Drugs called PDE5 inhibitors can help men achieve an erection (see Table 1) or better quality erection. These are not aphrodisiacs (i.e. they do not increase sex drive). They work by improving blood flow to the penis.

Direct penile stimulation is required to stimulate an erection when using these drugs. If the medication doesn’t work at the first attempt, it may be worth retrying on a regular basis, say every week or two. Men on hormone treatment may also be helped by the PDE5 drugs, but often their sexual desire is low.
One theory suggests that taking a low dose of the tablets daily (e.g. Cialis, 5 mg per day) as a ‘maintenance regime’, gives you the best chance of return of erectile function. In addition, to test whether you will get a response on demand, you can take a higher (standard) dose.

Table 1: PDE5* inhibitors (medications that assist erections)

Viagra (Sildenafil)Cialis (Tadalafil)Levitra (Vardenafil)
Taken as ‘Maintenance’ DoseLowLowLow
How often to takeEvery day or every second dayEvery day or every second dayEvery day or every second day
Taken as a ‘Booster’
Approximate time to be taken before intercourse 20–30 minutes30-45 minutes20-30 minutes
Time during which intercourse may still be possible2 hours
(possibly 4 hours)
36 hours4-5 hours

* Phosphodiesterase Type 5

These drugs are not subsidised by the Government Pharmaceutical Benefits Scheme, so cost may be a limiting factor. Current (2011) costs for four full-strength tablets are:

  • Viagra (sildenafil) around $60–80
  • Cialis (tadalafil) $80–85
  • Levitra (vardenafil) $45–50

Private health funds may provide some assistance.

There are side effects: Check with your doctor!

Men taking regular nitrate medication (e.g. anginine) for a heart condition must not use PDE5 medications as the risk of low blood pressure and even sudden death is increased. Your doctor will advise you on your risk or may recommend you seek advice from a heart specialist. Sexual activity is a form of exercise and heart attacks are more likely to occur during exercise than otherwise.

Headaches, facial flushing, indigestion and visual disturbances (not reported with Cialis) may be experienced by a few men. Muscle aches can also occur and may be troublesome enough to cause you to stop the drug.

A small number of medications taken at the same time may increase the risk of these side effects (e.g. the antibiotic erythromycin and antifungals such as ketoconazole).

Other products and ways of taking them will be made available in the future.

Injection therapy

Direct penile injections are the most effective form of therapy to achieve erections after a radical prostatectomy. A drug is injected each time an erection is required – this occurs without any direct sexual stimulation – it is a chemical response. Caverject Impulse (alprostadil) is the most commonly available. As with PDE5 inhibitors, it is not supported by the PBS scheme.

Start by injecting small doses (e.g. 2.5–5 micrograms) and then gradually increase the dose until a satisfactory result is achieved. This reduces the risk of one of the uncommon side effects – a painful prolonged erection, called priapism. Any erection lasting more than 4 hours with this type of medication requires prompt medical intervention, as priapism can permanently damage erectile function. Some doctors prescribe a tablet to help deflate the erection should it last for 3 hours or more, or be painful (e.g. pseudoephedrine 60–120 mg orally).

Most doctors recommend a maximum of three injections per week because more frequent use may lead to scarring within the penis. Scarring can lead to a bend in the shaft of the erect penis. The correct technique of injection therapy can be learned by most men, provided their eyesight and dexterity are reasonable.

Other injectable medications may be used, some in combination. All rely on a relatively normal blood supply to the penis; injection therapy can fail if this is inadequate.

Caverject Impulse is in a powder form that can be stored or transported at room temperature. When required it is mixed to a solution in the syringe. Other agents usually require refrigeration to store.