Dorzolamide is a
**Core Concept**
Dorzolamide is a carbonic anhydrase inhibitor (CAI) used in the treatment of glaucoma and ocular hypertension. Carbonic anhydrase is an enzyme that catalyzes the reversible reaction of carbon dioxide and water to form bicarbonate and protons, playing a crucial role in maintaining the pH balance and fluid dynamics within the eye.
**Why the Correct Answer is Right**
Dorzolamide works by competitively inhibiting the CA enzyme in the ciliary body, thereby reducing the production of aqueous humor and subsequent intraocular pressure (IOP). This is particularly beneficial in patients with glaucoma, where elevated IOP can lead to optic nerve damage and vision loss. By inhibiting CA, dorzolamide also reduces the transport of sodium, potassium, and bicarbonate ions across the ciliary epithelium, further contributing to the decrease in aqueous humor production.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because dorzolamide is not a beta-blocker, which is a different class of medication used to treat glaucoma by reducing aqueous humor production and increasing outflow.
**Option B:** This option is incorrect because dorzolamide is not an alpha-agonist, which is a type of medication used to treat glaucoma by reducing aqueous humor production and increasing outflow through a different mechanism.
**Option C:** This option is incorrect because dorzolamide is not a prostaglandin analog, which is a type of medication used to treat glaucoma by increasing the outflow of aqueous humor through the trabecular meshwork.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that dorzolamide can cause a reversible increase in liver enzymes, particularly alanine aminotransferase (ALT) and aspartate aminotransferase (AST), which may indicate liver damage. Regular monitoring of liver function tests is recommended when using dorzolamide, especially in patients with pre-existing liver disease.
**Correct Answer:** D. Carbonic anhydrase inhibitor