Understanding Dorzolamide-Timolol Availability
In 2025, the question of whether dorzolamide-timolol eye drops are discontinued is nuanced. While the brand name Trusopt (dorzolamide) has been discontinued by its manufacturer, Merck, and some specific generic versions have also been halted, the combination medication dorzolamide-timolol itself is not discontinued [1.9.5, 1.2.1]. It remains available, primarily in its generic form, which is equivalent to the brand name Cosopt [1.3.2].
Patients may encounter confusion due to intermittent shortages of the generic product, which have been attributed to manufacturing delays and market pressures [1.9.2, 1.9.1]. The FDA has listed dorzolamide as experiencing shortages at various times due to manufacturing and quality issues [1.2.2]. However, multiple manufacturers, including Akorn and Sandoz, continue to produce generic dorzolamide-timolol, including preservative-free (PF) single-use vials [1.4.1, 1.4.2]. The core takeaway for patients is that while a specific brand or manufacturer's version might be unavailable, the medication itself is still accessible through alternative generic suppliers.
How Dorzolamide and Timolol Work Together
Dorzolamide-timolol is a combination medication prescribed to treat elevated intraocular pressure (IOP) in patients with open-angle glaucoma or ocular hypertension [1.2.5]. High IOP is a major risk factor for optic nerve damage and subsequent vision loss [1.6.6]. The medication combines two active ingredients that lower eye pressure through different mechanisms:
- Dorzolamide: A carbonic anhydrase inhibitor. It works by decreasing the production of aqueous humor—the fluid inside the eye—by slowing the formation of bicarbonate ions in the ciliary body [1.6.1, 1.6.6].
- Timolol: A beta-blocker. It also reduces the production of aqueous humor, but by blocking beta-adrenergic receptors in the eye's ciliary processes [1.6.2, 1.6.1].
This dual-action approach results in a more significant reduction in IOP compared to using either medication as a monotherapy [1.6.6]. The standard dosage is typically one drop in the affected eye(s) twice daily [1.6.2].
Common Side Effects and Important Considerations
Although administered topically, dorzolamide-timolol can be absorbed systemically and cause side effects. Patients should be aware of both local and systemic reactions.
Potential Side Effects
The most common side effects are localized to the eye and include:
- Burning or stinging upon application [1.7.1]
- Blurred vision [1.7.1]
- A feeling of something in the eye [1.7.1]
- Itching or redness [1.7.1]
- Changes in taste (a bitter or unusual taste) [1.7.3]
Because the medication contains a sulfonamide (dorzolamide) and a beta-blocker (timolol), it carries warnings for more serious systemic effects, although rare. These can include respiratory reactions like bronchospasm (especially in patients with asthma) and cardiac reactions like a slowed heart rate or worsening heart failure [1.6.6]. Patients with asthma, severe COPD, bradycardia (slow heart rate), or heart failure are generally contraindicated from using this medication [1.6.2].
Patient Counseling Points
- Medical History: Inform your doctor of any history of asthma, lung disease, heart problems, diabetes, or sulfa allergies before starting treatment [1.7.4, 1.6.6].
- Contact Lenses: Remove soft contact lenses before instilling the drops and wait at least 15 minutes before reinserting them, as the preservative (benzalkonium chloride) can be absorbed by the lenses [1.6.6].
- Administration: To avoid contamination, do not let the dropper tip touch the eye or any other surface. If using other eye medications, wait at least 5-10 minutes between applications [1.7.3, 1.6.6].
- Surgery: Inform your doctor or dentist you are using this medication before any planned surgery [1.7.1].
Comparison of Glaucoma Eye Drop Medications
| Medication Class | Example(s) | Mechanism of Action | Common Dosing |
|---|---|---|---|
| Combination | Dorzolamide/Timolol (Cosopt) | Decreases fluid production (two ways) | Twice daily |
| Prostaglandin Analogs | Latanoprost (Xalatan), Travoprost | Increases fluid outflow [1.5.3] | Once daily |
| Beta-Blockers | Timolol (Timoptic) | Decreases fluid production [1.5.3] | Once or twice daily |
| Alpha-Adrenergic Agonists | Brimonidine (Alphagan P) | Decreases fluid production and increases outflow [1.5.3] | Twice or three times daily |
| Carbonic Anhydrase Inhibitors | Dorzolamide (Trusopt), Brinzolamide | Decreases fluid production [1.5.3] | Twice or three times daily |
Alternatives to Dorzolamide-Timolol
If a patient cannot use dorzolamide-timolol due to side effects, allergies, or availability issues, several other classes of medications are available to manage glaucoma and ocular hypertension. The choice of alternative depends on the patient's medical history, the target IOP, and tolerability.
Common alternatives include:
- Prostaglandin Analogs: Often considered a first-line treatment, these drugs (e.g., latanoprost, travoprost) work by increasing the outflow of fluid from the eye and are typically used once daily [1.5.3, 1.5.4].
- Other Combination Drops: If a combination therapy is still needed, options like Combigan (brimonidine/timolol) or Simbrinza (brimonidine/brinzolamide) offer different mechanisms of action [1.5.4].
- Monotherapy with a Different Class: A doctor might prescribe a single-agent eye drop from a different class, such as a prostaglandin analog, an alpha-adrenergic agonist, or a different carbonic anhydrase inhibitor if only one component of Cosopt was problematic [1.5.2].
- Rho Kinase Inhibitors: Newer medications like netarsudil (Rhopressa) lower eye pressure by increasing fluid drainage through the eye's main drainage pathway [1.5.3].
Conclusion
To summarize, the combination medication dorzolamide-timolol is not discontinued and remains an important treatment for glaucoma. However, specific brand-name versions like Trusopt (dorzolamide alone) and certain generic formulations have been discontinued [1.9.5, 1.2.6]. The medication is widely available as a generic equivalent to Cosopt, though periodic supply chain issues can cause temporary shortages [1.9.2]. Patients experiencing difficulty obtaining their prescription should speak with their pharmacist or ophthalmologist about available generic alternatives or other treatment options to ensure continuous management of their eye pressure.
For more information on glaucoma treatment, consult a qualified healthcare provider or visit the Glaucoma Research Foundation.
