Ophthalmics Flashcards
What receptor is targeted by the ocular drugs acetylcholine, pilocarpine, carbachol, and echothiophate? Are they agonists or antagonists, and direct or indirect acting?
Muscarinic receptor; all are agonists: acetylcholine, pilocarpine, and carbachol are direct, echothiophate is indirect
What are 2 therapeutic uses for acetylcholine, pilocarpine HCl, and carbachol in the eye? How do they work?
Reduce IOP in glaucoma and after cataract surgery; direct ACh agonists that cause pupillary constriction –> increased aqueous outflow
What disorder does echothiophate iodide treat, and how does it work?
Glaucoma; indirect muscarinic agonist that irreversibly binds AChE (increased ACh –> pupillary constriction –> increased aqueous outflow)
What side effects are associated with taking acetylcholine, pilocarpine HCl, carbachol, and echothiophate iodide?
muscarinic agonists cause SLUDGE (salivation, lacrimation, urination, diarrhea, GI irritation, emesis), and also bronchospasm
What receptor is targeted by the ocular drugs atropine, scopolamine, and homatropine, and how do they affect that receptor?
Muscarinic receptor antagonists
What receptor is targeted by the ocular drugs cyclopentolate and tropicamide, and how do they affect that receptor?
Muscarinic receptor antagonists
What are 2 therapeutic uses for atropine, scopolamine homatropine, cyclopentolate, and tropicamide?
Induce cycloplegia and mydriasis (ciliary muscle paralysis and pupil dilation) for eye exams, and improve comfort during uveitis (active eye inflammation)
Rank the 5 antimuscarinic agents in order from fastest to slowest recovery time.
Tropicamide (1/4 d) - cyclopentolate (1 d) - homatropine (1-3 d) - scopolamine (3-7 d) - atropine (7-12 d)
What side effects are associated with taking anticholinergics / muscarinic antagonists?
Insomnia, photophobia, urinary retention, and neurologic abnormalities (or: “dry as a bone, blind as a bat, red as a beet, mad as a hatter”)
Describe edrophonium: what kind of receptor does it affect, what is its mechanism of action, and what is its main therapeutic use?
Nicotinic (Nm) receptor agonist that works at the NMJ by destroying AChE. Used to diagnose myasthenia gravis
What receptors are targeted by the ocular drugs epinephrine, dipivefrin, hydroxyamphetamine, and cocaine; are they agonists or antagonists; and are they direct or indirect?
Adrenergic receptors; agonists; ephinephrine and its prodrug dipivefrin are direct while hydroxyamphetamine and cocaine are indirect
Which sympathetic agonist causes dilation of episcleral vessels in order to increase aqueous outflow? What ocular disease is it used to treat?
Epinephrine; glaucoma
Which sympathetic agonist prevents the reuptake of NE?
Cocaine
What sympathetic agonist is used to differentiate 1st and 2nd order neuron dysfunction from 3rd order neuron dysfunction in Horner’s syndrome, and how does it do so?
Hydroxyamphetamine. It causes NE release: if pupillary dilation occurs, the 3rd order neuron is intact, so the problem lies in a 1st or 2nd order neuron (more dangerous)
Which sympathetic agonist is a prodrug of epinephrine?
Dipivefrin
What receptors are targeted by the ocular drugs clonidine, apraclonidine, phenylephrine, and brimonidine tartrate, and are they agonists or antagonists?
Alpha adrenergic receptor agonists (phenylephrine targets α1, clonidine and brimonidine target α2, apraclonidine is nonspecific)
Which alpha specific sympathetic agonist is an amino derivative of clonidine that does not cross the BBB, and how does this alter its effect compared to clonidine?
Apraclonidine, allows it to decrease IOP without greatly affecting systemic blood pressure (in contrast, clonidine lowers IOP through CNS effects)
Which sympathetic agonist mimics NE? What effect does it have?
Phenylephrine (except that it is α1 specific); pupil dilation
Which 2 ocular drugs can cause side effects of extrasystoles, palpitation, hypertension, myocardial infarction, trembling, paleness, and sweating?
Epinephrine and phenylephrine
How does brimonidine tartrate act on the eye?
α2 agonism suppresses production of aqueous humor, which decreases IOP
Give 2 situations where brimonidine tartrate is contraindicated.
Should not be used with follicular conjunctivitis or with MAOIs
What receptors are targeted by the ocular drugs dapiprazole and tamsulosin, and are they agonists or antagonists?
Dapiprazole = non-specific α antagonist Tamsulosin = α1 specific antagonist
Which sympathetic antagonist, no longer widely available, reverses the pupillary dilation effects of tropicamide and phenylephrine? How does it do so?
Dapiprazole, it blocks α adrenergic receptors in the smooth dilator muscle of the iris
What alpha antagonist is mainly used to treat prostatic hypertrophy? How can it affect the eye?
Tamsulosin (α1 specific blocker); it prevents pupil dilation –> makes cataract surgery more difficult
What receptors are targeted by the ocular drugs timolol, levobunolol, metipranolol, carteolol, and betaxolol, are they agonists or antagonists, and what are they all used to treat?
Beta adrenergic antagonists / β-blockers (betaxolol is β1 specific, levobunolol is β2 specific, the rest are nonspecific); all are used to treat glaucoma
What glaucoma agent is contraindicated in patients with CHF or asthma?
Timolol
What mechanism do all the beta-blockers employ to treat glaucoma?
They reduce IOP by suppressing production of aqueous humor at the ciliary process
Which beta-blocker “doesn’t follow the rules” because it lacks significant intrinsic sympathomimetic activity?
Metipranolol (it has only weak effects on membrane stabilization and myocardial depression)
What side effect may result from long-term bradycardia secondary to timolol use?
Tachyphylaxis (acute decrease in response to a drug)
What receptors are targeted by the ocular drugs latanoprast, travoprost, bimatoprost and unoprostone isopryl, and are they agonists or antagonists?
Prostaglandin receptor agonists
What mechanism do the prostaglandin analogs use to treat glaucoma?
Increase outflow of aqueous humor
List 2 common side effects seen with the prostaglandin analog drugs, and 2 contraindications for their use.
Eyelash growth and change in iris color; contraindicated in patients with cystoid macular edema or herpes
What is unique about the effectiveness of travoprost and unoprostone isopryl in treating glaucoma?
Travoprost is more effective in African Americans; unoprostone isopryl is the least effective overall
Name the calcium channel blocker drug that is used to treat glaucoma. How does it work?
Nifedipine; increases ocular perfusion at the nerve head (does not act at the ciliary body or trabecular meshwork)
What proteins are inhibited by the ocular drugs dorzolamide HCl, brinzolamide, and acetazolamide? How are these drugs administered?
Carbonic anhydrase inhibitors; dorzolamide HCl and brinzolamide are topical, acetazolamide is oral
What disease do the carbonic anhydrase inhibitors treat, and how do they work?
Glaucoma; they reduce aqueous humor production by interfering with the Na/K ATPase pump
What side effects are seen with the two topical carbonic anhydrase inhibitors?
Red eyes and lid allergies (but far less systemic side effects than for acetazolamide)
What ocular drug is contraindicated in patients with sulfonamide allergies?
Dorzolamide HCl
