@fdixon63 , I have taken Myrbetriq for more than a year and have found it is quite successful at relieving OAB. I have not experienced any interactions with lamotrigine, the only other prescription drug I take. Myrbetriq is, indeed quite "spendy" running into thousands of dollars per year without the benefit of insurance. The there are several patents for mirabegron that won't expire until the 2030's, so I am looking into the several substitutes like oxybutynin that are available.

@colleenyoung, I appreciate your assistance in helping my getting answers to the question on Myrbetriq. Three days after my post to you I was admitted to the hospital for COVID--eight days. Delving into the question and answers became a very low priority. I never started the medication. I wanted to get myself back to pre-COVID condition so I could tell how I was responding. I did contact my cardiologist. They said they were ok for me to take Mybetriq but it might increase propafenone levels and I would need to get an EKG done after I start on it. When I said this to the Urology nurse she said the doc said OK to try Gemtesa 75 mg. He said there would be no interaction with my other meds. Thanks to all who stepped up with information. Best of health wishes coming your way.