Usage
- Latanoprost is prescribed for the reduction of elevated intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension. It is also used in pediatric patients with elevated IOP and pediatric glaucoma.
- Pharmacological Classification: Prostaglandin F2α analog, ocular hypotensive.
- Mechanism of Action: Latanoprost acid, the biologically active form of latanoprost, is a selective FP prostanoid receptor agonist that primarily works by increasing uveoscleral outflow of aqueous humor, thereby reducing IOP.
Alternate Names
- Latanoprost acid (active form)
- Brand Names: Xalatan, Xelpros, Monopost, Iyuzeh, Rocklatan (combined with netarsudil)
How It Works
- Pharmacodynamics: Latanoprost acid reduces IOP by increasing the uveoscleral outflow of aqueous humor. It has little to no effect on the pupil or aqueous humor production.
- Pharmacokinetics:
- Absorption: Latanoprost, an isopropyl ester prodrug, is administered topically to the eye. It is hydrolyzed by esterases in the cornea to latanoprost acid, its biologically active form.
- Metabolism: Latanoprost acid is primarily metabolized in the liver via fatty acid β-oxidation to inactive metabolites.
- Elimination: The major elimination pathways are hepatic and renal. The metabolites are mainly excreted in the urine. The elimination half-life is approximately 17 minutes.
- Mode of Action: Latanoprost acid binds to FP prostanoid receptors in the uveoscleral pathway, leading to relaxation of ciliary muscle and increased outflow of aqueous humor through the uveoscleral route.
- Receptor Binding: FP prostanoid receptor agonist.
- Enzyme Inhibition/Neurotransmitter Modulation: No significant enzyme inhibition or neurotransmitter modulation is associated with latanoprost’s IOP-lowering effect.
- Elimination Pathways: Hepatic metabolism followed by renal and fecal excretion.
Dosage
Standard Dosage
Adults:
- One drop in the affected eye(s) once daily, preferably in the evening.
- Do not exceed once daily application as more frequent administration can diminish the IOP-lowering effect.
Children:
- One drop in the affected eye(s) once daily, preferably in the evening.
- Safety and efficacy in preterm infants (less than 36 weeks gestational age) and children under one year of age have not been fully established. Limited data suggest similar dosing as adults.
Special Cases:
- Elderly Patients: Same dosage as adults.
- Patients with Renal Impairment: No dose adjustment is typically necessary, but use with caution.
- Patients with Hepatic Dysfunction: No dose adjustment is typically necessary, but use with caution.
- Patients with Comorbid Conditions: Use with caution in patients with active intraocular inflammation, a history of herpetic keratitis, macular edema risk factors, or severe asthma.
Clinical Use Cases
Latanoprost is not typically used in the clinical settings of intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations. It is intended for chronic management of glaucoma and ocular hypertension.
Dosage Adjustments
No routine dosage adjustments are needed based solely on renal or hepatic function. However, clinical judgment is advised in patients with severe dysfunction.
Side Effects
Common Side Effects
- Blurred vision
- Burning/stinging
- Eye redness/irritation/itching
- Increased tearing
- Foreign body sensation
- Increased iris pigmentation
- Eyelash changes (increased length, thickness, pigmentation)
- Eyelid skin darkening
Rare but Serious Side Effects
- Macular edema (especially in aphakic or pseudophakic patients)
- Iritis/uveitis
- Herpetic keratitis
- Bacterial keratitis
- Severe allergic reactions (e.g., rash, itching/swelling, severe dizziness, difficulty breathing)
Long-Term Effects
- Permanent increase in brown iris pigmentation
- Permanent eyelash changes
Adverse Drug Reactions (ADR)
- Severe allergic reaction
- Exacerbation of pre-existing macular edema or intraocular inflammation
Contraindications
- Hypersensitivity to latanoprost, benzalkonium chloride, or any component of the formulation.
- Active intraocular inflammation.
- Active herpes simplex keratitis.
Drug Interactions
- Other prostaglandin analogs (e.g., bimatoprost, travoprost): Combined use may decrease IOP-lowering effect or cause paradoxical IOP elevation.
- NSAIDs (ophthalmic or systemic): May alter IOP effects.
- Timolol: Additive IOP lowering effect.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: C (US FDA - Old System, being phased out). Limited human data. Animal studies showed some adverse effects at high doses. Use only if benefit outweighs risk.
- Breastfeeding: No information on human milk excretion is available, but due to minimal systemic absorption after ocular administration risk is considered low. Use with caution. Consider punctal occlusion after administration to reduce the risk of drug exposure through breast milk.
Drug Profile Summary
- Mechanism of Action: FP prostanoid receptor agonist; increases uveoscleral outflow of aqueous humor.
- Side Effects: Blurred vision, burning/stinging, eye redness/irritation, increased pigmentation of the iris, eyelash changes.
- Contraindications: Hypersensitivity to latanoprost, benzalkonium chloride, active intraocular inflammation, active herpetic keratitis.
- Drug Interactions: Other prostaglandin analogs, NSAIDs.
- Pregnancy & Breastfeeding: Limited human data; use cautiously if benefits outweigh risks.
- Dosage: Adults and children: One drop in the affected eye(s) once daily in the evening.
- Monitoring Parameters: IOP, iris color, eyelash growth, signs of intraocular inflammation, macular edema.
Popular Combinations
- Latanoprost/timolol fixed-combination eye drops are available and commonly used to achieve additive IOP lowering.
Precautions
- General Precautions: Monitor for changes in iris color, eyelash growth, and signs of macular edema or intraocular inflammation.
- Pregnant Women: Use only if the potential benefit justifies the potential risk to the fetus.
- Breastfeeding Mothers: Exercise caution.
- Children & Elderly: Similar dosing to adults. Monitor closely for side effects.
- Lifestyle Considerations: May cause transient blurred vision after instillation. Advise patients not to drive or operate machinery until vision clears.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Latanoprost?
A: One drop in the affected eye(s) once daily, preferably in the evening, for both adults and children.
Q2: Can Latanoprost permanently change eye color?
A: Yes, Latanoprost can gradually increase the amount of brown pigment in the iris, which can be permanent. Patients should be informed of this possibility before initiating treatment.
A: Contact lenses should be removed before instilling Latanoprost and can be reinserted after 15 minutes.
Q4: What are the signs of a serious allergic reaction to Latanoprost?
A: Signs include rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, and trouble breathing. Seek immediate medical attention if these occur.
Q5: Can Latanoprost be used during pregnancy?
A: There are limited human data. Animal studies showed some adverse effects at high doses. Use only if benefit outweighs risk after careful discussion with the patient.
Q6: Is it safe to use Latanoprost while breastfeeding?
A: No information is available on excretion into human milk. However, due to minimal systemic absorption after topical ocular administration, the risk is considered low. Use with caution and employ punctal occlusion technique after administration to minimize systemic exposure.
Q7: What are the main drug interactions with Latanoprost?
A: Clinically significant interactions can occur with other prostaglandin analogs, NSAIDS (both systemic and ophthalmic), which may interfere with IOP-lowering effects. Additive IOP-lowering may occur with concomitant Timolol.
Q8: What is the mechanism of action of Latanoprost?
A: Latanoprost acid, the active metabolite, primarily increases uveoscleral outflow of aqueous humor by acting as a selective FP prostanoid receptor agonist.
Q9: What should be done if a dose of Latanoprost is missed?
A: Skip the missed dose and resume the usual dosing schedule the next day. Do not double the dose.
Q10: How should Latanoprost be stored after opening the bottle?
A: Store below 25°C and use within four weeks of opening.
