Comprehensive medication guide to Istalol including estimated pricing, availability information, side effects, and how to find it in stock at your local pharmacy.
Estimated Insurance Pricing
$0–$10 copay for generic timolol (Tier 1 on most plans); brand-name Istalol may require prior authorization; step therapy toward generic common.
Estimated Cash Pricing
$482.74 retail for brand-name Istalol (5 mL); as low as $6.99–$35 with GoodRx or SingleCare coupons for generic timolol maleate 0.5% for a 30-day supply.
Medfinder Findability Score
68/100
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Istalol is the brand name for timolol maleate ophthalmic solution 0.5%, manufactured by Bausch + Lomb. It is a non-selective beta-adrenergic receptor blocker (beta-blocker) prescribed as a once-daily eye drop for the treatment of elevated intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension. The FDA first approved the Istalol formulation on June 4, 2004.
Istalol is unique among timolol formulations because its special formulation allows once-daily dosing in the morning — achieving the same intraocular pressure control as standard timolol 0.5% drops dosed twice daily. This once-daily schedule can improve patient adherence, which is critical in a chronic condition like glaucoma where missing doses can lead to irreversible vision loss.
A generic equivalent — timolol maleate ophthalmic solution 0.5%, once-daily — was FDA-approved in July 2024 (manufactured by Somerset Theraps LLC) and is therapeutically equivalent to brand-name Istalol.
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Istalol works by blocking beta-1 and beta-2 adrenergic receptors in the eye. The primary mechanism is reduction of aqueous humor production. Aqueous humor is the clear fluid that fills the front portion of the eye. It is continuously produced by the ciliary body and drains through channels at the edge of the iris. When production exceeds drainage, intraocular pressure rises — the main risk factor for glaucoma.
By blocking beta-2 receptors on the ciliary epithelium, timolol maleate inhibits the enzymatic activity that drives fluid production. Less fluid is produced, which lowers IOP. Studies have confirmed this mechanism using tonography and fluorophotometry. In clinical trials, Istalol 0.5% once daily reduced mean IOP from 25 mm Hg at baseline to approximately 18 mm Hg at peak — a clinically significant reduction of about 7 mm Hg (28%).
The onset of action is rapid — IOP begins falling within 15-30 minutes of instillation — and the effect lasts approximately 24 hours. Because timolol is absorbed systemically through the nasolacrimal duct (60-78% bioavailability), it can also affect the cardiovascular and respiratory systems, which is why patients with asthma, COPD, or certain heart conditions cannot use it.
0.5% (5 mg/mL) — ophthalmic solution (eye drops)
Standard Istalol formulation: one drop in affected eye(s) once daily in the morning. Available in 2.5 mL and 5 mL bottles.
Istalol has a findability score of 68 out of 100 — meaning it is findable with moderate effort, but not every pharmacy stocks the brand. Since the FDA approved a generic equivalent in July 2024, many pharmacies have transitioned to stocking the lower-cost generic timolol maleate once-daily 0.5% instead of the Istalol brand. Patients who specifically need the brand may need to check multiple pharmacies.
Related timolol products — particularly the gel-forming solution (generic Timoptic-XE) from Sandoz — have been on back order with no estimated release date. Standard generic timolol 0.5% solution (dosed twice daily) from manufacturers like Apotex is more widely available.
If you cannot find Istalol at your local pharmacy, medfinder can call pharmacies near you and text you which ones have it in stock. medfinder covers all medications and does the searching so you don't have to.
Istalol is not a controlled substance and does not require a DEA license or any special prescribing authority beyond a standard prescriber license. Any licensed prescriber in the United States can write a prescription for Istalol. In practice, the following providers are the most common prescribers:
Telehealth is available for prescription renewals for established glaucoma patients. However, a new diagnosis of glaucoma requires an in-person examination with IOP measurement (tonometry), visual field testing, and optic nerve assessment — which cannot be performed via telehealth. Telehealth platforms like Teladoc and specialty eye care services may support prescription renewals for stable patients.
No. Istalol is not a controlled substance and is not listed under any DEA schedule. It is a standard prescription medication — a beta-blocker — with no known potential for abuse or dependence. Istalol does not require a DEA-registered prescriber and can be prescribed by any licensed physician, optometrist (in most states), nurse practitioner, or physician assistant.
Prescriptions for Istalol can be phoned in, faxed, or sent electronically to the pharmacy. There are no special quantity limits or early refill restrictions associated with controlled substance regulations. However, some insurance plans may impose their own quantity limits or refill interval requirements unrelated to DEA scheduling.
The following side effects are common and generally mild:
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Latanoprost (Xalatan)
Prostaglandin analog; current first-line treatment for glaucoma. Increases aqueous outflow via uveoscleral pathway. Once daily at bedtime. Generic available for as low as $5-$15 with GoodRx. Safe for patients who cannot use beta-blockers.
Brimonidine (Alphagan)
Alpha-2 agonist with dual mechanism — reduces production and increases uveoscleral outflow. Used 2-3 times daily. Good add-on therapy or alternative for patients who cannot use beta-blockers.
Dorzolamide (Trusopt)
Carbonic anhydrase inhibitor (CAI). Reduces aqueous production through a different enzyme pathway — safe for patients with asthma or COPD. Used twice or three times daily. Available generically.
Betaxolol (Betoptic)
Selective beta-1 blocker eye drop. Potentially safer for patients with mild pulmonary disease compared to timolol. Less IOP-lowering efficacy than non-selective beta-blockers. Used twice daily.
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Calcium channel blockers (verapamil, diltiazem)
majorCan cause severe bradycardia, AV block, left ventricular failure, and hypotension when combined with timolol. Monitor cardiovascular function carefully.
Oral beta-blockers (atenolol, metoprolol, propranolol)
majorAdditive systemic beta-blockade resulting in compounding effects on heart rate, blood pressure, and (in susceptible patients) breathing.
Clonidine
moderateRisk of hypertensive rebound when clonidine is stopped abruptly; timolol may worsen this rebound effect. Taper clonidine carefully under medical supervision.
Quinidine
moderateInhibits CYP2D6, raising plasma timolol levels significantly and enhancing beta-blockade effects including bradycardia and fatigue.
Digitalis glycosides (digoxin)
moderateBoth digoxin and timolol slow AV conduction. Combined use increases risk of serious heart block.
Catecholamine-depleting drugs (reserpine)
moderateAdditive effects causing significant hypotension and bradycardia when combined with timolol.
Antidiabetic agents (insulin, oral hypoglycemics)
moderateTimolol masks the tachycardia symptom of hypoglycemia. Monitor blood sugar carefully in diabetic patients.
Istalol (timolol maleate ophthalmic solution 0.5%) is a clinically proven, once-daily beta-blocker eye drop for open-angle glaucoma and ocular hypertension. Its once-daily morning dosing makes it convenient for long-term use, and its efficacy — reducing IOP by approximately 28% in clinical studies — is well-established. The 2024 generic approval means patients now have access to an equivalent medication at dramatically lower cost.
The key to protecting your vision with Istalol is consistent, uninterrupted use. Missing doses allows IOP to rise and can lead to permanent vision damage. If cost or availability is a barrier, there are meaningful options: the generic equivalent at $6.99 with GoodRx, the Bausch + Lomb Patient Assistance Program, or discussion with your ophthalmologist about an equally effective alternative medication.
If you're having trouble finding Istalol at a pharmacy near you, medfinder is here to help. Simply tell us what you need and we'll call pharmacies near you to find it — so you can spend less time searching and more time focused on your health.
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