Yeah, for benign prostatic hyperplasia. Unfortunately, the examination for this involves the doctor, not to put too fine a point on it, fisting you to get a feel of your prostate. Really awfully, I hear that the nerves in your prostate hardwire to your unit so you're also likely to pop a boner.
Not recommended. If I were you I'd either persuade him to prescribe it off-script, or get it from the internet. If you're willing to go generic you could pay less than 10 pence a day.