Introduction
Latanoprost is a prostaglandin analog ophthalmic solution used primarily for the reduction of elevated intraocular pressure (IOP) in patients with open-angle glaucoma and ocular hypertension. First approved by the FDA in 1996, it has become a first-line treatment option due to its efficacy, once-daily dosing, and favorable safety profile.
Mechanism of Action
Latanoprost is a selective FP prostanoid receptor agonist that works by increasing uveoscleral outflow of aqueous humor. It enhances matrix metalloproteinase activity in the ciliary muscle, leading to remodeling of the extracellular matrix and reduced resistance to aqueous humor outflow through the uveoscleral pathway. This mechanism results in a significant reduction of intraocular pressure without affecting aqueous production.
Indications
- Reduction of elevated intraocular pressure in patients with open-angle glaucoma
- Ocular hypertension
- Off-label uses may include treatment of hypotrichosis of the eyelashes (as latanoprost 0.005% ophthalmic solution marketed specifically for this indication is available)
Dosage and Administration
Standard dosing: One drop (approximately 1.5 mcg) in the affected eye(s) once daily in the evening Route: Topical ophthalmic administration Special populations:- Hepatic impairment: No dosage adjustment necessary
- Renal impairment: No dosage adjustment necessary
- Pediatric patients: Safety and effectiveness established for pediatric patients
- Geriatric patients: No dosage adjustment necessary
Pharmacokinetics
Absorption: Latanoprost is absorbed through the cornea, where it is hydrolyzed to the active acid form. Systemic absorption is minimal. Distribution: The active acid reaches the anterior chamber within one hour after administration. Plasma concentrations are very low (below 10 pg/mL) after topical ocular administration. Metabolism: Undergoes hydrolysis in the cornea to the biologically active acid. Systemically, the active acid is metabolized primarily by fatty acid β-oxidation. Elimination: The metabolites are eliminated primarily via urine. The elimination half-life in plasma is approximately 17 minutes after both intravenous and topical administration.Contraindications
- Hypersensitivity to latanoprost, benzalkonium chloride, or any component of the formulation
- Patients with active intraocular inflammation (iritis/uveitis)
- Use with caution in patients with inflammatory ocular conditions, macular edema, or a history of herpetic keratitis
Warnings and Precautions
- May cause permanent changes in iris color, eyelid skin darkening, and increased eyelash growth (length, thickness, pigmentation, number of lashes)
- May gradually increase brown pigmentation of the iris, which may be permanent
- Use with caution in patients with risk factors for macular edema (aphakic patients, pseudophakic patients with torn posterior lens capsule)
- May cause ocular inflammation; discontinue if severe inflammation occurs
- Contact lenses should be removed prior to administration and may be reinserted 15 minutes after instillation
- Bacterial keratitis has been reported with the use of multiple-dose containers
Drug Interactions
- Concomitant use with other prostaglandin analogs is not recommended due to potential for additive effects
- No clinically significant pharmacokinetic interactions with systemic medications have been identified
- Theoretical potential for reduced efficacy when used with nonsteroidal anti-inflammatory drugs (NSAIDs) due to prostaglandin synthesis inhibition
Adverse Effects
Common (>10%):- Conjunctival hyperemia
- Foreign body sensation
- Eye pain
- Iris pigmentation changes (particularly in mixed-color irides)
- Eyelash changes (increased length, thickness, and darkness)
- Blurred vision
- Burning and stinging
- Eyelid edema
- Superficial punctate keratitis
- Photophobia
- Macular edema
- Anterior uveitis
- Eyelid skin darkening
- Herpetic keratitis reactivation
Monitoring Parameters
- Intraocular pressure measurement at regular intervals (typically every 3-6 months once stabilized)
- Regular ophthalmic examinations including visual field testing
- Assessment of iris color changes, particularly in patients with mixed-color irides
- Evaluation of periocular skin pigmentation and eyelash changes
- Monitoring for signs and symptoms of ocular inflammation or infection
- Assessment of visual acuity
Patient Education
- Administer one drop in the affected eye(s) once daily in the evening
- Do not touch the dropper tip to any surface to avoid contamination
- Wait at least 5 minutes between instillation of different ophthalmic products
- Remove contact lenses before administration and wait 15 minutes before reinsertion
- Iris color changes may be permanent and may result in heterochromia between eyes
- Eyelash changes may be reversible upon discontinuation
- Report any eye pain, conjunctival redness, vision changes, or light sensitivity
- Do not use while wearing soft contact lenses
- Store unopened bottles in refrigerator; may be stored at room temperature for up to 6 weeks after opening
References
1. Alm A, Grierson I, Shields MB. Side effects associated with prostaglandin analog therapy. Surv Ophthalmol. 2008;53 Suppl1:S93-S105. 2. FDA Prescribing Information: Xalatan (latanoprost) ophthalmic solution. 2021. 3. van der Valk R, Webers CA, Schouten JS, et al. Intraocular pressure-lowering effects of all commonly used glaucoma drugs: a meta-analysis. Arch Ophthalmol. 2005;123(10):1354-1361. 4. Noecker RJ, Dirks MS, Chopin NT, et al. A six-month randomized clinical trial comparing the intraocular pressure-lowering efficacy of bimatoprost and latanoprost in patients with ocular hypertension or glaucoma. Am J Ophthalmol. 2003;135(1):55-63. 5. European Glaucoma Society Terminology and Guidelines for Glaucoma, 5th Edition. Br J Ophthalmol. 2021;105(Suppl 1):1-169.