Long-term safety and efficacy of mirogabalin in Asian patients with postherpetic neuralgia: Results from an open-label extension of a multicenter randomized, double-blind, placebo-controlled trial

Efficacy of Paravertebral Injection of Interferon-α2b Combined with High-Voltage, Long-Term Pulsed Radiofrequency in DRG in Mitigation of Postherpetic Neuralgia: A Retrospective Study

OBJECTIVE

This investigation aims to evaluate the effectiveness of the paravertebral injection of recombinant human interferon-α2b in conjunction with high-voltage, long-term, pulsed radiofrequency (PRF) in the dorsal root ganglion for the mitigation of postherpetic neuralgia (PHN).

METHODS

This retrospective study included 84 individuals with acute PHN. The participants were divided into 3 groups. Group H was treated with interferon-α2b combined with high-voltage long-term PRF. Group C was treated with a combination of high-voltage, long-term PRF and a paravertebral injection (without recombinant human interferon-α2b), and group I was treated with interferon-α2b only. All the patients in the 3 groups were orally administered a 5-mg morphine hydrochloride quick-release tablet when a burst of pain occurred during treatment. The numerical rating scale for pain score, the interleukin-6 and galectin-3 levels, and the incidence of PHN were documented before and after therapy.

RESULTS

The pain intensity of all individuals decreased after therapy. Compared with group C, the numerical rating scale scores for group H were significantly reduced at 4, 8, and 12 weeks following therapy, and the PHN incidence was significantly lower. Compared with prior treatment, the recommended dosage of gabapentin capsules and immediate-release morphine hydrochloride tablets was reduced for group H. Compared with group C, the requirement for orally administrated gabapentin capsules and morphine hydrochloride tablets in group H was reduced significantly after treatment. No serious adverse reactions occurred in any of the 3 groups.

CONCLUSIONS

Within the context of treatment of acute PHN, the injection of interferon-α2b in conjunction with high-voltage, long-term application of PRF is more effective than PRF or the injection of interferon-α2b alone.

Efficacy and safety of add-on mirogabalin to conventional therapy for the treatment of peripheral neuropathic pain after thoracic surgery: the multicenter, randomized, open-label ADMIT-NeP study

BACKGROUND

For chronic pain after thoracic surgery, optimal timing of its diagnosis and effective treatment remains unresolved, although several treatment options are currently available. We examined the efficacy and safety of mirogabalin, in combination with conventional pain therapy (nonsteroidal anti-inflammatory drugs and/or acetaminophen), for treating peripheral neuropathic pain (NeP) after thoracic surgery.

METHODS

In this multicenter, randomized, open-label, parallel-group study, patients with peripheral NeP were randomly assigned 1:1 to mirogabalin as add-on to conventional therapy or conventional treatment alone.

RESULTS

Of 131 patients of consent obtained, 128 were randomized (mirogabalin add-on group, 63 patients; conventional treatment group, 65 patients). The least squares mean changes (95% confidence interval [CI]) in Visual Analogue Scale (VAS) score for pain intensity at rest from baseline to Week 8 (primary endpoint) were - 51.3 (- 54.9, - 47.7) mm in the mirogabalin add-on group and - 47.7 (- 51.2, - 44.2) mm in the conventional group (between-group difference: - 3.6 [95% CI: - 8.7, 1.5], P = 0.161). However, in patients with Self-administered Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) score (used for the screening of NeP) ≥ 12 at baseline, the greater the S-LANSS score at baseline, the greater the decrease in VAS score in the mirogabalin add-on group, while no such trend was observed in the conventional treatment group (post hoc analysis). This between-group difference in trends was statistically significant (interaction P value = 0.014). Chronic pain was recorded in 7.9% vs. 16.9% of patients (P = 0.171) at Week 12 in the mirogabalin add-on vs. conventional treatment groups, respectively. Regarding activities of daily living (ADL) and quality of life (QOL), changes in Pain Disability Assessment Scale score and the EQ-5D-5L index value from baseline to Week 8 showed significant improvement in the mirogabalin add-on group vs. conventional treatment group (P < 0.001). The most common adverse events (AEs) in the mirogabalin add-on group were dizziness (12.7%), somnolence (7.9%), and urticaria (3.2%). Most AEs were mild or moderate in severity.

CONCLUSIONS

Addition of mirogabalin to conventional therapy did not result in significant improvement in pain intensity based on VAS scores, but did result in significant improvement in ADL and QOL in patients with peripheral NeP after thoracic surgery.

TRIAL REGISTRATION

Japan Registry of Clinical Trials jRCTs071200053 (registered 17/11/2020).

Content and sentiment analysis of gabapentinoid-related tweets: An infodemiology study

INTRODUCTION

The increasing number of gabapentinoid (pregabalin and gabapentin) harms, including deaths observed across countries is concerning to health-care professionals and policy makers. However, it is unclear if the public shares these concerns. This study aimed to describe posts related to gabapentinoids, conduct a content analysis to identify common themes and describe adverse events or symptoms.

METHODS

Keywords of 'pregabalin' or 'Lyrica' or 'gabapentin' or 'Neurontin' were used to search for related tweets posted by people in the community between 8 March and 7 May 2021. Eligible tweets included a keyword in the post. We extracted de-identified data which included descriptive data of the total number of posts over time; and data on individual tweets including date, number of re-tweets and post content. Data were exported separately for pregabalin- and gabapentin-related tweets. A 20% random sample was used for the thematic analysis.

RESULTS

There were 2931 pregabalin-related tweets and 2736 gabapentin-related tweets. Thematic analysis revealed three themes (sharing positive experiences and benefits of taking gabapentinoids, people voicing their negative experiences, and people seeking opinions and sharing information). Positive experiences of gabapentinoids were related to sharing stories and giving advice. This was contrasted to negative experiences including ineffectiveness, withdrawals, side effects and frustration related to cost and insurance coverage. Brain fog was the most common adverse symptom reported. Gabapentinoid-related deaths were only mentioned in three tweets.

DISCUSSION

The increasing public health concern of gabapentinoid-related deaths was not translated to Twitter discussions.

Efficacy and safety of mirogabalin for chemotherapy-induced peripheral neuropathy: a prospective single-arm trial (MiroCIP study)

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is a painful, dose-limiting adverse effect of commonly used chemotherapeutic agents. The purpose of this exploratory study was to evaluate the efficacy and safety of mirogabalin in patients with moderate to severe CIPN during chemotherapy and the effects of 12 weeks' intervention on chemotherapy completion and CIPN severity.

METHODS

Patients experiencing moderate to severe CIPN while undergoing oxaliplatin- or taxane-containing chemotherapy for colorectal, gastric, non-small-cell lung, or breast cancer received mirogabalin at between 5 and 15 mg twice daily. The primary endpoint was change in numeric rating scale (NRS) score for pain from baseline to week 12. Secondary endpoints included NRS scores for tingling and sleep, completion of chemotherapy, severity of CIPN, and quality of life (QOL) scores. The safety endpoint was incidence of adverse events.

RESULTS

Of 58 patients who consented to participation, 52 were eligible and constituted the full analysis set and safety analysis set. From baseline to week 12 (last observation carried forward [LOCF]), NRS score decreased by 30.9%: mean change (95% confidence interval [CI]), - 1.7 (- 2.4 to - 1.0) (p < 0.001). Patients with baseline NRS of ≥ 6 experienced a 44.0% reduction in score from baseline to week 12 (LOCF): mean change (95% CI), - 3.3 (- 5.0 to - 1.5) (p = 0.002). Chemotherapy was discontinued in 18 (34.6%) patients; CIPN led to discontinuation in only 2 (3.8%). There was no notable worsening of CIPN severity in terms of Common Terminology Criteria for Adverse Events grade or Modified Total Neuropathy Score-reduced, although use of pain medications during chemotherapy might cause worsening of CIPN due to underestimation of subjective symptoms. QOL score based on the EuroQol five-dimensional descriptive system did not worsen during the 12 weeks. Thirty-one percent of patients experienced adverse drug reactions, and the most common event was somnolence (13.5%). Serious adverse events and death occurred in 3 patients and 1 patient, respectively; however, they were unrelated to mirogabalin treatment.

CONCLUSIONS

Intervention with mirogabalin during chemotherapy may be effective and safe for cancer patients with moderate to severe CIPN. It can contribute to completion of chemotherapy without worsening of CIPN.

TRIAL REGISTRATION

Japan Registry of Clinical Trials (jRCTs031210101, registered 20/5/2021).

Pharmacokinetics and Bioequivalence of Mirogabalin Orally Disintegrating Tablets and Conventional Tablets in Healthy Japanese Participants

This single-center, randomized, open-label, single-dose, 2-group, 2-stage crossover trial evaluated the bioequivalence of 15 mg of mirogabalin as orally disintegrating tablets (ODTs) with conventional mirogabalin tablets in healthy Japanese men. The trial involved two studies: in Study 1, the ODT formulation was taken without water, and in Study 2, the ODT formulation was taken with water. The conventional tablet was taken with water in both studies. We investigated the pharmacokinetic parameters and bioequivalence of the 2 formulations, including the maximum plasma concentration and the area under the plasma concentration-time curve up to the last quantifiable time. The plasma concentrations of mirogabalin were determined by a validated liquid chromatography with tandem mass spectrometry method. A total of 72 participants were enrolled and completed the trial. The geometric least-squares mean ratios of maximum plasma concentration of the ODT formulation to the conventional formulation were within the prespecified bioequivalence range of 0.80-1.25 (Study 1, 0.995; Study 2, 1.009), as was the area under the plasma concentration-time curve up to the last quantifiable time (Study 1, 1.023; Study 2, 1.035). No serious adverse events were observed. In conclusion, mirogabalin 15-mg ODTs, either with or without water, were bioequivalent to conventional 15-mg tablets.

Investigational Drugs for the Treatment of Postherpetic Neuralgia: Systematic Review of Randomized Controlled Trials

The pharmacological treatment of postherpetic neuralgia (PHN) is unsatisfactory, and there is a clinical need for new approaches. Several drugs under advanced clinical development are addressed in this review. A systematic literature search was conducted in three electronic databases (Medline, Web of Science, Scopus) and in the ClinicalTrials.gov register from 1 January 2016 to 1 June 2023 to identify Phase II, III and IV clinical trials evaluating drugs for the treatment of PHN. A total of 18 clinical trials were selected evaluating 15 molecules with pharmacological actions on nine different molecular targets: Angiotensin Type 2 Receptor (AT2R) antagonism (olodanrigan), Voltage-Gated Calcium Channel (VGCC) α2δ subunit inhibition (crisugabalin, mirogabalin and pregabalin), Voltage-Gated Sodium Channel (VGSC) blockade (funapide and lidocaine), Cyclooxygenase-1 (COX-1) inhibition (TRK-700), Adaptor-Associated Kinase 1 (AAK1) inhibition (LX9211), Lanthionine Synthetase C-Like Protein (LANCL) activation (LAT8881), N-Methyl-D-Aspartate (NMDA) receptor antagonism (esketamine), mu opioid receptor agonism (tramadol, oxycodone and hydromorphone) and Nerve Growth Factor (NGF) inhibition (fulranumab). In brief, there are several drugs in advanced clinical development for treating PHN with some of them reporting promising results. AT2R antagonism, AAK1 inhibition, LANCL activation and NGF inhibition are considered first-in-class analgesics. Hopefully, these trials will result in a better clinical management of PHN.

Long-Term Safety and Efficacy of Mirogabalin for Central Neuropathic Pain: A Multinational, Phase 3, 52-Week, Open-Label Study in Asia

INTRODUCTION

Central neuropathic pain (CNeP) is difficult to treat and has diverse etiology, including spinal cord injury (CNePSCI), Parkinson's disease (CNePPD), and central post-stroke pain (CPSP). The safety and efficacy of mirogabalin have been demonstrated in short-term trials, including patients with CNePSCI. The objective of our study was to confirm the safety/efficacy of mirogabalin in patients with CNePPD and CPSP, and obtain long-term data for CNePSCI.

METHODS

This 52-week, open-label extension of a previous randomized controlled study was conducted across Japan, Korea, and Taiwan. Patients with CNePSCI, CNePPD, or CPSP received twice daily (BID) 5-10 mg mirogabalin for a 4-week titration period, after which the dosage was maintained for 47 weeks at a maximum of 15 mg BID, followed by a 1-week taper period receiving the same dose but only administered once daily. The primary endpoint was safety, assessed primarily by incidence and severity of treatment-emergent adverse events (TEAEs). Efficacy was assessed in a post hoc analysis of data obtained by the short-form McGill Pain Questionnaire (SF-MPQ).

RESULTS

Of the 210 patients enrolled, 106, 94, and 10 had CNePSCI, CPSP, and CNePPD, respectively. The mean overall age of patients was 62.9 years, and most patients were male and of Japanese ethnicity. TEAEs occurred in 84.8% of patients, the most common being somnolence (16.7%), peripheral edema (12.4%), edema (11.4%), nasopharyngitis (11.0%), and dizziness (7.6%). Most TEAEs were mild. Severe and serious TEAEs occurred in 6.2% and 13.3% of patients, respectively. All patient groups experienced reductions in SF-MPQ visual analog scores for pain: mean ± standard deviation changes from baseline at week 52 were -2.3 ± 21.13 mm (CNePSCI), -17.0 ± 24.99 mm (CPSP), and -17.1 ± 35.32 mm (CNePPD).

CONCLUSION

Mirogabalin was generally safe, well tolerated, and effective for treatment of CNeP in this long-term study.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT03901352.

Relationship between the dose titration and adherence of mirogabalin in patients with peripheral neuropathic pain depending on renal function: a nationwide electronic medical record database study

BACKGROUND

Mirogabalin has been attracting attention for treating peripheral neuropathic pain. The package insert recommends that mirogabalin should be titrated depending on renal function. Here, we investigated the relationship between dose titration patterns and adherence, and persistence of mirogabalin treatment.

RESEARCH DESIGN AND METHODS

Peripheral neuropathic pain patients who initiated mirogabalin between March 2020 and May 2021 were identified using an electronic medical record database. The dose titration pattern was described according to degrees of renal function. Regression analyses were performed to compare adherence and persistence between the patients with and without titration.

RESULTS

Of the 4,138 identified patients, 1,696 (41.0%) titrated the dose within 45 days and were more adherent than those without titration (Adjusted odds ratio: 1.75, 95% CI 1.21, 2.54). Of the total 952 patients with renal function parameters, 229 (24.1%) titrated to the effective dose within 45 days and were less likely to discontinue than those without titration (Adjusted hazard ratio: 0.57, 95% CI 0.40, 0.81).

CONCLUSION

Mirogabalin dose titration was associated with better adherence and persistence. It is important for mirogabalin treatment to determine the initial prescription dose based on renal function and subsequent dose titration according to the package insert.

TRIAL REGISTRATION

UMIN000047313.

The Novel Gabapentinoid Mirogabalin Prevents Upregulation of α2δ-1 Subunit of Voltage-Gated Calcium Channels in Spinal Dorsal Horn in a Rat Model of Spinal Nerve Ligation

Gabapentinoids are specific ligands for the α₂δ-1 subunit of voltage-gated calcium channels. This class of drugs, including gabapentin and pregabalin, exert various pharmacological effects and are widely used for the treatment of epilepsy, anxiety, and chronic pain. The mechanism of action of gabapentinoids involves both direct modulation of calcium channel kinetics and inhibition of channel trafficking and expression, which contribute to the above pharmacological effects. In the present study, we investigated the effects of mirogabalin, a novel potent gabapentinoid, on expression levels of the α₂δ-1 subunit in the spinal dorsal horn in a rat model of spinal nerve ligation (SNL) as an experimental animal model for peripheral neuropathic pain. The neuropathic pain state was induced by SNL in male Sprague - Dawley rats. After the development of mechanical hypersensitivity, the animals received 10 mg/kg mirogabalin or vehicle orally for 5 consecutive days and were subjected to immunohistochemical analysis of α₂δ-1 subunit expression in the spinal cord. In the SNL model rats, expression of the α₂δ-1 subunit significantly increased in the spinal dorsal horn at the ipsilateral side of nerve injury, while mirogabalin inhibited this increase. In conclusion, the α₂δ-1 subunit was upregulated in the spinal dorsal horn of SNL model rats, and repeated administration of mirogabalin inhibited this upregulation. The inhibitory effect of mirogabalin on upregulation of the α₂δ-1 subunit after nerve injury is considered to contribute to its analgesic effects in peripheral neuropathic pain.

The Clinical Application and Progress of Mirogabalin on Neuropathic Pain as a Novel Selective Gabapentinoids

Background

Neuropathic pain is a complex sort of pain that is detrimental to individuals' health, both physically and mentally, but merely a small portion of them could witness pain alleviation. Mirogabalin, by distinctive binding characteristics of voltage-gated calcium channels, has won approval from the Japanese authority as a third member of gabapentinoids in Japan. Our review was aimed at encompassing the bulk of clinical research on mirogabalin, which included clinical trials, special considerations, coadministration studies, case reports, and cost-effectiveness studies.

Methods

A review was carried out on a series of platforms, such as PubMed, MEDLINE, and Scopus, up to December 2021 using the keywords as follows: "mirogabalin OR mirogabalin besylate OR Tarlige OR DS-5565" AND "neuropathic pain OR Neuropathy."

Results

Mirogabalin demonstrated analgesic activity and manageable adverse reactions and provides a new alternative for individuals with PHN or DPNP in 3 phase II and 4 III trials. Mirogabalin alleviated pain markedly in comparison with placebo. Administration of mirogabalin on a long-term basis is a flexible dosage regimen for patients with PHN. It is noteworthy that mirogabalin should be administrated cautiously when combined with probenecid and cimetidine on account of a slight increase in pharmacodynamics effects of mirogabalin.

Conclusion

The development of mirogabalin allows further optimization of individual treatment strategies so as to provide more therapeutic choices in this medical domain.

Managing Chronic Neuropathic Pain: Recent Advances and New Challenges

Aim. Neuropathic pain affects 7–10% of the population, with most of the patients receiving inadequate and incomplete treatment. Owing to the high financial burden and the poor quality of life of the patients and their caretakers, there is a dire need to address the challenges in diagnosing and treating chronic neuropathic pain. Methods. This literature review was conducted to review novel treatments and related challenges through a systematic search from sources such as PubMed, Google Scholar with the combination of MESH words such as neuropathic pain, management of neuropathic pain. Articles from non-English literature, reports without human subjects, animal studies, and abstracts/posters were excluded. However, human studies and studies published in English were included. Result. This review article discusses novel treatment modalities while acknowledging the challenges medical workers face while encountering neuropathic pain. Despite the recent advances in diagnosis and treatment modalities, several challenges still exist. Hence, there is still a need to explore the various treatment modalities, emphasizing the cause and underlying pathophysiology of neuropathic pain. Conclusion. We recommend integrated multimodal treatment with the current treatment facility, including various medical disciplines. However, a personalized approach would work the best depending on the ’patient’s medical history. Therefore, this article recommends an integrated, cause-specific, cost-effective approach to address this problem of chronic neuropathic pain.

Symptom-based pharmacotherapy for neuropathic pain related to spinal disorders: results from a patient-based assessment

Existing guidelines advocate an updated therapeutic algorithm for chronic neuropathic pain (NeP), but pharmacotherapeutic management should be individualized to pain phenotypes to achieve higher efficacy. This study was aimed to evaluate the efficacy of medications, based on NeP phenotypes, and to propose symptom-based pharmacotherapy. This retrospective study was enrolled 265 outpatients with chronic NeP related to spinal disorders. The patients were classified into three groups: spinal cord-related pain, radicular pain, and cauda equina syndrome. Data were obtained from patient-based questionnaires using Neuropathic Pain Symptom Inventory (NPSI) and the Brief Scale for Psychiatric Problems in Orthopaedic Patients, and from clinical information. The proportions of patients with ≥ 30% and ≥ 50% reduction in NPSI score for each pain subtype (spontaneous pain, paroxysmal pain, evoked pain, and paresthesia/dysesthesia) and drugs were evaluated. The pain reduction rate was significantly lower in patients with spinal cord-related pain, especially for paresthesia/dysesthesia. For spinal cord-related pain, duloxetine and neurotropin had insufficient analgesic effects, whereas mirogabalin was the most effective. Pregabalin or mirogabalin for radicular pain and duloxetine for cauda equina syndrome are recommended in cases of insufficient analgesic effects with neurotropin. The findings could contribute to better strategies for symptom-based pharmacotherapeutic management.

The Evidence for Effective Inhibition of INa Produced by Mirogabalin ((1R,5S,6S)-6-(aminomethyl)-3-ethyl-bicyclo [3.2.0] hept-3-ene-6-acetic acid), a Known Blocker of CaV Channels

Mirogabalin (MGB, Tarlige^®), an inhibitor of the α₂δ-1 subunit of voltage-gated Ca²⁺ (Ca_V) channels, is used as a way to alleviate peripheral neuropathic pain and diabetic neuropathy. However, to what extent MGB modifies the magnitude, gating, and/or hysteresis of various types of plasmalemmal ionic currents remains largely unexplored. In pituitary tumor (GH₃) cells, we found that MGB was effective at suppressing the peak (transient, I_Na(T)) and sustained (late, I_Na(L)) components of the voltage-gated Na⁺ current (I_Na) in a concentration-dependent manner, with an effective IC₅₀ of 19.5 and 7.3 μM, respectively, while the K_D value calculated on the basis of minimum reaction scheme was 8.2 μM. The recovery of I_Na(T) inactivation slowed in the presence of MGB, although the overall current-voltage relation of I_Na(T) was unaltered; however, there was a leftward shift in the inactivation curve of the current. The magnitude of the window (I_Na(W)) or resurgent I_Na (I_Na(R)) evoked by the respective ascending or descending ramp pulse (V_ramp) was reduced during cell exposure to MGB. MGB-induced attenuation in I_Na(W) or I_Na(R) was reversed by the further addition of tefluthrin, a pyrethroid insecticide known to stimulate I_Na. MGB also effectively lessened the strength of voltage-dependent hysteresis of persistent I_Na in response to the isosceles triangular V_ramp. The cumulative inhibition of I_Na(T), evoked by pulse train stimulation, was enhanced in its presence. Taken together, in addition to the inhibition of Ca_V channels, the Na_V channel attenuation produced by MGB might have an impact in its analgesic effects occurring in vivo.

Mirogabalin as a Novel Gabapentinoid for the Treatment of Chronic Pain Conditions: An Analysis of Current Evidence

: Neuropathic pain is a challenge for physicians to treat and often requires a multimodal approach with both pharmacologic and lifestyle interventions. Mirogabalin, a potent, selective ligand of the α2δ-1 and α2δ-2 subunits of voltage-gated calcium channels (VGCCs), provides analgesia by inhibiting neurotransmitter release at the presynaptic end of the neuron. Mirogabalin offers more sustained analgesia than its gabapentinoid counterparts in addition to a wider safety margin for adverse events. Recent clinical trials of mirogabalin have demonstrated both efficacy and tolerability of the drug for the treatment of diabetic peripheral neuropathic pain and postherpetic neuralgia, leading to its approval in Japan. While still not yet FDA approved, mirogabalin is still in its infancy and offers potential into the treatment of neuropathic pain and its associated comorbidities.

A large-scale database study for the prescription status of a new voltage-gated Ca2+ channel α2δ ligand, mirogabalin, in Japan

BACKGROUND

A new voltage-gated Ca²⁺ channel α₂δ ligand, mirogabalin, was first approved for treating peripheral neuropathic pain in Japan in 2019. This is the first report on the prescription status of mirogabalin using a large-scale prescription database.

RESEARCH DESIGN AND METHODS

The authors analyzed the prescription data of 12,924 patients prescribed mirogabalin between 1 June and 31 August 2020. The endpoints were the number of patients prescribed, prescription days, prescription doses, dose changes, co-prescription patterns, medication possession ratio (MPR), and treatment discontinuation rates (TDRs).

RESULTS

Mirogabalin was newly prescribed to 7,914 patients in the 3-month study period. Most patients were prescribed mirogabalin at about 10 mg/day during the study period, and 30.9% of patients were prescribed ≥ 20 mg/day on Day 90 after the first prescription. The most frequently prescribed concomitant drug was celecoxib. The MPR (80 to 110%) was 86.2%, indicating good treatment adherence. The cumulative TDRs during ≤ 7 Days, Days 31-60, and 61-90 were 14.0%, 70.0%, and 77.9%, respectively.

CONCLUSIONS

Mirogabalin was prescribed to a considerable number of patients. These results may be useful for optimizing mirogabalin use for patients with peripheral neuropathic pain in daily clinical practice.

CLINICAL TRIAL REGISTRATION NUMBER

UMIN000042592.

Mirogabalin treatment of postoperative neuropathic pain after thoracic surgery: study protocol for a multicenter, randomized, open-label, parallel-group, interventional trial

Background

Intercostal nerve damage due to thoracotomy or thoracoscopic manipulation is a major contributor to chronic postsurgical pain after pulmonary resection. Chronic postsurgical pain may last for months or years and can negatively impair physical functioning and daily activities. Global consensus on severe postoperative pain management is lacking, and chronic pain incidence after thoracic surgery remains high. Many patients report neuropathic pain, which can be difficult to treat with currently available therapies. The efficacy and safety of mirogabalin have been demonstrated for other types of neuropathic pain; thus, this study was planned to investigate the efficacy and safety of mirogabalin to treat neuropathic pain after thoracic surgery.

Methods

In this multicenter, randomized, open-label, parallel-group, interventional study, patients who are diagnosed with neuropathic pain following removal of a chest drain after lung resection will receive conventional therapy (non-steroidal anti-inflammatory drugs and/or acetaminophen) with or without the addition of a clinical dose of mirogabalin for 8 weeks. For patient stratification, a visual analog scale pain intensity score at baseline of <60 vs. ≥60 mm will be used. Treatment efficacy and safety with and without the addition of mirogabalin will be assessed using a questionnaire evaluating postoperative changes in pain severity and activity. The primary study endpoint is the change in pain intensity from baseline to Week 8, measured by the visual analog scale. Additionally, the presence of chronic pain at 12 weeks after enrollment in each treatment group will be recorded.

Discussion

This protocol has been reviewed and approved by the Clinical Research Review Board of Nagasaki University. Study data will be published in the Japan Registry of Clinical Trials database and peer-reviewed journals. Mirogabalin is already approved for the treatment of other types of neuropathic pain. It is anticipated that this study will provide data to elucidate the impact of mirogabalin treatment, in combination with conventional therapy, to benefit patients with neuropathic pain following thoracic surgery.

Trial Registration

Japan Registry of Clinical Trials Identifier: jRCTs071200053.

A review of a new voltage-gated Ca2+ channel α2δ ligand, mirogabalin, for the treatment of peripheral neuropathic pain

INTRODUCTION

Neuropathic pain (NeP) is a chronic and refractory condition in many patients, and its treatment is a challenge for physicians. A new voltage-gated Ca²⁺ channel α₂δ ligand, mirogabalin, has a high specific binding affinity for the α₂δ subunit, with a slower dissociation rate for α₂δ-1 than α₂δ-2 compared to that of pregabalin. Mirogabalin was shown to be effective in NeP animal models, with a margin of safety between central nervous system side effects and the analgesic effect of the dose. It exerted a favorable analgesic effect, was well tolerated in patients with peripheral NeP (P-NeP), and was first approved in Japan in 2019 and subsequently in Korea and Taiwan in 2020.

AREAS COVERED

The purpose of this article is to review the pharmacological characteristics, pharmacokinetics, and efficacy and safety of mirogabalin for NeP based on the results of non-clinical and clinical studies.

EXPERT OPINION

Although there are several first-line therapies for NeP, insufficient efficacy and adverse drug reactions of NeP drugs often cause patient dissatisfaction. Mirogabalin was effective and well tolerated with a step-wise dose increase in clinical studies on P-NeP patients. Thus, mirogabalin is expected to be a useful treatment option for patients with P-NeP.

Mirogabalin, a novel ligand for α2δ subunit of voltage-gated calcium channels, improves cognitive impairments in repeated intramuscular acidic saline injection model rats, an experimental model of fibromyalgia

Mirogabalin is a novel potent and selective ligand for the α₂δ subunit of voltage-gated calcium channels, and shows potent and sustained analgesic effects in neuropathic pain and fibromyalgia models. Fibromyalgia is often associated with multiple comorbid symptoms, such as anxiety, depression and cognitive impairment. In the present study, we investigated the effects of mirogabalin on cognitive impairments in an experimental animal model for fibromyalgia, repeated intramuscular acidic saline injection model (Sluka model) rats. Male rats received two repeated intramuscular injections of pH 4 acidic saline into their gastrocnemius muscle. After developing mechanical hypersensitivity as identified in the von Frey test, the animals received the test substance orally once daily for 13 days and were subjected to four cognitive function tests, (Y-maze, novel object recognition, Morris water maze and step-through passive avoidance). Sluka model rats showed cognitive impairments in all four tests. Oral administration of mirogabalin (3 and 10 mg/kg) improved the cognitive impairments in these rats. In conclusion, mirogabalin improved the impaired cognitive function in Sluka model rats. It may thus also alleviate cognitive impairments as well as painful symptoms in fibromyalgia patients.

Mirogabalin: could it be the next generation gabapentin or pregabalin?

Except for carbamazepine for trigeminal neuralgia, gabapentinoid anticonvulsants have been the standard for the treatment of neuropathic pain. Pregabalin, which followed gabapentin, was developed with the benefit of rapid peak blood concentration and better bioavailability. Mirogabalin besylate (DS-5565, Tarlige^®) shows greater sustained analgesia due to a high affinity to, and slow dissociation from, the α₂δ-1 subunits in the dorsal root ganglion (DRG). Additionally, it produces a lower level of central nervous system-specific adverse drug reactions (ADRs), due to a low affinity to, and rapid dissociation from, the α₂δ-2 subunits in the cerebellum. Maximum plasma concentration is achieved in less than 1 hour, compared to 1 hour for pregabalin and 3 hours for gabapentin. The plasma protein binding is relatively low, at less than 25%. As with all gabapentinoids, it is also largely excreted via the kidneys in an unchanged form, and so the administration dose should also be adjusted according to renal function. The equianalgesic daily dose for 30 mg of mirogabalin is 600 mg of pregabalin and over 1,200 mg of gabapentin. The initial adult dose starts at 5 mg, given orally twice a day, and is gradually increased by 5 mg at an interval of at least a week, to 15 mg. In conclusion, mirogabalin is anticipated to be a novel, safe gabapentinoid anticonvulsant with a greater therapeutic effect for neuropathic pain in the DRG and lower ADRs in the cerebellum.