Pilocarpine nitrate minims
How does it work?
Minims pilocarpine are single-use preservative-free eye drops that contain the active ingredient pilocarpine. This is a type of medicine known as a miotic, which means it constricts the pupil. It is used to lower the pressure inside the eyeball.
The pressure within the eyeball is naturally maintained by a continuous flow of liquid called aqueous humour through the eyeball. Aqueous humour is produced by a part of the eye called the ciliary body. It drains out of the eyeball through channels called the trabecular meshwork.
If the outflow of aqueous humour is blocked, as in glaucoma, the aqueous humour builds up inside the eye, increasing the pressure within the eyeball. This pressure needs to be reduced, as otherwise it can damage the optic nerve and impair vision.
Pilocarpine reduces pressure in the eyeball by acting on receptors in the circular muscle of the iris (the coloured part of the eye) to reduce the size of the pupil. When the pupil constricts, the iris is pulled away from the drainage channels of the eye (trabecular meshwork). This improves the drainage of the fluid out of the eyeball.
What is it used for?
- Glaucoma. Pilocarpine is mainly used in the emergency treatment of closed angle glaucoma.
- Reversing the effects of eye drops that dilate the pupil.
How do I use it?
- Your doctor will tell you how often to use the drops and how many drops to put in.
- Wash your hands before using the eye drops.
- Twist off the cap from the minim. Pull your lower eyelid down gently, and then gently squeeze the minim until one or two drops fall inside your lower eyelid. Make sure the dropper does not touch any parts of your eye or any other surface. Close your eyes to let the drops spread over the eyeball.
- You can minimise the amount of medicine absorbed into your bloodstream and maximise its action in your eye by pressing on the tear duct while putting in the drops, and for a few minutes after. The tear duct is at the corner of the eye closest to your nose.
- Repeat for the other eye if necessary, then throw away the minim even if some solution is left.
- You should not wear soft contact lenses while using these eye drops.
- Each minim is sterile and for single use only. It should contain enough solution to treat both eyes if required. If there is any solution left in the minim after use it should be discarded and not kept for future use, as it is likely to become contaminated with dirt or germs.
- As with all eye drops, your vision may be blurred after putting the drops in. Wait until your vision is clear before driving or using machines. These eye drops also cause your pupil to get smaller and as a result they may affect your ability to see at night or in poor lighting conditions. You should not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance.
Use with caution in
- Heart disease such as heart failure.
- High blood pressure (hypertension).
- Low blood pressure (hypotension).
- Peptic ulcer.
- People who suffer from spasms in the gut.
- People who have trouble passing urine due to an obstruction of the urinary tract, eg men with an enlarged prostate gland.
- Overactive thyroid gland (hyperthyroidism).
- Parkinson's disease.
- People with a scrape or scratch of the cornea, which is the transparent surface of the eye that covers the iris.
Not to be used in
- Situations where constricting the pupil is not wanted, for example in people with inflammation of the coloured part of the eye or the muscle that controls it (acute iritis or uveitis).
- Soft contact lens wearers.
This medicine should not be used if you are allergic to 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 for use during pregnancy has not been established. It should be avoided during pregnancy unless the expected benefit to the mother is greater than any possible risk to the developing baby. Seek medical advice from your doctor.
- It is not known if this medicine passes into breast milk. It should be avoided in women who are breastfeeding unless the expected benefit to the mother is greater than any possible risk to the baby. Seek medical advice from your doctor.
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. Just because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
- Burning, itching or stinging sensation in the eye when the drops are put in.
- Blurred vision when the drops are put in.
- Reduced ability to see clearly in dim light or darkness.
- Changes in the lens of the eye, after long-term use
- Congestion of the blood vessels in the lining (conjunctiva) of the eye.
- Short-sightedness (myopia).
- Inability of the pupil to change size (pupillary block).
- Bleeding into the chamber behind the lens of the eye (vitreous haemorrhage).
- Retinal detachment.
The following side effects occur only rarely after using pilocarpine in the eyes.
- Watery eyes.
- Slow heart rate (bradycardia).
- Low blood pressure.
The side effects listed above may not include all of the side effects reported by the medicine'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?
If you are using any other medicines it is important to seek advice from your pharmacist before using this one as well, to make sure the combination is safe.
If you are using more than one type of eye drop you should administer them at least five minutes apart, to prevent the second drop washing away the first. Use eye gels or ointments last.
This medicine is not known to affect any other medicines. However, the manufacturer states that the pupil constricting effect of pilocarpine may be reduced in people having long-term treatment with the following medicines (although this has not been clinically proven):
- anticholinergics such as oxybutynin
- antihistamines such as chlorphenamine
- corticosteroids such as prednisolone
- sympathomimetics such as ephedrine, phenylpropanolamine
- tricyclic antidepressants such as amitriptyline.
Other medicines containing the same active ingredient
Pilocarpine eye drops are also available in a multi-dose bottle (these contain a preservative).
The long-acting pilocarpine eye gel (Pilogel) has been discontinued by its manufacturer.