Glaucoma Agents Flashcards
If bicarbonate is in pH below it’s pKa will it be mostly ionized or non-ionized?
Non-ionized (In component form)
If bicarbonate is in pH above it’s pKa will it be mostly ionized or non-ionized?
Ionized (Acid form)
True or false, the acidosis caused by CAIs is part of the mechanism of action to lowering IOP
False
What are the systemically administered CAIs?
Acetalzolamide (Diamox)
Methazolamide (Neptazane)
What are the topically administered CAIs?
Dorzolamide (Trusopt) 2%
Brinzolamide (Azopt) 1%
Cosopt; 2% dorzolamide and 0.5% timolol
Describe the ocular effects with CAIs
DECREASE IN IOP VIA DECREASING AQUEOUS PRODUCTION
Metabolic acidosis
What effect will CAIs have on a normal non-glaucoma patient’s eye?
None
What’s the normal dose and onset for Diamox?
125-250mg 4X a day; 3-4 hours for max effect lasting 6-12 hours
What’s the normal dose for Diamox Sequels?
500mg 1-2x a day; lasts 18-24 hours
How long does Diamox need to take effect if given by IV?
30 minutes, lasts 2-4 hours
What’s the max effectiveness for oral methazolamide?
Taken 2x a day, after 7-8 hours for max effect and duration is 10-14 hours
Describe the toxicities seen with CAIs
Very common, dropout is 20-30% Parathesia; tingling/pins and needle sensation in the extremities that also can cause abnormal taste Headache, fatigue, dizziness, drowsy GI; Irritation, upset, cramping, weight loss, NVD, anorexia Muscle weakness and decreased libido Lethargy, depression and malaise Diuresis via K+ depletion Renal and colic stones Transient myopia Rarely aplastic anemia
What are the contraindications for CAIs?
SULFA DRUG ALLERGY Renal dysfunction Hypokalemia Liver cirrhosis Severe COPD (can develop respiratory alkalosis and be unable to maintain increased respiratory rate) Renal calculi (kidney stone) Pregnancy Do not use for chronic non-congestive angle closure
With topical dorzolamide, do you see the drift effect seen with beta blockers like Timolol?
No
How does the brinzolamide (azopt) suspension compare to the use of the topical drop dorzolamide?
Brinzolamide 1% suspension taken 2-3x day equals 2% dorzolamide 3x day
Less dose and systemic toxicity
What two drugs are in cosopt and how does cosopt’s efficacy compare to the agents comprising it alone?
2% dorzolamide and 0.5% timolol
More effective than either agent alone
Describe ocular toxicities with dorzolamide
Short term keratitis/mild irritation
Burning, blurry vision, FBS, ocular allergies less likely with brinzolamide
What is a possible corneal toxicity with dorzolamide or other similar topical CAIs?
Corneal edema or even corneal decomposition
If your patient has a history of an intraocular surgery such as a corneal transplant, what concern would arise from selecting a topical CAI?
Corneal endothelium compromise
Describe some systemic toxicities with dorzolamide
Sulfa allergy
Bitter taste
Headache
Concern with patients with compromised/history of compromised liver and/or kidney
Between a topical CAI (Dorzolamide) and a beta blocker (Timolol) which has better diurnal control of IOP?
Topical CAI
Name the class of drug that is now the gold standard for newly diagnosed glaucoma patients
Prostaglandin Analogs
Describe the MOA for Latanoprost
PGF2a analog; prodrug until esterases at cornea convert to active drug to then work at proper receptor
Increases UVEOSCLERAL OUTFLOW, as well as causing substantial remodeling of TM to reduce resistance to outflow via increasing MMP production to break down the TM’s extracellular matrix
What kind of tolerance/drift/absorption effects are present with Latanoprost (other prostaglandins)
No tolerance develops
IOP well controlled (equal to or better than Timolol 2x day)
No drift
No effect from iris color, age, race, sex, previous treatments, or type of glaucoma to be treated
