Dorzolamide

Products

Dorzolamide is commercially available in the form of eye drops (Trusopt). Fixed combinations with timolol (Cosopt) and generics are also available. Dorzolamide has been approved in many countries since 1995.

Structure and properties

Dorzolamide (C10H16N2O4S3, Mr = 324.4 g/mol) is a sulfonamide. It is present in drugs as dorzolamide hydrochloride, a white crystalline powder that is soluble in water.

Effects

Dorzolamide (ATC S01EC03) lowers intraocular pressure. Selective inhibition of carbonic anhydrase II in the ciliary body of the eye decreases aqueous humor secretion. This results in a decrease in intraocular pressure. Dorzolamide is absorbed in low concentrations into the bloodstream after local application, where it binds primarily to carbonic anhydrase in red blood cells. It takes up to four months for it to be completely excreted.

Indications

For the treatment of elevated intraocular pressure in patients with ocular hypertension and glaucoma.

Dosage

According to the SmPC. As part of monotherapy, 1 drop is placed in the affected eye 3 times daily. In combination with timolol, may be reduced to 1 drop 2 times daily. See also under Administration of eye drops.

Contraindications

For complete precautions, see the drug label.

Interactions

There are no known relevant drug-drug interactions. Combination with oral carbonic anhydrase inhibitors is not recommended due to possible additive effects.

Adverse effects

The most common potential adverse effects include local reactions to the eye such as a burning sensation, stinging, keratitis superficialis punctata, lacrimation, conjunctivitis, inflammation of the eyelid, itching, eyelid irritation, and blurred vision. Some of these reactions are also thought to be due to the preservative benzalkonium chloride. Other common side effects include headache, bitter taste, nausea, and fatigue and weakness. Systemic sulfonamide side effects such as hypersensitivity reactions, Stevens-Johnson syndrome, and toxic epidermal necrolysis cannot be excluded but are considered rare.