Latanoprost
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Open-angle glaucoma — IOP reduction | Adults | Monotherapy or adjunctive | FDA Approved |
| Ocular hypertension — IOP reduction | Adults | Monotherapy or adjunctive | FDA Approved |
Latanoprost is widely regarded as a first-line agent for lowering intraocular pressure in patients with primary open-angle glaucoma or elevated IOP. The European Glaucoma Society guidelines endorse prostaglandin analogues as the preferred initial medical therapy due to their once-daily dosing, potent IOP-lowering efficacy (typically 6–8 mmHg from a baseline of 24–25 mmHg), and favourable systemic safety profile. Latanoprost was the first topical prostaglandin analogue to receive FDA approval (1996) and remains one of the most widely prescribed ocular hypotensive agents globally.
Normal-tension glaucoma: Evidence supports IOP reduction of approximately 16% from low baseline pressures. Latanoprost is used to slow visual field progression even when IOP falls within the statistically normal range. (Evidence quality: Moderate)
Pediatric glaucoma: Used off-label in children with congenital or juvenile open-angle glaucoma at the adult dose of one drop once daily. A randomized trial demonstrated IOP reductions comparable to timolol in pediatric patients, with acceptable tolerability. FDA labelling states safety and effectiveness in pediatric patients have not been established. (Evidence quality: Moderate)
Pigmentary glaucoma: Applied off-label in patients with pigment dispersion syndrome and secondary IOP elevation. (Evidence quality: Low)
Latanoprost Dosing
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Primary open-angle glaucoma — initial monotherapy | 1 drop (0.005%) affected eye(s) once daily in the evening | Same as starting dose | 1 drop once daily | Evening dosing maximises IOP reduction over nocturnal and diurnal periods Do NOT exceed once daily; more frequent dosing may paradoxically raise IOP |
| Ocular hypertension — monotherapy | 1 drop once daily in the evening | Same as starting dose | 1 drop once daily | Expected IOP reduction: 6–8 mmHg from baseline of 24–25 mmHg Equivalent to timolol 0.5% BID in pivotal trials (FDA PI) |
| Open-angle glaucoma — adjunctive to other topical agents | 1 drop once daily in the evening | Same as starting dose | 1 drop once daily | Separate all topical ophthalmic drops by at least 5 minutes Do NOT combine with other prostaglandin analogues |
| Normal-tension glaucoma (off-label) | 1 drop once daily in the evening | Same as starting dose | 1 drop once daily | ~16% IOP reduction from low baselines; monitor visual fields for progression Evidence from multiple short-term studies |
| Pediatric glaucoma (off-label) | 1 drop once daily in the evening | Same as starting dose | 1 drop once daily | Adult dose used in paediatric studies with acceptable safety margin FDA labelling: safety and effectiveness not established |
Administering latanoprost more than once daily has been shown to decrease rather than increase its IOP-lowering effect, possibly through prostaglandin receptor desensitisation. If the patient is a non-responder to once-daily latanoprost, switching to a different prostaglandin analogue (travoprost, bimatoprost) or adding a second agent from a different class is preferable to increasing latanoprost frequency.
Administration Guidance
Remove contact lenses prior to instillation and wait at least 15 minutes before reinserting. When using multiple topical ophthalmic drugs, each should be administered at least 5 minutes apart. Patients should be instructed to avoid touching the dropper tip to the eye or surrounding tissue. The preserved multi-dose formulation (Xalatan, generics) contains benzalkonium chloride; the preservative-free single-dose formulation (Iyuzeh) is available for patients with ocular surface sensitivity. Unopened multi-dose bottles should be stored refrigerated (2–8°C); once opened, they may be kept at room temperature up to 25°C for up to 6 weeks.
Pharmacology
Mechanism of Action
Latanoprost is an isopropyl ester prodrug of prostaglandin F2α. After topical administration, corneal esterases hydrolyse the ester bond to release the biologically active latanoprost acid. This acid binds to the prostaglandin FP receptor in the ciliary muscle and trabecular meshwork. The primary mechanism of IOP reduction is enhancement of uveoscleral (non-conventional) aqueous humour outflow through remodelling of the extracellular matrix within the ciliary muscle and adjacent connective tissues. This involves upregulation of matrix metalloproteinases that degrade collagen in the uveoscleral pathway, widening intercellular spaces and reducing outflow resistance. Latanoprost may also modestly increase trabecular outflow. The onset of IOP reduction occurs within 3–4 hours of instillation, with peak effect at 8–12 hours, and clinically meaningful IOP lowering persists for at least 24 hours, supporting once-daily dosing.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Corneal absorption; prodrug hydrolysed to active acid; Tmax in aqueous humour ~2 h; detectable in plasma for ~1 h only | Local corneal depot effect provides sustained anterior segment drug exposure; negligible systemic levels minimise systemic side effects |
| Distribution | Vd = 0.16 ± 0.02 L/kg; peak aqueous humour concentration 15–30 ng/mL; active acid measurable in aqueous for first 4 h | Low systemic distribution volume reflects predominantly local ocular action |
| Metabolism | Corneal esterases (prodrug activation); hepatic β-oxidation to 1,2-dinor and 1,2,3,4-tetranor metabolites; no CYP450 involvement | No clinically significant systemic drug–drug interactions via hepatic metabolism; CYP-mediated interactions do not apply |
| Elimination | Plasma t½ = 17 min; systemic clearance ~7 mL/min/kg; ~88% recovered in urine (topical dosing), ~98% (IV dosing) | Extremely rapid systemic elimination further limits potential for systemic adverse effects; primarily renal excretion of inactive metabolites |
Side Effects
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Foreign body sensation | 13% | Usually mild and transient; more common than with timolol (8%); often improves with continued use |
| Punctate keratitis | 10% | May be partly attributable to benzalkonium chloride preservative; consider preservative-free formulation if persistent |
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Stinging on instillation | 9% | Self-limiting within seconds; comparable rate to timolol (12%) |
| Conjunctival hyperemia | 8% | Prostaglandin class effect; generally mild; <1% discontinue due to hyperemia |
| Blurred vision | 8% | Transient; occurs shortly after instillation and usually resolves within minutes |
| Itching | 8% | Typically mild ocular pruritus; rarely requires treatment discontinuation |
| Burning sensation | 7% | Immediate post-instillation event; often attributable to preservative or formulation pH |
| Increased iris pigmentation | 7% | Due to increased melanin in melanocytes (not melanocyte proliferation); likely permanent; more common in mixed-colour irides; onset usually within first year |
| Excessive tearing | 4% | Mild reflex lacrimation; self-resolving |
| Eyelid discomfort / pain | 4% | May relate to periorbital changes; monitor for deepening of eyelid sulcus |
| Dry eye | 3% | May be exacerbated by benzalkonium chloride; artificial tears may help; consider preservative-free latanoprost |
| Eye pain | 3% | Usually mild; persistent eye pain should prompt evaluation for other causes |
| Eyelid margin crusting | 3% | Routine lid hygiene measures are usually sufficient |
| Eyelid erythema | 3% | Mild periorbital redness; may be confused with allergic contact dermatitis |
| Photophobia | 2% | Mild; advise sunglasses if bothersome |
| Eyelash changes (length, thickness, pigmentation, number) | Majority with >6 months use | Prostaglandin class effect; usually reversible on discontinuation; may cause asymmetry if treating one eye |
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Cystoid macular oedema | Rare (<1%) | Weeks to months after initiation | Discontinue latanoprost; ophthalmology referral; may require topical NSAIDs or corticosteroids; higher risk in aphakic/pseudophakic patients with torn posterior capsule |
| Iritis / uveitis | Rare | Variable | Discontinue if active inflammation; topical corticosteroids; avoid use in patients with active intraocular inflammation |
| Herpes simplex keratitis reactivation | Rare | Variable; may occur at any point during therapy | Discontinue latanoprost immediately; initiate antiviral therapy; avoid re-challenge; use with caution in patients with history of HSV keratitis |
| Corneal oedema and erosions | Very rare | Variable | Ophthalmology assessment; consider discontinuation; may require temporary switch to alternative IOP-lowering agent |
| Asthma exacerbation | Very rare (postmarketing) | Variable | Assess respiratory status; consider alternative IOP-lowering therapy if asthma worsens; note that systemic absorption is minimal |
| Periorbital fat atrophy / deepening of eyelid sulcus (prostaglandin-associated periorbitopathy) | Uncommon (postmarketing) | Months to years of use | Cosmetic concern; may be partially reversible on discontinuation; discuss with patient if noticeable |
| Reason for Discontinuation | Incidence | Context |
|---|---|---|
| Conjunctival hyperemia | <1% | Only intolerance-based discontinuation reason specifically reported in pivotal trials (FDA PI) |
| All-cause withdrawal | 7% | Includes patient choice, loss to follow-up, and adverse effects combined; from three 6-month RCTs |
Iris colour change (increased brown pigmentation) occurs in approximately 7% of patients in controlled trials but may be observed in 12–18% of Caucasian patients treated for 1–2 years. The change is due to stimulation of melanogenesis within iris melanocytes, not melanocyte proliferation, and there is no evidence linking latanoprost to melanoma. The pigmentation is likely permanent and may not be noticeable for months to years. Patients with mixed-colour irides (blue-brown, grey-brown, green-brown, yellow-brown) are at highest risk. Patients should be counselled at initiation and examined regularly during treatment. Unilateral treatment may cause heterochromia.
Drug Interactions
Latanoprost has a minimal systemic drug interaction profile. The active acid is metabolised via fatty acid β-oxidation rather than CYP450 enzymes, eliminating concerns about hepatic drug–drug interactions. The interactions below are primarily pharmacological class effects or formulation-related.
Monitoring
-
Intraocular Pressure
Every 2–4 weeks until target achieved; then every 6 months
Routine Assess IOP response to confirm adequate lowering (typically 6–8 mmHg from baseline). Non-responders (defined as <15% IOP reduction) should be identified early and switched or supplemented with alternative agents. -
Iris Colour Assessment
Baseline; then at every routine visit
Routine Document baseline iris colour and photograph if possible. Changes may not appear for several months to years. Higher risk in mixed-colour irides. Change is likely permanent. -
Eyelash / Eyelid Changes
Each visit
Routine Monitor for increased length, thickness, pigmentation, and number of lashes. Assess for periorbital changes including eyelid skin darkening and deepening of the eyelid sulcus. Changes usually reversible on discontinuation. -
Fundoscopic Examination (Macula)
Baseline; then if symptoms arise
Trigger-based Rule out cystoid macular oedema before initiating in high-risk patients (aphakia, pseudophakia with torn posterior capsule, prior CME). Re-examine if patient reports decreased vision or metamorphopsia. -
Anterior Chamber Assessment
Baseline; then if pain or redness develops
Trigger-based Screen for intraocular inflammation (cells and flare). Use with caution in patients with a history of uveitis. Discontinue if active iritis develops. -
Visual Fields
Per glaucoma guidelines (typically every 6–12 months)
Routine Standard automated perimetry to detect glaucomatous progression despite adequate IOP control. Not specific to latanoprost but essential for overall glaucoma management.
Contraindications & Cautions
Absolute Contraindications
- Known hypersensitivity to latanoprost, benzalkonium chloride, or any excipient in the formulation (FDA PI Section 4)
Relative Contraindications (Specialist Input Recommended)
- Active herpes simplex keratitis — the FDA PI states latanoprost “should be avoided” because prostaglandin-mediated inflammation may exacerbate herpetic disease
- Active intraocular inflammation (iritis/uveitis) — latanoprost may worsen inflammation; generally avoid in active disease and use with caution in patients with a history of recurrent uveitis
- Aphakia or pseudophakia with torn posterior lens capsule — increased risk of cystoid macular oedema; consider alternative first-line agent or ensure close macular monitoring
- Known risk factors for macular oedema (history of CME, diabetic macular oedema, retinal vein occlusion) — weigh risk-benefit and monitor closely
- Pregnancy — prostaglandins stimulate uterine smooth muscle; animal studies show embryofetal toxicity at clinically relevant doses; prefer alternative IOP-lowering classes during pregnancy where possible
Use with Caution
- History of herpes simplex keratitis — latanoprost may trigger reactivation; monitor and discontinue promptly if recurrence occurs
- Contact lens wearers — remove lenses before instillation and wait 15 minutes; benzalkonium chloride may be absorbed by soft contact lenses
- Patients with mixed-colour irides — higher likelihood of iris pigmentation changes; counsel thoroughly at initiation
- Patients with severe or unstable asthma — though systemic absorption is minimal, there are rare postmarketing reports of asthma exacerbation
All prostaglandin analogue ophthalmic products carry labelling warnings about the potential for irreversible iris pigmentation changes, eyelid skin darkening, eyelash alterations, and periorbital changes (including deepening of the eyelid sulcus). These cosmetic effects are considered prostaglandin class effects and are included in the FDA-approved labelling for latanoprost, bimatoprost, travoprost, and tafluprost. Patients must be informed of these risks before initiating therapy, and the changes should be documented at regular intervals. While generally not harmful, the irreversible nature of iris colour change requires careful pre-treatment counselling.
Patient Counselling
Purpose of Therapy
Latanoprost is prescribed to lower the pressure inside the eye, which, if left untreated, can gradually damage the optic nerve and lead to irreversible vision loss (glaucoma). This medication controls the condition but does not cure it, so it must be used consistently and indefinitely unless the prescriber advises otherwise. Patients will not feel a difference in their vision from the medication itself — the benefit is the prevention of future damage.
How to Take
Instil one drop into the affected eye(s) once daily in the evening. If more than one type of eye drop is used, wait at least 5 minutes between each. Remove contact lenses before application and wait 15 minutes before putting them back in. Do not touch the dropper tip to the eye or any surface. If a dose is missed, continue with the next evening dose as scheduled — do not double the dose.
Sources
- Latanoprost Ophthalmic Solution 0.005% — Full Prescribing Information (Micro Labs). Revised January 2025. drugs.com Primary source for FDA-approved indications, dosing, adverse reactions with incidence rates, and pharmacokinetic data used throughout this monograph.
- Xalatan (latanoprost ophthalmic solution) 0.005% — Full Prescribing Information (Pfizer). DailyMed / NLM. dailymed.nlm.nih.gov Original innovator product PI; provides clinical trial data from three pivotal 6-month RCTs comparing latanoprost with timolol.
- Xelpros (latanoprost ophthalmic emulsion) 0.005% — Full Prescribing Information. FDA label 2024. accessdata.fda.gov Preservative-free emulsion formulation; additional pregnancy and lactation safety data.
- Camras CB; United States Latanoprost Study Group. Comparison of latanoprost and timolol in patients with ocular hypertension and glaucoma: a six-month, masked, multicenter trial in the United States. Ophthalmology. 1996;103(1):138–147. PMID: 8628544. Pivotal US RCT establishing latanoprost’s non-inferiority to timolol for IOP reduction, forming the basis of FDA approval.
- Watson P, Stjernschantz J; Latanoprost Study Group. A six-month, randomized, double-masked study comparing latanoprost with timolol in open-angle glaucoma and ocular hypertension. Ophthalmology. 1996;103(1):126–137. PMID: 8628543. International pivotal trial confirming 6–8 mmHg IOP reduction with once-daily latanoprost vs timolol twice daily.
- Alm A, Stjernschantz J; Scandinavian Latanoprost Study Group. Effects on intraocular pressure and side effects of 0.005% latanoprost applied once daily, evening or morning. Ophthalmology. 1995;102(12):1743–1752. PMID: 9098273. Established that evening dosing provides superior IOP control compared to morning dosing, informing current dosing recommendations.
- European Glaucoma Society. Terminology and Guidelines for Glaucoma. 5th Edition. 2020. eugs.org Endorses prostaglandin analogues as first-line medical therapy for open-angle glaucoma based on efficacy, tolerability, and once-daily dosing.
- American Academy of Ophthalmology. Preferred Practice Pattern: Primary Open-Angle Glaucoma. 2020. aao.org US-based guideline recommending prostaglandin analogues as initial medical therapy for most patients with POAG.
- Toris CB, Camras CB, Yablonski ME. Effects of PhXA41, a new prostaglandin F2α analog, on aqueous humor dynamics in human eyes. Ophthalmology. 1993;100(9):1297–1304. PMID: 8371915. Foundational study demonstrating that latanoprost (PhXA41) lowers IOP primarily by increasing uveoscleral outflow rather than reducing aqueous production.
- Stjernschantz J, Selén G, Sjoquist B, et al. Preclinical pharmacology of latanoprost, a phenyl-substituted PGF2α analogue. Adv Prostaglandin Thromboxane Leukotriene Res. 1995;23:513–518. Preclinical pharmacology establishing latanoprost’s selectivity for the FP receptor and its prodrug design for corneal penetration.
- Sjoquist B, Stjernschantz J. Ocular and systemic pharmacokinetics of latanoprost in humans. Surv Ophthalmol. 2002;47(Suppl 1):S6–S12. PMID: 12204697. Comprehensive PK study detailing the 17-minute plasma half-life, Vd, systemic clearance, and corneal depot effect of latanoprost.
- Enyedi LB, Freedman SF. Latanoprost for the treatment of pediatric glaucoma. Surv Ophthalmol. 2002;47(Suppl 1):S129–S132. PMID: 12204714. Review of latanoprost use in paediatric populations including congenital glaucoma, supporting off-label dosing with acceptable safety margins.
- Quaranta L, Biagioli E, Riva I, et al. Latanoprost ophthalmic solution in the treatment of open angle glaucoma or raised intraocular pressure: a review. Clin Ophthalmol. 2008;2(4):897–905. PMCID: PMC2699817. Comprehensive review covering PK, efficacy data across glaucoma subtypes including normal-tension glaucoma, and long-term safety.
- Hamacher T, Airaksinen J, Saarela V, Liinamaa MJ, Richter U, Ropo A. Efficacy and safety levels of preserved and preservative-free tafluprost are equivalent in patients with glaucoma or ocular hypertension. Acta Ophthalmol Suppl. 2008;86(s242):14–19. PMID: 18808793. Comparative data on preserved vs preservative-free prostaglandin analogue formulations relevant to latanoprost clinical decision-making.