Dorzolamide Eye Drops (dorzolamide hydrochloride (ophthalmic))
Also sold as: Dorzox, Trusopt, Cosopt (dorzolamide + timolol)
Pregnancy
Cat C
Lactation
Unknown
Schedule
H
Forms
Eye drops 2% solution (5 mL) +1
Indications
- Open-angle glaucoma (monotherapy or adjunct)
- Ocular hypertension
- Pseudoexfoliation glaucoma
- Adjunct when beta-blocker monotherapy is insufficient
Adult Dosing
Glaucoma / ocular hypertension (monotherapy)
1 drop of 2% solution in affected eye(s)
Three times daily (TDS)
Reduces IOP by ~20% via inhibition of carbonic anhydrase II in ciliary processes → decreased aqueous humor secretion.
Glaucoma (adjunct to beta-blocker)
1 drop of 2% solution in affected eye(s)
Twice daily (BD) — when used as adjunct
Consider fixed combination Cosopt (dorzolamide + timolol) for better compliance.
Cosopt (dorzolamide 2% + timolol 0.5%) fixed combination
1 drop in affected eye(s)
Twice daily (BD)
Preferred over separate drops when both are indicated — improves adherence. Apply nasolacrimal occlusion to reduce systemic timolol absorption.
Renal Dose Adjustment
| CrCl / eGFR | Dose Adjustment |
|---|---|
| CrCl ≥ 30 mL/min | No dose adjustment required |
| CrCl < 30 mL/min | Contraindicated — risk of systemic accumulation of sulfonamide metabolites |
Pregnancy & Lactation
Pregnancy: Category C
Systemic absorption occurs; carbonic anhydrase inhibition may affect fetal acid-base balance. Use only if potential benefit justifies risk. Avoid in 1st trimester if possible.
Lactation: Unknown
Excretion into breast milk unknown. Systemic absorption with ophthalmic use is low. Apply nasolacrimal occlusion to minimize exposure. Avoid use in nursing mothers if possible.
Top Drug Interactions
| Interacting Drug | Effect | Severity |
|---|---|---|
| Oral carbonic anhydrase inhibitors (acetazolamide, methazolamide) | Additive systemic carbonic anhydrase inhibition — risk of hypokalemia, metabolic acidosis, renal stones, and systemic toxicity | Major |
| High-dose salicylates (aspirin ≥ 500 mg/day) | Potentiates carbonic anhydrase inhibitor toxicity (acid-base disturbances, CNS effects) when significant systemic absorption occurs | Major |
| Systemic beta-blockers (when using Cosopt combination) | Additive systemic beta-blockade from timolol component — bradycardia, AV block, bronchospasm | Major |
| Sulfonamide antibiotics | Dorzolamide is a sulfonamide derivative — additive risk of sulfonamide-related adverse effects (rare with topical use) | Moderate |
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Side Effects
Common
- Burning, stinging, or discomfort on instillation
- Bitter taste (due to drainage through nasolacrimal duct)
- Superficial punctate keratitis
- Tearing / blurred vision (transient)
- Eyelid inflammation
- Conjunctival hyperemia (mild)
- Headache
Serious / Discontinue If
- Allergic reactions (urticaria, angioedema, bronchospasm — cross-reactivity with sulfonamides)
- Corneal edema / decompensation (in patients with low endothelial cell count)
- Metabolic acidosis (rare; risk in renal impairment)
- Urolithiasis (sulfonamide class effect; rare with topical use)
- Stevens-Johnson syndrome (rare, sulfonamide class)
Contraindications
- Hypersensitivity to dorzolamide or any sulfonamide
- Severe renal impairment (CrCl < 30 mL/min) — sulfonamide metabolites may accumulate
- Hyperchloremic acidosis
- Known sulfa allergy (absolute contraindication)
Available Indian Brands
| Brand | Manufacturer | Price (approx) |
|---|---|---|
| Dorzox 2% Eye Drops | Cipla | ₹125/5 mL |
| Trusopt 2% Eye Drops | MSD (Merck) | ₹185/5 mL |
| Cosopt Eye Drops (dorzolamide 2% + timolol 0.5%) | MSD (Merck) | ₹285/5 mL |
| Dorzox-T (dorzolamide 2% + timolol 0.5%) | Cipla | ₹175/5 mL |
Monitoring Required
- Intraocular pressure — baseline, 4 weeks post-initiation, then every 3 months
- Serum electrolytes and bicarbonate — if systemic absorption is suspected or patient has renal impairment
- Renal function (creatinine, CrCl) — before starting and periodically
- Corneal health — slit-lamp exam; endothelial cell count in at-risk patients
- Signs of sulfonamide hypersensitivity — especially in first 4 weeks
- Visual fields and optic disc — every 6–12 months
Patient Counseling Points
- Instil 1 drop in the affected eye(s) as prescribed — TDS (monotherapy) or BD (adjunct).
- A bitter taste in the mouth after instillation is normal — caused by drainage through the tear duct.
- Apply nasolacrimal duct pressure (finger at inner corner of eye) for 1 minute after instillation to reduce systemic absorption and the bitter taste.
- If you have a sulfa antibiotic allergy, inform your doctor immediately before starting this medication — it is a sulfonamide derivative.
- Do not take oral acetazolamide (Diamox) tablets simultaneously unless specifically prescribed — serious systemic side effects can occur.
- Remove contact lenses before instillation; reinsert after 15 minutes.
- If using with other eye drops, wait at least 5 minutes between different preparations.
- Store at room temperature (below 30°C), away from direct sunlight; discard 4 weeks after opening.
- Report any rash, facial swelling, difficulty breathing, or severe eye pain immediately.
- If using Cosopt (combination drop), read instructions for both dorzolamide and timolol components — systemic beta-blocker precautions apply.
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Clinically reviewed by: Dr. Ananya Pillai, MS (Ophthalmology), Glaucoma Specialist
Last reviewed: 2026-04-01
References
- Silver LH. Dose-response evaluation of the ocular hypotensive effect of dorzolamide. Am J Ophthalmol. 1998;126(3):344–351.
- Strohmaier K, et al. Dorzolamide / timolol fixed combination vs concurrent administration. Ophthalmology. 1998;105(10):1936–1944.
- MSD India. Trusopt prescribing information. 2023.
- American Academy of Ophthalmology. Glaucoma medications — mechanisms and drug interactions. 2021.