BIMATOPROST
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BIMATOPROST (BIMATOPROST).
Bimatoprost is a synthetic prostamide analog that selectively mimics the effects of prostamide F2α. It binds to prostaglandin F (FP) receptors on ciliary muscle cells and trabecular meshwork cells, increasing uveoscleral outflow and possibly trabecular outflow of aqueous humor, thereby reducing intraocular pressure. It also directly stimulates the prostaglandin FP receptor, leading to increased matrix metalloproteinase activity and remodeling of the extracellular matrix in the ciliary body.
| Metabolism | Bimatoprost is rapidly metabolized via hydrolysis to the more active free acid form by esterases in the cornea and plasma. Further metabolism occurs via oxidation, reduction, and conjugation, primarily in the liver. The major enzymes involved are hepatic cytochrome P450 (CYP) isozymes, with CYP2C9 and CYP3A4 contributing to minor oxidative metabolites. The free acid is subsequently glucuronidated. |
| Excretion | Renal: <67% (unchanged and metabolites), Biliary/fecal: ~25% |
| Half-life | Terminal half-life: ~45 minutes (intravenous); after topical ocular administration, systemic half-life is similar due to rapid systemic clearance, with clinical effect lasting 24 hours due to ocular tissue binding |
| Protein binding | ~88% bound to albumin |
| Volume of Distribution | 0.3–0.4 L/kg (indicates distribution primarily into extracellular fluid) |
| Bioavailability | Topical ocular: low systemic absorption (~50% absorbed into ocular tissues, with negligible systemic bioavailability due to hydrolysis in plasma) |
| Onset of Action | Topical ocular: 2–4 hours (reduction of intraocular pressure); peak effect at 8–12 hours |
| Duration of Action | Topical ocular: 24 hours (once-daily dosing effective for intraocular pressure control) |
One drop of 0.01% or 0.03% ophthalmic solution instilled into the affected eye(s) once daily in the evening.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No dose adjustment required for renal impairment; no specific GFR-based guidelines. |
| Liver impairment | Use with caution in severe hepatic impairment (Child-Pugh class C); no specific dose adjustments established. |
| Pediatric use | Not recommended for use in pediatric patients due to lack of safety and efficacy data. |
| Geriatric use | No specific dose adjustment required; same dosing as adults, but monitor for increased systemic absorption due to age-related ocular surface changes. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for BIMATOPROST (BIMATOPROST).
| Breastfeeding | Bimatoprost is excreted in rat milk, but no human data exist. The molecular weight (415.57 Da) suggests possible excretion into human breast milk. The M/P ratio is unknown. Because of the potential for serious adverse reactions in nursing infants, especially from systemic effects of prostaglandin analogs, breastfeeding is not recommended during treatment or for 6 hours after ophthalmic administration. |
| Teratogenic Risk | Bimatoprost is a prostaglandin analog. Animal studies have shown embryofetal toxicity including skeletal malformations and increased post-implantation loss at doses >30 times the human exposure. There are no adequate and well-controlled studies in pregnant women. Risk cannot be ruled out; avoid use in pregnancy unless benefit outweighs risk. First trimester: potential teratogenicity. Second and third trimesters: potential for premature labor or uterine hyperstimulation due to oxytocic effects. |
■ FDA Black Box Warning
None
| Common Effects | Application site reactions burning irritation itching and redness Blurred vision |
| Serious Effects |
Hypersensitivity to bimatoprost or any component of the formulation. Active intraocular inflammation (e.g., uveitis). Macular edema. Caution in patients with hepatic or renal impairment. Relative contraindication in pregnancy (category C) and breastfeeding.
| Precautions | May cause gradual, permanent changes to eyelashes (increased length, thickness, pigmentation) and periorbital tissue (darkening and deepening of the upper eyelid sulcus). Increased iris pigmentation (iridal melanocytes) is irreversible. Use with caution in patients with hepatic or renal impairment. Risk of macular edema, particularly in aphakic or pseudophakic patients with a torn posterior lens capsule. May exacerbate uveitis or cystoid macular edema. Contains benzalkonium chloride; avoid in patients with hypersensitivity to this preservative. Discontinue if signs of systemic absorption occur (e.g., flushing, hypotension). |
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| Fetal Monitoring | Monitor for signs of preterm labor or uterine hypercontractility. In ophthalmic use, systemic absorption is minimal; however, periodic ophthalmic examinations for intraocular pressure control and corneal adverse effects are advised. No specific fetal monitoring required unless systemic exposure occurs (e.g., accidental oral ingestion). |
| Fertility Effects | Bimatoprost has not been studied for effects on human fertility. In animal studies, no impairment of fertility was observed in rats at doses up to 100 times the human exposure. However, prostaglandin analogs may theoretically affect reproductive function via modulation of prostaglandin pathways. |
| Food/Dietary | No significant food interactions. No dietary restrictions are required. |
| Clinical Pearls | Bimatoprost is a prostaglandin analog used for lowering intraocular pressure (IOP) in open-angle glaucoma or ocular hypertension. It increases uveoscleral outflow. Administer once daily in the evening. Do not exceed once-daily dosing as it may reduce efficacy. Touching the dropper tip to the eye or surrounding structures can contaminate the solution. Remove contact lenses before instillation and wait 15 minutes before reinserting. Common side effects include conjunctival hyperemia, eyelash growth, and periorbital pigmentation. Monitor for cystoid macular edema in aphakic or pseudophakic patients with a torn posterior lens capsule. Use with caution in patients with active intraocular inflammation (e.g., iritis/uveitis). |
| Patient Advice | Use exactly as prescribed; do not use more than once a day. · Apply in the evening to maximize effectiveness. · Wash hands before and after application. · Remove contact lenses before using and wait 15 minutes before reinserting. · Do not let the dropper tip touch your eye or any surface. · If using more than one eye drop, wait at least 5 minutes between applications. · May cause temporary blurred vision; do not drive until vision clears. · May gradually darken eyelid skin and increase eyelash growth; this is reversible upon discontinuation. · Report any eye pain, vision changes, or signs of infection (redness, swelling) to your doctor. · Store at room temperature away from light and moisture. |