Eye pharm (Linger) Flashcards
Primary Applications of Ocular Drugs
Fundoscopic examination
Diagnostic (e.g., anisocoria)
Therapeutic
- Allergic conjunctivitis
- Infections
- Glaucoma
- Strabismus
- Uveitis
Surgical
- Preoperative
- Intraoperative
- Postoperative
Acetylcholinesterase inhibitors, muscarinic agonists such as pilocarpine, and β-blockers are among the drugs used to manage patients with glaucoma. They also share properties that are particularly relevant to patients with asthma. Which statement summarizes best what that relevance is?
A. Contraindicated for people with asthma
B. Degranulate mast cells, cause bronchocontriction
C. Raise IOP in patients with glaucoma and asthma
D. Trigger bronchoconstriction by activating H1 receptors
E. Useful for acute asthma, not for ambulatory patients
Contraindicated for people with asthma
Systemic Distribution of Ocular Drugs
Tears –> cornea–> aqueous humor–> iris–> systemic circulation
Tears–> conjunctiva–> sclera–> ciliary body–> systemic circulation
also cornea sclera
Autonomic Innervation of the Eye
Iris circular (Sphincter)- parasympathetic
Iris radial (dilator)- sympathetic
ciliary circular - parasympathetic
Iris circular
(Sphincter)
muscarinic agonist–> contraction; miosis
muscarinic antagonist –> relaxation; mydriasis
iris radial
alpha -1 agonist –> contraction; mydriasis
ciliary circular muscle
muscarinic agonist–> contraction; accomodation
muscarinic antagonist –> relaxation; cycloplegia
Carbachol, pilocarpine
Intraocular use for miosis during surgery, glaucoma
Side effects: Corneal edema, miosis, induced myopia, decreased vision, brow ache, retinal detachment
Echothiophate
Use for Glaucoma, accommodative esotropia (strabismus)
side effects: Blurred vision, burning sensation in eye, iritis, night blindness, uveitis
Atropine, homatropine, cyclopentolate, tropicamide, etc.
Use for: Cycloplegic retinoscopy, dilated funduscopic exam, cycloplegia
side effects: Photosensitivity, blurred vision, burning sensation in eye, raised IOP
pharmacologic eval of anisocoria
pilocarpine- cholinergic agent used for glaucoma/ can be used to test for cholinergic supersensitivity
cocaine - sympathetic agonist at norepinephrine reuptake transporter. Normal eye –> dilation. If smaller pupil does not dilate, then it means there’s not enough norepinaphrine around. Differentiates simple anisocoria from horner’s syndrome.
hydroxyamphetamine - causes release of NE stores. distinguishes preganglionic/ central horner’s (dilation) from postganglionic horner’s (no dilation)
horner syndrome
ptosis, miosis, anhydrosis
Pharmacologic Evaluation of Anisocoria: Apraclonidine
Alternative with similar efficacy as cocaine test
0.5% solution placed in both eyes
Affected pupil will dilate more than the normal pupil
Pharmacologic Evaluation of Anisocoria: Phenylephrine
Alternative with similar efficacy as hydroxyamphetamine test
1% solution placed in both eyes
Normal eye will dilate < 0.5 mm
If postganglionic lesion, affected eye will dilate more than unaffected eye
Glaucoma
Among the leading causes of blindness in the US
Increased pressure within the eyeball can result in damage to the optic disk and gradual loss of vision
Risk factors:
- Elevated intraocular pressure (IOP)
- Positive family history
- African-American heritage
- Myopia (nearsightedness)
- Hypertension
drugs for glaucoma do one of 2 things
increase drainage
or decrease production of aqueous humor
A patient with a history of angle-closure glaucoma experiences a sudden rise of intraocular pressure that is sufficiently severe. In addition to pain there is an imminent risk of permanent vision loss. He requires immediate treatment, one element of which is administration of echothiophate. What enzyme is affected by this drug?
Tyrosine hydroxylase – stimulated Acetylcholinesterase (AChE) – inhibited Catechol-O-methyltransferase (COMT) – inhibited Monoamine oxidase (MAO) – stimulated DOPA decarboxylase - stimulated
Acetylcholinesterase (AChE) – inhibited
Increasing contraction of the ciliary muscle and the sphincter iris muscle –> constriction of the pupils–> unsmushes the iris, promotes drainage of aqueous humor
Muscarinic agonists like pilocarpine and carbachol can also be used
Angle-Closure Glaucoma
AKA closed-angle or narrow-angle
Usually acute
Medical emergency
Surgical iridectomy
Short-term drug therapy with muscarinic agonists; sometimes also AChE inhibitors
Antimuscarinics, some antihistamines (dirty drugs- anti-muscarinic actions), and α1-adrenergic agonists are contraindicated
Open-Angle Glaucoma
AKA primary or chronic glaucoma
Most common type
Affects ~3 million Americans
Pharmacotherapy reduces IOP, but may or may not slow progression
A variety of ophthalmic drugs, working by several main mechanisms of action, are useful for managing chronic open-angle glaucoma. Which one reduces intraocular pressure by decreasing the formation of aqueous humor, rather than by changing the size of the pupil(s)?
Carbachol Echothiophate Pilocarpine Prazosin Timolol
Timolol
Drugs for Open-Angle Glaucoma: Mechanisms of Action: Decreased Aqueous Secretion
Beta-blockers
Alpha-2-selective agonists
Carbonic Anhydrase Inhibitors (CAIs)
Drugs for Open-Angle Glaucoma: Mechanisms of Action: Increased Outflow
Prostaglandin F2α analogs Alpha-2-selective agonists Cholinomimetics - Muscarinic agonists - Acetylcholinesterase (AChE) inhibitors
Prostaglandin F2α Analogs
Prototype: Latanoprost
Other agents: Bimatoprost (Latisse), Travoprost, and Unoprostone
1st line therapy for open-angle glaucoma
Low systemic side effects; ocular side effects include conjunctival hyperemia, irritation, increased number and length of lashes, changes in iris and lash pigmentation
Once-daily topical administration
Potent reduction of IOP
Sites of drug action
uveoscleral outflow: prostaglandin agonists
Trebecular outflow: muscarinic agonists
Aqueous humor inflow: beta blockers, alpha 2 AR agonists, CAIs
A 55-year-old woman has just been diagnosed with chronic open-angle glaucoma, and you conclude that drug therapy is indicated. She also tends to be tachycardic. Notes written by her family practice physician indicate that she has Stage 2 essential hypertension. Which one of the following drugs would be the most rationale choice for this woman?
Captopril Carteolol Diltiazem Hydrochlorothiazide Verapamil
Carteolol- beta blocker
Beta-blockers
Non-selective (β1 and β2): Timolol, levobunolol, metipranolol, and carteolol
β1-selective: Betaxolol (less efficacious than non-selective agents because the β receptors in the eye are largely of the β2 subtype)
Twice daily dosing; fewer ocular side effects
Systemic distribution may cause serious adverse effects
Asthma, COPD, and some cardiac dysrhythmias are relative contraindications
α-Adrenergic Agonists
α2-selective: apraclonidine, brimonidine
Nonselective: epinephrine, dipivefrin (prodrug)
Common adverse effects
- Stinging, burning, blurring, or other discomfort in the eye
- Dry mouth, headaches, and increased blood pressure
Drug interactions
- Antidepressants may alter metabolism
A patient presents with chronic open-angle glaucoma. What “renal” drug, or a drug in the same chemical and pharmacologic class, might be prescribed as an adjunct to lower intraocular pressure and help manage this condition?
Acetazolamide Amiloride Furosemide Spironolactone Triamterene
Acetazolamide
- carbonic anhydrase inhibitor
not used a ton in HTN or glaucoma but is decent for both things at the same time
Carbonic Anhydrase Inhibitors
Topical: dorzolamide, brinzolamide
Oral: acetazolamide, methazolamide
Frequent dosing; topical agents are less effective than other pharmacologic therapies
Side effects
- Topical: stinging, redness, dry eyes, and blurred vision
- Oral: malaise, fatigue, depression, paresthesias, and nephrolithiasis
Cholinomimetics
Muscarinic agonists: pilocarpine, carbachol
AChE inhibitors: echothiophate
Previously 1st line therapy
Frequent dosing
Side effects
- Visual blurring from induced myopia
- Fixed, small pupils
- Can promote retinal tears
- AChE inhibitors can promote cataract formation
A patient has mild cutaneous and systemic manifestations of a seasonal allergic response. Before you prescribe a short course of diphenhydramine for symptom relief, you should realize that this drug has a mechanism of action resembling, causes many side effects similar to, and shares many contraindications, that apply to an “autonomic” drug, with which you should be very familiar. What is that drug?
Atropine Bethanecol Norepinephrine Phentolamine Physostigmine Propranolol
Atropine
Drugs Contraindicated in Angle-Closure Glaucoma
Antimuscarinics
Some antihistamines
α1-adrenergic agonists
Medical Marijuana for Glaucoma
Pros Lowers IOP (unknown mechanism)
Cons
Short duration of action
Altered mood and mental capacity
Adverse effects include lung and brain damage
Systemic hypotension could complicate vision loss
Lack of quality control
