Usage
Bimatoprost is primarily prescribed for the reduction of elevated intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension. It’s also used to treat eyelash hypotrichosis (inadequate or not enough eyelashes). Pharmacologically, it is classified as a prostamide, a synthetic prostaglandin analog. Bimatoprost’s mechanism of action involves increasing the outflow of aqueous humor, the fluid in the eye, thereby lowering IOP.
Alternate Names
Bimatoprost is also known by the brand names Lumigan (for glaucoma) and Latisse (for eyelash growth).
How It Works
Pharmacodynamics: Bimatoprost primarily acts on prostamide receptors, distinct from prostaglandin receptors, in the eye, increasing uveoscleral outflow of aqueous humor. This leads to a significant reduction in intraocular pressure. For eyelash growth, it prolongs the anagen (growth) phase of the eyelash hair cycle.
Pharmacokinetics:
- Absorption: After ophthalmic administration, bimatoprost is absorbed through the cornea and sclera. Peak plasma concentration is reached within approximately 10 minutes.
- Metabolism: It undergoes oxidation, N-deethylation, and glucuronidation in the liver, forming various metabolites. Though CYP3A4 plays a role, multiple metabolic pathways are involved.
- Elimination: Primarily eliminated through the urine (up to 76%) and feces (around 25%), with a half-life of approximately 45 minutes.
Dosage
Standard Dosage
Adults: One drop in the affected eye(s) once daily, administered in the evening. Do not exceed once daily, as more frequent administration may lessen the IOP-lowering effect. For eyelash growth, apply to the upper eyelid margin at the base of the eyelashes once daily at night, using a sterile applicator.
Children: Use is not recommended for the treatment of glaucoma or ocular hypertension in children under 16. Safety and efficacy have not been established for eyelash growth in children.
Special Cases:
- Elderly Patients: Use with caution; monitor for potential systemic effects.
- Patients with Renal Impairment: Use with caution, as it has not been studied in patients with moderate to severe renal impairment.
- Patients with Hepatic Dysfunction: Use with caution in patients with moderate to severe hepatic impairment. Monitor liver function tests.
- Patients with Comorbid Conditions: Use with caution in patients with respiratory issues (asthma, COPD) or heart problems (bradycardia, heart block).
Clinical Use Cases
Bimatoprost ophthalmic solution is not indicated for use in situations like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations like cardiac arrest.
Side Effects
Common Side Effects:
- Conjunctival hyperemia (eye redness)
- Itching
- Dry eyes
- Increased pigmentation of the iris, eyelashes, and periorbital skin
- Eyelash growth
- Blurred vision
Rare but Serious Side Effects:
- Eye pain
- Vision changes
- Cystoid macular edema
- Uveitis exacerbation
- Allergic reactions
Long-Term Effects:
- Permanent darkening of the iris
- Potential for worsening of respiratory or cardiovascular disease in susceptible patients
Adverse Drug Reactions (ADR):
- Allergic reactions like skin rash, hives, swelling of the face, lips, or throat require urgent medical attention.
Contraindications
- Hypersensitivity to bimatoprost or any of the ingredients
- Prior adverse reaction to benzalkonium chloride leading to discontinuation of eye drops.
Drug Interactions
- Latanoprost: Concurrent use may increase or decrease intraocular pressure. Avoid combined use.
- Other prostaglandin analogs (e.g., tafluprost, travoprost): Avoid combined use.
- NSAIDS (ophthalmic or systemic): Conflicting reports on effects on IOP; monitor closely.
Pregnancy and Breastfeeding
- Pregnancy: Pregnancy Category C. Use only if the potential benefit justifies the potential risk to the fetus.
- Breastfeeding: Bimatoprost may be excreted in breast milk. Consider discontinuing breastfeeding or the drug.
Drug Profile Summary
- Mechanism of Action: Increases uveoscleral outflow of aqueous humor.
- Side Effects: Conjunctival hyperemia, itching, dry eyes, pigmentation changes, eyelash growth.
- Contraindications: Hypersensitivity to bimatoprost or benzalkonium chloride.
- Drug Interactions: Other prostaglandin analogs, NSAIDS.
- Pregnancy & Breastfeeding: Use with caution; potential fetal risk and excretion in breast milk.
- Dosage: One drop daily in the evening.
- Monitoring Parameters: Intraocular pressure, iris pigmentation, periorbital skin changes.
Popular Combinations
Bimatoprost/timolol fixed-dose combination is available and often used for enhanced IOP lowering.
Precautions
- General Precautions: Monitor for allergies, liver or kidney problems, history of cataract surgery, dry eye, corneal problems.
- Specific Populations: Use with caution in pregnant/breastfeeding women, children, elderly, and patients with respiratory or cardiovascular issues.
- Lifestyle Considerations: Transient blurred vision may occur after instillation; avoid driving or using machines until vision clears.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Bimatoprost?
A: One drop in the affected eye(s) once daily in the evening for glaucoma or ocular hypertension. For eyelash growth, once daily at night to the upper eyelid margin.
Q2: How long does it take for Bimatoprost to work?
A: IOP reduction begins around 4 hours after administration, with maximum effect in 8-12 hours. Eyelash growth is typically noticeable within 8 weeks, with full results in 12-16 weeks.
Q3: What are the most common side effects of Bimatoprost?
A: Eye redness, itching, dry eyes, increased pigmentation of the iris, eyelashes, and eyelid skin, eyelash growth.
Q4: Can Bimatoprost permanently change eye color?
A: Yes, increased iris pigmentation can be permanent.
Q5: Is Bimatoprost safe during pregnancy or breastfeeding?
A: Use with caution; discuss the risks and benefits with your physician. Bimatoprost can be excreted in breast milk.
A: Remove contact lenses before administration and wait at least 15 minutes before reinserting. Bimatoprost can discolor soft contact lenses.
Q7: What should I do if I miss a dose?
A: Instill the missed dose as soon as remembered, then return to the regular schedule. Do not double the dose.
Q8: How should Bimatoprost be stored?
A: Store between 2-25°C (36-77°F).
Q9: Can I use Bimatoprost with other eye drops?
A: Yes, but administer other eye drops at least 5 minutes apart.
Q10: What are the long-term effects of using Bimatoprost for glaucoma?
A: Most people use bimatoprost long-term without significant issues, but rare systemic side effects like changes in blood pressure have been reported.
