Novel Drug Targets and Emerging Pharmacotherapies in Neuropathic Pain

Comparative analysis of analgesic and anxiolytic effects of alcoholic extracts from Eryngium billardieri and Urtica dioica in a rat model of chronic pain

OBJECTIVE

The treatment of neuropathic pain is crucial, as it not only alleviates physical discomfort but also reduces anxiety associated with pain, ultimately enhancing the quality of life for affected individuals. This study investigates the protective effects of hydro-alcoholic extracts from Eryngium billardieri (Er) and Urtica dioica (Ur) on neuropathic pain and anxiety responses in an animal model.

METHODS

40 male Wistar rats were used to investigate neuropathy induced by the chronic constriction injury (CCI) model. Animals were divided into five experimental groups (N = 8): [sham], [CCI], [CCI+Er], [CCI+Ur], and [CCI+Imipramine]. Er and Ur were administered orally for 30 days, starting on the day of surgery. Behavioral tests, including acetone for cold allodynia, the elevated plus maze for anxiety-like behaviors, and the open field for innate anxiety, were conducted on day -1 (before CCI) and on days 2, 4, 6, 14, 21, and 30. Data were analyzed by one-way analysis of variance test, and P < 0.05 was considered significant.

RESULTS

Neuropathic surgery resulted in cold allodynia and anxiety-like behaviors throughout the experiment as compared to the sham. Er extract significantly decreased both cold allodynia and anxiety-like behaviors in the CCI group. However, Ur extract only significantly reduced cold allodynia (and not anxiety-like behaviors). Additionally, there was no difference between the analgesic effects of Er and Ur extracts.

CONCLUSIONS

These findings support the use of Er as a potential comprehensive treatment for neuropathic pain and anxiety symptoms. Future research should focus on exploring the specific mechanisms behind these effects and the potential for synergistic treatments to improve outcomes for individuals suffering from neuropathy.

Effect of an experimental pregabalin gel on dental sensitivity and color change after bleaching with 35% hydrogen peroxide: a randomized clinical trial

OBJECTIVE

This clinical study evaluated an experimental pregabalin (PG) gel in reducing dental sensitivity (DS) and color change after dental bleaching.

MATERIALS AND METHODS

Seventy-five volunteers were selected and randomized into three groups: GPG (10% pregabalin gel), GKF (5% potassium nitrate and 2% sodium fluoride), and GP (placebo gel). Prior to the bleaching treatment, GPG and GKF received applications of the respective desensitizing gels for 10 min. The GP group received an application of placebo gel, similar to the other groups. The bleaching was performed with 35% hydrogen peroxide in 3 sessions, with a 7-day interval between sessions. Post-bleaching DS was assessed using the visual analog scale (VAS) over 21 days of follow-up. Color Assessment (ΔE00, ΔWID, and ΔEab) and luminosity (L) were measured at baseline (T0) and 7 days after the third session (T1). Friedman, Kruskal-Wallis, one-way ANOVA, and Tukey tests were used, with α = 5%.

RESULTS

Intergroup analysis showed that on the 1st, 8th, and 15th days, DS was higher for GP (p < 0.006; p = 0.004; p < 0.001) and did not differ between GKF and GPG (p = 0.203; p = 0.178; p = 0.09). In the intragroup analysis, GP showed a significant increase in DS on the 15th day (p < 0.001).

CONCLUSIONS

The experimental 10% pregabalin gel reduced dental sensitivity and did not interfere with bleaching results.

CLINICAL SIGNIFICANCE

The topical application of 10% pregabalin gels and NKF was effective in reducing tooth sensitivity 24 hoursafter whitening with 35% hydrogen peroxide.

TRIAL REGISTRATION

ClinicalTrials.gov trial registry with the identifier NCT06180707.

The irreversible, towards fatalic neuropathy: from the genesis of diabetes

Diabetic neuropathy is the most prevalent diabetes-associated complication that negatively impacts the quality of life of the patients. The extensive complications of diabetic peoples in the world are the leading cause of neuropathic pain, and over-activation of different biochemical signalling process induces the pathogenic progression and are also corresponding the epidemic painful symptom of diabetic neuropathy. The main prevalent abnormality is neuropathy, which further causing distal symmetric polyneuropathy and focal neuropathy. The exact pathological complication of diabetes associated neuropathic algesia is still unclear, but the alteration in micro-angiopathy associated nerve fibre loss, hyper polyol formation, MAPK signalling, WNT signalling, tau-derived insulin signalling processes are well known. Furthermore, the post-translational modification of different ion channels, oxidative and nitrosative stress, brain plasticity and microvascular changes can contributes the development of neuropathic pain. However, in the current review we discussed about these pathogenic development of neuropathic pain from the genesis of diabetes, and how diabetes affects the physiological and psychological health, and quality of life of the patients. Furthermore, the treatment of diabetic neuropathy with conventional monotherapy and emerging therapy are discussed. In addition, the treatment with phytochemical constituents their mechanisms and clinical evidences are also reported. The future investigation is required on pathological alteration occurs in neuropathic individuals, and on molecular mechanisms as well as the adverse effect of phytochemicals to determine all aspects of neuropathic algesia including effective treatments, which will prevents the sympathetic pain in patients.

Emerging Therapeutic Modalities and Pharmacotherapies in Neuropathic Pain Management: A Systematic Review and Meta-Analysis of Parallel Randomized Controlled Trials

Background: Neuropathic pain (NP) is a chronic condition caused by abnormal neuronal excitability in the nervous system. Current treatments for NP are often ineffective or poorly tolerated. Hence, we reviewed the efficacy and safety of novel drugs or devices that target neuronal excitability in NP patients compared with placebo, sham, or usual care interventions. Methods: Six databases were searched for parallel randomized controlled trials (RCTs) reporting novel devices (rTMS, SCS, and TENS) or drugs (EMA401, capsaicin 8% patch, and Sativex) for NP. Data were extracted and quality was assessed using the ROB2 tool. The random-effects inverse variance method was used for analysis. Results: In our review of 30 RCTs with 4251 participants, device-based interventions were found to be more effective in reducing pain scores than control interventions (SMD = -1.27, 95% CI: -1.92 to -0.62). However, high heterogeneity was seen (p < 0.01, I 2 = 91%), attributable to the etiology of NP (R 2 = 58.84%) and year of publication (R 2 = 49.49%). Funding source and type of control comparator were ruled out as cause of heterogeneity. Although drug interventions did not differ from placebo interventions in absolute pain reduction (SMD = -1.21, 95% CI: -3.55 to 1.13), when comparing relative change in pain intensity from baseline, drug interventions were found to be effective (SMD = 0.29, 95% CI: 0.04-0.55). Asymmetry in the funnel plot was visualized, suggesting publication bias. Certainty of evidence was very low according to GRADE assessment. Conclusions: Our review indicates that device-based interventions are more effective than control interventions in reducing pain intensity in NP. Nevertheless, available evidence is limited due to heterogeneity and publication bias, prompting the need for more high-quality RCTs to confirm the efficacy and safety of these interventions.

Spinal antinociceptive effect of the PnTx4(5-5) peptide is possibly mediated by the NMDA autoreceptors

BACKGROUND

Medications currently used to treat pain are frequently associated with serious adverse effects and rapid development of tolerance. Thus, there is a need to develop more effective, and safer medicines for the population. Blocking NMDA receptors (NMDAR) has shown to be a promising target for the development of new drugs. That statement is due to NMDAR activation and glutamate release in the spinal cord which affects chronic pain modulation. Therefore, the aim of this study was to evaluate the possible spinal antinociceptive activity of PnTx4(5-5) toxin. The peptide is purified from the venom of the spider P. nigriventer and its affinity for NMDAR and sodium channels Nav1.2-1.6 has already been established.

METHODS

We compared its effect and safety with MK-801 (NMDAR antagonist) and evaluated its influence on glutamate and reactive oxygen species (ROS) levels in CSF. PnTx4(5-5) was administered intrathecally in the Formalin test and co-administered with NMDA in the Spontaneous pain test. After three minutes of observation, mice cerebrospinal fluid was collected to measure glutamate and ROS levels.

RESULTS

The spider peptide inhibited nociception as post-treatment in the inflammatory phase of the Formalin test. Furthermore, it inhibited spontaneous nociception induced by NMDA, being more potent and effective than MK-801 in both models tested. A glutamate rise level in the CSF of mice was significantly reduced by the toxin, but ROS increase was not affected. The animals' motor skills were not affected by the tested doses of NMDAR inhibitors.

CONCLUSION

In conclusion, the results suggest PnTx4(5-5) may mediate its antinociceptive effect in the spinal cord not only by inhibiting postsynaptic receptors but probably also by acting on autoreceptors. This effect does not affect the motricity of mice at the highest dose tested, which suggests that it has therapeutic potential and safety for use as a painkiller.

A Review of the Lidocaine in the Perioperative Period

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

A Nutritional Supplement as Adjuvant of Gabapentinoids for Adults with Neuropathic Pain following Spinal Cord Injury and Stroke: Preliminary Results

Gabapentinoids are first choice drugs for central neuropathic pain (CNP) despite limited evidence of efficacy and side effects affecting therapy outcomes. Nutraceuticals could improve their efficacy and tolerability. Our aim is to investigate the effect of NACVAN®, in addition to gabapentinoids, on pain symptomatology in CNP patients. The effect of 6 weeks of treatment of NACVAN® was preliminary observed among 29 adult inpatients with spinal cord injury (SCI) or stroke-related CNP recruited to the experimental group. Pain intensity, neuropathic pain, and quality-of-life were measured at baseline (T0) and after 3 (T1) and 6 weeks (T2). Change in each outcome over time was assessed through a repeated measures analysis of variance or Wilcoxon matched-pairs test. Preliminary results show a significant reduction in pain intensity (T0 → T1, p = 0.021; T0 → T2, p = 0.011; T1 → T2, p = 0.46), neuropathic symptoms (T0 → T1, p = 0.024; T0 → T2, p = 0.003), and evoked pain (T0 → T2, p = 0.048). There were no significant reductions in other neuropathic pain dimensions and in quality-of-life components. No side-effects were detected. NACVAN® could have a beneficial adjuvant effect when used as an add-on to gabapentinoids in patients suffering from CNP due to SCI or stroke, with no adverse effect. Future analysis on a larger sample, compared with a placebo condition, could confirm these preliminary results.