How does it work?

This medicine contains the active ingredient sildenafil, which is a medicine used in the treatment of erectile dysfunction (impotence). Sildenafil is called a phosphodiesterase type 5 inhibitor, and works by preventing the action of a chemical in the body called phosphodiesterase type 5. An erection is produced via a complex chain of events, involving signals from the nervous system and the release of chemical messengers within the tissues of the penis. One of these chemical messengers is called cyclic GMP. Cyclic GMP causes the blood vessels in the penis to widen by relaxing a thin layer of muscle found in the blood vessel walls. This allows more blood to enter the penis, which ultimately results in the penis becoming rigid and erect. Cyclic GMP is normally broken down by another chemical in the body called phosphodiesterase type 5. Sildenafil works by preventing the action of phosphodiesterase type 5, thus stopping the breakdown of cyclic GMP. This means that the blood vessels are kept dilated for longer, improving blood flow to the penis and maintaining an erection. As sildenafil enhances the actions of the chemical messengers responsible for producing an erection, it will only work once these messengers are present. This means that sexual stimulation is required for it to produce and maintain an erection. The dose should be taken approximately one hour before intended intercourse.

What is it used for?

Impotence (erectile dysfunction)

Warning!

This medicine should not be taken more than once a day.

This medicine may cause dizziness and visual disturbances. You should make sure you are aware of your reactions to this medicine before driving or operating machinery.

This medicine should be taken on an empty stomach, as if it is taken with food it may take longer to work and be less effective.

Use with caution in

Active peptic ulcer

Bleeding disorders

Conditions such as sickle cell disease, bone cancer or leukaemia in which there is an increased risk of prolonged erections (priapism)

Decreased kidney function

Decreased liver function

Disease involving the heart and blood vessels

Elderly people

Physical abnormality of the penis, such as severe curvature, scarring or Peyronie's disease

Not to be used in

Children or adolescents under 18 years of age

Conditions in which sexual activity is not advisable, for example severe heart disorders

Hereditary degeneration of the back of the eyeball (retina)

Low blood pressure (hypotension)

People taking any form of nitrate medications, eg glyceryl trinitrate

People who have recently had a heart attack

People who have recently had a stroke

Severely decreased liver function

Women

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.

Headache

Rash

Nasal congestion

Visual disturbances

Abnormal heart beats (arrhythmias)

Indigestion (dyspepsia)

Low blood pressure (hypotension)

Dizziness

Flushing

Persistent painful erection of the penis (priapism)

Heart attack (myocardial infarction)

High blood pressure (hypertension)

Chest pain (angina pectoris)

Bleeding into the tissue of the brain (cerebrovascular haemorrhage)

Sudden loss of brain function with full recovery within 24 hours (transient ischaemic attack)

Blue tinge to vision

The side effects listed above may not include all of the side effects reported by the drug's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

How can this medicine affect other medicines?

Sildenafil must not be taken with any form of nitrate medication, as this combination can produce a severe drop in blood pressure that can cause dizziness, fainting, or even a heart attack. Nitrate medications include the following: - nicorandil - glyceryl trinitrate, isosorbide mononitrate, isosorbide dinitrate, used for angina or heart failure - amyl nitrate (also known as "poppers"). Sildenafil should not be taken with other treatments for erectile dysfunction. The following medicines may increase the blood level of sildenafil: - erythromycin - itraconazole - ketoconazole - cimetidine - HIV protease inhibitors such as saquinavir. Tell your doctor if you are taking any of these as you may need a lower sildenafil dose. The HIV protease inhibitor ritonavir can cause a large increase in the blood level of sildenafil. Sildenafil is not recommended for people taking this medicine. Grapefruit juice taken with sildenafil may cause a modest increase in the blood level of sildenafil.

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