indication

For prevention or reduction of intraoperative and postoperative increases in intraocular pressure (IOP) before and after ocular laser surgery when used prophylactically. Also used as a short-term adjunctive therapy in patients with open-angle glaucoma who are on maximally tolerated medical therapy requiring additional IOP reduction.

pharmacology

Apraclonidine significantly lowers intraocular pressure with minimal effects on cardiovascular and pulmonary parameters. It lowers intraocular pressure by reducing aqueous humor production and increasing uveoscleral outflow.

mechanism of action

Apraclonidine is a relatively selective alpha2 adrenergic receptor agonist that stimulates alpha1 receptors to a lesser extent. It has a peak ocular hypotensive effect occurring at two hours post-dosing. The exact mechanism of action is unknown, but fluorophotometric studies in animals and humans suggest that Apraclonidine has a dual mechanism of action by reducing aqueous humor production through the constriction of afferent ciliary process vessels, and increasing uveoscleral outflow.

toxicity

Accidental or intentional ingestion of oral apraclonidine has been reported to cause apnea, arrhythmias, asthenia, bradycardia, conduction defects, diminished or absent reflexes, dryness of the mouth, hypotension, hypothermia, hypoventilation, irritability, lethargy, miosis, pallor, respiratory depression, sedation or coma, seizure, somnolence, transient hypertension, and vomiting.

absorption

Topical use of apraclonidine ophthalmic solution leads to systemic absorption. Studies of apraclonidine (0.5% ophthalmic solution) dosed one drop three times a day in both eyes for 10 days in normal volunteers yielded mean peak and trough concentrations of 0.9 ng/mL and 0.5 ng/mL, respectively.

half life

8 hours

drug interactions

Tranylcypromine: The MAO inhibitor, Tranylcypromine, may increase the vasopressor effect of the alpha2-agonist, Apraclonidine. Concomitant therapy is contraindicated.

Treprostinil: Additive hypotensive effect. Monitor antihypertensive therapy during concomitant use.