Roy is a 64 year old gardener who returns to the surgery with ongoing urinary symptoms especially nocturia. He was seen three months ago and after a thorough history and examination, along with a normal PSA level, he was commenced on Tamsulosin for a likely diagnosis of Benign Prostatic Hyperplasia (BPH). After some benefit he returns as his symptoms have not improved, but there are no red flag symptoms currently. After discussion, he agrees to commence Finasteride.
Which of the following statements is most correct with regards to Finasteride?