Unoprostone

Unoprostone Overview

Unoprostone is a synthetic docosanoid eicosanoid derivative and prostaglandin F2α (PGF2α) ester analogue. Chemically, it belongs to the class of organic compounds known as prostaglandins and related compounds within the eicosanoids sub-class of fatty acyls. Structurally, it consists of a 22-carbon docosanoid skeleton possessing a substituted cyclopentane ring bearing two hydroxyl groups at the C-9 and C-11 positions, an α-chain esterified with an isopropyl group, and a modified 10-carbon ω-side chain featuring a C-15 keto group, with a molecular weight of 424.62 g/mol.

What Is Unoprostone and How Does It Work?

Unoprostone acts primarily through corneal esterase cleavage into active unoprostone, followed by activation of BKCa potassium and ClC-2 chloride channels in trabecular meshwork cells and weak FP receptor agonism, driving relaxation of trabecular meshwork tissue, increased conventional/uveoscleral aqueous humor outflow, and sustained intraocular pressure reduction.

Is Unoprostone FDA Approved?

Unoprostone isopropyl 0.15% ophthalmic solution received its initial New Drug Application (NDA 021214) approval from the U.S. Food and Drug Administration (FDA) on August 3, 2000 under the trade name Rescula for lowering intraocular pressure in patients with open-angle glaucoma or ocular hypertension. Following commercial re-prioritization, sales were voluntarily discontinued in March 2015, and the FDA formally withdrew approval of NDA 021214 effective July 21, 2017 (82 FR 28322) upon voluntary request by the application holder. This regulatory withdrawal was driven by commercial factors rather than safety or efficacy concerns. Its official regulatory standing remains classified as Discontinued / Withdrawn Status in FDA drug databases.

What Was/Is Unoprostone Used For?

• Reduction of elevated intraocular pressure (IOP) in patients with open-angle glaucoma who are inadequately controlled on or intolerant to first-line monotherapies (β-blockers, latanoprost).
• Lowering intraocular pressure in patients with ocular hypertension at high risk for glaucomatous optic neuropathy.
• Adjunctive second-line combination therapy alongside topical β-blockers (timolol) or carbonic anhydrase inhibitors (dorzolamide) to achieve target IOP.

Before Taking Unoprostone: Contraindications & Precautions

Do not administer Unoprostone to patients with a known severe hypersensitivity to unoprostone, unoprostone isopropyl, prostaglandin analogues, or formulation excipients (including benzalkonium chloride). Exercise caution in patients with active intraocular inflammation (iritis, uveitis), as prostaglandin derivatives can exacerbate blood-aqueous barrier breakdown and intraocular inflammation.

Who Should Not Take Unoprostone?

• Individuals with known severe hypersensitivity or allergy to Unoprostone isopropyl or prostanoid analogues.
• Patients with active intraocular inflammation (active anterior uveitis, iridocyclitis).
• Patients wearing soft contact lenses during instillation (benzalkonium chloride is absorbed by soft lenses).

Unoprostone, Pregnancy & Safety

Systemic absorption following topical ocular instillation of Unoprostone is minimal due to rapid plasma clearance (t1/2 < 14 minutes). However, prostaglandins can induce uterine contractions and alter vascular tone. Animal reproduction studies evaluating systemic unoprostone demonstrated embryofetal toxicity and increased pregnancy loss at high parenteral doses. It is classified as Pregnancy Category C.

Tell Your Doctor Before Taking Unoprostone

Inform your ophthalmologist or physician if you have a history of uveitis, iritis, macular edema, eye surgery, cataract extraction, dry eye syndrome, or severe asthma, or if you are using other topical eye drops.

Unoprostone Dosage & Administration

Formulated as a sterile, topical ophthalmic solution (0.15% w/v [1.5 mg/mL] unoprostone isopropyl).

Unoprostone dosing requires strict adherence to twice-daily administration protocols.

Standard Unoprostone Dosing

• Ophthalmic IOP-Lowering Dosing (Adults & Elderly): Instill 1 drop of 0.15% Unoprostone solution into the conjunctival sac of the affected eye(s) twice daily (in the morning and evening).
• Combination Topical Therapy Dosing: If using more than one topical ophthalmic drug, separate instillation times by at least 5 minutes to prevent washout of active ingredients.
• Dosing Ceiling Threshold: Administration more frequently than twice daily is not recommended, as frequent dosing can paradoxical decrease the IOP-lowering efficacy of prostaglandin analogues.

How Was/Is Unoprostone Administered

• Tilt head back, pull lower eyelid down to form a pouch, hold dropper bottle vertically, and instill 1 drop into the pouch without touching the eye or eyelid.
• Perform Nasolacrimal Occlusion: Close the eye gently and press finger against the inner corner of the eye (lacrimal sac) for 1 to 2 minutes post-instillation to reduce systemic absorption.
• Remove soft contact lenses prior to instillation; wait at least 15 minutes before reinserting lenses.

Unoprostone Clinical Efficacy & Research

In clinical ophthalmology and glaucoma research, Unoprostone is established as a second-line ocular hypotensive docosanoid. Multi-center randomized double-blind clinical trials evaluating Unoprostone isopropyl 0.15% twice daily in patients with open-angle glaucoma or ocular hypertension demonstrate a statistically significant mean IOP reduction of 3 to 5 mmHg (15% to 22% baseline reduction) over 6 to 12 months. Comparative clinical trials indicate that while Unoprostone provides modest IOP lowering compared to high-potency FP agonists like latanoprost or bimatoprost, it exhibits a significantly lower incidence of severe conjunctival hyperemia, iris color changes, and periocular fat atrophy.

Unoprostone Side Effects & Safety Profile

Unoprostone exhibits a favorable ocular and systemic safety profile. Safety hazards stem primarily from localized ocular surface changes, cosmetic pigmentation shifts, and low-grade ocular irritation.

Adverse effects are localized predominantly to the anterior segment of the eye.

Common Unoprostone Side Effects

• Ophthalmic Application (10% to 25% incidence): Mild conjunctival hyperemia (eye redness), burning, stinging upon instillation, ocular itching (pruritus), dry eye sensation, increased lacrimation, and feeling of a foreign body in the eye.
• Ophthalmic Application (1% to 10% incidence): Corneal erosion, superficial punctate keratitis, eyelid edema, blepharitis, blurred vision, and mild headache.

Serious Unoprostone Adverse Events

• Irreversible Iris Hyperpigmentation: Increased brown pigment deposition in the iris stroma secondary to stimulated melanogenesis in iridial melanocytes; changes are permanent and may cause heterochromia if only one eye is treated.
• Reversible Eyelid & Periocular Changes: Darkening of the eyelid skin (hyperpigmentation) and hypertrichosis (increased length, thickness, and number of eyelashes); changes resolve upon drug cessation.
• Cystoid Macular Edema (CME): Retinal swelling and diminished visual acuity in high-risk pseudophakic or aphakic patients.
• Reactivation of Intraocular Inflammation: Exacerbation of anterior uveitis, iritis, or herpes simplex keratitis.

Managing Unoprostone Side Effects

If severe ocular burning or keratitis develops, evaluate corneal integrity using fluorescein staining. If cystoid macular edema is suspected, perform optical coherence tomography (OCT) and discontinue Unoprostone. Warn patients that iris color changes are permanent.

Unoprostone Drug Interactions & What to Avoid

Unoprostone displays minimal systemic drug-drug interactions due to negligible plasma concentrations, but ocular interactions occur with specific agents.

Co-administration with specific ophthalmic drug classes requires clinical awareness.

Unoprostone Drug-Drug Interactions

• Topical Non-Steroidal Anti-Inflammatory Drugs (NSAIDs – Ketorolac, Bromfenac, Nepafenac): Concurrent use of topical NSAIDs may theoretically blunt the FP-receptor-mediated uveoscleral outflow component of Unoprostone; monitor IOP closely if combined.
• Thimerosal-Containing Ophthalmic Solutions: Mixing Unoprostone directly with thimerosal-containing eye drops forms precipitates; separate instillation by at least 10 minutes.
• Concomitant Antiglaucoma Agents (β-Blockers, Alpha-2 Agonists): Additive IOP-lowering effect when combined with timolol, brimonidine, or dorzolamide; excellent compatibility for combination regimens.

Unoprostone, Food & Alcohol

Systemic food and alcohol interactions do not occur with topical ophthalmic administration.

Unoprostone: Missed Dose, Overdose & Storage

Proper handling of Unoprostone involves consistent twice-daily instillation and proper solution storage. Overdose is rare with topical application.

Adherence to proper storage parameters prevents chemical hydrolysis and bacterial contamination.

Missed Dose of Unoprostone

Instill the missed drop as soon as remembered, unless near the time for the next scheduled dose. Skip the missed dose if near the next dose; do not instill double drops to make up for a missed dose.

Unoprostone Overdose & Emergency

Topical ocular overdose is self-limiting due to excess liquid flushing out of the conjunctival sac. Accidental oral ingestion of an entire 5 mL bottle of 0.15% solution yields 7.5 mg of unoprostone isopropyl, which undergoes rapid first-pass hepatic metabolism. Symptoms of systemic exposure may include flushing, abdominal cramps, diarrhea, and dizziness. Treatment is supportive; flush eyes with saline if topical overdose occurs.

How to Store Unoprostone

Store unopened and opened Unoprostone 0.15% ophthalmic bottles at controlled room temperature between 2°C and 25°C (36°F to 77°F). Protect strictly from freezing and direct light exposure. Keep bottle tightly closed when not in use. Keep out of reach of children.

Unoprostone Patient Management & Monitoring

Clinical oversight for patients taking Unoprostone focuses on measuring intraocular pressure, inspecting the optic nerve head, and monitoring for ocular surface changes.

Regular clinical tracking ensures successful IOP control without progressive ocular surface toxicity.

Tests Before Starting Unoprostone

Baseline intraocular pressure (IOP) measurement via Goldmann applanation tonometry; baseline optic nerve head examination and retinal nerve fiber layer (RNFL) imaging; baseline visual field testing; baseline iris photograph to document eye color.

Monitoring During Unoprostone Treatment

Re-evaluating IOP at 4 weeks and 12 weeks post-initiation; inspecting anterior segment and cornea for punctate keratitis or hyperemia; inspecting iris and eyelid for hyperpigmentation; performing annual visual field and OCT optic nerve scans.

Unoprostone Do’s and Don’ts

• Do instill Unoprostone drops twice daily (morning and evening) as prescribed.
• Do press the inner corner of your eye for 1 to 2 minutes after applying drops to stop systemic absorption.
• Do remove soft contact lenses before instilling drops and wait 15 minutes before reinserting them.
• Do not touch the dropper tip to your eye, fingers, or any surface to avoid contamination.
• Do not double your dose if you miss an application.
• Do not stop using your eye drops without consulting your ophthalmologist, as pressure can rise rapidly.

Frequently Asked Questions

References

• DrugBank Database – Unoprostone Clinical Profile (DB06826)
• Classyfire Database – Prostaglandins and Related Compounds / Eicosanoids Taxonomy Profile
• Surveys of Ophthalmology – Unoprostone Isopropyl 0.15%: Ophthalmic Mechanism and Clinical Efficacy

Legal Disclaimer

The detailed medical and chemical information provided on this specific web page is intended strictly for educational and informational purposes regarding complex pharmacological mechanisms. It absolutely does not constitute professional medical advice, medical diagnosis, or specific treatment recommendations. Always consult a licensed healthcare provider before making any personal decisions regarding complex medical conditions, medication adjustments, or dietary changes.