Glaucoma drugs

Question 1

What causes open angle glaucoma?

Answer 1

Caused by clogging of the trabecular
meshwork with decreased drainage of the aqueous humor.
Often undetected by patients until it is advanced, because it is
not painful. Causes elevated eye pressures, optic nerve
atrophy, and decreased vision once disease is advanced.

Question 2

What causes closed angle (acute) glaucoma?

Answer 2

A MEDICAL EMERGENCY. Patients can lose all vision in the eye within hours. Most common
mechanism is a pupillary block. The lens is attached to the iris, and pushes the iris anteriorly, which closes the angle between the
iris and the cornea. As the iris-corneal angle closes, the trabecular meshwork gets blocked. With no exit pathway, fluid builds up in
the chambers and creates a pressure gradient rapidly and acutely, which then damages the optic nerve.

Presentation: Acute eye pain, red eye, poorly reactive pupil, seeing halos, Increased Intra-Ocular Pressure (IOP), N/V

Question 3

What are the prostaglandin analogues?

Answer 3

Latanaprost, travaprost, bimatoprost, unoprostone.

“Prost” drugs

Question 4

What is MOA of prostaglandin analogues?

Answer 4

Lower IOP by increasing the
rate of fluid outflow from the
eye by increasing uveoscleral
outflow (space between
choroid and sclera)
- Increases the rate of fluid
outflow from traditional
meshwork outflow

Question 5

Prostaglandin analogues: Indications

Answer 5

Can be used with all glaucomas
(with rare exceptions).
Contraindicated with herpes keratitis
(viral infection of the eye caused by
HSV; causes rare inflammatory
glaucoma).

Question 6

Prostaglandin analogues: Side Effects

Answer 6

• Ocular irritation and conjunctival injection
• Increased iris and periocular skin pigmentation
  with longer. Thicker eyelashes

POSSIBLY DANGEROUS:

• Uveitis
• Possible herpes activation
• Cystoid macular edema

Question 7

What are beta-blockers used for glaucoma treatment?

Answer 7

Timolol (Non-selective), carteolol (non-selective), levobunolol (non-selective), metipranolol (non-selective), betaxolol (selective)

Question 8

Beta-blockers: MOA

Answer 8

All are eyedrops. Reduce IOP
by blocking beta-adrenergic
R’s within the ciliary body
epithelium to reduce the
production of aqueous fluid.

Question 9

Beta-blockers: Indications

Answer 9

All types of glaucoma.
Non-selectives are absolutely
contraindicated with asthma, COPD
and greater than 1st degree heart
block. 

All beta-blockers are
absolutely contraindicated with
CHF.

Relative contraindication with sinus
bradycardia, hypotension, hx of syncope, hx of life threatening
depression, brittle insulin dependent
diabetes, impotence.

Question 10

Beta-blockers: Side effects

Answer 10

• Due to topical route: corneal toxicity and
  allergic reaction.
• Non-selective (1st 4) can be absorbed
  systemically and have SE’s of
  SOB/bronchospasm/CHF; decreased
  libido/impotence’ arrhythmias, bradycardia;
  depression.

To reduce level of beta-blocker absorbed into systemic circulation, pts should be taught
nasolacrimal occlusion method of eye drop
application.

Question 11

What are the alpha-2-agonists?

Answer 11

Brimonidine and apraclonidine

Question 12

Alpha-2-agonists: MOA

Answer 12

Decrease IOP by: Lowering amount of aqueous fluid produced and increasing the
outflow through the
uveoscleral outflow
pathway.

Question 13

Alpha-2-agonists: Indications

Answer 13

Use brimonidine for all types of
glaucoma.
Use apraclonidine for IOP spikes
following laser surgery for glaucoma.

Contraindicated with MAO-inhibitor
use and for patients less than 2 yrs.

Question 14

Side effects of brimonidine?

Answer 14

Dry mouth, fatigue, ocular redness,

ocular irritation.

Question 15

Side effects of apraclonidine?

Answer 15

Severe allergic blepharitis,
tachyphyalaxis with chronic use, mydriasis, eyelid
retraction and conjunctival branching.

Question 16

Which drugs can cause systemic side effects?

Answer 16

Prostaglandin analogues, beta-blockers and CAIs can case systemic side effects

• α-2-agonists don’t have many systemic effects unless used chronically, but do drip into mouth -> dry mouth

Question 17

Which drugs reduce IOP by decreasing amt of aqueous fluid produced?

Answer 17

Beta-blockers and CAIs reduce IOP by reducing the amount of aqueous fluid produced

Question 18

Which drugs reduce IOP by increasing outflow of fluid from eye?

Answer 18

Prostaglandins reduce IOP by increasing the outflow of fluid from the eye

Question 19

Which drugs reduce production of aqueous fluid and increase outflow?

Answer 19

Alpha-2 agonist reduce the production of aqueous fluid AND increase the outflow

Question 20

What reaction does carbonic anhydrase catalyze?

Answer 20

Hydration of CO2 and dehydration of bicarbonate.

Parietal cells use CA to secrete stomach into acid.

Pancreatic duct cells use CA to secrete bicarbonate.

RBC convert CO2 to bicarbonate fro transport then back to CO2 to be exhaled by lungs using CA.

Renal tubules secrete H+ to maintain acid-base and fluid balance using CA.

Cells producing CSF, aqueous fluid in eye, endolymph of semicircular canals, cochlear duct, perilymph of scala vestibuli and scala tympnai all contain high levels of CA.

Question 21

What are the carbonic anhydrase inhibitors (CAIs)?

Answer 21

Dorzolamide (topical)
Brinzolamide (topical)
Acetazlamide (oral)
Methazolamide (oral)

Question 22

CAI: MOA

Answer 22

Inhibiting CA in ciliary body

epithelium. Decreases IOP.

Question 23

CAI: Indications

Answer 23

Acetazolamide was first CAI used,
the “prototype”, used as diuretic.

Has
remained in popular use worldwide
for effects on specific tissues as
described above, and today’s main
use is in the tx of glaucoma.

Used topically for all glaucomas.
Can be used orally for rapid
lowering of acute increases in IOP;
when a patient has poorly tolerated
other topical glaucoma medications

Absolute contraindication:
sulfonamide allergy, SCD, aplastic
anemia, thrombocytopenia

Relative contraindication: adrenal
insufficiency, hepatic failure, chronic
respiratory acidosis, renal failure,
metabolic acidosis, repeated kidney
stones.

Question 24

CAI: Side Effects

Answer 24

TOPICAL: Stinging, burning, redness /dermatitis / conjunctivitis, allergy, transient
myopia, metallic taste.

ORAL: Parasthesis, frequent urination,
metabolic acidosis, metallic taste.

These drugs are structurally similar to
sulfonamides – so if a patient has an allergy, they
should not take CAIs.