Incidence of somnolence and dizziness induced by mirogabalin and pregabalin under opioid treatment: a single-center observational study

Background: The gabapentinoids pregabalin and mirogabalin are utilized to treat neuropathic pain, especially in patients with cancer receiving opioid analgesics. Pregabalin combined with strong opioids increases somnolence and dizziness, while mirogabalin causes fewer central adverse events. This study aimed to determine whether mirogabalin leads to a lower incidence of somnolence and dizziness than pregabalin in patients with cancer receiving strong opioids. Methods: We analyzed inpatients with cancer treated with mirogabalin or pregabalin along with strong opioids at Fujita Health University Hospital (April 2019–December 2023) and assessed cumulative incidence rates, hazard ratios (HRs) for somnolence and dizziness occurrence, and changes in morphine milligram equivalents (MMEs). Results: Among the 89 patients included in the analysis (mirogabalin: 39, pregabalin: 50), the median time to somnolence and dizziness was significantly shorter in the mirogabalin group than in the pregabalin group (8.0 vs. 17.0 days, p = 0.039). The multivariable Cox proportional regression model showed a higher risk with mirogabalin, although with no significance (HR: 1.74, p = 0.117). MMEs increased in the pregabalin group but not in the mirogabalin group. Conclusions: Mirogabalin and pregabalin contribute to somnolence and dizziness in patients receiving strong opioids, necessitating careful monitoring.