post treatment 3-month MIDAS score was lower in both patients compared with pretreatment 3-month score; 3 versus 30 and 55 versus 90. Severe disability preprocedure by MIDAS was reduced to little or no disability postprocedure in one patient.

CONCLUSIONS

Intra-arterial lidocaine resulted in amelioration of headache in patients with intractable headache and those with status migrainosus with improvement lasting longer than the short half-life of lidocaine possibly related to central desensitization.

Sodium Channel Blockers Modulate Abnormal Activity of Regenerating Nociceptive Corneal Nerves After Surgical Lesion

Purpose

To test the effect of different sodium channel blockers on the electrical activity of corneal nociceptors in intact and surgically injured corneas.

Methods

In anesthetized guinea pigs, a 4-mm diameter corneal flap was performed in one eye at a midstromal depth using a custom-made microkeratome. At different times after surgery (3 hours to 15 days), the electrical activity of corneal nociceptor fibers was recorded from ciliary nerve filaments in the superfused eye in vitro. Mechanical threshold was measured using calibrated von Frey hairs; chemical stimulation was performed applying 30-second CO2 gas pulses. The characteristics of the spontaneous and stimulus-evoked activity of corneal nociceptors recorded from intact and lesioned corneas, before and after treatment with the sodium channel blockers lidocaine, carbamazepine, and amitriptyline, were compared.

Results

No spontaneous or stimulus-evoked impulse activity was detected inside the flap at any of the studied time points. However, both were recorded from mechanonociceptor and polymodal nociceptors fibers in the surrounding corneal tissue, being significantly higher (sensitization) 24 to 48 hours after surgery. In these fibers, none of the tested drugs affected mechanical threshold, but they significantly reduced the CO2 response of polymodal nociceptors of intact and injured corneas. Likewise, they diminished significantly the transient increase in spontaneous and stimulus-evoked activity of sensitized polymodal nociceptors.

Conclusions

Na+ channel blockers decrease the excitability of intact and sensitized corneal nociceptor fibers, thus acting as potential tools to attenuate their abnormal activity, which underlies the spontaneous pain, hyperalgesia, and allodynia often accompanying surgical corneal lesions, as occurs after photorefractive surgery.

Engineering of highly potent and selective HNTX-III mutant against hNav1.7 sodium channel for treatment of pain

Human voltage-gated sodium channel Na_v1.7 (hNa_v1.7) is involved in the generation and conduction of neuropathic and nociceptive pain signals. Compelling genetic and preclinical studies have validated that hNa_v1.7 is a therapeutic target for the treatment of pain; however, there is a dearth of currently available compounds capable of targeting hNav1.7 with high potency and specificity. Hainantoxin-III (HNTX-III) is a 33-residue polypeptide from the venom of the spider Ornithoctonus hainana. It is a selective antagonist of neuronal tetrodotoxin-sensitive voltage-gated sodium channels. Here, we report the engineering of improved potency and Na_v selectivity of hNa_v1.7 inhibition peptides derived from the HNTX-III scaffold. Alanine scanning mutagenesis showed key residues for HNTX-III interacting with hNa_v1.7. Site-directed mutagenesis analysis indicated key residues on hNa_v1.7 interacting with HNTX-III. Molecular docking was conducted to clarify the binding interface between HNTX-III and Nav1.7 and guide the molecular engineering process. Ultimately, we obtained H4 [K0G1-P18K-A21L-V] based on molecular docking of HNTX-III and hNa_v1.7 with a 30-fold improved potency (IC₅₀ 0.007 ± 0.001 μM) and >1000-fold selectivity against Na_v1.4 and Na_v1.5. H4 also showed robust analgesia in the acute and chronic inflammatory pain model and neuropathic pain model. Thus, our results provide further insight into peptide toxins that may prove useful in guiding the development of inhibitors with improved potency and selectivity for Na_v subtypes with robust analgesia.

A randomized clinical trial on the effect of a lidocaine patch on shoulder pain relief in laparoscopic cholecystectomy

The incidence of laparoscopy-related shoulder pain reaches 90% in women. We evaluated the effect of lidocaine patch 5% on the shoulder pain after laparoscopic cholecystectomy (LC) in female patients. Total 63 female patients were randomly allocated to patch group (n = 31) and control group (n = 32). Patch group received lidocaine patch 5% and dressing retention tape on both shoulder, and control group received only dressing retention tape. Abdominal and shoulder pains were evaluated with rating on numeric rating scale (0 = no pain and 10 = the worst pain) at baseline and at 30 min, 6 h, 24 h, and 48 h after surgery. There were no significant differences in patient characteristics and operation details. The overall incidence of shoulder pain was significantly lower in patch group than in control group (42% vs. 78%, P = 0.005). The severity of shoulder pain also was significantly reduced in patch group compared to control group at 24 h and 48 h after surgery (P = 0.01 and P = 0.015, respectively). Complications related to lidocaine patch were not found except nausea. Lidocaine patch 5% reduced the incidence and severity of postoperative shoulder pain in female patients undergoing LC without complications.

Visible light-mediated cross-coupling of electrophiles: synthesis of α-amino amides from isocyanates and ketimines

Cross-couplings between the electrophilic ketimines and isocyanates are achieved via the visible light-mediated reactivity inversion of the ketimines, affording the desired α-amino amides in high yields, with both metal and metal-free systems.

Status of peripheral sodium channel blockers for non-addictive pain treatment

The effective and safe treatment of pain is an unmet health-care need. Current medications used for pain management are often only partially effective, carry dose-limiting adverse effects and are potentially addictive, highlighting the need for improved therapeutic agents. Most common pain conditions originate in the periphery, where dorsal root ganglion and trigeminal ganglion neurons feed pain information into the CNS. Voltage-gated sodium (Na_V) channels drive neuronal excitability and three subtypes - Na_V1.7, Na_V1.8 and Na_V1.9 - are preferentially expressed in the peripheral nervous system, suggesting that their inhibition might treat pain while avoiding central and cardiac adverse effects. Genetic and functional studies of human pain disorders have identified Na_V1.7, Na_V1.8 and Na_V1.9 as mediators of pain and validated them as targets for pain treatment. Consequently, multiple Na_V1.7-specific and Na_V1.8-specific blockers have undergone clinical trials, with others in preclinical development, and the targeting of Na_V1.9, although hampered by technical constraints, might also be moving ahead. In this Review, we summarize the clinical and preclinical literature describing compounds that target peripheral Na_V channels and discuss the challenges and future prospects for the field. Although the potential of peripheral Na_V channel inhibition for the treatment of pain has yet to be realized, this remains a promising strategy to achieve non-addictive analgesia for multiple pain conditions.

A Comprehensive Review of the Treatment and Management of Myofascial Pain Syndrome

PURPOSE OF REVIEW

Myofascial pain syndrome (MPS) is a musculoskeletal pain condition that stems from localized, taut regions of skeletal muscle and fascia, termed trigger points. The purpose of this comprehensive review is to provide updated information on prevalence, pathophysiology, and treatment modalities with a focus on interventional modalities in managing MPS.

RECENT FINDINGS

Though MPS can present acutely, it frequently presents as a chronic condition, affecting up to 85% of adults during their lifetime. MPS is an often-overlooked component of pain with overarching effects on society, including patient quality of life, physical and social functioning, emotional well-being, energy, and costs on health care. The prevalence of MPS is generally increased among patients with other chronic pain disorders and has been associated with various other conditions such as bladder pain syndrome, endometriosis, and anxiety. MPS is poorly understood and remains a challenging condition to treat. Non-pharmacologic treatment modalities such as acupuncture, massage, transcutaneous electrical stimulation, and interferential current therapy may offer relief to some patients with MPS. Additional studies are warranted to get a better understanding of managing myofascial pain.

The efficacy of intravenous lidocaine and its side effects in comparison with intravenous morphine sulfate in patients admitted to the ED with right upper abdominal pain suspected of biliary colic

BACKGROUND

Intravenous (IV) Lidocaine can be used as analgesic in acute pain management in the emergency department (ED).

OBJECTIVE

Efficacy of IV Lidocaine in comparison with IV morphine in acute pain management in the ED.

METHOD

This is a double-blind randomized clinical trial on adult (18-64 year) patients with right upper abdominal pain suspected of biliary colic who needed pain management. Participants randomly received IV lidocaine (5 cc = 100 mg) or morphine sulfate (5 cc = 5 mg). In both groups, patients' pain scores were recorded and assessed by Numeric Rating Scale (NRS) at baseline, 10, 20, 30, 45, 60 and 120 min after drug administration. Adverse side effects of lidocaine and morphine sulfate and changes in vital signs were also recorded and compared.

RESULTS

A total number of 104 patients were enrolled in the study, including 49 men and 55 women. IV lidocaine reduced pain in less time in comparison with morphine sulfate. Mean (±SD) basic pain score was 8.23 (±1.76) in the lidocaine group and 8.73 (±0.96) in the morphine group. Patients' mean (±SD) pain score in both groups had no significant difference during the study except that of NRS2 (10 min after drug administration), which was 5.05 (±2.69) in lidocaine group compared with 6.39 (±2.06) in the morphine group and NRS4 (30 min after drug administration), which was significantly lower (P-value = 0.01) in the morphine group [3.84(±1.73) vs 4.41(±2.82)]. Only 9 patients had adverse effects in either group.

CONCLUSION

The findings of this study suggest that IV lidocaine can be a good choice in pain management in biliary colic and can reduce pain in less time than morphine sulfate (in 10 min) without adding significant side effects; however, our primary outcome was the comparison of these two drugs after 60 min of drug administration in pain reduction which showed no significant difference between two groups.

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

Lidocaine, as the only local anesthetic approved for intravenous administration in the clinic, can relieve neuropathic pain, hyperalgesia, and complex regional pain syndrome. Intravenous injection of lidocaine during surgery is considered as an effective strategy to control postoperative pain, but the mechanism of its analgesic effect has not been fully elucidated. This paper intends to review recent studies on the mechanism of the analgesic effect of lidocaine. To the end, we conducted an electronic search of the PubMed database. The search period was from 5 years before June 2019. Lidocaine was used as the search term. A total of 659 documents were obtained, we included 17 articles. These articles combined with the 34 articles found by hand searching made up the 51 articles that were ultimately included. We reviewed the analgesic mechanism of lidocaine in the central nervous system.

Drug Delivery and Drug Efficacy from Amorphous Poly(thioether anhydrides)

The correlation between erosion and drug (lidocaine and 6-mercaptopurine, 6-MP) release from amorphous poly(thioether anhydrides), which are synthesized using radical-mediated thiol-ene polymerization, is reported. Cytotoxicity studies of the polymer toward human fibroblast human dermal fibroblasts adult, melanoma A-375, and breast cancer MCF-7 cells are conducted, and drug efficacy of a cancer and autoimmune disease drug (6-MP) when released from the poly(thioether anhydrides) is examined against two cancerous cell types (A-375 and MCF-7). Erosion and drug release studies reveal that lidocaine release is governed by network erosion whereas 6-MP is released by a combination of erosion and diffusion. The cytotoxicity studies show that all three cell types demonstrate high viability, thus cytocompatibility, to poly(thioether anhydrides). Toxicity to the material is dose dependent and comparable to other polyanhydride systems. The 6-MP cancer drug is shown to remain bioactive after encapsulation in the poly(thioether anhydride) matrix and the polymer does not appear to modify the efficacy of the drug.

Intravenous Lidocaine for Intractable Renal Colic Unresponsive to Standard Therapy

CLINICAL FEATURES

Renal colic is defined as a flank pain radiating to the groin caused by kidney stones in the ureter (urolithiasis). Renal colic is a frequent cause of Emergency Department visits. Most renal colic cases present as acute distress and severe back and/or abdominal pain that require prompt treatment with analgesics.

THERAPEUTIC CHALLENGE

Nonsteroidal anti-inflammatory drugs and opioids are traditionally used for renal colic in the Emergency Department. This trend of practice is based on clinical experience and expert opinion. Consensus guidelines that provide evidence-based approach for the management of renal colic are limited. One consensus guideline from Europe provides a systematic approach for the management of pain with the use of nonsteroidal anti-inflammatory drugss and opioids. However, no guidance is provided on how to manage patients who do not respond to these agents.

SOLUTION

Intravenous lidocaine 120 mg in 100 mL normal saline was infused over 10 minutes for pain management for intractable renal colic unresponsive to standard therapy. Three minutes after initiation of lidocaine infusion, the patient reported numeric pain rating scale 1/10. At 5 minutes, the reported numeric pain rating scale was 0/10 and remained for 60 minutes after initiation of lidocaine infusion. No adverse events were reported during or after the infusion, and no subsequent analgesia was required.

Ventral tegmental area inactivation alters hormonal, metabolic, and locomotor responses to inescapable stress

Context: The involvement of unilateral and bilateral inhibition of the ventral tegmental area (VTA) in response to stress is not well understood. Objective: In the present study, the effect of unilateral and bilateral inhibition of the VTA on hormonal, metabolic, and locomotor responses to stress was assessed. Material and methods: Male rats seven days after cannulation into the VTA received electro foot-shock stress for seven consecutive days. Twenty minutes before induction of stress, 2% lidocaine hydrochloride or sterile saline (control) was injected either uni- or bi-laterally into the VTA. Results: Results showed that stress significantly increased serum corticosterone level, adrenal gland weight and anorexia, reduced weight gain, food-intake, and locomotor activity. However, bilateral inactivation of VTA prevented stress-induced these parameters changes. Conclusion: The present study demonstrated that the bilateral VTA blockade effectively relieves the symptoms of stress, while the unilateral VTA blockade does not significantly improve the changes caused by stress.

Emerging role of nanomedicine in the treatment of neuropathic pain

Neuropathic pain (NeP) is a complex chronic pain condition associated with nerve injury. Approximately, 7-10% of the general population across the globe is suffering from this traumatic condition, but the existing treatment strategies are inadequate to deliver pain relief and are associated with severe adverse effects. To overcome these limitations, lot of research is focussed on developing new molecules with high potency and fewer side effects, novel cell and gene-based therapies and modification of the previously approved drugs by different formulation aspects. Nanomedicine has attracted a lot of attention in the treatment of many diverse pathological conditions because of their unique physiochemical and biological properties. In this manuscript, we highlighted the emerging role of nanomedicine in different therapies (drug, cell and gene), also we emphasised on the challenges associated with nanomedicine such as development of well-characterised nanoformulation, scaling of batches with reproducible results and toxicity along with this we discussed about the future of nanomedicine in the treatment of neuropathic pain.

Tertiary Care Clinical Experience with Intravenous Lidocaine Infusions for the Treatment of Chronic Pain

Objective

To evaluate the safety of and long-term pain relief due to intravenous lidocaine infusion for the treatment of chronic pain in a tertiary pain management clinic.

Design

Retrospective chart review.

Methods

Medical records were reviewed from 233 adult chronic pain patients who underwent one to three lidocaine infusions. The initial lidocaine challenge consisted of 1,000 mg/h administered intravenously for up to 30 minutes until infusion was complete, full pain resolution, the patient requested to stop, side effects (SEs) became intolerable, and/or if there were any safety concerns. Subsequent infusions were tailored to patient response. Data reviewed included pain diagnosis, lidocaine dose, SEs, and duration of pain relief documented at a follow-up visit.

Results

Patients primarily had neuropathic pain (80%), were 94% white, 58% were female, and there was an average pain duration of 7.9 years. SEs were usually mild and transient, including perioral tingling, dizziness, tinnitus, and nausea/vomiting, and they were uncommon after the initial infusion. Overall, 41% of patients showed long-lasting pain relief, with positive response to the initial infusion associated with receiving and benefitting from subsequent infusions. Benefit by pain diagnoses varied from 32% to 58%.

Conclusions

Our retrospective study in a heterogeneous population with chronic pain suggests that intravenous lidocaine is a safe treatment. Data also suggest long-term pain relief in a significant proportion of patients. Additional study is important in order to delineate patient selection, determine optimal dosing and treatment frequency, assess pain reduction and duration, and treatment cost-effectiveness.

Noninvasive Transdermal Delivery System of Lidocaine Using an Acoustic Droplet-Vaporization Based Wearable Patch

Current technologies for managing acute and chronic pain have focused on reducing the time required for achieving high therapeutic efficiency. Herein a wearable transdermal patch is introduced, employing an acoustic droplet vaporization (ADV) methodology, as an effective noninvasive transdermal platform, for a fast local delivery of the anesthetic agent lidocaine. The skin-worn patch consists of a flexible drug reservoir containing hundreds of micropores loaded with lidocaine, and mixed with the perfluorocarbon (PFC) emulsion. The ultrasound-triggered vaporization of the PFC emulsion provides the necessary force to breach dermal barriers. The drug release kinetics of our model was investigated by measuring the amount of lidocaine that passed through phantom tissue and pigskin barriers. The ADV platform increases the payload skin penetration resulting in shorter treatment times compared to passive diffusion or ultrasound alone, holding considerable promise for addressing the delayed therapeutic action and slow pain relief of existing delivery protocols. It is envisioned that the integration of ADV-based transdermal devices could be expanded to the depth-dependent delivery of other pain management, vaccines, and gene therapy modalities.

Supraspinal modulation of neuronal synchronization by nociceptive stimulation induces an enduring reorganization of dorsal horn neuronal connectivity

KEY POINTS

The state of central sensitization induced by the intradermic injection of capsaicin leads to structured (non-random) changes in functional connectivity between dorsal horn neuronal populations distributed along the spinal lumbar segments in anaesthetized cats. The capsaicin-induced changes in neuronal connectivity and the concurrent increase in secondary hyperalgesia are transiently reversed by the systemic administration of small doses of lidocaine, a clinically effective procedure to treat neuropathic pain. The effects of both capsaicin and lidocaine are greatly attenuated in spinalized preparations, showing that supraspinal influences play a significant role in the shaping of nociceptive-induced changes in dorsal horn functional neuronal connectivity. We conclude that changes in functional connectivity between segmental populations of dorsal horn neurones induced by capsaicin and lidocaine result from a cooperative adaptive interaction between supraspinal and spinal neuronal networks, a process that may have a relevant role in the pathogenesis of chronic pain and analgesia.

ABSTRACT

Despite a profusion of information on the molecular and cellular mechanisms involved in the central sensitization produced by intense nociceptive stimulation, the changes in the patterns of functional connectivity between spinal neurones associated with the development of secondary hyperalgesia and allodynia remain largely unknown. Here we show that the state of central sensitization produced by the intradermal injection of capsaicin is associated with structured transformations in neuronal synchronization that lead to an enduring reorganization of the functional connectivity within a segmentally distributed ensemble of dorsal horn neurones. These changes are transiently reversed by the systemic administration of small doses of lidocaine, a clinically effective procedure to treat neuropathic pain. Lidocaine also reduces the capsaicin-induced facilitation of the spinal responses evoked by weak mechanical stimulation of the skin in the region of secondary but not primary hyperalgesia. The effects of both intradermic capsaicin and systemic lidocaine on the segmental correlation and coherence between ongoing cord dorsum potentials and on the responses evoked by tactile stimulation in the region of secondary hyperalgesia are greatly attenuated in spinalized preparations, showing that supraspinal influences are involved in the reorganization of the nociceptive-induced structured patterns of dorsal horn neuronal connectivity. We conclude that the structured reorganization of the functional connectivity between the dorsal horn neurones induced by capsaicin nociceptive stimulation results from cooperative interactions between supraspinal and spinal networks, a process that may have a relevant role in the shaping of the spinal state in the pathogenesis of chronic pain and analgesia.

Dental Management of Patients Who Have Undergone Oral Cancer Therapy

Oral cancer therapies are associated with orofacial complications that could result in dose-limiting cancer treatment and consequent suboptimal tumor control. Oral cancer treatment complications include oral mucositis, salivary gland hypofunction, odontogenic infections, pain, dermatitis, neurotoxicity, soft tissue fibrosis, trismus, osteoradionecrosis, and potential cancer recurrence. These complications significantly affect cancer survivorship, quality of life, and psychosocial status. Effective dental management of patients with oral cancer involves the coordination of care among several health care professionals before, during, and after cancer therapy. The goal is to minimize complications, and establish optimal quality of life for survivors.

The Use of Intravenous Lidocaine for the Management of Acute Pain Secondary to Traumatic Ankle Injury: A Case Report

Sports-related injuries are a frequent cause of visits to the emergency department (ED) across the United States. A majority of these injuries affect the lower extremities with the ankle as the most frequently reported site. Most sports-related injuries are not severe enough to require inpatient hospitalization; however, they often lead to acute distress and pain which require prompt treatment with analgesics. Approximately 22% of patients who presented to the ED required pharmacotherapy for acute pain management. Opioids have been traditionally used for the management of severe acute pain in the ED; however, there are growing concerns for opioid overuse and misuse. As a result, there is growing controversy regarding the appropriate selection of analgesic agents, optimal dosing, and need for outpatient therapy which has contributed to changes in prescribing patterns of opioids in the ED. Lidocaine, a class 1b antiarrhythmic, has been utilized as an analgesic agent. Its use has been documented for the management of intractable chronic pain caused by cancer, stroke, neuropathies, or nephrolithiasis. However, literature describing the use of intravenous lidocaine for the management of acute pain secondary to trauma is limited to a single case series. This case report describes the use of intravenous lidocaine in a 17-year-old male who presented to the ED in acute distress secondary to ankle dislocation and fracture. This report serves to describe additional clinical experience with intravenous lidocaine for the management of acute pain secondary to ankle fracture in the emergency department.

The Efficacy of Systemic Lidocaine in the Management of Chronic Pain: A Literature Review

Context

Despite recent advances in the understanding of the chronic pain concept, its diagnosis and management remains a daily challenge for clinicians and patients. Based on the published literature, this review discusses and tries to organize the current knowledge and the up-to-date clinical experience about the efficacy and safety of the use of intravenous lidocaine in treatment and prevention of chronic pain.

Evidence Acquisition

To prepare this narrative review, we performed an in depth literature review using the PubMed searching engine. We extracted all relevant articles published in English, up to April 2016.

Results

Lidocaine, administered as transdermal patch or intravenous lidocaine, is a safe and effective modality in the treatment of post-herpetic neuralgia (PHN), complex regional pain syndrome, as well and for prevention of chronic pain. It may be effective in the management of neuropathic pain syndromes, chronic pain, post-operative pain, and refractory cancer pain.

Conclusions

Intravenous lidocaine and lidocaine patch are effective and safe for the treatment of several chronic or neuropathic pain syndromes. The use of lidocaine during surgery could prevent the development of some chronic post-surgical pain syndromes.