Glaucoma - Alpha-adrenergic agonists (Ophthalmology)
Ophthalmic agents - Home PageGlaucoma - Home Page [<Go Back] 
Navigation
Background
Alpha-adrenergic agonists (decrease inflow)
Overview
- Decrease aqueous humor production as well as an increase in uveoscleral outflow.
- No tachyphylaxis.
- Brimonidine: no effect on mean heart rate, blood pressure, or pulmonary function.
- Should not be given with oral monoamine oxidase inhibitor antidepressants due to the risk of hypertensive crisis.
- Allergic conjunctivitis is common with Brimonidine but may be delayed for up to 18 months.
- Brimonidine- 23 times more alpha-2 selective than apraclonidine
- Contraindicated in children under 2 years old (crosses the blood–brain barrier) - risk of side effects including bradycardia, hypotension, and hypothermia.
Brimonidine tartrate ophthalmic solution 0.2%
Brimonidine tartrate ophthalmic solution 0.2% 
Pharmacology: Brimonidine tartrate ophthalmic solution 0.2% is a relatively selective alpha-2 adrenergic receptor agonist with a peak ocular hypotensive effect occurring at two hours post-dosing.
Fluorophotometric studies in animals and humans suggest that brimonidine tartrate has a dual mechanism of action by reducing aqueous humor production and increasing uveoscleral outflow.
Dosing: One drop in the affected eye(s), three times daily, approximately 8 hours apart.
Side effects: Most common adverse reactions occurring in approximately 10% to 30% of patients receiving brimonidine ophthalmic solution 0.2% included oral dryness, ocular hyperemia, burning and stinging, headache, blurring, foreign body sensation, fatigue/drowsiness, conjunctival follicles, ocular allergic reactions, and ocular pruritus.
Efficacy: In comparative clinical studies with timolol 0.5%, lasting up to one year, the IOP lowering effect of brimonidine tartrate ophthalmic solution was approximately 4 to 6 mm Hg compared with approximately 6 mm Hg for timolol. In these studies, both patient groups were dosed BID; however, due to the duration of action of brimonidine tartrate ophthalmic solution, it is recommended that brimonidine tartrate ophthalmic solution be dosed TID.
ALPHAGAN® P (brimonidine tartrate ophthalmic solution) 0.1% and 0.15%
brimonidine tartrate ophthalmic solution 0.1% and 0.15% -ALPHAGAN® P
BAK-Free: PURITE® 0.005% (0.05 mg/mL) as a preservative
Pharmacology: ALPHAGAN® P is a relatively selective alpha-2 adrenergic receptor agonist with a peak ocular hypotensive effect occurring at two hours post-dosing.
Fluorophotometric studies in animals and humans suggest that brimonidine tartrate has a dual mechanism of action by reducing aqueous humor production and increasing uveoscleral outflow.
Dosing: One drop in the affected eye(s), three times daily, approximately 8 hours apart.
Side effects: Most common adverse reactions occurring in approximately 5% to 20% of patients receiving brimonidine ophthalmic solution (0.1%-0.2%) included allergic conjunctivitis, burning sensation, conjunctival folliculosis, conjunctival hyperemia, eye pruritus, hypertension, ocular allergic reaction, oral dryness, and visual disturbance
Efficacy: Clinical studies were conducted to evaluate the safety, efficacy, and acceptability of ALPHAGAN® P (brimonidine tartrate ophthalmic solution) 0.15% compared with ALPHAGAN® administered three-times-daily in patients with open-angle glaucoma or ocular hypertension. Those results indicated that ALPHAGAN® P (brimonidine tartrate ophthalmic solution) 0.15% is comparable in IOP lowering effect to ALPHAGAN® (brimonidine tartrate ophthalmic solution) 0.2%, and effectively lowers IOP in patients with open-angle glaucoma or ocular hypertension by approximately 2-6 mmHg.
A clinical study was conducted to evaluate the safety, efficacy, and acceptability of ALPHAGAN® P (brimonidine tartrate ophthalmic solution) 0.1% compared with ALPHAGAN® administered three-times-daily in patients with open-angle glaucoma or ocular hypertension. Those results indicated that ALPHAGAN® P (brimonidine tartrate ophthalmic solution) 0.1% is equivalent in IOP lowering effect to ALPHAGAN® (brimonidine tartrate ophthalmic solution) 0.2%, and effectively lowers IOP in patients with open-angle glaucoma or ocular hypertension by approximately 2-6 mmHg.
Apraclonidine HCI 0.5%, 1% (Iopidine®)
Apraclonidine HCI 0.5%, 1% (Iopidine®)
Apraclonidine Ophthalmic Solution, USP 0.5% as base is indicated for short-term adjunctive therapy in patients on maximally tolerated medical therapy who require additional IOP reduction. Patients on maximally tolerated medical therapy who are treated with Apraclonidine Ophthalmic Solution, USP 0.5% as base to delay surgery should have frequent follow-up examinations and treatment should be discontinued if the intraocular pressure rises significantly.
The addition of Apraclonidine Ophthalmic Solution, USP 0.5% as base to patients already using two aqueous suppressing drugs (i.e., beta-blocker plus carbonic anhydrase inhibitor) as part of their maximally tolerated medical therapy may not provide additional benefit. This is because Apraclonidine Ophthalmic Solution, USP 0.5% as base is an aqueous suppressing drug and the addition of a third aqueous suppressant may not significantly reduce IOP.
The IOP lowering efficacy of Apraclonidine Ophthalmic Solution, USP 0.5% as base diminishes over time in some patients. This loss of effect, or tachyphylaxis, appears to be an individual occurrence with a variable time of onset and should be closely monitored. The benefit for most patients is less than one month.
CONTRAINDICATIONS
Apraclonidine ophthalmic solution is contraindicated in patients with hypersensitivity to apraclonidine or any other component of this medication, as well as systemic clonidine. It is also contraindicated in patients receiving monoamine oxidase inhibitors (MAO inhibitors).
Pharmacology: Apraclonidine hydrochloride is a relatively selective alpha-2-adrenergic agonist. When instilled in the eye, apraclonidine ophthalmic solution has the action of reducing elevated, as well as normal, intraocular pressure (IOP), whether or not accompanied by glaucoma. Ophthalmic apraclonidine has minimal effect on cardiovascular parameters.
Dosing: One to two drops of apraclonidine ophthalmic solution should be instilled in the affected eye(s) three times daily. Since apraclonidine ophthalmic solution will be used with other ocular glaucoma therapies, an approximate 5 minute interval between instillation of each medication should be practiced to prevent washout of the previous dose. NOT FOR INJECTION INTO THE EYE.
Side effects: In clinical studies the overall discontinuation rate related to apraclonidine ophthalmic solution was 15%. The most commonly reported events leading to discontinuation included (in decreasing order of frequency) hyperemia, pruritus, tearing, discomfort, lid edema, dry mouth, and foreign body sensation.
Efficacy: Repeated dose-response and comparative studies (0.125% to 1.0% apraclonidine) demonstrate that 0.5% apraclonidine is at the top of the dose/response IOP reduction curve.
The clinical utility of apraclonidine ophthalmic solution is most apparent for those glaucoma patients on maximally tolerated medical therapy. Patients on maximally tolerated medical therapy with uncontrolled IOP and scheduled to undergo laser trabeculoplasty or trabeculectomy surgery were enrolled into a double-masked, placebo-controlled, multi-center clinical trial to determine if apraclonidine ophthalmic solution, dosed three times daily, could delay the need for surgery for up to three months.
