Mirabegron
"Recently had a stent put in to widen urethra in order to have an operation on my kidney in a couple of weeks. Hospital prescribed me this advising it will relax the bladder and reduce the pain stent may cause. I followed the instructions and took 1 tablet in ten morning, usually around 8am. Didn't notice anything different until between 9pm-10pm when I was having uncontrollable spasms, keeling over in pain and felt like I was going through labour. The pains would last for a couple of hours or so. After a few days, I stopped taking the drug just to see what would happen. Behold, no labour pains. I cannot explain how painful it was when it occurred. Avoid this drug if you really don't need it, it's not worth it."