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Ophthomalogy
Ben-Schlomo
86
Pharmacology
11/04/2011

Additional Pharmacology Flashcards

 


 

Cards

Term
Targets of ophthalmic pharmacotherapy
Definition

Extraocular structures: conjunctiva, cornea, tears

Iris

Ciliary body and drainage angle

Lens

Vitreous and retina

Posterior orbit

Term
Methods of medicating eye depends on:
Definition

Target tissue

amount of drug needed at site

characteristics of drug

convenience and safety (o/s vs o/o; hazardous drugs

Client compliance (frequency, physical limitations)

Cost

Term
Routes of administration
Definition

Topical

Subconjunctival injection

intraocular injection

systemic

 

Term
Topical adminstration sites
Definition

lids

conjunctiva

cornea

sclera

anterior uvea

Term
Subconjunctival injection administration
Definition

cornea

sclera

anterior uvea

vitreous

Term
intraocular injection administration
Definition

anterior segment

posterior segment

Term
Systemic administration
Definition

oral or parenteral

eyelids

sclera

anteroir and posterior uvea

vitreous

retina

optic nerve

orbit

limited to cornea

Term

Topical administration

 

Cornea

Definition

First barrier->multiple layers

lipophilic: epithelium and endothelium

hydrophilic: stroma

 

the first barrier is epithelium: affected by different pathologies

 

tear layer: combination of water and lipids

Term
indications for topical
Definition

eyelids, conjunctival, corneal and uveal dz

 

two possible ways for absorption:

1. Penetration through the cornea

2. Systemic absorption through the conjunctiva and nasolacrimal duct

Term

Topical administration

increased drug concentration

Definition

1. increase frequency

2. increase concentration

Term
Topical Opthalmic drops
Definition

solution/suspension (saturated solution)

easy to apply

suspension-saturated solution with poorly soluble drugs

particles seen-shake well

short contact time-75% lost through lacrimal drainage

Multiple drops administration-first drop with dilute and wash the first one->wait 5 minutes between different types of drops

Term

Topical

 

Ophthalmic ointment

Definition

longer contact time

reduce loss through lacrimal drainage

more stable than drops

lubricant

application is more challenging than drops (SA)

may slow down ulcer healing

 

Dz ex-dystechia-cause corneal ulcer, secondary infections

Term

Topical

 

Effect on drug penetration and side effects

Definition

pH-7.2 (5-9 tolerate)

molecule size

drug concentration

vehicle and preservatives

Term

Topical

 

Subpalpebral lavage (SPL)

Definition

Can be used in horses to facilitate frequent or long term treatment

more than few days

 

 

Term
Continuous lavage
Definition

very problematic

drugs interaction-pH, precipitation, stability

refrigeration

exposure to light

suspensions

 

He likes injection cup not a pump

if put more than 1 drug in pump->drug interaction

Term
Fate of drugs following topical admin
Definition

75% lost through lacrimal drainage

 

only a small amount absorbed

 

Absrobed through cornea->aqueous->taken up in uvea or lens or lost to aqeous outflow

 

penetrates conjunctiva->into/thru the sclera->uvea or lost in venous blood (no lymphatics in eye)

Term
Methods of topical admin
Definition

Periodic drops (topically or via SPL) or ointments

continuous lavage

soft contact lenses

extended delivery membranes

liposome

microbeads

Term

Subconjunctival injections

 

Penetration:

Definition

Bypass conjunctiva and cornea barriers for direct scleral absorption

Leaks back onto surface of eye->absorbed through the cornea

Only small amount absorbed into the eye but injection site has large amount of drug (depot effect)

Term

Subconjunctival injections

 

how it is applied/works

Definition

drug may las several days in the "depot"

 

no better than frequently applied topical medication

 

treats anterior segment of eye and vitreous

Term

Subconjunctival injections

 

indications/advantages

Definition

for animals that will not permit repeated topicals, wildlife

for water soluble drugs that poorly penetrat cornea

for long acting drugs (ex: methylprednisolone acetate)

to achieve high concentrations of drug for short time

confine the drug's effect to the eye

Term

Subconjunctival injections

 

disadvantages

Definition

cannot change medication once injected

 

occasionally painful due to drug or vehicles

 

may develop granuloma at injection site

 

no better than frequently administered topical medication

Term
Intraocular injections
Definition

into anterior chamber or vitreous

 

seldom done if systemic admin works

 

drug/vehicle may have deleterious effect on ocular structures

 

should be done by ophthomologist-can damage eye

Term
Retrobulbar injections
Definition

usually limited to regional anesthesia

drug may penetrate the posterior sclera and enter choroid

can damage the ON or globe

Can cause retrobulbar hemorrhage

Term

Systemic administration

 

sites and uses

Definition

Oral, IV, IM, SC

more effective when blood-ocular barrier disrupted

mostly for tx of posterior segment of eye or orbital disease

Term

Antibiotics

 

indication

Definition
treat or prevent infection (pre-op)
Term

Antibiotics

 

drug choice

Definition

choice depends on culture and sensivity or common flora

most antibiotics have poor corneal penetration

when empiric a/b tx doesn't help->culture and sensitivity->look for underplaying cause for recurrent infection

Ex: ectopic cilia, dry eye, foreign body

Not all antibiotics available topically

Term

Antibiotics

 

polypeptides

Definition

Bacitracin

Gramicidin

Polymyxin

Term

Antibiotics

 

Aminoglycosides

Definition

Neomycin

Gentamicin

Tobramycin

Term

Antibiotics

 

Quinolones

Definition

Ciprofloxacin

Ofloxacin

Lomefloxacin

Term

Antibiotics

 

Others

Definition

Tetracyclines

Erythromycin

Chloramphenicol

Sulfonamides

Cephalosporin

Penicillin

Term
Polypeptides
Definition

Bactericidal

effective empiric tx

topical use only-toxic systemically

Usually in combos->

neomycin+polymyxin+bacitracin (NeoPolyBac)-ointment

neomycin+polymyxin+gramicidin (NeoPolyGram)-solution

Term
Aminoglycosides
Definition

Bacteriocidal, broad spectrum, mainly for G-

toxic systemically

epitheliotoxic

tobramycin, amikacin, gentamicin-pseudomonas (melting corneal ulcer)

Tobramycin is cheap and more effective, less epitheliotoxic than gentamycin

Neomycin variable efficacy vs pseudomonas

Term

Cephalosporins

 

Cefazolin

Definition

Mainly for staph/strep

well tolerated

low corneal permeability

effective vs resistant staph

no ophthalmic prep

can be compounded easily

Term

Sulfonamides

 

Definition

Bacteriostatic, broad spectrum

inactivated in combo with discharge/topical anesthesia

limited permeability

may irritate eye

commercially available

Term
Tetracyclines
Definition

Bacteriastatic, broad spectrum

well tolerated

effective against: mycoplasma and chlamydophila (kittens) rickettsia

"pink eye" cattle (mixed Moraxella bovis/Mycoplasma)

Ophthalmic prep:tetracycline Hydrochlorid Ophthalmic Ointment-sometimes in combo with other antibiotics

Term
Tetracycline advantages
Definition

anti-inflammatory

anti-protease

faciliatates healing of indolent ulcers

Ophthalmic prep tetracycline hydrochloride ophthalmic ointment

systemic doxycycline-secrete in tears

 

only disadvantage-only ointment

Term
Penicillin
Definition

Bactericidal, non-toxic

Staphy and strep

no topical prep

rare in ophtho

used for Bovine keratoconjunctivitis IBK or pink eye in cattle by subconjunctival injection

Term
Quinolons
Definition

Broad spectrum, limited against anaerobes

use it when really needed (C&S)

 

Term

Quinolons

 

ophthalmic prep

Definition

Ciprofloxacin

Ofloxacin

Moxifloxacin

Lomefloxacin-good corneal penetration; use for anterior segment

Term
Chloramphenicol
Definition

Bacteriostatic

broad spectrum

G+

not to be used in food animals

Side effects: irritation, redness, itching, aplastic anemia

Term
Antifungal indication
Definition
Mycotic keratitis/keratomycosis of the horse
Term

Antifungals

 

 

Definition

Miconazole

Natamycin

Voriconazole

Term

Antifungals

 

Miconazole

Definition

effective against aspergillus spp and G+ cocci

aspergillus spp. common in equine eye infection

 

low corneal permeability

use 4-6 times/day

cheap

no commercial ophthalmic preparation-needs to be compounded as both ointment or solution

Term

Antifungals

 

Natamycin

Definition

only commerical antifungal ophthalmic preparation

5% ophthalmic suspension

3% for SPL

effective against Fusarium spp.

Low corneal permeability

use 4-6 times/day

Expensive-amphotericin B is cheaper, less effective

Term

Antifungals

 

Voriconazole

Definition

Third generation of azole

 

effective against Fusarium (2nd most common in equine eyes) and Aspergillus spp.


 Better corneal penetration than miconazole

 

use 4-6 times/day

 

Expensive

Term
Antiviral
Definition

Nucleoside analogs (and interferons) are currently used in vet ophthalmology

 

most frequently for feline herpesvirus (<<horses)

 

inhibit or alter DNA synthesis

virostatic-require functional cellular immunity and Ig's in tears

unable to eradicate latent infection

expensive (new generation's)

Term

Antiviral

 

Idoxuridine

Definition

effective

 

no commerical opthalmic prep

compounded as solution or ointment

 

use q 2h for 2 d, then 4-6x/day for 3-5 wks

cheap

 

can be very irritative-makes difficult to admin

Term

antiviral

 

new generation

Definition

Ganciclovir-same efficacy idoxuridine, double penciclovir and cidofovir

penciclovir

cidofovir-effective can be given BID (less issues with admin to a cat)

expensive

no commerical prep

Acyclovir not effective vs feline herpes

Term

Antiviral

 

Interferon

Definition

compounded from IV preparation

 

affect transcription

 

stimulat the immunological defense

-immune cell-mediated lysis of virus-infected cells)

Term

Antiviral

 

L-lysine

Definition

Ties up arginine so it is not available for viral replication

 

add to food daily for life to limit chronic recurring infections

 

use 250-500 mg/cat q24h for prevetion

250-500 mg/cat q12h for active disease

 

available in health food stores and as prep for cats

-recommend prep for cats due to cat compliance

Term

Anti-inflammatory corticosteroids

 

topical use

Definition
Do not use topical steroids on an eye with ulcerative keratitis
Term

Anti-inflammatory corticosteroids

 

MOA

Definition

1. decrease arachidonic acid release from injured cell membranes

2. block degranulation of neutrophils, mast cells, basal cell

3. prevent protease, histamine, bradykinin release

4. reduce capillary permeability, vasodilation, neovascularization

Term

Anti-inflammatory corticosteroids

 

effects

Definition

reduce edema, redness and pain

reduce cellular exudation

reduce leukocyte infiltration of lesions

suppress lymphocyte proliferation

epithlial and stromal dystophy/degeneration with long term use

Term

Anti-inflammatory corticosteroids

 

uses

 

disadvantages

Definition

topical, subconjunctival, retrobulbar, systemic

 

increase intraocular pressure

does not cause cataracts like in people

inhibit fibrosis

interfere with epithelial regeneration

potential proteinases break down collage->corneal melting

Term
Indication for topical steroids
Definition

reduce signs of inflammation and effects

redness, swelling, pain reduced

allergy, hypersensitivity and

immune-mediate disease (chronic superficial keratitis-Pannus, granulomatous episcleritis, uveritis)

Infection-careful!!!

Trauma-careful!!!

reduce scarring-fibrosis

preventrion of inflammation pre-op

Term

Anti-inflammatory corticosteroids

 

corneal penetration and dosing

Definition

Corneal penetration: acetate>alcohol>phosphate

Prednisolone acetate 1.%-better corneal penetration->prefer for uveitis and intraocular inflammation

Dexamethasone Na phosphate 0.1%-more potent, longer action-poor corneal penetration, use for extraocular inflammation

Dexamethasone alcohol 0.1% for uveitis-corneal penetrate

Combo with antibiotics-hydrocortisone, dexamethasone, betamethasone

 

Term
Subconjunctival steroids
Definition

Short term: dexamethasone solution, triamcinolone (Kenalog) suspension

 

long term: greater granuloma risk at injection site

1. betamethasone (Betasone) suspension

2. methylprednisolone (Depo-Medrol) suspension

3. Triamcinolone (Kenalog) suspension

 

once there cannot remove->less than ideal option

Term
Systemic corticosteroids
Definition

limited to severe intraocular inflammation, orbit, optic nerve disease

 

Small animals-prenisone, prednisolone PO is adequate

 

Horse-dexamethasone but careful-laminitis

uncommonly used

Term
Contraindications for topical steroid use
Definition

ulcerative keratitis:

-inhibit fibroblast responses

-interfere with epithelial regneration

-potientiate proteinases that break down collagen

uncontrolled/severe infections

-may use with antibiotics to block uncontrolled inflammation (blindness)

Mature scars->no point, won't help anything

Corneal degenerations

Careful with metabolic dz-diabetes, especially in small animals

may facilitate fungal infections in prolonged use

may cause epithlial and stromal dystrophy/degeneration

may increase intraocular pressure

do not cause cataracts

Term

NSAID's

 

indications

Definition

when steroids contraindicated

complimentary to corticosteroids

pre cataract surgery

Term

NSAID's

 

MOA

Definition

prevent formation of prostaglandins from arachdonic acid

 

prostaglandins->primary mediators or ocular inflammation

Term

NSAID's

 

topical

Definition

delay healing of epithelium but not as deleterious as corticosteroids

 

expensive compared to steroids

 

Flubiprofen-0.03% ophthalmic solution

Diclofenac-0.1% ophthalmic solution

 

best not to use any NSAID's or topical steroids with corneal ulcer->last resort use NSAID's before steroids

Term
Systemic NSAID's
Definition

Small animals

Carprofen (Rimadyl)

Meloxican (Metacam)

 

Horses:

Flunixin meglumin (Banamine)-most effective in horses; monitor kidney function long term, protect GI with omeprazole

Piroxicam-tx SCC (80-160 mg/horse/day); limited data in literature

Term
Immunosuppresive agents
Definition

used in place or in combo with corticosteroids-synergic

 

Cyclosporine A (optimmune) ointment 0.2%-compounded 1-2% ophthalmic solution in oil

(irritating and rarely may cause alopecia)

Tacrolimus-no ophthalmic prep

compounded 0.02%-0.03% ophthalmic solution in veg. oil

Term
Cyclosporine
Definition

T lymphocyte suppressor

 

inhibit lymphokine production and release

 

use for immune-mediate problems of lids, conj, cornea (KCS, pannus, episcleritis)

KCS common, painful, sight-threatening

post corneal transplantation

Term

Cylosporine

 

clinical effects

Definition

most common tx for KCS

reverses immune-mediated changes to lacrimal gland (eventually)

 

stimulates tear production (lacrostimulation)-increase tear quantity and quality

reverse inflammatory changes in conj and cornea-slow

 

legal issues (still under patent), safety issues (gloves, wash hands)

Term
Antiproteases
Definition

used to stop devastating effects of proteinases (collagenases and gelatinases) on cornea

 

keratomalacia (melting cornea) commonly caused by infection

 

No ophthalmic prep

Term

Antiprotease

 

Drugs

Definition

Serum

N-Acetylcysteine

EDTA 1%

Tetracycline

Term

Antiprotease

 

Serum

Definition

Antiproteolitic properties-collagenase and gelatinases

due to presence of macroglobulins

 

has epitheliotrophic properties

promote corneal healing

Term

Anti protease

 

N-Acetylcysteine

Definition

5%-10%

 

irritating

lower concentration

no effect on gelatinases

short shelf life

Term

Antiprotease

 

EDTA

Definition

1%

 

irritating to eye

cheap

limited data on clinical effectiveness

Term

Antiprotease

 

Tetracycline

Definition

concentrates in cornea following topical or systemic admin

 

chelation

inhibition of gene expression

Term
Autonomic drugs
Definition

Autonomic innervation of eye is primarily to iris, ciliary body, upper eyelid and orbital cone

arterioles in uvea

 

used:

Manipulate pupil

limit aqueous production

facilitate outflow of aqeous

mostly anti-gluacoma drugs

Term

Parasympathomimetics (miotics)

 

Direct acting

Definition

cholinergic

 

directly stimulate Ach receptor of iris and ciliary body

 

act at myoneuronal junction (iris sphincter)

causes pupil to constrict (miosis)

produces accommodation, opens drainage angle

dilates blood vessels of conj and iris, increase vascular permeability

stimulates lacrimation

Term

Parasympathomimetics

 

Inidirect acting

Definition

Cholinesterase inhibitors

 

inhibit hydrolysis of Ach at nerve ending resulting in prolongues presence of neurotransmitter

Term

Direct acting parasympathomimetics

 

Pilocarpine

Definition

muscarinic

0.5-10% solution or ointment

inexpensive

constricts pupil

glaucoma to facilitate outflow

lacrimomimetic

10 minutes to onset, duration 8 hours

Term

Direct acting parasympathomimetics

 

Pilocarpine

 

adverse effects

Definition

transient stinging

salivation, vomiting, diarrhea

ciliary spasm= "eye ache"

myopia=near sighted

blurred vision

poor dark adaption

bradycardia, hypotension, bronchospasm

Term
Parasympatholytics (Mydriatics)
Definition

Block Ach receptors in iris and ciliary body

Dilate pupil by paralyzing sphincter, dilator is unopposed->mydriasis

ciliary muscle paralysis (cycloplegia)->prevent ciliary muscle spasm induced by uveitis, reduce pain and discomfort

Accomadation is lost due to mydriasis

Term

Parasympatholytics (Mydriatics)

 

uses

Definition

Control miosis cuased by ulcer and uveitis, help with prevention of posterior synechia

 

reduce pain of smooth muscle spasm in ciliary body and iris caused by corneal ulcers and uveitis

 

reduce clinical signs of uveitis->reduce vascular permeability

 

facilitate vision if animal has central corneal opacity or nuclear cataract

Term

Parasympatholytics (Mydriatics)

 

Atropine

Definition

0.5-2% o/s or 1% o/o

inexpensive

onset 30-60 min; recovery 96-120 hr-dog; 60hr-cat

may extend more than 14 days in horse

dose to effect

readily absorved through cornea

affinity for pigmented tissue-iris and ciliary body

Term

Parasympatholytics (Mydriatics)

 

Atropine adverse effects

Definition

affects autonomic nervous system

may cause colic in horses-gut stasis

increased intraocular pressure if narrow angle

blurred vision

dries tears, saliva, gastric secretions

bitter taste causes salivation, nausea (use ointment)

tachycardia

Term

Parasympatholytics (Mydriatics)

 

Tropicamide

Definition

0.5-1% solution

 

short onset, 15-20 min

duration 3-4 hrs

best mydriatic for eye exam

Term

Carbonic anhydrase inhibitors (CAI)

 

Anti-glaucoma

Definition

topical

block enzyme CA

synergic with Beta blockers

 

Term

Carbonic anhydrase inhibitors (CAI)

 

Anti-glaucoma

 

ophthalmic preps

Definition

dorzolamide 2% o/s

 

Dorzolamide+Timolol o/s

 

Brinzolamide 1% o/s (doesn't work well in cats)

Term

Prostaglandin analogues

 

Anti-gluacoma

Definition

Reduce IOP by increasing uveoscleral outflow

 

cause profound miosis

 

long lasting-usually SID-BID

Term

Prostaglandin analogues

 

Anti-gluacoma

 

ophthalmic preps

Definition

Latanoprost 0.005% o/s

 

Travoprost 0.004% o/s