Erectile dysfunction (ED) is increasingly recognised as a distressing condition for the patient and a powerful marker for a number of chronic diseases including diabetes mellitus, CHD, generalised atherosclerosis and depression.
The Massachusetts Male Ageing Study of 1994 found that 52 per cent of men aged over 40 years had at least some erectile problems.
Other prevalence studies show varying rates; up to 22 per cent of men in their 50s, up to 49 per cent of men in their 60s and up to 53 per cent of men in their 70s. Currently it is estimated that the overall prevalence is about a quarter of the male population.
The prevalence in the male diabetic population is even higher. As the general population continues to age and the prevalence increases, the absolute number of men with this condition will increase.
After taking a thorough history and examination for signs of vascular disease, there are a number of investigations that are important, such as fasting blood lipids, fasting blood glucose and 9am testosterone.
Other investigations include FBC, prostate-specific antigen, prolactin, follicle-stimulating hormone and luteinising hormone and a second 9am testosterone if the initial one is <12.
PDE5 inhibitors (sildenafil, tadalafil and vardenafil) are the gold standard of oral therapies. They act by promoting penile cavernous and vascular smooth muscle relaxation inducing an erection in response to sexual stimulation.
There are important differences in recommended starting dosages, amount of time before intercourse they need to be taken and cumulative success rate.
The advantages of these drugs include ease of use, high patient acceptability and efficacy. The disadvantages are few but include specific contraindications such as concomitant use of nitrates.
Sildenafil and vardenafil can be used with alpha-blockers and tadalafil and vardenafil can be used with tamsulosin; although they should only be initiated in patients who have been stabilised (often dosing at different times is recommended) and only at the lowest dose of 5mg.
PGE1 (alprostadil) is the most widely used intracavernosal therapy; it offers good efficacy and tolerability.
Papaverine was the first drug to be used but is rarely used alone now, though it can be used in combination.
Phentolamine when used alone has only a modest effect but can be used in combination with alprostadil or papaverine.
Problems with injectable therapies can include penile pain, priapism and/or scarring. Only about one patient in four continues treatment three to four years after starting.
Alprostadil in small pellet form can be administered into the urethra as MUSE (medicated urethral system for erection). There is a range of dosages and the onset of action is at around 20 minutes. The strength of the erection can be improved by using a constriction ring.
Efficacy is less than the PDE5 inhibitors or intracavernosal therapy. Penile pain is a common side-effect and more rarely dizziness, so MUSE is not widely used now.
Vacuum tumescence devices (VTDs) consist of a plastic cylinder, a vacuum pump to produce an erection and a constriction ring to maintain it.
The advantages of VTDs is that they are non-invasive and very effective.
However, it is cumbersome, needs good manual dexterity, and can lead to coldness, bruising and cyanosis of the penis and ejaculatory block.
In men with ED and/or low libido, a clear indication, in the form of a clinical picture together with biochemical evidence of hypogonadism, should exist prior to the initiation of androgen therapy.
Contraindications should also be ruled out (prostate cancer, breast cancer or severe bladder neck obstruction). Testosterone can be given orally, transdermally (patch or gel) or intramuscularly.
As this is a long-term treatment, patients must be monitored closely for side-effects or contraindications such as abnormal liver function tests, hyperlipidaemia, polycythaemia, prostatic problems (cancer or severe bladder outflow obstruction) or sleep apnoea.
Androgen replacement therapy has been shown to improve symptoms of low libido but long-term monitoring is vital.
Penile implants are the last resort when all other treatments have failed. The role of penile vascular surgery in ED is still not well defined.
ED is a distressing condition and a marker for some important chronic conditions. It warrants proper investigation. Most cases are quite easy to treat with oral PDE5 inhibitors. For the more difficult cases, a range of treatments is available, either used alone or in combination.
ED is a rewarding condition to treat for the patient and GP.