Latanoprost — NZ Medication Guide

What is Latanoprost?

Latanoprost (generic name: latanoprost) is a medication used primarily for lowering intraocular pressure in open-angle glaucoma and ocular hypertension. Latanoprost 0.005% eye drops (Xalatan and generics) are funded by Pharmac as first-line treatment for open-angle glaucoma and ocular hypertension. It is one of the most commonly prescribed glaucoma medications in New Zealand.

What is Latanoprost Used For?

Latanoprost is prescribed by healthcare professionals in New Zealand for the following indications:

• Open-angle glaucoma (first-line treatment)
• Ocular hypertension
• Normal-tension glaucoma
• Paediatric glaucoma (selected cases under specialist supervision)

How Does Latanoprost Work?

Latanoprost is a prostaglandin F2-alpha analogue that reduces intraocular pressure primarily by increasing uveoscleral outflow of aqueous humour. It is a prodrug that is converted to the active acid form in the cornea. Latanoprost is widely used as first-line treatment for open-angle glaucoma because of its efficacy (typically 25–35% IOP reduction), once-daily dosing, and generally good tolerability.

How to Take Latanoprost

Apply one drop of latanoprost 0.005% eye drops into the affected eye(s) once daily in the evening. Evening dosing is preferred as it provides the maximum intraocular pressure-lowering effect. Do not use more than once daily — more frequent use may reduce efficacy. Remove soft contact lenses before instillation and wait at least 15 minutes before reinserting. Store unopened bottles in the refrigerator; opened bottles can be kept at room temperature for 4–6 weeks.

Common Side Effects

• Iris pigmentation change — gradual permanent darkening of the iris (especially in hazel/mixed-colour eyes)
• Increased eyelash growth — lashes may become longer, thicker, and darker
• Periorbital skin darkening
• Mild ocular burning or stinging
• Conjunctival hyperaemia (red eye)
• Dry eye symptoms

Serious Side Effects — Seek Medical Attention

• Macular oedema — particularly in patients with aphakia (no lens) or pseudophakia
• Anterior uveitis (inflammatory reaction inside the eye)
• Reactivation of herpes simplex keratitis in susceptible patients
• Periorbital fat atrophy (sunken appearance around eyes) with long-term use
• Severe allergic conjunctivitis

Drug Interactions

• Bimatoprost, travoprost (other prostaglandins) — not recommended to combine; may reduce IOP-lowering effect and increase side effects
• NSAIDs (systemic or topical ocular) — may reduce prostaglandin efficacy
• Thimerosal-containing eye drops — precipitate if used simultaneously; allow 5-minute interval

New Zealand Prescribing Information

In New Zealand, Pharmac funds generic latanoprost, making it the first-line funded glaucoma treatment. Patients should be informed of the iris colour change side effect before starting — this change is permanent even after stopping the medication. This is particularly relevant when treating only one eye (asymmetric eye colour may result). Regular ophthalmologist review of intraocular pressure and optic nerve health is essential.

Frequently Asked Questions

Will latanoprost change the colour of my eyes?

Yes — latanoprost can gradually increase the amount of brown pigment in the iris (coloured part of the eye). This change is more common in eyes that are originally hazel, green, or blue-brown. The change is usually permanent, even after stopping the medication. It does not affect vision. If you are only using the drops in one eye, the treated eye may become a different colour to the untreated eye. This should be discussed with your ophthalmologist.

Why should I use latanoprost in the evening?

Evening instillation produces the most effective intraocular pressure lowering over the following 24 hours. Studies have shown that morning use is slightly less effective. Using once at the same time each evening also makes it easier to remember. Do not use more than once a day as more frequent use can paradoxically reduce the effectiveness of the drops.

References & Further Information

The following New Zealand and international resources were used to inform this page:

• New Zealand Formulary — Latanoprost
• Pharmac — Funded Medicines Schedule
• Glaucoma NZ — Eye Drop Information
• Medsafe — Xalatan Eye Drops Data Sheet

Reviewed by a Registered Pharmacist — KiwiMeds New Zealand