Treating erectile dysfunction

The advent of effective medical therapy allows GPs to initiate and supervise the care of these patients.

The treatment of erectile dysfunction (ED) has changed fundamentally with the arrival of safe and effective oral therapies, which can easily be initiated in general practice for the majority of patients.

Before 5-phosphodiesterase inhibitors became available, the principal treatment for ED was psychosexual therapy. However this was time-consuming and had to be limited to small numbers of patients because of problems with resources.

With the advent of medical therapy, increasing numbers of GPs are initiating and supervising care, and specialist input in the treatment of ED has been shifted to urology and genito-urinary medicine.

The algorithm shown below is one that is currently used at the Royal Victoria Hospital, Belfast, and is intended as a straightforward guide to the management of ED.

Oral therapies

Oral therapies are now firmly recognised as first-line treatment for ED in general practice and secondary care.

The principal drugs used are sildenafil, tadalafil and vardenafil. Apomorphine is licensed but not widely used because it is perceived to have low efficacy, although it has a rapid onset of action. It is unusual for apomorphine to work where 5-phosphodiesterase inhibitors are unsuccessful.

Patients are eligible for NHS prescription under schedule 11.

Sildenafil

Sildenafil was launched in 1998. It can be given in an escalating dose until the effective dose is found. Many specialists prefer to start with the maximum dose (100mg) and titrate down until the minimum effective dose is found.

This has the advantage that the patient has the greatest chance of the drug working with initial dosing and therefore forms a positive view of the therapy.

The disadvantage is the increased incidence of side-effects. The main side-effects are facial flushing, nausea and headache; these are usually mild and seldom cause patients to discontinue treatment. It is recommended that sildenafil is taken an hour before food to facilitate maximum plasma levels. It remains effective for several hours.

Tadalafil

Tadalafil was launched in 2003. It can be taken with food and alcohol, and is clinically effective within 15-20 minutes, with maximum effect at two hours. The licence gives a duration of action of 36 hours, but with a 17-hour half-life, the effect is often seen for much longer than this. Tadalafil has been dubbed the 'weekend pill' because a dose taken on Friday is often still effective on the Sunday.

Vardenafil

Vardenafil was launched in 2003 and is usually given in 10-20mg doses.

Its duration of action is similar to sildenafil, but it can be taken with food and the manufacturers claim an onset of action within 11 minutes.

It has a similar duration of action to sildenafil. Side-effects are similar across the group of drugs and are usually dose related.

In the practice

ED is frequently mentioned at the end of a consultation and in these circumstances it might be best to bring the patient back another day.

When the patient presents with ED, the essential issues are the duration and the severity of the problem; is it present in all situations, or is it intermittent?

It is also important to ask the patient about his erection pattern. If the patient has morning erections, this indicates that the problem is at least partially psychological. It should be remembered that psychological and physical factors commonly co-exist.

If the patient is having partial erections that are difficult to obtain and may suddenly collapse this could indicate vascular disease.

Often partners suspect the man with ED is having an affair or is not sexually interested in them, so it is important to try to gauge the effect of the ED on the patient's relationship.

You should also establish whether any other problems might be contributing, such as diabetes, depression or neurological disease. In particular, find out if they are taking any medication which has ED as a side-effect, such as SSRIs and beta-blockers.

Finally, enquire about low libido because this might be an indication of testosterone deficiency. Examination is considered unnecessary by many urologists.

Tests and treatment

Lipids analysis is important because ED might be an early sign of more generalised vascular disease. Testosterone and prolactin can be measured if the patient has low libido.

The treatment of choice is one of the 5-phosphodiesterase inhibitors.

They should be given a reasonable chance to work, that is, they should be started at an effective dose and a minimum of four to eight treatments used. If one 5-phosphodiesterase inhibitor does not work, try another.

Specialist referral should be made at the patient's request, for those patients who do not respond to the initial therapy, and those patients who want to know more about why they are having this problem.

Patients with severe cardiac or other systemic disease should also be referred if either the GP, or the patient himself, is uncomfortable about the option of prescribing 5-phosphodiesterase inhibitors.

- Dr Dinsmore is consultant in GU medicine, Department of Genito-Urinary Medicine, Royal Victoria Hospital, Belfast.

PDE5 INHIBITORS

- Sildenafil has the longest safety profile.

- Tadalafil has a 17-hour half-life, relieving patients of time pressure.

- Vardenafil and tadalafil may be taken with food.

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