what are they?
What are prostaglandins?
Prostaglandins are a diverse group of compounds which act as signals to control several different processes within the body, such as the regulation of the body’s immune response.
What are prostaglandin analogues?
PGAs are a synthetic version of the body’s natural compound, and come in the form of eye drops. It’s the eye drop that binds to the receptor in order to stimulate the desired effect and help drain the fluid efficiently.
How do prostaglandin analogues treat glaucoma?
The eye can drain fluid through two usual ‘pathways’. The first is called the trabecular meshwork (a layer of tissue beneath the cornea), and this is the ‘common pathway’ for the eye to drain fluid through.
The second is called the uveoscleral pathway. Unlike the trabecular meshwork, this is not actually a ‘pathway’. It simply refers to the act of fluid drainage from the anterior chamber (the space between the cornea and the iris that contains the aqueous humour) through a means other than the trabecular meshwork; fluid essentially seeps through to the anterior chamber.
Studies have shown that PGAs may have a role in supporting the way the eye drains fluid by relaxing the muscles in the interior structure of the eye. This, in turn, improves the permeability of the sclera.3 The sclera is the protective outer layer of your eye commonly known as the ‘white of the eye’. This, as a result, can help increase the outflow through the uveoscleral pathway.
Recent research has also shown that PGAs can improve the drainage of fluid through the trabecular meshwork.4 As such, by supporting the drainage of fluid from both pathways, PGAs can potentially reduce IOP by 25% to 30%.5
Types of prostaglandins used to treat glaucoma
Currently, there are four different types of prostaglandin analogue eye drops available for glaucoma treatment in the UK:
Lantanoprost was the first PGA eye drop developed to lower IOP, and remains the most commonly prescribed.
However, glaucoma is a complex condition. As such, your ophthalmologist will recommend which PGAs are best suited to your individual needs depending on the type of glaucoma you have and how you respond to them over time. They will work with you to ensure you’re receiving the most effective treatment possible.
Are there any common side effects for PGAs?
Generally, each of the PGAs mentioned above share some common side effects, however these tend to not be systemic (affecting the whole body):
Red (stinging) eyes
Increased pigmentation of the iris
It’s usually recommended that if you are pregnant or breastfeeding that you do not take any PGAs for glaucoma treatment.6,7,8,9
If you are suffering from any side effects, contact your ophthalmologist as they will be able to analyse why you might be responding to a specific PGA in a certain way and adjust your treatment plan accordingly.
Combination therapy with prostaglandin analogues
Despite the excellent IOP-lowering efficacy of PGAs, many people with glaucoma or ocular hypertension require more than one medication to sufficiently lower their IOP.
Although PGAs are considered as the most effective class of drugs for reducing IOP, they are frequently combined with other medications such as beta-blockers, adrenergic agonists or carbonic anhydrase inhibitors for increasing the efficacy of treatment.
Thankfully, there are now more options of treatment as a fixed combination. This not only simplifies the dosing and administration of the drops but also avoids washing out the first drop with the second. Studies have shown that the fixed combinations are as effective as individual medications administered separately.10
If you find this information on glaucoma eye drops useful, you can find similar information on the other information on the different treatment options for glaucoma here. You can also explore the dedicated resources in our specialist glaucoma resource to learn more regarding glaucoma causes and glaucoma diagnosis
1. Winkler, N. S., & Fautsch, M. P. (2014). Effects of Prostaglandin Analogues on Aqueous Humor Outflow Pathways. Journal of Ocular Pharmacology and Therapeutics, 30(2-3), 102–109. doi:10.1089/jop.2013.0179Y
2. Hata, A.N., and Breyer, R.M. Pharmacology and signaling of prostaglandin receptors: multiple roles in inflammation and immune modulation. Pharmacol. Ther. 103:147–166, 2004
3. Colina-Chourio, J.A., Godoy-Godoy, N., and Avila-Hernandez, R.M. Role of prostaglandins in hypertension. J. Hum. Hypertens. 14 Suppl 1:S16–S19, 2000
4. Winkler, N. S., & Fautsch, M. P. (2014). Effects of Prostaglandin Analogues on Aqueous Humor Outflow Pathways. Journal of Ocular Pharmacology and Therapeutics, 30(2-3), 102–109. doi:10.1089/jop.2013.0179
5. Lee AJ, McCluskey P. Clinical utility and differential effects of prostaglandin analogs in the management of raised intraocular pressure and ocular hypertension. Clin Ophthalmol. 2010;4:741–764. Published 2010 Jul 30. doi:10.2147/opth.s10441
6. Pharmacia & Upjohn Inc. Xalatan (latanoprost) sterile ophthalmic solution 0.005% (50 mcg/mL) prescribing information. Kalamazoo, MI; 2003 Sep
7. Alcon Pharmaceuticals. Travatan (travoprost) ophthalmic solution 0.004% prescribing information. Fort Worth, TX; 2004 May.
10. Aptel, F., Chiquet, C., & Romanet, J.-P. (2012). Intraocular Pressure-Lowering Combination Therapies with Prostaglandin Analogues. Drugs, 72(10), 1355–1371.