Prostaglandin analogues are first-line drugs in the management of glaucoma due to their high efficacy, once-daily dosing, and minimal systemic side effects. Among all antiglaucoma medications, this class produces the greatest reduction in intraocular pressure (IOP), making it a favorite in modern ophthalmic practice.
The most commonly used prostaglandin analogues are Latanoprost and Travoprost. These drugs are essential topics in pharmacology, ophthalmology, nursing exams, and clinical training.
Therapeutic and Pharmacologic Class
Prostaglandin analogues are classified as:
1. Antiglaucoma agentsThey primarily act by increasing aqueous humor outflow, rather than reducing its production.
Understanding Intraocular Pressure (Quick Concept)
In glaucoma, increased intraocular pressure damages the optic nerve, leading to progressive vision loss.
IOP depends on:
- Production of aqueous humor
- Outflow of aqueous humor
Prostaglandin analogues work by enhancing aqueous humor outflow, especially through the uveoscleral pathway.
Mechanism of Action (High-Yield)
Latanoprost and Travoprost are prostaglandin F₂α analogues.
Their key actions include:
- Remodeling of extracellular matrix in the ciliary muscle
- Increased uveoscleral outflow of aqueous humor
- Reduction in intraocular pressure
They do not significantly affect aqueous humor production, which explains their excellent safety profile.
Latanoprost
Latanoprost is one of the most commonly prescribed first-line drugs for glaucoma worldwide.
Mechanism of Action
Latanoprost increases uveoscleral outflow, leading to sustained reduction in intraocular pressure.
Therapeutic Uses
Latanoprost is used in:
- Primary open-angle glaucoma
- Ocular hypertension
It is typically administered once daily at night, improving patient compliance.
Adverse Effects
Most side effects are local and include:
- Eye irritation or stinging
- Foreign body sensation
- Increased eyelash growth
- Increased brown pigmentation of the iris (may be permanent)
Systemic side effects are rare.
Travoprost
Travoprost is pharmacologically similar to latanoprost and belongs to the same drug class.
Mechanism of Action
Travoprost:
- Enhances uveoscleral aqueous humor outflow
- Lowers intraocular pressure effectively
Therapeutic Uses
Travoprost is indicated for:
- Open-angle glaucoma
- Ocular hypertension
Like latanoprost, it is administered once daily, usually in the evening.
Adverse Effects
Travoprost shares side effects similar to latanoprost:
- Conjunctival hyperemia
- Increased eyelash length and thickness
- Gradual darkening of iris color
- Mild eye discomfort
Adverse Reactions and Side Effects (Class Effects)
Eye, Ear, Nose, Throat (EENT)
- Local irritation and stinging
- Foreign body sensation
- Increased eyelash growth
- Increased brown pigmentation of iris and periocular skin
Cardiovascular
Rare palpitations (with excessive systemic absorption)Unlike beta-blockers or adrenergic drugs, prostaglandin analogues do not commonly cause systemic cardiovascular or respiratory effects.
Important Nursing and Patient-Care Instructions
Patients should be advised to:
- Instill drops into the conjunctival sac, not directly onto the eyeball
- Apply nasolacrimal duct pressure for 1 minute after instillation to reduce systemic absorption
- Remove contact lenses before administration and wait before reinsertion
- Avoid activities requiring sharp visual acuity if temporary visual disturbance occurs
Monitoring and Safety (“Make the Connection”)
Healthcare providers should:
- Monitor intraocular pressure (tonometry) regularly
- Monitor visual acuity during follow-up visits
- Educate patients about possible permanent eye color changes
- Monitor blood pressure and pulse when therapy is initiated (precautionary)
Contraindications and Precautions
Use with caution in patients with:
- Active uveitis or iritis
- History of macular edema
- Eye surgery (recent or planned)
Prostaglandin analogues are generally safe and well tolerated, even for long-term use.
Nursing Diagnosis (Exam-Relevant)
Common nursing diagnoses include:
- Disturbed sensory perception (visual)
- Risk for injury related to visual disturbances
- Knowledge deficit related to eye-drop administration technique
High-Yield Exam Points
1. Prostaglandin analogues are first-line therapy for open-angle glaucoma.
2. They lower IOP by increasing uveoscleral outflow.
3. Once-daily dosing improves compliance.
4. Iris pigmentation changes may be permanent.
5. They have minimal systemic side effects compared to other antiglaucoma drugs.
Simple Mnemonic for Recall
“PROST = Pressure Outflow Strong Therapy”
PROST → Prostaglandin
Outflow → Increases uveoscleral outflow
Strong → Most effective IOP-lowering drugs
Therapy → First-line in glaucoma
FAQs on Prostaglandin Analogues
Why are prostaglandin analogues first-line drugs for glaucoma?
Because they provide maximum IOP reduction with once-daily dosing and minimal systemic side effects.
How do latanoprost and travoprost reduce eye pressure?
They increase aqueous humor outflow through the uveoscleral pathway.
Can eye color change with these drugs?
Yes, increased brown iris pigmentation may occur and can be permanent.
Are these drugs safe for long-term use?
Yes, they are among the safest antiglaucoma medications for chronic therapy.
Why should contact lenses be removed before use?
To prevent drug absorption into lenses and eye irritation.
