Does mirabegron have a potential role as a medical expulsive therapy in the treatment of distal ureteral stones? A prospective randomized controlled study

Background: The existence of beta 3 receptors in the bladder and ureter was documented in many studies on animals and humans, it was documented that relaxation of the lower ureteral segment is achieved by the stimulation of these receptors. Our aim was to assess the efficacy and safety of mirabegron as a medical expulsive therapy (MET) for distal ureteral stones in comparison with silodosin and placebo.Methods: One hundred eighty patients with distal ureteral stone of 5-10 mm size were included in our study. They were divided into three groups, and each one consisted of 60 patients. Group I was given silodosin 8 mg, group II mirabegron 50 mg and group III placebo once daily. The treatment was prescribed for all the cases till stone expulsion or a maximum duration of 4 weeks. Primary outcome was the stone expulsion rate (SER). While secondary outcomes were stone expulsion time, side effects of the used drugs, hospital visits number for pain, and amount of analgesic taken.Results: We found that the SER was significantly higher in silodosin than mirabegron and placebo groups (61%, 38.6%, and 36.7%, respectively) (p = 0.013). Also, the stone expulsion interval was significantly shorter in silodosin than mirabegron and control groups (p < 0.001). While hospital visits number for pain, and amount of analgesic taken were comparable. There was no difference between the studied medications in terms of the adverse effects except for retrograde ejaculation (silodosin = 63.3%, mirabegron = 0%, and placebo = 0%; p < 0.001).Conclusion: Mirabegron has no medical expulsive effect. While silodosin improves SER and stone expulsion time. However, retrograde ejaculation was its main side effect and occurred in 63.3% of the male patients. Therefore, more research is needed to discover a more tolerable MET.