Pharmacotherapy of glaucoma

Dr. Samten Dorji

Outline

• Introduction• Pharmacotherapy• Classification and mechanism of action• Summary

Introduction

• Glaucoma is a group of ocular disorders with multifacorial aetiology united by a clinically characterstic intraocular pressure-associated optic neuropathy.

Pharmacotherapy

• Prevention or modification of risk factor

Intraocular pressure

Classification

Topical drugs• Cholinergic agents• Adrenergic agonists• Beta blockers• Prostaglandin analogs• Carbonic anhydrase

inhibitors

Systemic drugs• Carbonic anhydrase

inhibitors• Osmotic agents

Mechanism of action

• Decrease aqueous production in the ciliary body

• Increase aqueous humor outflow through the trabecular meshwork and uveoscleral pathway

Cholinergic drugs

Direct acting miotic

Cholinesterase inhibitors

Pilocarpine (direct acting)

• Relieves the pupillary block in angle closure glaucoma

• Increases the trabecular outflow • 0.5-0.4%• Last for 4-8 hours• superficial punctate keratitis, ciliary muscle spasm

which can lead to browache, induced myopia, miosis, possible retinal detachments, progression of cataract and corneal endothelial toxicity

Cholinesterase inhibitors

• Short acting-Physostigmine, neostigmine and demecarium

• Long acting- ecothiophate and isofluorophate• angle closure and open angle glaucoma• profound muscle weakness and cystoid

macular edema

Adrenergic agonist

• Decreases aqueous humor production and increases trabecular outflow

• May last upto 72 hours• Conjunctival decongestion and transient

mydriasis. Systemic hypertension, stinging, browache, conjunctival hyperemia, adenochrome deposits and allergic lid reactions

Adrenaline

Brimonidine

• First line agent• Highly selective alpha 2 receptor agonist• 0.2%• suppressing the rate of aqueous humor flow

and enhancing uveoscleral flow

Beta adrenergic antagonist(timolol)

• Inhibits both beta 1 and beta 2 adrenergic activity• First line agent• 0.25% or 0.5%• Duration of action exceeds 7 hours• localized irritation of the corneal epithelium can

result in blurred vision, conjunctival hyperemia, superficial punctate keratopathy and dry eye symptoms

• Short term escape and long term drift

Prostaglandin analogues

• Mediated by prostanoid receptors• Enhancing uveoscleral outflow• 0.005% and instilled at night• Duration of action 24 hours• Mild conjunctival hyperemia, punctate

corneal erosions and lengthening and thickening of eyelashes

Latanaprost

Carbonic anhydrase inhibitors

• It reversibly blocks the enzyme carbonic anhydrase in the ciliary body and thus suppresses aqueous humor production

• 125-250mg four times daily• Gastrointestinal upset, myopia, pulmonary

failure, renal stones, aplastic anaemia, metabolic acidosis, hypersensitivity reactions and peripheral neuropathy

Acetazolamide

Dorzolamide

• Topical ophthalmic use• It penetrates cornea, inhibits carbonic

anhydrase-II in the ciliary body, slows the production of local bicarbonates and thus decreases sodium and fluid transport which in turn reduces the secretion of aqueous humor

• 2% twice daily• irreversible corneal edema in patients having a

compromised endothelium

Osmotic agents

• Enhance the osmotic pressure of plasma• Mannitol, glycerol and urea• Acute angle closure glaucoma and pre

operative raised IOP• nausea, vomiting, diuresis, headache,

diarrhea, chills and fever

Summary

Thank you