Brimonidine Composition
Brimonidine tartrate ophthalmic solution 0.2% contains the active ingredient brimonidine tartrate at 2 mg/mL (0.2%), along with inactive ingredients including citric acid, polyvinyl alcohol, sodium chloride, sodium citrate, and purified water, with benzalkonium chloride (0.05 mg/mL) as a preservative. 1
Active Ingredient
- Brimonidine tartrate: 0.2% (2 mg/mL)
- Chemical name: 5-bromo-6-(2-imidazolidinylideneamino) quinoxaline L-tartrate
- Molecular weight: 442.24 (as the tartrate salt)
- Mechanism: Highly selective alpha-2 adrenergic agonist 1
Inactive Ingredients
The formulation includes several inactive components that maintain solution stability and pH:
- Citric Acid - pH buffer
- Polyvinyl Alcohol - viscosity agent
- Sodium Chloride - tonicity agent
- Sodium Citrate - pH buffer
- Purified Water - vehicle
- Hydrochloric Acid and/or Sodium Hydroxide - pH adjusters (as needed) 1
Preservative
Benzalkonium chloride (BAK): 0.05 mg/mL (0.005%) 1
Important Caveats About BAK
The benzalkonium chloride preservative warrants specific attention:
Contact lens interaction: BAK is absorbed by soft contact lenses. Patients must wait at least 15 minutes after instillation before inserting soft contact lenses 1
Goblet cell toxicity: Research demonstrates that BAK concentration correlates with damage to conjunctival goblet cells. At 0.005% BAK concentration (as in brimonidine), cell viability remained at 93% after 30 minutes and 74% after 6 hours of exposure, showing minimal toxicity compared to formulations with higher BAK concentrations 2
Barrier function effects: Despite lower toxicity, brimonidine with sodium chlorite preservative can cause widening of intercellular junctions in corneal epithelium, potentially reducing barrier function 3
Physical Properties
The solution has specific characteristics 1:
- Appearance: Clear, greenish-yellow color
- Osmolality: 280-330 mOsm/kg
- pH: 5.6-6.6
Available Formulations
Brimonidine is supplied in plastic bottles with controlled drop tips in 5 mL and 10 mL sizes 1. Preservative-free formulations are also available for patients sensitive to BAK or at increased risk of ocular surface disease 4.