BRIMONIDINE TARTRATE
Clinical safety rating: safe
Animal studies have demonstrated safety
Selective alpha-2 adrenergic receptor agonist; reduces aqueous humor production and increases uveoscleral outflow by activating presynaptic alpha-2 receptors, inhibiting norepinephrine release and decreasing cAMP in ciliary epithelium.
| Metabolism | Primarily hepatic metabolism via aldehyde oxidase and cytochrome P450 (CYP2D6 and CYP3A4) to inactive metabolites; minor renal excretion. |
| Excretion | Renal excretion of unchanged drug and metabolites accounts for approximately 74% of the dose; fecal excretion accounts for approximately 22%. The remainder is eliminated via biliary secretion. |
| Half-life | Terminal elimination half-life is approximately 2 hours in adults; in neonates and infants, half-life may be prolonged (up to 8–12 hours) due to immature renal function. |
| Protein binding | Approximately 29% bound to serum proteins (predominantly albumin). |
| Volume of Distribution | Volume of distribution is approximately 1.2 L/kg, indicating extensive tissue distribution. In neonates and infants, Vd may be larger due to higher total body water. |
| Bioavailability | Ocular: Systemic bioavailability after topical administration is 10–30% (due to nasolacrimal drainage and conjunctival absorption). Oral: High, but not used clinically due to extensive first-pass metabolism. |
| Onset of Action | Ocular: Plasma concentrations peak within 1–2 hours after topical application; reduction in intraocular pressure occurs within 1–4 hours. |
| Duration of Action | Ocular: Duration of action is up to 12 hours after a single dose, supporting twice-daily dosing. Maximal effect occurs at 2–5 hours. |
1 drop of 0.1% or 0.15% solution in the affected eye(s) twice daily, approximately 12 hours apart.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No dose adjustment required for GFR ≥30 mL/min. For GFR <30 mL/min, use with caution; data insufficient for specific dose modification. |
| Liver impairment | No specific dose adjustment for Child-Pugh A or B. For Child-Pugh C, contraindicated due to risk of systemic toxicity. |
| Pediatric use | Children ≥2 years: 1 drop of 0.1% or 0.15% solution in the affected eye(s) twice daily. Safety and efficacy not established in children <2 years. |
| Geriatric use | No specific dose adjustment. Monitor for increased systemic absorption due to altered pharmacokinetics; use lowest effective dose and observe for hypotension, bradycardia, and somnolence. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
CNS depressants may potentiate effects MAOIs may potentiate vasoconstrictive effect May cause fatigue and drowsiness in some patients.
| Breastfeeding | Brimonidine is excreted in human milk after oral administration but no data on ophthalmic use. The M/P ratio is not established. Due to potential for serious adverse reactions in nursing infants (e.g., bradycardia, hypotension), caution advised. Discontinue nursing or drug based on importance to mother. |
| Teratogenic Risk | Brimonidine tartrate is classified as Pregnancy Category B. In animal studies, no teratogenic effects were observed at doses up to 2.8 mg/kg/day (approximately 150 times the human plasma AUC at the maximum recommended human ophthalmic dose). No adequate and well-controlled studies in pregnant women exist. Risk to fetus during first trimester remains theoretical; second and third trimester risks include potential fetal bradycardia due to alpha-2 agonism, especially with systemic exposure. Avoid use unless clearly needed. |
■ FDA Black Box Warning
None
| Common Effects | ocular hypertension |
| Serious Effects |
Hypersensitivity to brimonidine or any component; concomitant use with monoamine oxidase inhibitors (MAOIs); use in neonates and infants (risk of apnea and bradycardia); severe renal impairment (for systemic formulations).
| Precautions | May cause systemic hypotension, bradycardia, and syncope; use caution in patients with cardiovascular disease, cerebral or coronary insufficiency, Raynaud's phenomenon, orthostatic hypotension, or severe hepatic impairment. CNS depression possible; avoid concurrent use with CNS depressants. Topical ophthalmic use may cause allergic conjunctivitis, blurred vision, and ocular hyperemia. Caution in nursing infants (excreted in breast milk). |
| Food/Dietary |
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| Fetal Monitoring | Monitor maternal blood pressure and heart rate periodically. In neonates exposed in utero, observe for bradycardia, hypotension, and respiratory depression. No specific fetal monitoring required unless maternal toxicity evident. |
| Fertility Effects | No human data on fertility effects. Animal studies at oral doses up to 1 mg/kg/day (approx. 100 times the human ophthalmic dose) showed no impairment of fertility. |
| No known food interactions. |
| Clinical Pearls | Brimonidine tartrate is a selective alpha-2 adrenergic agonist used to reduce intraocular pressure (IOP) in open-angle glaucoma or ocular hypertension. Onset of action is 1 hour, peak effect at 2 hours, duration 12 hours. Avoid in patients with MAO inhibitor therapy or severe cardiovascular disease. Monitor for systemic hypotension and bradycardia. Can cause conjunctival folliculosis with long-term use. Use with caution in renal impairment (CrCl <30 mL/min). |
| Patient Advice | Instill one drop in the affected eye(s) three times daily, about 8 hours apart. · Wash hands before use; avoid touching the dropper tip to any surface. · Remove contact lenses before instillation and wait 15 minutes before reinserting. · If using other eye drops, separate by at least 5 minutes. · May cause blurred vision, dry mouth, or fatigue; do not drive if vision is blurred. · Report eye pain, vision changes, or persistent redness to your doctor. · Do not use if solution is discolored or contains particles. |