In the absence of abnormal clinical findings, a trial of phosphodiesterase inhibitors is appropriate. Tadalafil and Sildenafil are currently on the Highland Formulary:

Tadalafil 10mg initially with titration up to 20mg according to the patient’s response. Take at least 30 minutes before intercourse and can be effective for up to 30 hours. Not affected by food.

Sildenafil 50mg initially with titration up to 100mg or down to 25mg according to the patient’s response. Take 1 hour before intercourse and can be effective for up to 6 hours. Onset of effect may be delayed by food.

Note: Sildenafil and Tadalafil are contra-indicated in patients receiving nitrates and Nicorandil and should be used with caution in patients on alpha-blockers e.g. Doxazosin, Tamsulosin.  If prescribing after myocardial infarction/acute coronary syndrome, advise re-introduction at 1 month after cardiac event if patient is pain free and does not require nitrates or Nicorandil.

Both Tadalafil and Sildenafil should be tried at their maximum doses on several occasions before referring the patient to Urology for consideration of other therapies e.g. transurethral or intra-cavernosal Alprostadil or vacuum devices.

Due to low cost of generic preparations, it is generally now longer the case that daily Tadalafil is more cost effective if the patient anticipates frequent use. The advantage for daily dosing is really for spontaneity.