Tramadol, fentanyl and sufentanil but not morphine block voltage-operated sodium channels

Comparative Evaluation of the Local Anesthetic Action of Tramadol Hydrochloride With Adrenaline Versus Lidocaine Hydrochloride With Adrenaline for Maxillary Exodontia: A Randomized Control Trial

BACKGROUND

Tramadol hydrochloride (T-HCl) has demonstrated to have a local anesthetic effect similar to lidocaine hydrochloride (L-HCl) when administered locally for minor oral surgical procedures.

PURPOSE

Our study aimed to compare the anesthetic effect of T-HCl versus L-HCl in maxillary premolar extraction.

STUDY DESIGN, SETTING AND SAMPLE

The study is a split-mouth, double-blind randomized clinical trial at the Faculty of Dental Sciences, Ramaiah University of Applied Sciences, Bengaluru, India. The study sample was composed of patients referred for maxillary bicuspid extraction. Patients were excluded from the sample if, allergic to the study drugs, pregnant or lactating females, and smokers.

EXPOSURE VARIABLE

The variable is an anesthetic drug administered for local anesthesia and it is grouped into 2 categories, T-HCl and L-HCl. A supraperiosteal infiltration of T-HCl with adrenaline on one side and L-HCl with adrenaline on the contralateral side was injected.

MAIN OUTCOME VARIABLE

The primary outcome variable was profound anesthesia of T-HCl, where the patient sensed the loss of sensation of touch, temperature, and pain. Secondary outcomes were onset and duration of anesthesia, intraoperative pain, postoperative analgesia, and adverse reactions, were recorded.

ANALYSES

Inferential statistics, the χ2 Test, the Mann-Whitney Test, and the Wilcoxon signed-rank test were used to compare the parameters. The level of significance was set at ≤ 0.05.

RESULTS

A total of 40 patients were included, and 80 teeth were extracted. Profound anesthesia was achieved in all the cases. The mean subjective duration of anesthesia in the T-HCl and L-HCl groups was 130.80 ± 20.01 minutes and 111.40 ± 14.87 minutes, respectively, with a P value of .001. The mean Visual Analogue Scale (VAS) score for pain during the procedure in the T-HCl and L-HCl groups was 0.60 ± 0.67 and 1.10 ± 0.71, respectively, with a P value of .002. The mean Visual Analogue Scale score for pain postoperatively in the T-HCl and L-HCl groups was 0.70 ± 0.72 and 1.40 ± 0.67, respectively, with a P value of .001. Six patients in T-HCl required postoperative analgesia when compared to 18 patients in L-HCl (P value < .003).

CONCLUSIONS AND RELEVANCE

T-HCl provides similar anesthetic outcomes in the extraction of maxillary bicuspids as L-HCl.

Nitric oxide and potassium channels but not opioid and cannabinoid receptors mediate tramadol-induced peripheral antinociception in rat model of paw pressure withdrawal

Tramadol, an analgesic classified as an "atypical opioid", exhibits both opioid and non-opioid mechanisms of action. This study aimed to explore these mechanisms, specifically the opioid-, cannabinoid-, nitric oxide-, and potassium channel-based mechanisms, which contribute to the peripheral antinociception effect of tramadol, in an experimental rat model. The nociceptive threshold was determined using paw pressure withdrawal. To examine the mechanisms of action, several substances were administered intraplantarly: naloxone, a non-selective opioid antagonist (50 µg/paw); AM251 (80 µg/paw) and AM630 (100 µg/paw) as the selective antagonists for types 1 and 2 cannabinoid receptors, respectively; nitric oxide synthase inhibitors L-NOArg, L-NIO, L-NPA, and L-NIL (24 µg/paw); and the enzyme inhibitors of guanylatocyclase and phosphodiesterase of cGMP, ODQ, and zaprinast. Additionally, potassium channel blockers glibenclamide, tetraethylammonium, dequalinium, and paxillin were used. The results showed that opioid and cannabinoid receptor antagonists did not reverse tramadol's effects. L-NOarg, L-NIO, and L-NPA partially reversed antinociception, while ODQ completely reversed, and zaprinast enhanced tramadol's antinociception effect. Notably, glibenclamide blocked tramadol's antinociception in a dose-dependent manner. These findings suggest that tramadol's peripheral antinociception effect is likely mediated by the nitrergic pathway and sensitive ATP potassium channels, rather than the opioid and cannabinoid pathways.

The opioid tramadol blocks the cardiac sodium channel Nav1.5 in HEK293 cells

AIMS

Opioids are associated with increased risk of sudden cardiac death. This may be due to their effects on the cardiac sodium channel (Nav1.5) current. In the present study, we aim to establish whether tramadol, fentanyl, or codeine affects Nav1.5 current.

METHODS AND RESULTS

Using whole-cell patch-clamp methodology, we studied the effects of tramadol, fentanyl, and codeine on currents of human Nav1.5 channels stably expressed in HEK293 cells and on action potential (AP) properties of freshly isolated rabbit ventricular cardiomyocytes. In fully available Nav1.5 channels (holding potential -120 mV), tramadol exhibited inhibitory effects on Nav1.5 current in a concentration-dependent manner with an IC50 of 378.5 ± 33.2 µm. In addition, tramadol caused a hyperpolarizing shift of voltage-gated (in)activation and a delay in recovery from inactivation. These blocking effects occurred at lower concentrations in partially inactivated Nav1.5 channels: during partial fast inactivation (close-to-physiological holding potential -90 mV), IC50 of Nav1.5 block was 4.5 ± 1.1 μm, while it was 16 ± 4.8 μm during partial slow inactivation. The tramadol-induced changes on Nav1.5 properties were reflected by a reduction in AP upstroke velocity in a frequency-dependent manner. Fentanyl and codeine had no effect on Nav1.5 current, even when tested at lethal concentrations.

CONCLUSION

Tramadol reduces Nav1.5 currents, in particular, at close-to-physiological membrane potentials. Fentanyl and codeine have no effects on Nav1.5 current.

Pharmaceutical treatment of osteoarthritis

OBJECTIVE

To review the current state of pharmaceutical treatment recommendations for the management of osteoarthritis.

METHOD

A narrative review was drafted to describe treatment guidelines, mechanism of action, pharmacokinetics, and toxicity for nine classes of pharmaceuticals: 1) oral nonsteroidal anti-inflammatory drugs (NSAIDs), 2) topical NSAIDs, 3) COX-2 inhibitors, 4) duloxetine, 5) intra-articular corticosteroids, 6) intra-articular hyaluronic acid, 7) acetaminophen (paracetamol), 8) tramadol, and 9) capsaicin.

RESULTS

In general, oral and topical NSAIDs, including COX-2 inhibitors, are strongly recommended first-line treatments for osteoarthritis due to their ability to improve pain and function but are associated with increased risks in patients with certain comorbidities (e.g., heightened cardiovascular risks). Intra-articular corticosteroid injections are generally recommended for osteoarthritis management and have relatively minor adverse effects. Other treatments, such as capsaicin, tramadol, and acetaminophen, are more controversial, and many updated guidelines offer differing recommendations.

CONCLUSION

The pharmaceutical management of osteoarthritis is a constantly evolving field. Promising treatments are emerging, and medicines that were once considered conventional (e.g., acetaminophen) are gradually becoming less acceptable based on concerns with efficacy and safety. Clinicians need to consider the latest evidence and recommendations to make an informed decision with their patients about how to optimize treatment plans for patients with knee, hip, polyarticular, or hand osteoarthritis.

Tramadol as a Voltage-Gated Sodium Channel Blocker of Peripheral Sodium Channels Nav1.7 and Nav1.5

Tramadol is an opioid analog used to treat chronic and acute pain. Intradermal injections of tramadol at hundreds of millimoles have been shown to produce a local anesthetic effect. We used the whole-cell patch-clamp technique in this study to investigate whether tramadol blocks the sodium current in HEK293 cells, which stably express the pain threshold sodium channel Na_v1.7 or the cardiac sodium channel Na_v1.5. The half-maximal inhibitory concentration of tramadol was 0.73 mM for Na_v1.7 and 0.43 mM for Na_v1.5 at a holding potential of -100 mV. The blocking effects of tramadol were completely reversible. Tramadol shifted the steady-state inactivation curves of Na_v1.7 and Na_v1.5 toward hyperpolarization. Tramadol also slowed the recovery rate from the inactivation of Na_v1.7 and Na_v1.5 and induced stronger use-dependent inhibition. Because the mean plasma concentration of tramadol upon oral administration is lower than its mean blocking concentration of sodium channels in this study, it is unlikely that tramadol in plasma will have an analgesic effect by blocking Na_v1.7 or show cardiotoxicity by blocking Na_v1.5. However, tramadol could act as a local anesthetic when used at a concentration of several hundred millimoles by intradermal injection and as an antiarrhythmic when injected intravenously at a similar dose, as does lidocaine.

Local Tramadol Improves the Anesthetic Success in Patients with Symptomatic Irreversible Pulpitis: A Meta-Analysis

Symptomatic irreversible pulpitis is a painful clinical condition with a broad inflammatory component. Dental anesthesia in these patients is affected by the inflammatory process, reporting a high incidence of anesthesia failure. The aim of this systematic review and meta-analytical evaluation was to determine the effect of pre-treatment with tramadol in patients with symptomatic irreversible pulpitis, as well as for pain control and adverse effects. This study was registered in PROSPERO (ID: CRD42021279262). PubMed was consulted to identify clinical investigations comparing tramadol and placebo/local anesthetics in patients with symptomatic irreversible pulpitis. Data about the anesthesia, pain control, and adverse effects were extracted. Both the anesthetic success index and the adverse effects of local tramadol and placebo were compared with the Mantel−Haenszel test and odds ratio. Data analysis showed that the local administration of tramadol increased the anesthetic success rate when compared to placebo in patients with symptomatic irreversible pulpitis (n = 228; I2 = 0; OR = 2.2; 95% CIs: 1.30 to 3.79; p < 0.004). However, local administration of tramadol increased the risk of adverse effects when compared to placebo/local anesthetics (n = 288; I2 = 0; OR = 7.72; 95% CIs: 1.37 to 43.46; p < 0.02). In conclusion, this study shows that the local administration of tramadol increases the anesthetic success index when compared to placebo in patients with symptomatic irreversible pulpitis.

The additive effect of clonidine to lidocaine on postoperative pain management after root canal treatment on mandibular molars with symptomatic irreversible pulpitis: A prospective randomised double-blind clinical trial

Context:

Postoperative pain control has been a common challenge to clinicians in endodontics.

Aims:

This double-blind randomized clinical trial assessed the efficacy of clonidine added to lidocaine for postoperative pain following endodontic treatment of mandibular molars with symptomatic irreversible pulpitis (SIP).

Methods:

One hundred participants with lower molars experiencing SIP were recruited and randomly assigned to two groups. 1.8 mL of 2% lidocaine with either epinephrine (1:80,000) or clonidine (15 µg/mL) was administered to each group via an inferior alveolar nerve block. A Heft–Parker Visual Analog Scale was used to rate preoperative pain and at 6, 12, 24, 36, 48, and 72 h following endodontic treatment. Their postoperative analgesic consumption was recorded.

Statistical Analysis Used:

The analgesic efficacy was analyzed by Chi-square test, paired t-test, and repeated measures ANOVA (P < 0.05).

Results:

Early postoperative pain was significantly lower in the lidocaine/clonidine group than the lidocaine/epinephrine group (6 h: P = 0.038; 12 h: P = 0.031). The lidocaine/clonidine group consumed a significantly lower amount of analgesics (P = 0.048).

Conclusions:

The administration of clonidine added to lidocaine may reduce early postoperative pain and consumption of analgesics following endodontic treatment in lower molars with SIP.

Effectiveness of tramadol compared to lignocaine as local anesthesia in the extraction of firm teeth: a randomized controlled trial

Background

The aim of this study was to compare the local anesthetic effect of tramadol with that of lignocaine in the extraction of immobile (grade 0) maxillary first molars.

Methods

This was a randomized, double-blind, equally balanced, controlled trial conducted on a sample population of 116 patients. The patients were randomly divided into two groups: group A (control) and group B (study). Group A and group B participants received 1.8 ml of 2% lignocaine without adrenaline and 1.8 ml of 5% tramadol, respectively through the supra-periosteal infiltration technique before extraction. Intraoperative pain was recorded on the Visual Analog Scale (VAS) and was evaluated using two unpaired t-tests.

Results

Intraoperative pain was evaluated in both the control and study groups. In the control group, the mean VAS score was 0.71 ± 0.81, while in the study group, the mean intraoperative VAS score was 1.21 ± 0.86, with the difference between the two mean values being statistically significant (P = 0.001).

Conclusion

Tramadol has a less potent local anesthetic effect than lignocaine. As a higher dose of tramadol is required to obtain the desired anesthetic effect, it should be used as a supplement to lignocaine in extensive surgical procedures. It can also be used in patients allergic to lignocaine.

Buprenorphine: Far Beyond the "Ceiling"

Chronic pain, including neuropathic pain, represents an untreated disease with important repercussions on the quality of life and huge costs on the national health system. It is well known that opioids are the most powerful analgesic drugs, but they represent the second or third line in neuropathic pain, that remain difficult to manage. Moreover, these drugs show several side effects that limit their use. In addition, opioids possess addictive properties that are associated with misuse and drug abuse. Among available opioids compounds, buprenorphine has been suggested advantageous for a series of clinical reasons, including the effectiveness in neuropathic pain. Some properties are partly explained by its unique pharmacological characteristics. However, questions on the dynamic profile remain to be answered. Pharmacokinetics optimization strategies, and additional potentialities, are still to be explored. In this paper, we attempt to conceptualize the potential undiscovered dynamic profile of buprenorphine.

The role of adenosine A1 receptor in the peripheral tramadol's effect in the temporomandibular joint of rats

Peripheral tramadol's delivery in the temporomandibular joint (TMJ) leads to significant analgesic outcomes and inflammatory process's resolvent actions. Mechanistically, these properties are apart from the opioid system. Nevertheless, the molecular mechanisms behind these effects are still unclear. Therefore, the present study investigated the hypothesis that adenosine A₁ receptors are involved in the tramadol-induced analgesic and anti-inflammatory effects in the TMJ. Animals were pretreated with an intra-TMJ injection of DPCPX (antagonist of A₁ receptor) or tramadol and subsequent nociceptive challenge with an intra-TMJ injection of 1.5% formalin. For over 45 min, the nociceptive behavior was quantitated, and by the end of this assessment, the animals were euthanized, and the periarticular tissue was collected. Lastly, an in vitro assay of BMDM (Bone Marrow-Derived Macrophages) was performed to investigate tramadol activity in macrophages. The intra-TMJ injection of tramadol ameliorates formalin-induced hypernociception along with inhibiting leukocyte migration. The tramadol's peripheral anti-inflammatory effect was mediated by the adenosine A₁ receptor and was associated with increased protein expression of α2a-adrenoceptor in the periarticular tissues (p < 0.05: ANOVA, Tukey's test). Also, tramadol inhibits formalin-induced leukocyte migration and protein expression of P2X7 receptors in the periarticular tissue (p < 0.05); however, DPCPX did not alter this effect (p > 0.05). Moreover, DPCPX significantly reduced the protein expression of the M2 macrophage marker, MRC1. In BMDM, tramadol significantly reduces inflammatory cytokines release, and DPCPX abrogated this effect (p < 0.05). We identify tramadol's peripheral effect is mediated by adenosine A₁ receptor, possibly expressed in macrophages in the TMJ tissue. We also determined an important discovery related to the activation of A₁R/α2_a receptors in the tramadol action.

Inhibition of Fast Nerve Conduction Produced by Analgesics and Analgesic Adjuvants-Possible Involvement in Pain Alleviation

Nociceptive information is transmitted from the periphery to the cerebral cortex mainly by action potential (AP) conduction in nerve fibers and chemical transmission at synapses. Although this nociceptive transmission is largely inhibited at synapses by analgesics and their adjuvants, it is possible that the antinociceptive drugs inhibit nerve AP conduction, contributing to their antinociceptive effects. Many of the drugs are reported to inhibit the nerve conduction of AP and voltage-gated Na⁺ and K⁺ channels involved in its production. Compound action potential (CAP) is a useful measure to know whether drugs act on nerve AP conduction. Clinically-used analgesics and analgesic adjuvants (opioids, non-steroidal anti-inflammatory drugs, ₂-adrenoceptor agonists, antiepileptics, antidepressants and local anesthetics) were found to inhibit fast-conducting CAPs recorded from the frog sciatic nerve by using the air-gap method. Similar actions were produced by antinociceptive plant-derived chemicals. Their inhibitory actions depended on the concentrations and chemical structures of the drugs. This review article will mention the inhibitory actions of the antinociceptive compounds on CAPs in frog and mammalian peripheral (particularly, sciatic) nerves and on voltage-gated Na⁺ and K⁺ channels involved in AP production. Nerve AP conduction inhibition produced by analgesics and analgesic adjuvants is suggested to contribute to at least a part of their antinociceptive effects.

A single dose of tramadol in continuous wound analgesia with levobupivacaine does not reduce post-sternotomy pain: a randomized controlled trial

Background

Medial sternotomy is commonly used in cardiac surgery, although it results in intense post-operative pain. The placement of a sternal wound catheter for the administration of local anesthetic represents an effective technique. An initial bolus of tramadol in the sternal wound catheter could potentiate the effect of the local anesthetic and decrease both the post-operative pain and the morphine consumption.

Patients and methods

We conducted a prospective, randomized, double-blind study at the University Hospital Center, Dijon, France. Patients requiring scheduled or non-extreme emergency surgery for valve disease, aorta disease, atrial myxoma, or coronary artery bypass graft via sternotomy were included. A sternal wound catheter was inserted at the end of the surgery. The patients were randomized to receive either a 2 mg/kg bolus of tramadol (n=80) or a placebo (n=80) in the wound catheter. The bolus administration was followed by a continuous infusion of 1.25% levobupivacaine for the first 48 hrs following surgery. The patients’ morphine consumption during the first 48 hrs after extubation was recorded. The other investigated variables were the patients’ rescue analgesia, arterial blood gasses, and length of stay in the intensive care unit and in hospital, as well as the incidence of chronic pain at the four-month follow-up point.

Results

The morphine consumption was found to be comparable in the two groups (38 mg vs 32 mg, p=0.102). No effect was found in terms of the arterial blood gasses, lengths of stay, or incidence of chronic pain.

Conclusion

The addition of tramadol to the local anesthetic delivered via a wound catheter following sternotomy did not reduce the patients’ post-operative morphine consumption.

Trial registration

Clinicaltrials.gov identifier: NCT02851394.

Acute Tramadol-Induced Cellular Tolerance and Dependence of Ventral Tegmental Area Dopaminergic Neurons: An In Vivo Electrophysiological Study

Introduction

Ventral Tegmental Area (VTA) is a core region of the brainstem that contributes to different vital bio-responses such as pain and addiction. The Dopaminergic (DA) cellular content of VTA has major roles in different functions. This study aims to evaluate the cellular effect of tramadol on the putative VTA-DA neurons.

Methods

Wistar rats were assigned into three groups of control, sham, and tramadol-treated. The animals were anesthetized and their VTA-DA neuronal activity was obtained under controlled stereotaxic operation. The firing rate of the neurons was extracted according to principal component analysis by Igor Pro software and analyzed statistically considering P<0.05 as significant. Tramadol (20 mg/kg) was infused intraperitoneally.

Results

Overall, 121 putative VTA-DA neurons were isolated from all groups. In tramadol-treated rats, the inhibition of the neuronal firing was proposed as tolerance and the excitation period as dependence or withdrawal. The Mean±SD inhibition time lasted up to 50.34±10.17 minutes and 31% of neurons stopped firing and silenced after 24±3 min on average but the remaining neurons lowered their firing up to 43% to 67% of their baseline firing. All neurons showed the excitation period, lasted about 56.12±15.30 min, and the firing of neurons increased from 176% to 244% of their baseline or pre-injection period.

Conclusion

The tolerance and dependence effects of tramadol are related to the changes in the neuronal firing rate at the putative VTA-DA neurons. The acute injection of tramadol can initiate neuroadaptation on the opioid and non-opioid neurotransmission to mediate these effects.

Revisiting Tramadol: A Multi-Modal Agent for Pain Management

Tramadol-an atypical opioid analgesic-has a unique pharmacokinetic and pharmacodynamic profile, with opioidergic, noradrenergic, and serotonergic actions. Tramadol has long been used as a well-tolerated alternative to other drugs in moderate pain because of its opioidergic and monoaminergic activities. However, cumulative evidence has been gathered over the last few years that supports other likely mechanisms and uses of tramadol in pain management. Tramadol has modulatory effects on several mediators involved in pain signaling, such as voltage-gated sodium ion channels, transient receptor potential V1 channels, glutamate receptors, α₂-adrenoceptors, adenosine receptors, and mechanisms involving substance P, calcitonin gene-related peptide, prostaglandin E₂, and proinflammatory cytokines. Tramadol also modifies the crosstalk between neuronal and non-neuronal cells in peripheral and central sites. Through these molecular effects, tramadol could modulate peripheral and central neuronal hyperexcitability. Given the broad spectrum of molecular targets, tramadol as a unimodal analgesic relieves a broad range of pain types, such as postoperative, low back, and neuropathic pain and that associated with labor, osteoarthritis, fibromyalgia, and cancer. Moreover, tramadol has anxiolytic, antidepressant, and anti-shivering activities that could improve pain management outcomes. The aim of this review was to address these issues in the context of maladaptive physiological and psychological processes that are associated with different pain types.

Tramadol hydrochloride: An alternative to conventional local anaesthetics for intraoral procedures- a preliminary study

Purpose

To evaluate and compare the soft tissue anaesthesia produced by tramadol hydrochloride on gingival tissues in maxilla.

Methods

A total of 50 ASA physical status I subjects between 18 and 35 years of age, both male and female were included in the study. Each individual received 0.5 ml of 50 mg tramadol in the soft tissues over maxillary canine tooth as local infiltration on one and 0.5 ml of 20 mg lignocaine on the contralateral side in a double-blinded fashion. After completing the injection, the author recorded pain on injection, the onset of action, duration of anaesthesia, side effects, and feedback from patient.

Results

The mean onset of anaesthesia for tramadol was 172.00 s (standard deviation 39.898) while for lignocaine it was 162.60 s (standard deviation 35.098) and there was no statistically significant difference between the two groups (p = 0.214). The mean duration of anaesthesia for tramadol group was 45.70 min with a standard deviation of 8.512 min whereas for lignocaine group it was 44.70 min with a standard deviation of 8.107 min. There was no statistical relevant difference between the two groups in duration of anaesthesia (p = 0.549). None of the subjects reported any side effect in both the groups. There was no significant difference in pain on injection between the two groups.

Conclusions

Tramadol has a local anaesthetic effect similar to lignocaine when injected as infiltration in oral soft tissues.

DARK Classics in Chemical Neuroscience: Fentanyl

Fentanyl rose to prominence as an alternative analgesic to morphine nearly 50 years ago; today, fentanyl has re-emerged as a dangerous recreational substance. The increased potency and analgesic effect of fentanyl are advantageous in the treatment of pain but are also responsible for the rise in unintentional opioid overdose deaths. In response to this crisis, fentanyl, its analogues, and even precursors are under heightened regulatory scrutiny. Despite this controversial history, derivatization of fentanyl has resulted in numerous synthetic analogues that provide valuable insights into opioid receptor binding and signaling events. In this review, the impact of fentanyl on chemical neuroscience is shown through its synthesis and properties, manufacturing, metabolism, pharmacology, approved and off-label indications, adverse effects, and the responsibility it has in the opioid epidemic.

Comparison of Local Anaesthetic Efficacy of Tramadol Versus Lignocaine for Extraction of Tooth Under Supraperiosteal Infiltration

Background

Tramadol has been shown to have a local anaesthetic effect when used as infiltration anaesthesia.

Methods

The local anaesthetic efficacy of tramadol was compared with that of lignocaine for the extraction of teeth in terms of their onset of action, duration of action, intraoperative pain, post-operative analgesic effect and adverse reactions. Apart from this, incidence of allergic reaction was also recorded for both the drugs. A total of 100 patients were divided into two groups randomly. Each patient was assigned to receive either a maximum of 2 ml of 5% tramadol (Supridol 50 mg, Neon laboratories), Group T (n = 50), as a local anaesthetic solution for extraction of maxillary premolar for orthodontic reason under supraperiosteal infiltration following strict aseptic precaution or a maximum of 2 ml of 2% lignocaine (Lox 2%, Neon laboratories), Group L (n = 50), in a double-blinded fashion.

Results

In group T, the mean subjective onset of action was 33.66 s, while in group L it was 33.06 s (p = 0.881). In group T, the mean objective onset of action was 3.04 min, while in group L it was 3.18 min (p > 0.05). The mean duration of action in group T was 55.60 min, while in group L it was 57.50 min (p = 0.432). Only 2 patients in group T and 1 patient in group L had nausea (p = 0.245).

Conclusion

We conclude that 5% tramadol has a local anaesthetic efficacy similar to 2% lignocaine but is comparatively a weaker agent.

Unsafe Drug Use and Arrhythmic Events in Brugada Patients with ICD: Results of a Long-Term Follow-Up

PURPOSE

Brugada syndrome is a hereditary disease linked with an increased risk of sudden death that may require an implantable cardioverter-defibrillator (ICD) in order to halt the arrhythmic events. The aim of this study was to identify possible triggers for appropriate ICD therapies in patients with Brugada syndrome, focusing on their past and current therapeutic profiles.

METHODS

Thirty patients with high-risk Brugada syndrome, with ICD implanted at the Coimbra Hospital and University Center, were enrolled. Patients were questioned about their Brugada syndrome history, previous cardiac events, comorbidities, present and past medications, and physical activity. Patients were followed up during 5.8 ± 5.3 years. The ICD was interrogated, and arrhythmic events and device therapies were recorded. The cohort who received appropriate ICD therapies was compared with the remaining patients to determine the potential link between clinical variables and potentially fatal arrhythmic events.

RESULTS

More than half of the patients (53.3%) took at least one non-recommended drug, and 16.7% received appropriate ICD therapies, with a long-term rate of 4.0%/year. There was a tendency for more appropriate ICD therapies in patients who took unsafe drugs (85.7 versus 45.5%, p = 0.062), and the mean time between unsafe drug intake and appropriate ICD therapies was 3.8 ± 7.5 days.

CONCLUSIONS

This study revealed that the medical community is still unaware of the pharmacological restrictions imposed by Brugada syndrome. Patients who took non-recommended drugs seem to have a higher risk of ventricular arrhythmic events.

Tramadol use in a patient with Brugada syndrome and morphine allergy: a case report

Brugada syndrome is a rare syndrome characterized by arrhythmias and sudden death, particularly in younger individuals. A mutation in a gene encoding the human cardiac sodium channels is responsible for this syndrome. In the literature, there are several case reports of Brugada syndrome in association with the use of several anesthetic agents. Herein, we present our anesthetic practice and the use of tramadol in a 75-year-old female patient who underwent pulmonary lobectomy under general anesthesia and was diagnosed with Brugada syndrome.

New Findings on Local Tramadol Use in Oral Surgery

In modern times, all procedures in oral surgery need to be painless and management of postoperative pain needs to be adequate. The surgical extraction of the third molar or alveolectomy of the wisdom tooth is one of the most common surgical procedures carried out in oral surgery and it includes rising a flap, bone removal and suturing. These surgical procedures usually cause swelling, trismus and moderate to severe pain. Third molar surgery is often used as a model in clinical trials that are directed toward reducing postoperative pain and improving its management. Tramadol is a well-known central acting opioid analgesic that produces analgesia against multiple pain conditions such as postsurgical pain, obstetric pain, terminal cancer pain, pain of coronary origin and neuropathic pain. Tramadol is an atypical opioid. When administered locally, it has both analgesic and anesthetic properties. The aim of this paper was to present new findings on local effects of tramadol in oral surgery.

Ambroxol for the treatment of fibromyalgia: science or fiction?

Fibromyalgia appears to present in subgroups with regard to biological pain induction, with primarily inflammatory, neuropathic/neurodegenerative, sympathetic, oxidative, nitrosative, or muscular factors and/or central sensitization. Recent research has also discussed glial activation or interrupted dopaminergic neurotransmission, as well as increased skin mast cells and mitochondrial dysfunction. Therapy is difficult, and the treatment options used so far mostly just have the potential to address only one of these aspects. As ambroxol addresses all of them in a single substance and furthermore also reduces visceral hypersensitivity, in fibromyalgia existing as irritable bowel syndrome or chronic bladder pain, it should be systematically investigated for this purpose. Encouraged by first clinical observations of two working groups using topical or oral ambroxol for fibromyalgia treatments, the present paper outlines the scientific argument for this approach by looking at each of the aforementioned aspects of this complex disease and summarizes putative modes of action of ambroxol. Nevertheless, at this point the evidence basis for ambroxol is not strong enough for clinical recommendation.

The anti-inflammatory effect of tramadol in the temporomandibular joint of rats

Tramadol is a centrally acting analgesic drug able to prevent nociceptor sensitization when administered into the temporomandibular joint (TMJ) of rats. The mechanism underlying the peripheral anti-inflammatory effect of tramadol remains unknown. This study demonstrated that intra-TMJ injection of tramadol (500µg/TMJ) was able to inhibit the nociceptive response induced by 1.5% formalin or 1.5% capsaicin, suggesting that tramadol has an antinociceptive effect, acting directly on the primary nociceptive neurons activating the nitric oxide/cyclic guanosine monophosphate signaling pathway. Tramadol also inhibited the nociceptive response induced by carrageenan (100µg/TMJ) or 5-hydroxytryptamine (225µg/TMJ) along with inhibition of inflammatory cytokines levels, leukocytes migration and plasma extravasation. In conclusion, the results demonstrate that peripheral administration of tramadol has a potential antinociceptive and anti-inflammatory effect. The antinociceptive effect is mediated by activation of the intracellular nitric oxide/cyclic guanosine monophosphate pathway, at least in part, independently from the opioid system.

Loperamide inhibits sodium channels to alleviate inflammatory hyperalgesia

Previous studies demonstrated that Loperamide, originally known as an anti-diarrheal drug, is a promising analgesic agent primarily targeting mu-opioid receptors. However some evidences suggested that non-opioid mechanisms may be contributing to its analgesic effect. In the present study, Loperamide was identified as a Nav1.7 blocker in a pilot screen. In HEK293 cells expressing Nav1.7 sodium channels, Loperamide blocked the resting state of Nav1.7 channels (IC₅₀ = 1.86 ± 0.11 μM) dose-dependently and reversibly. Loperamide produced a 10.4 mV of hyperpolarizing shift for the steady-state inactivation of Nav1.7 channels without apparent effect on the voltage-dependent activation. The drug displayed a mild use- and state-dependent inhibition on Nav1.7 channels, which was removed by the local anesthetic-insensitive construct Nav1.7-F1737A. Inhibition of Nav1.7 at resting state was not altered significantly by the F1737A mutation. Compared to its effects on Nav1.7, Loperamide exhibited higher potency on recombinant Nav1.8 channels in ND7/23 cells (IC₅₀ = 0.60 ± 0.10 μM) and weaker potency on Nav1.9 channels (3.48 ± 0.33 μM). Notably more pronounced inhibition was observed in the native Nav1.8 channels (0.11 ± 0.08 μM) in DRG neurons. Once mu-opioid receptor was antagonized by Naloxone in DRG neurons, potency of Loperamide on Nav1.8 was identical to that of recombinant Nav1.8 channels. The inhibition on Nav channels may be the main mechanism of Loperamide for pain relief beyond mu-opioid receptor. In the meanwhile, the opioid receptor pathway may also influence the blocking effect of Loperamide on sodium channels, implying a cross-talk between sodium channels and opioid receptors in pain processing.

Endotracheal Administration of Sufentanil and Tetracaine During Awake Fiberoptic Intubation

Combined use of local anesthetics and low-dose opioids enhances the effects of local anesthetics. This study aimed to evaluate the efficacy of combined administration of sufentanil and tetracaine through the cricothyroid membrane during awake nasal intubation using fiberoptic bronchoscopy in patients with difficult airways. Forty patients were divided into 2 groups: group A received endotracheal administration of 25 μg of sufentanil and 2 mL of 1% tetracaine mixture; group B received endotracheal administration of 2 mL 1% tetracaine and routine local anesthetic sprays followed by slow intravenous injection of 25 μg of sufentanil. The results showed that endotracheal intubation was safely completed in all patients and vital signs including blood pressure, heart rate, and pulse oxygen saturation were not significantly different between groups A and B. However, time required for local anesthesia to take effect, time required to complete intubation, cough reflex, patient tolerance during intubation, and hemodynamic indices were significantly better in group A than in group B. In conclusion, our results suggest that endotracheal administration of sufentanil combined with tetracaine is safe, effective, and feasible in the context of awake nasal intubation using fiberoptic bronchoscopy.

Pharmacological comparison of a nonhuman primate and a rat model of oxaliplatin-induced neuropathic cold hypersensitivity

Oxaliplatin is a first‐line treatment for colorectal cancer. However, shortly following treatment, cold‐evoked hypersensitivity appears in the extremities and over time, the pain is such that oxaliplatin dosing may need to be markedly reduced or even terminated. There is currently a lack of efficacious treatments for oxaliplatin‐induced peripheral neuropathy, which is due in part to the difficulty in translating findings obtained from preclinical rodent models of chemotherapy‐induced peripheral neuropathy. Nonhuman primates (NHP) are phylogenetically closer to humans than rodents and may show drug responses that parallel those of humans. A significant decrease in tail withdrawal latency to 10°C water (“cold hypersensitivity”) was observed beginning 3 days after intravenous infusion of oxaliplatin (5 mg/kg) in Macaca fascicularis. A single treatment of duloxetine (30 mg/kg, p.o.) ameliorated oxaliplatin‐induced cold hypersensitivity, whereas pregabalin (30 mg/kg, p.o.) and tramadol (30 mg/kg, p.o.) did not. By contrast, in rats, no significant cold hypersensitivity, or increased responsiveness to acetone applied to the hind paws, was observed 3 days after the first injection of oxaliplatin (5 mg/kg, i.p., once per day, two injections). Therefore, rats were tested after six treatments of oxaliplatin, 17 days after the first treatment. All analgesics (30 mg/kg, p.o.) significantly ameliorated cold hypersensitivity in rats. The activity of analgesics in the oxaliplatin‐treated macaques parallel clinical findings. The current results indicate that the NHP could serve as a bridge species to improve translatability of preclinical findings into clinically useful treatments for oxaliplatin‐induced peripheral neuropathy.

Inhibition of voltage-gated sodium channels by sumatriptan bioisosteres

Voltage-gated sodium channels are known to play a pivotal role in perception and transmission of pain sensations. Gain-of-function mutations in the genes encoding the peripheral neuronal sodium channels, hNav1.7–1.9, cause human painful diseases. Thus while treatment of chronic pain remains an unmet clinical need, sodium channel blockers are considered as promising druggable targets. In a previous study, we evaluated the analgesic activity of sumatriptan, an agonist of serotonin 5HT_1B/D receptors, and some new chiral bioisosteres, using the hot plate test in the mouse. Interestingly, we observed that the analgesic effectiveness was not necessarily correlated to serotonin agonism. In this study, we evaluated whether sumatriptan and its congeners may inhibit heterologously expressed hNav1.7 sodium channels using the patch-clamp method. We show that sumatriptan blocks hNav1.7 channels only at very high, supratherapeutic concentrations. In contrast, its three analogs, namely 20b, (R)-31b, and (S)-22b, exert a dose and use-dependent sodium channel block. At 0.1 and 10 Hz stimulation frequencies, the most potent compound, (S)-22b, was 4.4 and 1.7 fold more potent than the well-known sodium channel blocker mexiletine. The compound induces a negative shift of voltage dependence of fast inactivation, suggesting higher affinity to the inactivated channel. Accordingly, we show that (S)-22b likely binds the conserved local anesthetic receptor within voltage-gated sodium channels. Combining these results with the previous ones, we hypothesize that use-dependent sodium channel blockade contributes to the analgesic activity of (R)-31b and (S)-22b. These later compounds represent promising lead compounds for the development of efficient analgesics, the mechanism of action of which may include a dual action on sodium channels and 5HT_1D receptors.

Local analgesic effect of tramadol is not mediated by opioid receptors in early postoperative pain in rats

BACKGROUND AND OBJECTIVES

Tramadol is known as a central acting analgesic drug, used for the treatment of moderate to severe pain. Local analgesic effect has been demonstrated, in part due to local anesthetic-like effect, but other mechanisms remain unclear. The role of peripheral opioid receptors in the local analgesic effect is not known. In this study, we examined role of peripheral opioid receptors in the local analgesic effect of tramadol in the plantar incision model.

METHODS

Young male Wistar rats were divided into seven groups: control, intraplantar tramadol, intravenous tramadol, intravenous naloxone-intraplantar tramadol, intraplantar naloxone-intraplantar tramadol, intravenous naloxone-intravenous tramadol, and intravenous naloxone. After receiving the assigned drugs (tramadol 5mg, naloxone 200 μg or 0.9% NaCl), rats were submitted to plantar incision, and withdrawal thresholds after mechanical stimuli with von Frey filaments were assessed at baseline, 10, 15, 30, 45 and 60 min after incision.

RESULTS

Plantar incision led to marked mechanical hyperalgesia during the whole period of observation in the control group, no mechanical hyperalgesia were observed in intraplantar tramadol group, intraplantar naloxone-intraplantar tramadol group and intravenous naloxone-intraplantar tramadol. In the intravenous tramadol group a late increase in withdrawal thresholds (after 45 min) was observed, the intravenous naloxone-intravenous tramadol group and intravenous naloxone remained hyperalgesic during the whole period.

CONCLUSIONS

Tramadol presented an early local analgesic effect decreasing mechanical hyperalgesia induced by plantar incision. This analgesic effect was not mediated by peripheral opioid receptors.

[Local analgesic effect of tramadol is not mediated by opioid receptors in early postoperative pain in rats]

BACKGROUND AND OBJECTIVES

Tramadol is known as a central acting analgesic drug, used for the treatment of moderate to severe pain. Local analgesic effect has been demonstrated, in part due to local anesthetic-like effect, but other mechanisms remain unclear. The role of peripheral opioid receptors in the local analgesic effect is not known. In this study, we examined role of peripheral opioid receptors in the local analgesic effect of tramadol in the plantar incision model.

METHODS

Young male Wistar rats were divided into seven groups: control, intraplantar tramadol, intravenous tramadol, intravenous naloxone-intraplantar tramadol, intraplantar naloxone-intraplantar tramadol, intravenous naloxone-intravenous tramadol, and intravenous naloxone. After receiving the assigned drugs (tramadol 5mg, naloxone 200μg or 0.9% NaCl), rats were submitted to plantar incision, and withdrawal thresholds after mechanical stimuli with von Frey filaments were assessed at baseline, 10, 15, 30, 45 and 60min after incision.

RESULTS

Plantar incision led to marked mechanical hyperalgesia during the whole period of observation in the control group, no mechanical hyperalgesia were observed in intraplantar tramadol group, intraplantar naloxone-intraplantar tramadol group and intravenous naloxone-intraplantar tramadol. In the intravenous tramadol group a late increase in withdrawal thresholds (after 45min) was observed, the intravenous naloxone-intravenous tramadol group and intravenous naloxone remained hyperalgesic during the whole period.

CONCLUSIONS

Tramadol presented an early local analgesic effect decreasing mechanical hyperalgesia induced by plantar incision. This analgesic effect was not mediated by peripheral opioid receptors.

HIV, opiates, and enteric neuron dysfunction

Human immune deficient virus (HIV) is an immunosuppressive virus that targets CD4(+) T-lymphocytes. HIV infections cause increased susceptibility to opportunistic infections and cancer. HIV infection can also alter central nervous system (CNS) function causing cognitive impairment. HIV does not infect neurons but it does infect astrocytes and microglia in the CNS. HIV can also infect enteric glia initiating an intestinal inflammatory response which causes enteric neural injury and gut dysfunction. Part of the inflammatory response is HIV induced production of proteins including, Transactivator of transcription (Tat) which contribute to neuronal injury after release from HIV infected glial cells. A risk factor for HIV infection is intravenous drug use with contaminated needles and chronic opiate use can exacerbate neural injury in the nervous system. While most research focuses on the actions of Tat and other HIV related proteins and opiates on the brain, recent data indicate that Tat can cause intestinal inflammation and disruption of enteric neuron function, including alteration of Na(+) channel activity and action potential generation. A paper published in this issue of Neurogastroenterology and Motility extends these findings by identifying an interaction between Tat and morphine on enteric neuron Na(+) channels and on intestinal motility in vivo using a Tat expressing transgenic mouse model. These new data show that Tat protein can enhance the inhibitory actions of morphine on action potential generation and propulsive motility. These findings are important to our understanding of how HIV causes diarrhea in infected patients and for the use of opioid drugs to treat HIV-induced diarrhea.

Partial block by riluzole of muscle sodium channels in myotubes from amyotrophic lateral sclerosis patients

Denervated muscles undergo fibrillations due to spontaneous activation of voltage-gated sodium (Na(+)) channels generating action potentials. Fibrillations also occur in patients with amyotrophic lateral sclerosis (ALS). Riluzole, the only approved drug for ALS treatment, blocks voltage-gated Na(+) channels, but its effects on muscle Na(+) channels and fibrillations are yet poorly characterized. Using patch-clamp technique, we studied riluzole effect on Na(+) channels in cultured myotubes from ALS patients. Needle electromyography was used to study fibrillation potentials (Fibs) in ALS patients during riluzole treatment and after one week of suspension. Patients were clinically characterized in all recording sessions. In myotubes, riluzole (1 μM, a therapeutic concentration) reduced Na(+) current by 20%. The rate of rise and amplitude of spikes evoked by depolarizing stimuli were also reduced. Fibs were detected in all patients tested during riluzole treatment and riluzole washout had no univocal effect. Our study indicates that, in human myotubes, riluzole partially blocks Na(+) currents and affects action potentials but does not prevent firing. In line with this in vitro finding, muscle Fibs in ALS patients appear to be largely unaffected by riluzole.

The opioid methadone induces a local anaesthetic-like inhibition of the cardiac Na⁺ channel, Na(v)1.5

BACKGROUND AND PURPOSE

Treatment with methadone is associated with severe cardiac arrhythmias, a side effect that seems to result from an inhibition of cardiac hERG K⁺ channels. However, several other opioids are inhibitors of voltage-gated Na⁺ channels. Considering the common assumption that an inhibition of the cardiac Na⁺ channel Na(v)1.5, is the primary mechanism for local anaesthetic (LA)-induced cardiotoxicity, we hypothesized that methadone has LA-like properties leading to a modulation of Na(v)1.5 channels.

EXPERIMENTAL APPROACH

The whole-cell patch clamp technique was applied to investigate the effects of methadone on wild-type and mutant human Na(v)1.5 channels expressed in HEK293 cells. A homology model of human Na(v)1.5 channels was used to perform automated ligand-docking studies.

KEY RESULTS

Methadone inhibited Na(v)1.5 channels in a state-dependent manner, that is, tonic block was stronger with inactivated channels than with resting channels and a use-dependent block at 10 Hz. Methadone induced a concentration-dependent shift of the voltage dependency of both fast and slow inactivation towards more hyperpolarized potentials, and impaired recovery from fast and slow inactivation. The LA-insensitive mutants N406K and F1760A exhibited reduced tonic and use-dependent block by methadone, and docking predictions positioned methadone in a cavity that was delimited by the residue F1760. Dextromethadone and levomethadone induced discrete stereo-selective effects on Na(v)1.5 channels.

CONCLUSIONS AND IMPLICATIONS

Methadone interacted with the LA-binding site to inhibit Na(v)1.5 channels. Our data suggest that these channels are a hitherto unrecognized molecular component contributing to cardiac arrhythmias induced by methadone.

Methadone is a local anaesthetic-like inhibitor of neuronal Na+ channels and blocks excitability of mouse peripheral nerves

BACKGROUND

Opioids enhance and prolong analgesia when applied as adjuvants to local anaesthetics (LAs). A possible molecular mechanism for this property is a direct inhibition of voltage-gated Na(+) channels which was reported for some opioids. Methadone is an effective adjuvant to LA and was recently reported to inhibit cardiac Na(+) channels. Here, we explore and compare LA properties of methadone and bupivacaine on neuronal Na(+) channels, excitability of peripheral nerves, and cell viability.

METHODS

Effects of methadone were explored on compound action potentials (CAP) of isolated mouse saphenous nerves. Patch clamp recordings were performed on Na(+) channels in ND7/23 cells, the α-subunits Nav1.2, Nav1.3, Nav1.7, and Nav1.8, and the hyperpolarization-activated cyclic nucleotide-gated channel 2 (HCN2). Cytotoxicity was determined using flow cytometry.

RESULTS

Methadone (IC50 86-119 µM) is a state-dependent and unselective blocker on Nav1.2, Nav1.3, Nav1.7, and Nav1.8 with a potency comparable with that of bupivacaine (IC50 177 µM). Both bupivacaine and methadone also inhibit C- and A-fibre CAPs in saphenous nerves in a concentration-dependent manner. Tonic block of Nav1.7 revealed a discrete stereo-selectivity with a higher potency for levomethadone than for dextromethadone. Methadone is also a weak blocker of HCN2 channels. Both methadone and bupivacaine induce a pronounced cytotoxicity at concentrations required for LA effects.

CONCLUSIONS

Methadone induces typical LA effects by inhibiting Na(+) channels with a potency similar to that of bupivacaine. This hitherto unknown property of methadone might contribute to its high efficacy when applied as an adjuvant to LA.

Peripheral synergism between tramadol and ibuprofen in the formalin test

Preclinical Research Analgesics with different mechanisms of action can be combined in order to obtain pharmacological synergism, employing lower doses of each agent, thus diminishing side effects. For instance, an atypical dual analgesic such as tramadol (TMD) and a nonsteroidal anti-inflammatory drug such as ibuprofen (IBU) are good candidates to be evaluated when combined and applied peripherally. The present study was conducted to evaluate possible local synergism between TMD and IBU when combined peripherally using the formalin test in rats. The effects of the individual analgesics and their combinations were evaluated simultaneously using a 5% formalin dilution. Dose-effect curves were determined for TMD (50-400 μg/paw) and IBU (1-100 μg/paw). Experimental effective doses were evaluated and isobolographic analyses were constructed to evaluate TMD-IBU combination synergism. Both drugs produced a dose-dependent analgesic effect when applied separately. Isobolographic analysis showed synergism during phase 1 (0-10 min) and phase 2 (15-60 min) when compared with theoretical doses (P < 0.05), with interaction indexes of 0.06 and 0.09, respectively. The present information supports the peripheral analgesic effect of TMD and IBU, especially when combined at appropriate doses.

Transient unilateral brachial plexopathy and partial Horner's syndrome following spinal anesthesia for cesarean section

A healthy 21-year-old primigravida presented for elective cesarean section. At 45 min after intrathecal (IT) injection of bupivacaine, morphine and fentanyl she developed dysphagia, right sided facial droop, ptosis and ulnar nerve weakness. This constellation of signs and symptoms resolved 2 h later. Based on the time course and laterality of her symptoms, as well as the pharmacologic properties of spinal opioids, we believe her symptoms can be attributed to the IT administration of fentanyl.

Contributions of peripheral, spinal, and supraspinal actions to analgesia

Pain signaling involves several main compartments that can be considered as potential sites for analgesic drug actions. When drugs are given systemically, they can act at spinal, supraspinal and peripheral sites, and several methods have been developed for identifying where they act. These include (1) localized delivery of drugs to specific sites (via intracerebral, intrathecal, and intraplantar injections), (2) systemic delivery of drugs with localized delivery of antagonists for the receptor on which the drug acts or for a system recruited by the drug, (3) use of peripherally restricted analogs, and (4) use of conditional knockout technology to selectively deplete receptors on nociceptors. Delivery of drugs simultaneously to several sites (spinal/supraspinal, peripheral/spinal, and peripheral/supraspinal) reveals "self-synergy" between sites for some agents. Knowledge of peripheral contributions to drug actions is important because of the potential to develop peripherally restricted analgesics (with a diminished side effect profile due to not entering the central nervous system), the potential to deliver drugs peripherally (e.g. topically) to act on sensory nerve endings and adjacent tissue (with a diminished side effect profile due to limited systemic absorption), and the potential to use combinations of topical and oral drug regimens to obtain improved pain relief (without increasing the side effect burden). This review considers methods used for compartmental analysis, and results of such site analysis for several major classes of analgesic drugs that are in current use.

Pharmacological characterization of standard analgesics on oxaliplatin-induced acute cold hypersensitivity in mice

Oxaliplatin, a platinum-based chemotherapeutic agent, causes an acute peripheral neuropathy triggered by cold in almost all patients during or within hours after its infusion. We recently reported that a single administration of oxaliplatin induced cold hypersensitivity 2 h after the administration in mice. In this study, we examined whether standard analgesics relieve the oxaliplatin-induced acute cold hypersensitivity. Gabapentin, tramadol, mexiletine, and calcium gluconate significantly inhibited and morphine and milnacipran decreased the acute cold hypersensitivity, while diclofenac and amitriptyline had no effects. These results suggest that gabapentin, tramadol, mexiletine, and calcium gluconate are effective against oxaliplatin-induced acute peripheral neuropathy.

[ICU acquired neuromyopathy]

ICU acquired neuromyopathy (IANM) is the most frequent neurological pathology observed in ICU. Nerve and muscle defects are merged with neuromuscular junction abnormalities. Its physiopathology is complex. The aim is probably the redistribution of nutriments and metabolism towards defense against sepsis. The main risk factors are sepsis, its severity and its duration of evolution. IANM is usually diagnosed in view of difficulties in weaning from mechanical ventilation, but electrophysiology may allow an earlier diagnosis. There is no curative therapy, but early treatment of sepsis, glycemic control as well as early physiotherapy may decrease its incidence. The outcomes of IANM are an increase in morbi-mortality and possibly long-lasting neuromuscular abnormalities as far as tetraplegia.