Flashcards in Ocular Pharmacology Deck (47):
Name the 3 direct muscarinic agonists and their mechanism of action
Acetylcholine, Pilocarpine, Carbachol
cause pupillary constriction and increase aqueous outflow
What are the direct muscarinic agonists used to tx and what are their side effects
Tx: Cataract surgery, tx of glaucoma
Side Effects: SLUDGE + bronchospasm, sweating
Name the indirect muscarinic agonist, it's mechanism of action and what it's used to tx
1) Echothiophate iodide
2) MOA: irreversibly binds cholinesterase
3) Cycloplegia for eye exams, improves discomfort during active eye inflammation (uveitis)
Name the 5 antimuscarinic ocular drugs
Atropine, Scopolamine, Homatropine, Cyclopentolate, Tropicamide
What is the mechanism of action for the antimuscarinic drugs?
Pupillary dilation, paralysis of ciliary body
What do the antimuscarinic drugs tx?
Cycloplegia (paralysis of ciliary muscle) for eye exams, improve discomfort during active eye inflammation (uveitis)
What are the side effects of the antimuscarinic drugs?
Ataxia, nystagmus, restlessness, mental confusion, hallucination, violent and aggressive behavior, insomnia, photophobia, urinary retention
Which of the antimuscarinics has the longest recovery time and which has the shortest (and thus is most preferred in typical eye exams)?
1) longest = Atropine (7-10 day recovery)
2) shortest = Tropicamide (several hrs recovery)
What type of drug is Edrophonium? What's it's mechanism and what does it diagnose?
It's a Nm agonist that destroys acetylcholinesterase. It's used to diagnose myasthenia gravis
How does epinephrine act in the eye? What does it treat?
Epinephrine is a direct adrenergic agonist; it dilates the episcleral vessels to increase aqueous outflow; thus it treats glaucoma
What are the side effects of epinephrine? What is the name of an epinephrine prodrug?
Side effects include extrasystoles, palpitation, HTN, myocardial infarction, trembling, paleness, sweating.
Prodrug of epi is Dipivefrin HCl
Name two indirect adrenergic agonists and how they act?
1) Hydroxyamphetamine -- releases NE
2) Cocaine -- prevents reuptake of NE
How does Hydroxyamphetamine help diagnose Horner's syndrome?
It separates 1st and 2nd from 3rd order neuron dysfunction. A positive dilation upon administration means 1st or 2nd order neuron problem (an ominous sign)
What type of drug is Apraclonidine and what is it used to treat?
It's a direct alpha agonist (and an amino derivative of clonidine).
It does not cross BBB so has minimal effect on systemic blood pressure
What type of drug is Phenylephrine and what does it tx?
It's a direct alpha 1 agonist used to dilate the pupil.
What type of drug is Clonidine and what is its MOA?
It's a direct alpha 2 agonist.
It lowers IOP through CNS effects
What type of drug is Brimonidine tartrate and what is it's MOA?
It's a direct alpha 2 agonist. It suppresses aqueous humor production through action of cAMP in non-pigmented ciliary epithelium
When is Brimonidine tartrate contraindicated?
Contraindicated with follicular conjunctivitis; and when used with MAO inhibitor it can cause fatigue/drowsiness
Name the alpha antagonist that blocks alpha adrenergic receptors in smooth dilator muscle of the iris. Which drugs does it reverse the action of?
Dapiprazole. It reverses tropicamide and phenylephrine
What type of drug is Tamsulosin? What effects does it have on the eye? Where else in the body does it treat?
1) alpha 1 antagonist
2) it blocks iris dilator muscle to make cataract surgery much more difficult with more complications
3) also treats prostate hypertrophy
Name the 5 beta blockers used to treat glaucoma
Timolol, Levobunolol, Metipranolol, Carteolol, Betaxolol
How do Timolol, Levobunolol and Betaxolol act?
They reduce intraocular pressure by reducing aqueous production at ciliary process
How does Metipranolol act?
It's a nonselective B1/B2 blocker w/out significant intrinsic sympathomimetic activity (weak membrane stabilization, weak myocardial depressant)
What are the side effects for all of the beta blockers except for Betaxolol?
bradycardia, hypotension, syncope palpitation, congestive heart failure, bronchospasm, mental confusion, depression, fatigue, lightheadedness, hallucinations, memory impairment, sex dysfunction, hyperkalemia
What are the contraindications of Timolol?
Contraindicated in CHF and asthma; bradycardia over time may produce tachyphylaxis (sudden decrease in drug response)
Name the 4 prostaglandin analogs used to treat Glaucoma
Latanoprast, Travoprost, Bimatoprost, Unoprostone isopryl
What is the MOA of prostaglandin analogs and what are their important side effects?
1) increase uveoscleral outflow
2) eyelash growth, change in iris color
Which of the prostaglandin analogs is more effective in African Americans?
Which of the prostaglandin analogs is least effective overall?
What are some of the contraindications for prostaglandin analogs?
Cystoid macular edema and herpes
Name the Calcium channel blocker used to treat glaucoma and it's MOA
Nifedipine; increases ocular perfusion at nerve head
Name the 3 carbonic anhydrase inhibitors and whether they are oral or topical
1) Dorzolamide Hcl - topical
2) Acetazolamide - oral
3) Brinzolamide - topical
How do the carbonic anhydrase inhibitors act?
Reduce aqueous production via interference w/active transport of Na through Na-K-ATPase pump
WHat are some side effects of the topical carbonic anhydrase inhibitors (Dorzolamide and Brinzolamide)?
red eyes, lid allergies. Dorzolamide is contraindicated if a sulfonamide allergy present.
What test can you do to test for predisposition to angle closure of the eye?
Shine light from temporal side of eye. If nasal iris has a shadow over it, the anterior chamber may be shallow due to iris bowing forward. This predisposes to angle closure.
Compare lesions pre vs postganglionic in the parasympathetic system. Which is more dangerous?
Postganglionic --> from Adie's syndrome; usually benign (occurs after synapse at ciliary ganglion)
Preganglionic --> from vascular accident, demyelinization, tumors, nerve compression, ischemia etc; much more dangerous
At what sites do muscarinic receptors act?
1) iris sphincter (to constrict the pupil)
2) circular fibers of ciliary muscle (to constrict the pupil)
3) longitudinal fibers of ciliary muscle (places tension on trabecular meshwork to open it up)
At what sites do adrenergic receptors act?
1) iris dilator muscle (dilates pupil)
2) superior palpebral muscle of Muller (lifts eyelid)
3) ciliary epithelium (facilitates aqueous production)
4) smooth muscle of ocular blood vessels (dilates blood vessels)
5) trabecular meshwork (increases outflow of aqueous)
Horner's syndrome symptoms
miosis, ptosis (lost innervation of Mueller's muscle in upper lid), anhydrosis (lost sympathetic tone to sweat ductules)
Initial dx of Horners (ie present or not present) is made with what drug? What results do you see?
Cocaine 10%. Abnormal pupil will fail to dilate and normal pupil will dilate
What drug determines if Horners is pre (1st or 2nd order neuron) or post ganglionic (3rd order)? What results do you see?
Paredrine 1%. If Preganglionic, both pupils will dilate. If postganglionic, the abnormal pupil will fail to dilate. (for Paradrine to work, the 3rd order neuron must be intact)
What drugs can be used to test for a tonic pupil (chronically denervated nerve ) seen in Adie's syndrome? What are the results?
Pilocarpine 1/8% or Methacholine 2.5% will constrict the abnormal pupil and have no reaction in the normal pupil
What drug is used to test for iatrogenic (ie pharmacologic) block of a pupil?
Pilocarpine at 1%. This should cause pupillary constriction under almost any circumstance except pharm block. Thus, this will show no constriction for the abnormal pupil and constriction of the normal pupil
Name 3 syndromes that cause light-near dissociation
1) Adie's syndrome
2) Parinaud's syndrome
3) Argyll Robertson syndrome
What does a patient present with when they have Adie's syndrome
usually a young female with a loss of patellar reflex (rare in elderly males and never with ataxia)
What does a patient present with when they have Parinaud's syndrome?
Young children with midbrain (pineal) tumor