Pharmacotherapy of glaucoma

1. Pharmacotherapy of
. Glaucoma
Dr Manjuprasad
Moderator: Dr Vijayalaxmi M.K

2. Overview
• Introduction
• Anatomy
• Aqueous humour dynamics
• pathophysiology
• Drugs used in the treatment
• Recent advances
• Conclusion
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3. Introduction
• Glaucoma – ancient greek
meaning clouded or blue- green hue
• In Hippocratic aphorisms
Glaucoma – blindness coming from advancing years
• Second leading cause of blindness
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4. • Glaucoma is not a single disease process but a group of
disorders characterized by a progressive optic neuropathy
resulting in a characteristic appearance of optic disc & specific
pattern of irreversible visual field defects that are associated
frequently but not invariably with ↑IOP
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5. Anatomy of the eye
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6. Aqueous humor
• Derived from the plasma
• 2.3µl/min
Production:
• Ultrafiltration
• Secretion
• Diffusion
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7. Aqueous humor dynamics
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8. Classification
• Congenital glaucoma
- Primary congenital glaucoma
- Developmental glaucoma
• Primary adult glaucoma
- Primary open angle glaucoma
- Primary angle closure glaucoma
- Primary mixed mechanism glaucoma
• Secondary glaucoma 8

9. Pathogenesis
• All types of glaucoma – progressive optic neuropathy due to the
death of retinal ganglion cells(RGCs)
• RGCs death is initiated – block in transport of neurotrophins
from brain to RGCs
damaging cascade activation
Apoptosis of RGCs
• RGCs death – loss of retinal fibers – optic neuropathy & visual
field defects 9

10. • Mechanical theory :
↑IOP – mechanical stretch of lamina cribrosa – axonal
deformation & altered capillary blood flow -- ↓neurotrophins
to reach RGC`s
• Pressure independent factors
- Failure of autoregulation
- Vasospasm
- Systemic hypotension
- Blood / fluid loss
• Excitotoxicity theory:
glutamate , oxygen free radicals, nitric oxide
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11. Congenital glaucoma
• Seen in 1 in 10,000 births
• Pathology- mal development
of trabeculum
• True congenital glaucoma
• Infantile glaucoma
• Juvenile glaucoma
• Diagnosis – corneal diameter measurement
- ophthalmoscopic evaluation of disc
- gonioscopic examination 11

12. Primary open angle glaucoma
• No obvious cause
• Polygenic inheritence
• ↑incidence in smokers
• Blacks > whites
• Pathology:
- Age related thickening & sclerosis of trabeculae
- Absence of giant vacuoles in cell lining canal of schlemm
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13. Primary angle closure glaucoma
• Increase in IOP – due to closure of angle of anterior chamber.
Acute & chronic
• Chronic PACG:- progress slowly with / without symptoms
• Acute PACG:-
-Is an emergency
-Severe eye pain
-Nausea, vomiting, prostration
-Redness, photophobia, lacrimation
-Rapid, progressive impairment of vision
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14. Risk factors:
• Hypermetropic eye
• Small eye
• 5th decade
• Female > male
• > in rainy season and dim light
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15. Secondary glaucomas
• Lens induced glaucoma
• Pigmentary glaucoma
• Neovascular glaucoma
• Glaucoma associated with intravascular tumor
• Traumatic glaucoma
• Steroid induced glaucoma
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16. 16

17. Drugs used in the treatment
DRUGS THAT REDUCE AQUEOUS HUMOUR PRODUCTION
I. Beta-Blockers : levobunolol, timolol, carteolol,
betaxolol
II. Alpha-2 Adrenergic Agonists : apraclonidine,
brimonidine
III. Carbonic Anhydrase Inhibitors :acetazolamide,
dorzolamide 17

18. DRUGS THAT INCREASE AQUEOUS OUTFLOW
I. Nonspecific Adrenergic Agonists :epinephrine,
dipivefrin
II. Parasympathomimetics : pilocarpine, carbachol,
echothiophate
III. Prostaglandin Analogues : latanoprost
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19. Cholinergic agonists
• Most commonly used – Pilocarpine
• Derived from shrub – pilocarpus jaborandi
MOA:-
• Acts on M3 receptors
– contraction
of sphincter pupillae
• Causes contraction of
longitudinal ciliary muscle →
trabecular outflow
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20. • Onset of action – rapid
peak effect – 30min
lasts for 4 – 6hrs
• S/E:-
• LOCAL:- Superficial punctate keratitis , brow ache,
induced myopia, increased risk of retinal
detachment & iritis
• SYSTEMIC – rare
• Available as 0.5 to 10 % eye drops
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21. • Pilocarpine gel (pilocarpine HCl 4%) HS
• Membrane controlled delivery system:-
-Insert placed in cul-de-sac that gradually release drug
at rate of 20mcg/hr
-Effective for 7 days
• Pilocarpine soaked contact lens
• Liposomal pilocarpine
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22. ADRENERGIC AGONISTS
Includes:
• Non selective – epinephrine & dipivefrin
• Selective alpha2 agonists- Apraclonidine, Brimonidine
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23. • EPINEPHRINE:-
• Directly acting sympathomimetic
• MOA:
• Reduced aqueous production due to alpha action
• trabecular outflow via Beta receptor stimulation
• Due to its CVS s/e , allergic reaction – no longer used
• DIPIVEFRIN:-
• Is a prodrug
• Formed by di-esterification of epinephrine –
lipophilicity– increased penetration to anterior
chamber .
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24. • Onset of action-30min, peak effect – 1hr
• Used as an adjuvant therapy
• Available as 0.1% solution , dosage BD
A/E :
• Less compared to epinephrine
• Follicular conjunctivitis, blurring of vision, stinging
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25. ALPHA2 AGONISTS
MOA:-
• Decrease aqueous humour production by alpha2
action on ciliary epithelium.
APRACLONIDINE:
• Also known as para amino clonidine
• Available as 0.5 – 1 % , dosage BD
• Short term use – Post op rise in IOP & adjuvant in
POAG
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26. BRIMONIDINE:-
• 30 times more selective α2 agonist than apraclonidine
• Additional neuroprotective effect
• Available as 0.2 - 0.5% , applied BD
• Uses:- in patients with contraindications to beta
blockers,
-short term use in post op raise in IOP
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27. BETA BLOCKERS
• Introduced in 1979
• Considered to be 1st line therapy for all types of glaucoma
• Good efficacy
• Minimal S/E
MOA:
• Decreases aqueous humour production by blocking
beta2 receptors on ciliary epithelium.
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28. TIMOLOL:
• Introduced 1978 as 1st approved beta blocker for
glaucoma
• Most widely used ocular hypotensive agent
• Due to its non selective beta action – cautious in
COPD, asthma & heart failure
• Available as 0.5 % solution & gel
• S/E:-
• Systemic
• Local:- superficial punctate keratitis, corneal
anesthesia
CARTEOLOL:
• Available as 1% solution
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29. • LEVOBUNOLOL
• Available as 0.5 – 1% solution, applied BD /OD
• Metabolized to di- hydrolevobunolol
• BETAXOLOL
• Introduced in 1980s as 1st topical β1 blocker used in
glaucoma
• Clinical trials – lesser efficacy in reducing IOP
compared to timolol
• Additional neuroprotective effect.
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30. CARBONIC ANHYDRASE INHIBITORS
2 types:-
• Systemic CA inhibitors:-
• Acetazolamide, Methazolamide
• Topical CA inhibitors:-
• Dorzolamide, Brinzolamide
MOA:-
• Blocks CA enzyme reversibly in ciliary body – reduces
aqueous humour production
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31. SYSTEMIC CARBONIC ANHYDRASE INHIBITORS
DOSAGE:-
• Acetazolamide 125mg, 250mg p.o TID or QID
• Methazolamide 25mg, 50mg p.o BD or TID
SIDE EFFECTS:-
• High risk of systemic S/Es.
• Paraesthesias, Kidney stones, aplastic anaemia,
depression
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32. TOPICAL CARBONIC ANHYDRASE INHIBITOR
• DORZOLAMIDE:-
• 1st topical CA inhibitor launched in market
• Advantage – not absorbed systemically
• Available as 2 % solution- applied TID
• S/E:- systemic is minimal
- local S/E includes corneal edema, allergic reaction,
burning & stinging sensation
• BRINZOLAMIDE
• Available as 1% solution
• Better tolerated than dorzolamide – its pH is 7.4 32

33. PROSTAGLANDIN ANALOGUES
• Includes latanoprost, unoprostone, bimatoprost,
travoprost.
• MOA:-
• Decreases IOP by increasing uveoscleral
outflow
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34. LATANOPROST:-
• Introduced in 1996
• An ester prodrug analogue of PGF2α
• Available as 0.0005% solution, OD (evening)
• Requires refrigeration & protection from sunlight
• S/E – conjunctival hyperemia ( initially), Iris
pigmentation, cystoid macular odema
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35. UNOPROSTONE:-
• Available as 0.15% solution, BD
• Additional neuroprotective effect – increasing
microcirculation in optic nerve head.
BIMATOPROST:
• A synthetic prostamide analogue
• Available as 0.03% solution , OD
• Does not require refrigeration
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36. TRAVAPROST
• Synthetic PGF2α analogue
• Available as 0.004% solution, OD at evening
• Does not require refrigeration/ protection from
sunlight
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37. Surgical procedures
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• Trabeculoplasty
• Iridotomy
• Iridectomy
• Filtering procedures
• Canaloplasty
• Goniotomy
• Goniocurettage
• Cyclodialysis
• Ciliarotomy

38. Other treatment modalities
ALPHA LIPOIC ACID:-
• Powerful antioxidant
• Useful in glaucoma by decrease in nerve cell damage
due to oxidative stress
VITAMIN C :-
• Said to increase aqueous outflow by reducing viscosity
of hyaluronic acid in trabecular meshwork
SALVIA MILTIORRHIZA:-
• Chinese herb, given i.v said to improve
microcirculation of RGCs 38

39. CANNABINOIDS
• Believed to improve uveoscleral outflow
• Not yet available for this purpose
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40. Herbal products
• Boerhavia Diffusa
• Emblica Officinalis
• Terminalia Chebulia
• Commiphora Mukul
• Curcuma Longa
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41. FUTURE GLAUCOMA THERAPY
• NMDA receptor antagonist:-
• Provides neuroprotection by blocking glutamate
mediated death of RGCs
• Includes memantine & eliprodil
• Riluzole:-
• Is a presynaptic glutamate release inhibitor
• Neuroprotective nature
• Neuroprotective vaccines:- R16
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42. Erythropoetin:-
• Neuroprotective by inhibiting RGCs apoptosis
• In animal studies – intravitreal injection enhances
RGC survival
Caspase inhibitors:-
• Inhibits apoptosis of RGCs
• Promising approach in terms of Rx of glaucoma
iNOS inhibitors:-
• Increased level of NO – neuronal damage via
apoptosis
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43. DRUG ELUTING MICRO STENTS
• Microstents were coated with a polymer-drug compound
and is implanted in the angle of iris and cornea
• Diffusion controlled
release of paclitaxel or
mitomycin is used to
avoid blocking of stent
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44. Acute angle closure glaucoma
• IOP – 40-70 mmHg
• Systemic hyperosmotic agent- IV mannitol 1mg/kg
• Actazolamide 500mg IV followed by 250mg TID
• Analgesics and Antiemetics
• Corticosteroids e/d like dexamethasone 3-4/day to reduce
inflammation
• Sx- periferal iridotomy
filteration surgery
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45. BIBLIOGRAPHY
• Pharmacological aspects of therapeutics – Goodman and Gilman – 12th edition
• Principles of pharmacology Sharma and sharma 2nd edition
• Textbook of medical pharmacology – Dr.PadmajaUdaykumar – third edition
• Essentials of medical pharmacology – K.D.Tripathi
• A. K. Khurana - comprehensive ophthalmology
• Quigley HA, Broman AT. The number of people with glaucoma worldwide in
2010 and 2020. Br J Ophthalmol. 2006;90:262–7
• Killer HE, Miller NR, Flammer J, Meyer P, Weinreb RN, Remonda L, Jaggi GP.
Cerebrospinal fluid exchange in the optic nerve in normal-tension glaucoma.
Br J Ophthalmol. 2012;96:544–8.
• Collaborative Normal-Tension Glaucoma Study Group. The effectiveness of
intraocular pressure reduction in the treatment of normal-tension glaucoma.
Am J Ophthalmol. 1998;126:498–505
• . Bergeå B, Bodin L, Svedbergh B. Impact of intraocular pressure regulation on
visual fields in open-angle glaucoma. Ophthalmology. 1999;106:997–1004
• Rao HL, Addepalli UK, Jonnadula GB, Kumbar T, Senthil S, Garudadri CS.
Relationship between intraocular pressure and rate of visual field progression
in treated glaucoma. J Glaucoma. 2012 In press.
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