Erectile Dysfunction Treatment Options

When contemplating the use of these drugs it is important to know that certain conditions prevent their use. You should consult your doctor before commencing these medications.

Contraindications to prescribing PDE5 inhibitors:

1. Patients who are taking nitrate (GTN) spray or tablets for heart disease due to synergistic effect of dropping blood pressure.

2. Sildenafil (Viagra) contraindicated in patients on alpha- blocker (doxazosin). Caution with other two PDE5 inhibitors.

3. Patients with a heart attack within the past 90 days.

4. Patients with unstable angina/chest pain during sexual intercourse.

5. Patients with significant heart failure in the previous six months.

6. Patients with uncontrolled irregular heart beats, low or high blood pressure.

7. Patients suffering a stroke within the past six months.

8. Retinitis pigmentosa (a rare eye condition).

Sildenafil (Viagra) was the first PDE5 inhibitors to be developed in 1998. Viagra is usually well tolerated and safe even in those with mild to moderate heart disease provided these patients don't use nitrates.

However, in patients who develop chest pain following use of any PDE5 inhibitor, nitrates are contra-indicated for the following 24 hours. The small number of limitations to its use includes its duration of action (four to five hours) and its absorption is worse with food and alcohol.

It has an onset of action after approximately one hour. As with all PDE5 inhibitors, sexual stimulation is necessary for it to work and is effective in approximately 60-80 per cent of patients.

Common side effects of Viagra include headache, facial flushing, indigestion, blocked or runny nose and reversible alteration in colour vision, increased light sensitivity or blurred vision.

Another PDE5 inhibitor, Tadalafil (Cialis), does not appear to be affected by food or alcohol. It also has a longer duration of action (17.5 hours) making timing less of an issue and confers significant activity 24 hours post-dosing but reaches maximum levels at about two hours.

Headache, runny or blocked nose and indigestion are the most frequent adverse events but visual symptoms and flushing are less of an issue compared with the other PDE5 agents. Some men complain of muscle or back pain.

Vardenafil (Levitra) is the third PDE5 inhibitor, which is well absorbed and tolerated. It has duration of action similar to Viagra. Its absorption is affected by food with a high fat content but not affected by alcohol.

There is some evidence to suggest that Levitra has a better effect in diabetics and patients who have had their prostate gland removed, although the reasons for this are unclear.

Overall, oral agents have improved dramatically the management of erectile dysfunction.

This weekly column is edited by Thomas Lynch, consultant urological surgeon, St James's Hospital, Dublin with a contribution from Rowan Casey, specialist registrar in Urology, St James's Hospital, Dublin