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

OBJECTIVE: Postherpetic neuralgia (PHN) is a condition that results from nerve dysfunction following an episode of acute herpes zoster (shingles). Mirogabalin is a novel, selective oral α(2)δ ligand that demonstrated safety and efficacy in a multicenter, randomized, double-blind, placebo-controlled 14-week study in Asian patients with PHN. This 52-week, open-label extension study investigated the long-term safety and efficacy of flexible-dosage mirogabalin in Asian patients with PHN. METHODS: This open-label extension study enrolled patients who completed the placebo-controlled study. Patients started with a dose of 5 mg mirogabalin twice daily (BID), which was followed by a flexible dose of 10 or 15 mg BID. During the study, patients assessed their pain using the Short-Form McGill Pain Questionnaire (SF-MPQ). Adverse events were monitored throughout the study. RESULTS: Of 239 enrolled patients, 184 (77.0%) completed the study and 185 patients (77.4%) received the 15 mg BID dose most during the treatment duration. Most treatment-emergent adverse events (TEAEs) were mild or moderate. The most common TEAEs were nasopharyngitis, somnolence, dizziness, weight increased, and edema. All SF-MPQ scales decreased from baseline to week 52. CONCLUSIONS: This study showed the safety and stable pain management of a long-term flexible dosing regimen of mirogabalin 10 or 15 mg twice daily for 52 weeks in patients with PHN. CLINICAL TRIAL REGISTERED AT CLINICALTRIALS.GOV: NCT02318719. SUMMARY FOR TABLE OF CONTENTS: Mirogabalin—a novel α(2)δ oral ligand—was shown to be effective and well tolerated for treating postherpetic neuralgia (PHN) in an Asian multicenter, randomized, double-blind, placebo-controlled, 14-week study. This open-label, 52-week study was conducted as an extension of the double-blind study to demonstrate long-term safety and efficacy of mirogabalin.