Paper I
2022 July (Supplementary) (2019 Scheme) · 100 marks · 180 min

Question

Classify drugs used in treatment of chronic simple glaucoma. Write the mechanism of action and adverse effects of Beta blockers. (4+4)

Q58 marksShort Essays

Answer

Classification of drugs for chronic simple (open-angle) glaucoma

ClassMechanismExamples
Prostaglandin analogues↑uveoscleral outflowLatanoprost, Bimatoprost
Beta-blockers↓aqueous humour productionTimolol, Betaxolol
Alpha-2 agonists↓aqueous production, ↑outflowBrimonidine
Carbonic anhydrase inhibitors↓aqueous productionAcetazolamide (systemic), Dorzolamide (topical)
Miotics (cholinergic agonists)↑trabecular outflow (ciliary muscle contraction)Pilocarpine

Beta-blockers — mechanism and adverse effects Mechanism: timololblocks beta receptors on the ciliary epithelium↓cAMP-mediated aqueous humour formation → lowers intraocular pressure, given topically with minimal systemic absorption at ocular doses.

Adverse effects: local — burning/stinging on instillation, dry eyes; systemic (from the fraction that is absorbed, particularly relevant in patients with pre-existing disease) — bradycardia, bronchospasm (contraindicated in bronchial asthma/COPD), can mask hypoglycemia symptoms in diabetics, and worsen heart block/decompensated heart failure.

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