Dipivefrin

Mechanism of Action

Dipivefrin is available as an ophthalmic solution. It causes vasoconstriction, decreased aqueous humor production, and decreases Intra-Ocular Pressure (IOP) of the eye. The Dipivefrin prodrug delivery system is a more efficient way of delivering the therapeutic effects of epinephrine and it is an active agent that stimulates alpha- adrenergic receptors and/or beta-adrenergic receptors increasing aqueous humor outflow with fewer side effects than are associated with conventional epinephrine therapy.

Dipivefrin hydrochloride is converted to epinephrine inside the human eye by enzyme hydrolysis. The liberated epinephrine, which is an adrenergic agonist, appears to exert its action by decreasing aqueous production and by enhancing outflow facility.

Cinical Uses

Dipivefrin hydrochloride is a member of a class of drugs known as prodrugs (substances administered in an inactive form that is then metabolized in the body in vivo into the active compound).

Dipivefrin is used to treat primary open-angle glaucoma by decreasing IOP. It metabolizes in epinephrine and cause constriction of afferent vessels in the ciliary processes via binding to and stimulation of alpha-1 receptor resulting in reduction in aqueous production. Therefore, when aqueous production is lesser than aqueous drainage, IOP decreases.

Ocular Effects

Common ocular side effects are stinging and burning. Corneal vascularization, eyelid ectropion, papillary conjunctivitis, blepharoconjunctivitis, macular edema, corneal toxicity for example dendritic keratitis, punctate keratitis or epitheliopathy, and blurred vision has been reported.
However, some patients treated with Dipivefrin reported discomfort due to photophobia, glare or light sensitivity.

There are cases of follicular conjunctivitis, mydriasis and allergic reactions to Dipivefrin reported infrequently.

Systemic effects

Systemic side effects of using Dipivefrin are slight increases in heart rate and diastolic blood pressure.

Tachycardia, arrhythmias and hypertension have been also reported with ocular administration of epinephrine.

Indications

Dipivefrin hydrochloride ophthalmic solution is indicated as initial therapy for the control of intraocular pressure in chronic open-angle glaucoma. Patients responding inadequately to other anti-glaucoma therapy may respond to addition of Dipivefrin.

According to studies, in controlled and open-label studies of glaucoma, Dipivefrin demonstrated a statistically significant intraocular pressure lowering effect. Patients using Dipivefrin twice daily in studies with mean durations of 76-146 days experienced mean pressure reductions ranging from 20-24%.

Contraindications

Dipivefrin hydrochloride should not be used if patient has a known allergy to Dipivefrin.

Patients with narrow angle glaucoma also should not use Dipivefrin hydrochloride since any dilation of the pupil may increase the risk of the patient of getting an attack of angle-closure glaucoma.

 Aqueous drainage through trabecular meshwork.

During dilation, crystalline lens becomes bigger and pushes iris towards the corneal endothelium,  leading to obstruction of aqueous drainage through trabecular meshwork, therefore IOP increases which may result in angle closure glaucoma.

Compare and Contrast for Phenylephrine and Dipivefrin