Istalol Shortage: What Providers and Prescribers Need to Know in 2026

Istalol (timolol maleate ophthalmic solution 0.5%, Bausch + Lomb) remains a commonly prescribed once-daily beta-blocker for open-angle glaucoma and ocular hypertension. In 2025 and 2026, clinicians have faced growing patient inquiries about availability and cost, as pharmacy stocking of the brand has become inconsistent following the approval of a generic equivalent in July 2024. This guide provides prescribers with the clinical and logistical context they need to support their glaucoma patients effectively.

Current Timolol Supply Landscape (2026)

Istalol brand is not currently on the FDA Drug Shortage Database. However, prescribers should be aware of the following supply conditions affecting their patients:

• Istalol brand: Available but inconsistently stocked. Many pharmacies have shifted purchasing to the FDA-approved generic equivalent following its July 2024 approval (Somerset Theraps LLC). Patients with DAW prescriptions may face difficulty locating the brand.
• Generic timolol gel-forming solution: Sandoz has the 0.25% and 0.5% gel-forming solutions (generic Timoptic-XE) on back order with no estimated release date. Patients prescribed this formulation may need to be transitioned.
• Dorzolamide/timolol combination (generic Cosopt): Has experienced manufacturing delays with partial supply restoration. Prescribers should verify availability before initiating or renewing this combination.
• Standard generic timolol 0.5% solution: Widely available from multiple manufacturers including Apotex. This remains the most accessible timolol formulation for patients and should be the default recommendation when Istalol is unavailable.

Clinical Implications: Istalol vs. Generic Timolol

Istalol's key clinical distinction is its once-daily dosing. A controlled, double-masked, parallel study in 332 patients demonstrated that Istalol 0.5% once daily (morning) was equivalent to standard timolol 0.5% twice daily in IOP reduction, lowering mean IOP from 25 mm Hg at baseline to approximately 18 mm Hg at peak and 19 mm Hg at trough.

The FDA-approved generic timolol maleate once-daily 0.5% (Somerset Theraps) maintains this once-daily dosing schedule. When substituting, prescribers do not need to adjust dosing instructions. If switching to standard twice-daily timolol 0.5%, counsel patients that the morning drop time remains important for peak IOP control during waking hours.

When to Consider Switching to an Alternative Drug Class

If patients cannot access any timolol formulation, the following evidence-based alternatives are appropriate for most open-angle glaucoma and ocular hypertension patients:

• Latanoprost 0.005% (Xalatan and generics): Current first-line treatment per most clinical guidelines. Once-daily at bedtime. Reduces IOP approximately 25-30%. Safe for patients with respiratory or cardiac contraindications to beta-blockers.
• Brimonidine 0.2% (Alphagan and generics): Alpha-2 agonist with dual mechanism (reduces production, increases uveoscleral outflow). Used BID-TID. Note: Avoid in children under 2 due to CNS/respiratory depression risk. May provide neuroprotective benefit — still under investigation.
• Dorzolamide 2% (Trusopt and generics): Carbonic anhydrase inhibitor. Safe for asthma/COPD patients. Appropriate as monotherapy or add-on. Avoid in sulfonamide allergy.
• Betaxolol 0.5% (Betoptic): Selective beta-1 blocker; less bronchospasm risk than timolol. Suitable for patients with mild pulmonary disease who require a beta-blocker. Less IOP-lowering efficacy than timolol.

Important Prescribing Considerations

When managing glaucoma patients during availability challenges, keep the following in mind:

• Benzalkonium chloride (BAK): Istalol contains BAK 0.010%, a preservative that may cause ocular surface issues with long-term use. If switching to preservative-free options, counsel patients accordingly.
• Systemic absorption: Timolol is systemically absorbed through the nasolacrimal duct, with peak plasma concentrations within 15 minutes. Nasolacrimal occlusion (digital pressure on the inner corner of the eye for 1-2 minutes after instillation) reduces systemic exposure significantly. Counsel patients on this technique.
• Contraindications remain regardless of formulation: Beta-blocker eye drops including all timolol formulations remain contraindicated in bronchial asthma, severe COPD, sinus bradycardia, 2nd/3rd degree AV block, overt cardiac failure, and cardiogenic shock.
• DAW prescriptions during shortage: Consider removing DAW requirements if Istalol brand is unavailable — the generic equivalent is FDA-approved and therapeutically equivalent. This reduces patient burden.

How medfinder Supports Your Patients

For patients struggling to locate Istalol, recommend medfinder — a service that calls pharmacies on the patient's behalf to find in-stock medications and texts results directly. For your full toolkit as a prescriber, see How to help your patients find Istalol in stock: A provider's guide.