Anti Glaucoma Drugs Classification and Pharmacology for GPAT and NEETPG

ANTI-GLAUCOMA DRUGS

Glaucoma is managed primarily by lowering intraocular pressure (IOP) by either reducing aqueous humor production or increasing its outflow.

🗂️ CLASSIFICATION OF ANTI-GLAUCOMA DRUGS

A. Drugs that Decrease Aqueous Humor Production

1. Beta Blockers

   • Examples: Timolol, Betaxolol, Levobunolol

   • Mechanism: Block β-receptors in ciliary body → ↓ aqueous production

   • Notes: No effect on pupil size

2. Alpha-2 Adrenergic Agonists

   • Examples: Brimonidine, Apraclonidine

   • Mechanism: ↓ aqueous production + ↑ uveoscleral outflow

   • Side Effect: Allergic conjunctivitis, dry mouth

3. Carbonic Anhydrase Inhibitors (CAIs)

   • Topical: Dorzolamide, Brinzolamide

   • Oral: Acetazolamide, Methazolamide

   • Mechanism: Inhibit carbonic anhydrase → ↓ aqueous humor secretion

   • Side Effects: Paresthesia, renal stones, metabolic acidosis (systemic)

B. Drugs that Increase Aqueous Humor Outflow

1. Prostaglandin Analogues (first-line)

   • Examples: Latanoprost, Travoprost, Bimatoprost

   • Mechanism: ↑ uveoscleral outflow

   • Side Effects: Iris pigmentation, eyelash growth

2. Cholinergic (Miotics)

   • Examples: Pilocarpine, Carbachol

   • Mechanism: Contract ciliary muscle → opens trabecular meshwork → ↑ outflow

   • Side Effects: Brow ache, myopia, miosis, retinal detachment risk

3. Rho kinase inhibitors

   • Examples: Netarsudil

   • Mechanism: ↑ trabecular outflow + ↓ episcleral venous pressure

   • Newer class

   • Important Books for GPAT

C. Combination Therapies

• Timolol + Dorzolamide

• Timolol + Brimonidine

• Latanoprost + Timolol

🔬 MECHANISM SUMMARY TABLE

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📝 Important MCQ Points

1. First-line drug in open-angle glaucoma → Latanoprost (PG analog)

2. Systemic CAI used in acute angle-closure glaucoma → Acetazolamide

3. Beta-blocker safe in asthma patients → Betaxolol (β1-selective)

4. Side effect of PG analogs → Iris pigmentation, eyelash thickening

5. Drug contraindicated in sulfonamide allergy → Acetazolamide