Drugs: Pilocarpine Timolol Atropine Acyclovir Cyclopentolate

 

Ophthalmic Pharmacology Essentials

NEET PG / Board Exam Pharmacology Pearls

Drug Class/Mechanism Primary Clinical Use
Pilocarpine Parasympathomimetic (M-agonist) Acute angle-closure glaucoma, pupillary constriction.
Timolol Beta-blocker (Non-selective) Glaucoma (decreases aqueous production).
Atropine Anticholinergic (M-antagonist) Cycloplegic/mydriatic; treats ciliary spasm in uveitis.
Acyclovir Antiviral (Guanoisine analog) Herpes simplex keratitis.
Cyclopentolate Anticholinergic (M-antagonist) Diagnostic cycloplegic/mydriatic (shorter duration than atropine).

Clinical Pharmacology Pearls

  • Pilocarpine: Causes miosis and increases trabecular outflow. *Caution:* Can increase iris-lens contact, worsening pupil block in specific scenarios; contraindicated in anterior uveitis due to risk of synechiae.
  • Timolol: *Contraindicated* in patients with asthma or COPD due to potential systemic beta-2 receptor blockade.
  • Atropine vs. Cyclopentolate: Atropine has a very long duration of action (up to 7–10 days). Cyclopentolate is preferred for routine clinical refraction due to its shorter duration (approx. 24 hours).
  • Acyclovir: Topical or oral; essential for treating epithelial keratitis. Note: Topical steroids are strictly *contraindicated* in active HSV epithelial keratitis as they promote viral replication and geographical ulceration.
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