[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Antiglaucoma agents](https://durgical.com/en/pharmacology/classes/antiglaucoma-agents/) › Dorzolamide

# Dorzolamide

## Antiglaucoma agents?

Antiglaucoma agents

A carbonic anhydrase inhibitor eye drop that lowers eye pressure by making less fluid. A sulfonamide, with a typical bitter taste.

Updated Nov 1, 2026

## Quick facts

**Group**
[Antiglaucoma agents](https://durgical.com/en/pharmacology/classes/antiglaucoma-agents/)

**Target**
Carbonic anhydrase II

**Used for**
Open-angle glaucoma · Ocular hypertension

**Key effects**
Burning or stinging right after the drop

**Monitor**
Intraocular pressure · Cornea in patients

**ATC**
S01EC03

No doses: the clinician sets them by the current guideline.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## Mechanism of action

✂**Carbonic anhydrase II**Dorzolamide

ⓘ The figure shows dorzolamide bound to the zinc ion in the active site of human carbonic anhydrase II.

**Target in 3D:** Carbonic anhydrase II. PDB structure 4M2U (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/4M2U) · Drag to rotate · pinch to zoom

Dorzolamide inhibits carbonic anhydrase II in the ciliary processes. Less bicarbonate is formed, and because aqueous humour secretion depends on it, less fluid is made and intraocular pressure falls. Given as an eye drop it avoids most of the systemic acidosis of oral acetazolamide, but it is still a sulfonamide.

- Dorzolamide blocks carbonic anhydrase II in the ciliary body
- Less bicarbonate is formed
- Less aqueous humour is secreted; pressure falls

## Indications

- Open-angle glaucoma [Open-angle glaucoma →](https://durgical.com/en/conditions/open-angle-glaucoma/)
- Ocular hypertension

## Adverse effects

### Common

- Burning or stinging right after the drop
- Bitter taste
- Superficial punctate keratitis
- Allergic eye reactions: conjunctivitis, eyelid reactions
- Blurred vision, tearing, dryness, light sensitivity

### Serious (rare, important)

- Sulfonamide reactions, rarely fatal: Stevens-Johnson syndrome, toxic epidermal necrolysis, blood disorders
- Corneal oedema when endothelial cell counts are low
- Kidney stones (rare)

## Contraindications

- Hypersensitivity to any component
- Not recommended in severe kidney impairment (drug and metabolite leave by the kidney)

## Key interactions

**Oral carbonic anhydrase inhibitors (acetazolamide)**
Additive systemic effects; the combination is not recommended

**High-dose salicylates**
Acid–base and electrolyte changes may lead to salicylate toxicity, as seen with oral inhibitors

## What is monitored

- Intraocular pressure
- Skin rash or signs of a blood disorder (fever, sore throat, bleeding)
- Cornea in patients with low endothelial counts

## Administration and safety

- Soft contact lenses come out before the drop and go back in 15 minutes later (benzalkonium chloride).
- Other eye drops are spaced at least 5 minutes apart.
- The dropper tip must not touch the eye, to avoid contaminating the bottle.

## Pregnancy and breastfeeding

There are no adequate studies in pregnant women; high oral doses caused vertebral malformations in rabbits, so it is used only if clearly needed.

## Nursing care

- Ask about sulfonamide allergy before starting.
- Explain that a bitter taste is common and harmless.
- Teach the patient to report rash, eyelid swelling or red, sticky eyes; the drop is stopped and the eye reviewed.
- Remember that acute angle-closure glaucoma needs more than pressure-lowering drops.

## Pharmacokinetics

**Absorption**
Reaches the systemic circulation after eye drops; plasma levels are usually too low to measure

**Distribution**
Accumulates in red blood cells bound to carbonic anhydrase II; its metabolite binds carbonic anhydrase I

**Elimination**
Mostly unchanged in the urine

**Half-life**
Very long washout from red blood cells (terminal half-life of about four months)

## Memory aid

Dor-ZOLAMIDE ends like aceta-ZOLAMIDE: same enzyme, but as a drop. Sulfa allergy and a bitter taste come with it.

## Test yourself

Think of the answer, then tap the question to see it.

## Which enzyme does dorzolamide inhibit, and where?

Carbonic anhydrase II in the ciliary processes of the eye.

## Why is a sulfonamide allergy relevant for dorzolamide?

Dorzolamide is a sulfonamide; it can cause sulfonamide reactions such as Stevens-Johnson syndrome.

## Why is dorzolamide not combined with oral acetazolamide?

Both inhibit carbonic anhydrase, so systemic effects add up.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/dorzolamide/)

[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## Connections

## Related drugs 3

- [Acetazolamide](https://durgical.com/en/pharmacology/acetazolamide/)
- [Timolol](https://durgical.com/en/pharmacology/timolol/)
- [Latanoprost](https://durgical.com/en/pharmacology/latanoprost/)

## Related conditions 1

- [Open-angle glaucoma](https://durgical.com/en/conditions/open-angle-glaucoma/)

[← Back to the class: Antiglaucoma agents](https://durgical.com/en/pharmacology/classes/antiglaucoma-agents/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [DailyMed - DORZOLAMIDE HYDROCHLORIDE OPHTHALMIC SOLUTION- dorzolamide hydrochloride solution/ drops](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=4698e4e1-c5f6-4db1-9328-74464a85afea) (DailyMed (U.S. National Library of Medicine), 2026); [Dorzolamide and Timolol Ophthalmic: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a602022.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=S01EC03) (WHO Collaborating Centre for Drug Statistics Methodology, 2026); [RCSB PDB - 4M2U: Carbonic Anhydrase II in complex with Dorzolamide](https://www.rcsb.org/structure/4M2U) (RCSB Protein Data Bank, 2026).

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Representative model, for educational purposes only.

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