ALPHAGAN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ALPHAGAN (ALPHAGAN).
Selective alpha-2 adrenergic receptor agonist; reduces intraocular pressure by decreasing aqueous humor production and increasing uveoscleral outflow.
| Metabolism | Primarily hepatic via oxidation and reduction; minor role of CYP450 enzymes. |
| Excretion | Renal: approximately 70-80% as unchanged drug and metabolites; fecal: 5-10%. |
| Half-life | 2.5-3.0 hours in adults; in renal impairment, half-life is prolonged (up to 6 hours). |
| Protein binding | 25-30% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | 1.2-1.5 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Ophthalmic: <10% systemic absorption; oral: 100% (not clinically used). |
| Onset of Action | Ophthalmic: 1-2 hours post-instillation for intraocular pressure reduction. |
| Duration of Action | Ophthalmic: 8-12 hours; used twice daily for glaucoma. |
1 drop of 0.1% or 0.15% solution in the affected eye(s) three times daily, approximately 8 hours apart.
| Dosage form | SOLUTION/DROPS |
| Renal impairment | No dosage adjustment required for GFR >30 mL/min. Use with caution in severe renal impairment (GFR <30 mL/min) due to potential for increased systemic exposure; monitor for adverse effects. |
| Liver impairment | No specific guidelines; use with caution in Child-Pugh class B or C due to decreased drug metabolism; monitor for systemic effects. |
| Pediatric use | Not recommended for use in children under 2 years of age. For children ≥2 years: same as adult dosing; limited data available. |
| Geriatric use | No specific dose adjustment needed; monitor for hypotension, bradycardia, and fatigue due to potential increased systemic absorption in elderly with reduced tear production. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ALPHAGAN (ALPHAGAN).
| Breastfeeding | Not recommended for use in breastfeeding women. Brimonidine is excreted in animal milk; M/P ratio unknown. Risk of neonatal hypotension, bradycardia, and apnea. |
| Teratogenic Risk | Pregnancy Category B. No evidence of teratogenicity in animal studies; however, no adequate human studies. Potential for fetal bradycardia if maternal systemic absorption occurs. Use only if benefit outweighs risk. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Common Effects | Blurred vision Drowsiness Headache Dryness in mouth Conjunctivitis Conjunctival hyperemia Eye itching Burning sensation Follicular conjunctivitis Allergic reaction in eye Eyelid inflammation Photophobia Corneal erosion Dry eye Visual disorder Dizziness Taste change Upper respiratory tract infection Conjunctival blanching Gastrointestinal discomfort Fatigue Stinging sensation |
| Serious Effects |
Hypersensitivity to brimonidine or any component; use in neonates and infants (especially those under 2 years of age) due to risk of CNS depression.
| Precautions | Potential for central nervous system depression (e.g., somnolence, dizziness), particularly in children and elderly; use with caution in patients with cardiovascular disease (e.g., bradycardia, hypotension), depression, or cerebral insufficiency; may cause ocular allergic reactions and corneal edema. |
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| Monitor maternal heart rate and blood pressure for systemic effects. Fetal heart rate monitoring if maternal systemic symptoms occur. Assess for signs of CNS depression in neonate if used near term. |
| Fertility Effects | No specific human fertility studies reported. Animal studies show no impairment of fertility at therapeutic doses. |
| Food/Dietary |
| No significant food interactions. Avoid alcohol as it may increase dizziness or drowsiness. No dietary restrictions required. |
| Clinical Pearls | Alphagan (brimonidine) is a selective alpha-2 adrenergic agonist used primarily for lowering intraocular pressure in open-angle glaucoma or ocular hypertension. It can cause conjunctival hyperemia, blurred vision, and dry mouth. Apraclonidine is a similar but less selective agent; Alphagan has lower risk of allergic reactions. Avoid use in neonates or infants due to risk of CNS depression. Contraindicated in patients on MAOIs or tricyclic antidepressants. |
| Patient Advice | Apply one drop in the affected eye(s) three times daily, about 8 hours apart. · After instilling the drop, keep your eye closed and press on the tear duct (nasolacrimal sac) for 1 minute to minimize systemic absorption. · Do not touch the dropper tip to your eye or any surface to avoid contamination. · Wait at least 5 minutes between applying different eye medications. · You may experience temporary blurred vision, eye redness, or a dry mouth; these usually resolve with continued use. · If you experience severe eye pain, vision changes, or signs of allergic reaction (rash, swelling), stop use and contact your doctor. · Remove contact lenses before instilling drops and wait at least 15 minutes before reinserting. · Do not drive or operate machinery until your vision clears. |