Lec.11: Medical Management of Glaucoma 2 Flashcards
where are beta-1 receptors found?
in the heart (stimulation causes increase heart rate, cardiac contractility and atrioventricular conduction)
where are beta-2 receptors found?
in bronchial muscle, blood vessels and uterus
what is the mechanism for ocular beta blockers (OBB’s)?
act by reduction in aqueous formation
(T/F) a patient on OBB can experience a decrease in aqueous formation by as much as 50%?
true
what are the indications for beta blockers?
lowering IOP in ocular hypertension and open angle glaucoma, secondary glaucoma and angle closure glaucoma
what are the contraindications for beta blockers?
pulmonary disease, bronchial asthma and severe COPD
what are the benefits for betaxolol?
not contraindicated for pulmonay disease, bronchial asthma or COPD
if a patients baseline heart rate is less than 60 bpm can you still use OBB?
no
if OBB’s are only used once daily (off label use), what time of day should they be used?
morning (AM)
according to product label, what should the treatment regimen be for OBB?
twice daily
what is the most commonly used form of timolol?
0.5% timolol maleate
what is the selectivity of timolol?
non selective
some patients experience decrease efficacy of timolol over time, why is that?
may be an up regulation of beta receptors in target tissue
what is the typical time period for a wash out period?
4 weeks
what are the benefits of gels compared to drops?
improve bioavailability, decreases systemic absorption, once a day dose, not preserved with BAK
what drug is formulated with potassium sorbate and has lower BAK concentration?
istalol
is betaxolol solution still available in the United States?
no. only betaxolol suspension
why can betaxolol be used in patients with pulmonary disease?
because it is a selective beta blocker
how do BAK issues multiply beta blocker issues?
decrease tear production, decreased goblet cell density and dry eye symptoms
which beta blocker is associated with granulomatous uveitis?
metipranolol
what is the concentration of betaxolol suspension that is most commonly prescribed?
0.25%
what are the trough plasma values?
0.8-7.2 ng/milli liter
what are the plasma levels when 2 drops of timolol are taken?
5.0-9.6 ng/milli liter
what are the CNS adverse affects of taking timolol?
anxiety, depression, fatigue, lethargy, confusion, sleep, disturbance, memory loss, sexual dysfunction, decreased libido
why would timoptic XE have less systemic absorption?
because it is a gel that tends to stay in the eye
what OBB has fewer CNS adverse affects and can be safely used in patients with pulmonary disease?
betaxolol
what are the metabolic adverse effects for patients on timolol?
12% increase in triglycerides
9% decrease in HDL
why do diabetic patients taking beta blockers have to be extra careful?
beta blocker mask symptoms of hypoglycemia
name the common adrenergic agents used by optometrist.
clonidine, apraclonidine, brimonidine
what are the side effects of clonidine?
sedation, systemic hypotension, narrow therapeutic index
what is the mechanism for apraclonidine?
decreased aqueous production, improves trabecular outflow and decreases episcleral venous pressure
which adrenergic agents are used to prevent poster laser treatment spikes in IOP?
apraclonidine and brimonidine
what drug is contraindicated for patients on monoamine oxidase inhibitors (MAO)?
brimonidine
what are the adverse effects of brimonidine?
conjunctival follicles, ocular allergic reactions, ocular pruritus, headache, oral dryness, ocular hyperemia, blurring, fatigue/drowsiness
what 2 drugs make up combigan? and how many times a day is it taken?
Brimonidine and timolol
take twice a day
what is the usual treatment regimen for brimonidine?
TID
what 2 drugs make up Simbrinza? and what is the treatment regimen for simbrinza?
brinzolamide and brimonidine
take TID
which drugs approved for use in glaucoma have a indication for neuroprotection?
none (animal data suggest brimonidine is neuroprotective)
what is pilocarpine indicated for?
angle closure glaucoma with pupillary block
what is the mechanism for pilocarpine?
contraction of ciliary muscle causes unfolding of trabecular meshwork and widening of Schlemm’s Canal
in the event of a pupillary block and angle closure at what interval should pilocarpine be administered?
1% or 2%, 2-3 times in 30 mins
when will the max IOP reduction occur for a patient taking pilocarpine?
after 75 minutes
what are the side effects of pilocarpine?
stinging/burning, risk of hyphema during surgeries, ciliary spasm, temporal or supraorbital headache and induced myopia, decrease in VF (due to miosis), constant accommodation
what is the pharmacological antagonist for pilocarpine?
atropine
what has a greater chance of formation if the pupil remains contracted and immobilized?
synechiae formation
what class of drugs should patients with sulfa allergies avoid?
carbonic anhydrase inhibitors (CAI’s)
how do CAI’s decrease aqueous production?
cause reversible reduction of bicarbonate ions in posterior chamber, which prevents movement of Na+ and water
what are the common topical CAI’s and how many times a day should they be taken?
dorzolamide and brinzolamide
taken TID
what are the contraindications for CAI’s?
sulfa allergies, diabetic patients susceptible to ketoacidosis, patients with hepatic insufficiency, COPD, kidney disease
what are the more prominent side effects of CAI’s?
numbness, anorexia, nausea, flatulence, diarrhea and depression
