Unoprostone Isopropyl

Cross-section of the eye. Aqueous humor is present in the anterior and posterior chambers. It is drained by the trabecular meshwork near the junction of the iris and cornea. Source: Gray's Anatomy, 1918

Unoprostone isopropyl (Rescula) is a prescription ocular solution used to lower intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension. Like other IOP-lowering medications, unoprostone isopropyl is a prostaglandin analog. It is the only prostaglandin analog belonging to the docosanoid family.

Uses

Unoprostone isopropyl is indicated for the lowering of IOP in patients with open-angle glaucoma or ocular hypertension. It is generally prescribed to patients who are intolerant of other IOP-lowering medications or insufficiently responsive to another IOP-lowering medication.

How Unoprostone Isopropyl is Taken

The recommended dosage is one drop in the affected eye(s) twice daily.

If other IOP-lowering eyedrops are used concurrently, the two medications should be administered at least five minutes apart.

How It Works

Intraocular pressure is a measure of the fluid pressure inside the eye. The fluid, or aqueous humor maintains the shape of the eye and nourishes the structures of the eye. The eye produces aqueous humor, which normally circulates and is drained. The normal intraocular pressure is between 10 and 21 mm Hg (average 16). If the pressure is consistently elevated (above 21 mm Hg), intraocular hypertension results. This may lead to glaucoma and can permanently damage the optic nerve and cause loss of vision.

Often, intraocular hypertension results from a problem with the ocular drainage system.

Unoprostone isopropyl is believed to reduce elevated intraocular pressure (IOP), by increasing the outflow of aqueous humor.

How the Body Affects Unoprostone Isopropyl

After application to the eye, unoprostone is absorbed through the cornea and conjunctival epithelium where it is hydrolyzed by esterases to unoprostone free acid.

Elimination of unoprostone free acid from human plasma is rapid, with a half-life of 14 minutes. The metabolites are excreted predominately in urine.

Benefits

The benefit of lowering intraocular pressure is to prevent presure on the optic nerve and eventual loss of vision.

Specific benefits of unoprostone isopropyl are:

• A possible additive effect with other prostaglandin drugs
• No refrigeration needed for storage
• May be more effective in African-American patients (a group that can have IOP which is difficult to control). This theory did not pan out when studied. ^[1]

Side Effects

Unoprostone's side effect profile, like that of other drugs in its class, is generally favorable, and very few patients taking the drug need to discontinue taking it because of adverse events.^[2] The most common side effects (in >1% of patients) associated with Unoprostone Isopropyl use are:

• Burning or stinging of the eyes
• Dry eyes
• Itching
• Increased length of eyelashes
• Bloodshot eyes
• Abnormal vision
• Eyelid disorder
• Foreign body sensation
• Tearing disorder
• Change in eye color (increase in brown pigment)
• Flu syndrome

Risks

Complications

Serious damage to the eye and subsequent loss of vision may result from using contaminated solutions.

Patients should also be advised that if they develop an intercurrent ocular condition (e.g., trauma or infection) or have ocular surgery, they should immediately seek their physician's advice concerning the continued use of the multidose container.

Patients should be advised that if they develop any ocular reactions, particularly conjunctivitis and eyelid reactions, they should immediately seek their physician's advice.

Interactions

There is no clinical evidence of drug interactions with Unoprostone Isopropyl.

History

Unoprostone isopropyl is marketed by CIBA Vision, an eye care division of Novartis, as Rescula. It received FDA approval on August 3, 2000.

Alternatives

Medication

There are several different classes of medicine used to treat elevated IOP. Most are eye drops.

Alpha adrenergic agents

These medicines decrease the production of aqueous humor. Examples include includeapraclonidine (Iopidine) and brimonidine (Alphagan). Side effects include fatigue, dizziness, red itchy eyes, dry mouth and allergic reactions.

Beta blockers

Beta blockers also decrease the production of aqueous humor. Levobunolol (Betagan), timolol (Betimol, Timoptic), carteolol (Ocupress), betaxolol (Betoptic) and metipranolol (OptiPranolol) are some examples. Side effects include breathing difficulties, slow heart rate, fatigue, weakness, and depression. These medicines can also interact with other medications and must be used with care.

Carbonic anhydrase inhibitors

Drugs like dorzolamide (Trusopt) and brinzolamide (Azopt), reduce the amount of aqueous humor. Side effects are frequent urination and tingling in the extremities. These medicines should not be used in combination with sulfa drugs.

Epinephrine

Eye drops with epinephrine increase the drainage of the aqueous humor. Side effects include allergic reaction, pounding heart, headache, anxiety and headache.

Miotics

Miotic eye drops like pilocarpine also increase the rate of outflow of the aqueous humor. Side effects include pain in and around the eyes, stuffy nose, sweating and increased salivation.

Prostaglandin analogues

These drops, of which unoprostone isopropyl is an example, increase the outflow of aqueous humor. Other drugs in this class include latanoprost (Xalatan), bimatoprost (Lumigan) and travoprost (Travatan). Side effects are similar to those of unoprostone isopropyl.

Surgery

Surgery, either conventional or laser, involves opening the drainage channels in the eye so the fluid can drain more easily, decreasing the intraocular pressure. Laser treatment is less invasive, but the effects may be less permanent.

Statistics

One clinical study shows unoprostone reduced IOP by 5 mm Hg compared with baseline and with placebo.^[3]

Research

Recent research has shown that unoprostone isopropyl may have a neuroprotective effect in the eye, in addition to decreasing intraocular pressure. ^[4]

References

1. ↑ Ocular Hypertension Treatment Study Group. Comparison of initial intraocular pressure response with topical beta-adrenergic antagonists and prostaglandin analogues in African American and white individuals in the Ocular Hypertension Treatment Study. Arch Opthamol. 2007 Apr;125(4):454-9. Abstract
2. ↑ Holló G.The side effects of the prostaglandin analogues.Expert Opin Drug Saf. 2007 Jan;6(1):45-52. Abstract
3. ↑ Toris CB, Zhan G, Camras CB. Increase in Outflow Facility With Unoprostone Treatment in Ocular Hypertensive Patients. Arch Ophthalmol. 2004;122:1782-1787. Abstract
4. ↑ Munemasa Y, Kitaoka Y, Hayashi Y, et al. Effects of unoprostone on phosphorylated extracellular signal-regulated kinase expression in endothelin-1-induced retinal and optic nerve damage. Vis Neurosci. 2008 Mar-Apr;25(2):197-208. Abstract

External Links

The New York Times: Glaucoma Drug Approved

FDA: Patient Information Sheet