MS-2638

A 85-year-old male presents with a 2-week history of urinary frequency and urgency. He explains the symptoms are particularly bothersome at night where he wakes up three to four times to urinate. Additionally, he feels as though he cannot fully empty his bladder.

During examination, a digital rectal exam reveals a smooth enlarged prostate.

What is the mechanism of action of the medication prescribed for symptomatic relief?