Mirogabalin was found to be safe, well tolerated, and effective to alleviate postherpetic neuralgia-associated pain, according to a study published in Pain.

Although pharmacologic intervention is generally recommended for neuropathic pain relief, there is no consensus on the most effective option, which often leaves patients resorting to polypharmacy, thus increasing the risk for side effects and adverse events. Investigators sought to evaluate the efficacy of mirogabalin — an α2 δ1 calcium channel subunit ligand — for the treatment of postherpetic neuralgia. This drug may reduce the influx of calcium, which is enhanced in this condition, by binding calcium channels, thereby reducing neuronal excitability.

For this multicenter phase 3 double-blind placebo-controlled study (Clinicaltrials.gov identifier: NCT02318719), a total of 763 Asian participants (mean age, 66.5 years; 60.3% men; 80.0% Japanese; 14.1% Korean) were enrolled between January 2015 and January 2017. Study participants were ≥20 years of age and had been diagnosed with postherpetic neuralgia. Individuals were randomly assigned 2:1:1:1 to receive placebo (n=303), mirogabalin 15 mg/day (n=152), mirogabalin 20 mg/day (n=153), or mirogabalin 30 mg/day (n=155) for a period of 14 weeks.

The study’s primary outcome was the change in average daily pain score (ADPS; assessed using a 0 to 10 numeric rating scale and averaged for the week) from baseline to the 14-week follow-up. At baseline, the mean ADPS for the cohort was 5.71. The majority of participants had postherpetic neuralgia in the thoracic region (45.9%). There were 671 (87.7%) participants who finished the trial.

Patients in all groups indicated lower pain intensity at 14 weeks compared with baseline. Participants treated with mirogabalin vs placebo reported greater and faster reductions in ADPS, with greater reductions in least squares ADPS means with increasing doses of mirogabalin. At the end of the study, the ADPS least squares mean change from baseline was -1.20 for placebo and -1.61, -1.68, and -1.97 for mirogabalin at 15, 20, and 30 mg/day, respectively. The ADPS mean change differences in patients treated with mirogabalin vs placebo were -0.41 for mirogabalin 15 mg/day (95% CI, -0.74 to -0.07; P =.0170), -0.48 for mirogabalin 20 mg/day (95% CI, -0.81 to -0.14; P =.0058), and -0.77 for mirogabalin 30 mg/day (95% CI, -1.10 to -0.44; P <.0001).

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All treatment-emergent adverse events (TEAE) were considered mild to moderate and resolved spontaneously, with the most frequent being dizziness, somnolence, nasopharyngitis, weight increase, and edema. AEs were more common in participants treated with mirogabalin vs placebo. A total of 48 patients (6.3%) experienced ≥1 TEAE that led to study discontinuation, and another 15 participants reported serious TEAEs.

Study limitations include inclusion of Asian participants only and the lack of participants with renal impairment.

“[M]irogabalin has demonstrated a well-balanced profile of efficacy and safety and may provide an alternative therapeutic option for the treatment of [postherpetic neuralgia],” noted the study authors.

Funding and Conflicts of Interest Disclosures

This study was funded by Daiichi Sankyo, Inc.

EM, MS, NM, SO, and YK are employees of Daiichi Sankyo Co., Ltd. JK reports personal fees from Daiichi Sankyo Co., Ltd., during the conduct of the study; and personal fees from Pfizer Japan Inc.; Eisai Co., Ltd.; and Mochida Pharmaceutical Co., Ltd.

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Reference

Kato J, Matsui N, Kakehi Y, Murayama E, Ohwada S, Sugihara M.Mirogabalin for the management of postherpetic neuralgia a randomized, double-blind, placebo-controlled Phase 3 study in Asian patients. Pain. doi:10.1097/j.pain.0000000000001501