Effect of mirabegron on overactive bladder symptoms in patients with myasthenia gravis disease

Aim: Overactive bladder (OAB) is a chronic, bothersome disease that decreases the quality of life and can be treated with antimuscarinic or β(3)-adrenergic agonist drugs, such as mirabegron. Myasthenia gravis (MG) is an autoimmune disease, in which neurotransmission is blocked by antibodies. Mirabegron is recommended as the first-line medical treatment for OAB compared with antimuscarinic drugs, which have several severe side effects. In this study, we assessed the efficacy of mirabegron in patients with MG and OAB. Methods: A total of 57 MG patients with OAB were included in this study. The participants received 50 mg mirabegron once daily and were followed up for 4 weeks. Subsequently, patients were evaluated using the International Consultation on Incontinence-Short Form and the "Overactive Bladder Symptom Score" (OABSS) and tasked to complete a 3-day micturition diary. Results: According to the 4-week follow-up results, the decrease in the OABSS scores following mirabegron administration was statistically significant (p<0.001). In addition, the frequency of daily micturition, nocturia, and need for a daily pad decreased dramatically (p=0.001, p=0.002, and p<0.001, respectively). In contrast, the average voiding volume increased significantly (p=0.001). Conclusions: Although they induce several side effects, antimuscarinic drugs are commonly used for OAB treatment. However, only a few autoimmune response-inducing drugs, with minimal side effects, are favored in MG comorbidity treatments. Thus, mirabegron is a promising candidate drug for the treatment of this type of comorbidity