Erectile dysfunction (ED) is defined as the persistent inability to attain and maintain an erection sufficient to permit satisfactory sexual performance, with up to 20% of men having moderate-to-severe ED. 

Risk factors for ED include obesity, smoking, cardiovascular disease, hypercholesterolaemia, diabetes and previous radical prostatectomy. 

The history should focus on a sexual, medical and psychosocial history, in particular identifying the reversible and irreversible risk factors for ED and also the patient’s psychosocial status. The history may identify other sexual dysfunctions such as premature ejaculation, increased latency time associated with age and psychosexual relationship issues. 

Examination, management and treatment

The physical examination should try to identify if the patient has any penile deformities (Peyronie’s disease, hypospadias, congenital curvature, phimosis or a tight frenular band), a history of trauma, smoking, lack of exercise, prostatic disease, signs of hypogonadism and also a thorough cardiovascular and neurological examination as ED shares many risk factors with cerebrovascular disease. Laboratory testing should be tailored to the patient’s risk factors. All patients should have their lipid profile and a fasting glucose performed and an early morning sample for testosterone and perhaps a prostate-specific antigen (PSA) test. If testosterone levels are low then prolactin, follicle-stimulating hormone (FSH) and luteinising hormone (LH) should be checked and the patient referred to an appropriate specialist. 

The aim of management for ED is to identify and treat the cause and not just the symptom, especially given that a lot of risk factors are modifiable and reversible. A multifactorial management plan is necessary to address the treatable causes of ED, lifestyle changes and risk factor modification and to educate and counsel the patient and his partner.

The current treatment options include oral phosphodiesterase type 5 (PDE5) inhibitors, intra-urethral alprostadil, intracavernous vasoactive drug injection, vacuum constriction devices and penile prosthesis implantation. These treatment options should be used in a methodical step-wise process. 

For men with low testosterone an option is to treat them with a six-month trial of testosterone replacement for their ED. Treatment options include three-monthly injections or a daily transdermal testosterone gel or patch.

Phosphodiesterase type 5 (PDE5) inhibitors

Oral PDE5 inhibitors are used as first-line treatment, unless contraindicated. These (sildenafil, tadalafil and vardenafil) are potent, reversible and competitive inhibitors of PDE5. The PDE5 enzyme hydrolyses cyclic guanosine monophosphate (cGMP) in the cavernosum tissue of the penis. Inhibition of this enzyme results in increase in arterial blood flow which should result in smooth muscle relaxation, vasodilatation and subsequently penile erection. 

It should be noted that sexual stimulation is still required to initiate an erection in the presence of PDE5 inhibitors and doses may need to be titrated up to the maximum dose. Patients with intermediate-to-high-risk cardiovascular disease should defer treatment of ED until their cardiac condition is stabilised.

Side-effects are in general mild and transient and include headache, facial flushing, muscle aches and rarely sildenafil can cause a temporary blue-green change in vision. Another side-effect is priapism, a prolonged painful erection. These patients should be encouraged to seek medical advice if an erection persists for greater than four hours.

Nitrates (used for angina) are an absolute contraindication for the use of PDE5 inhibitors. These result in cGMP accumulation and unpredictable falls in blood pressure and symptoms of hypotension.

The selection of PDE5 inhibitor should depend on the patient’s expectations and how frequently they have intercourse. Patients should be told whether they are on a short or long-acting PDE5 inhibitor due to the advantages and disadvantages of each and their duration of side-effects.

Sildenafil is effective within 30-60 minutes after administration with dosages ranging from 25-100mg and can remain effective up to 12 hours. The recommended initial starting dose is 50mg and can be titrated according to response. 

Tadalafil is effective within 30 minutes of administration with peak efficacy achieved after two hours with dosages ranging from 10-20mg. However, its efficacy can be maintained for up to 36 hours. Vardenafil is also effective within 30 minutes of administration with dosages of 5mg, 10mg and 20mg. 

Vacuum constriction devices

A vacuum constriction device (VCD) is a plastic tube applied over the penis which creates a seal with the skin at the base of the penis. A pump creates a vacuum within the tube and an erection ensues. A tight constricting band is then placed over the base of the penis to maintain the erection. Side-effects include pain, numbness, inability to ejaculate, skin bruising and blistering. 

Intracavernous injections

Patients who do not respond to oral medications may be offered intracavernosal injections, which can have quite a high success rate. Alprostadil can be injected directly into the corpora cavernosum in dosages ranging from 5-40microg. An erection usually results within five to 10 minutes. However multiple outpatient attendances are required to assess dose response and to teach the patient the technique. Side-effects include pain at the site of injection, prolonged erections, priapism and fibrosis. A contraindication is patients with bleeding disorders and a previous history of hypersensitivity to alprostadil. 

The intraurethral suppository avoids the need to inject into the side of the penis, however, it is not as effective. Side-effects include a burning sensation in the penis and a risk of priapism. Patients who develop priapism need to be referred urgently to a urologist as they will require the penis to be aspirated and may require an intracavernosal injection of phenylephrine. Patients who develop priapism will require a reduced dosage of alprostadil in the future.

Penile prostheses

If the above methods fail then an option is for referral to a urologist with a special interest in andrology. An option would include the insertion of a penile prosthesis or implant under general anaesthetic.

For men who have ED after a radical prostatectomy, the same treatment options pertain, including PDE5 inhibitors, intercavernosal injections, urethral suppositories, vacuum devices and penile implants. 

Patients who have undergone a nerve-sparing radical prostatectomy should have regular PDE5 as it preserves the smooth muscle of the corpora cavernosum and an improvement in spontaneous normal erectile function. Patients should be seen on a regular basis to assess treatment.