How does it work?

Adrenaline is a chemical that occurs naturally in the body. It acts on many areas of the body and has many different effects. In the eye, adrenaline acts on receptors (adrenoceptors) in the walls of blood vessels. This causes the blood vessels to narrow which restricts the flow of blood through the vessels. Reduced blood flow leads to a decrease in the production of the watery fluid (aqueous humour) that fills the back of the eye. Adrenaline also increases the drainage of this fluid from the eye although the mechanism is not fully understood. In addition, adrenaline causes contraction of the radial amuscle of the iris (the coloured part of the eye) which leads to dilatation of the pupil. Guanethidine acts in the eye to increase and prolong the effects of adrenaline. It does this by preventing adrenaline being absorbed by the tissues of the eye. This allows adrenaline to act on the receptors for a longer period of time, which results in greater effectiveness of adrenaline in the eye. Adrenaline is used in the treatment of glaucoma. This is a condition where the fluid drainage from the eye is impaired, resulting in fluid build-up and increased pressure in the eye. Guanethidine allows further reduction of fluid volume and therefore pressure within the eye. Adrenaline and guanethidine are used as eye drops so that they may act directly where they are needed and decrease the likelihood of side effects elsewhere in the body.

What is it used for?

Open angle glaucoma

Warning!

This medicine may reduce your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance.

You should not wear soft contact lenses while you are using this medicine. This it because the medicine contains a preservative that can be absorbed by soft contact lenses and cause eye irritation.

Prolonged use of guanethidine eye drops may result in thickening and scarring of the lining of the eye (conjunctival fibrosis). This can lead to changes in the front covering of the eye (cornea). It is important to have eye examinations at least every 6 months.

Use with caution in

Diabetes mellitus

Disease involving the heart and blood vessels

Heart disease

High blood pressure

Thyrotoxicosis

Not to be used in

Closed angle glaucoma

Known sensitivity or allergy to any ingredient

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.

Pregnancy and Breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

The safety of this medicine during breastfeeding has not been established. Seek medical advice from your doctor.

The safety of this medicine during breastfeeding has not been established. Seek medical advice from your doctor.

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

Blurred vision

Dislike of light (photophobia)

Headache across the forehead (browache)

Eye pain

Reddening of the eye following administration of the medication

Burning, itching and painful sensations in the eye

Red and irritated eyes

Thickening and scarring of the lining of the eye (conjunctival fibrosis)

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.

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