Pharmacology Flashcards
where does occular obsorption come from
the cornea
where does systemic absorption of drugs by the eye come from
conjunctiva and mucous of the nasopharynx
what are the routes of topical eye administration
drops (more frequently)
ointment (sooth eye but blur vision)
what is the stroma
a mesenchymal tissue, the thickest layer of the cornea, and is ‘sandwiched’ between the epithelium and the inner endothelium
made of collagen
what makes up the tear film
lipid, water, lipid barrier
is epithelium lipophilic/phobic and
hydrophilic/phobic
epithelium is hyrophobic and lipophillic
is stroma lipophilic/phobic and
hydrophilic/phobic
stroma is lipophobic and hydrophillic
what types of drugs penetrate the epithelium of the eye
lipid soluble
what types of drugs penetrate the stroma
water soluble drugs
what drugs are good at crossing the cornea
drugs with a LMW
what type of drugs get through the eye furthest
lipid soluble
or drugs that are both lipo and hydro philic (chloramphenicol)
what drugs will not get through the surface of the eye
lipophobic (water soluble)
what can increase penetration of a drug into the eye
ocular surface inflammation (reduces the hydrophobic nature of the endothelium- innermost layer of the cornea)
what in tear film might impede drug penetration
lipid layer
what limits hydrophilic drugs in the eye
epithelium
what limits hydrophobic drugs in the epithelium
stroma (better penetration in these drugs)
what properties do topical steroids for the eye need
hydrophobic and hydrophilic capability
alcohol/ acetate makes steroids more hydrophobic
phosphate makes it more hydrophilic
when is prednisolone acetate used
post op, intraocular inflammation cataracts
hydrophic, good penetration in uninflamed cornea
what is prednisolone phosphate used
cornea disease/ when you want low dose steroids
hydrophilic, poor penetration in uninflamed cornea
what pathogen is the most common to cause infection in contact lenses
pseudomonas
what is the role of benzalkonium
disrupts lipid layer of tear film, aids penetration of some drugs
used to lower IOP in glaucoma
what a side effect of benzalkonium
makes eyes red and black
what can limit systemic absorption of a drug at the nasopharynx
punctal occulsion
what are the routes of administration of drugs into the eye
topical sub conjunctival subtenons (fibrous layer that starts at the limbus- this route will go back into the orbit) intra vitreal intracameral oral intra venous
what anti inflammatory agents are used in the eye
steroids, topical NSAIDs, anti-histamines, mast cell stabilisers
what drugs for allergic reactions (hayfever/ allergic conjunctivitis)
anti-histamines, mast cell stabilisers
what are the actions of steroids in the eye
suppress inflammation, allergy and immune responses
when are steroids used topically in the eye
post op cataracts
uveitis
prevent corneal graft rejection
what is uveitis
inflammation of the uvea (iris, ciliary body and choroid)
what route of steroids for inflammation at the back of the eye
systemic steroids
what are the features of temporal arteritis
sudden onset temporal pain, jaw claudication
multinucleated giant cells
can have vague visual symptoms/ complete visual loss
is a blinding condition
how is temporal arteritis treated
systemic steroids 40 if no visual disturbance, 60 if affected
what does the optic disc look like in anterior ischaemic neuropathy
swollen due to infarction of the optic nerve
what are the local effects of steroids
cataract, glaucoma, exacerbation of viral infection
what are the systemic effects of steroids
gastric ulceration, immunosuppression, osteoporosis, weight gain, diabetes, neuropsychiatric effects
what can you give to reduce gastric ulceration in steroids
PPI
list the topical eye steroids from most to least potent
FML
Predsol (prednisolone phosphate)
Betamathasone
Dexamethasone/ prednisolone acetate
when are NSAIDs used in the eye
for pain relief/ anti inflammatory
what can you give for corneal abrasion
NSAIDs
local anaesthetic will stop it healing
what is glaucoma
group of disorders characterised by a progressive neuropathy (damage to the optic nerve) resulting in characteristic field defects
what is the only modifiable risk factor for glaucoma
raised IOP
what happens to the cup in glaucoma
gets bigger
how do you functionally test for glaucoma
field test
what can slow the progression of glaucoma
lowering IOP - either by reducing the production of aqueous or unblock the drain
what visual defects in glaucoma
not tunnel vision - brain fills in the gap
what glaucoma medications open the drain
prostanoids (lanaoprost)
parasympathomimetic (pilocarpine)
what glaucoma medication prevents the absorption of aqueous
beta blockers
what glaucoma medications stop production of aqueous and open the drain
carbonic anhydrase inhibitors (topical- dorzolamide, systemic- acetazolamide) (opens drain and reduces production of aqueous)
alpha adrenergic agonist (brimonidine) ( turns of production and opens drain via vasodilation)
why do people with glaucoma wear tinted glasses
to reduce glare
what is the main route of antibiotic administration in endophthalmitis
intravitreal
what drugs are delivered intra vitreal
antibiotics intra ocular steroids anti VEGF (reduce oedema)
what is a hypopyon
inflammatory cells in the anterior chamber of the eye
how do local anaesthetics work within the eye
blocks sodium channels and impedes nerve conduction
what does diagnostic dye fluorescein show
shows corneal abrasion dendritic ulcer leaks (seidel test) tonometry nasolacrimal duct obstruction angiography
what do mydriatics do (tropicamide, cyclopentolate)
dilate pupils, block parasympathetic supply to the iris cause cyclopegia (stop lens from focusing)
what are the side effects of mydriatics
AACG, blurring
why do you dilate the pupil
to see the back of the eye
what is the presentation of acute angle closure glaucoma
very painful, throwing up, sudden onset headache, pupil mid dilated not reacting
what do sympathomimetics do
act on sympathetic system causing the pupil to dilate
e.g. tropicamide, atropine- can cause cyclopegia
what is the long term use of atropine
given to child with a squint as takes 7-9 days to wear off- will help strengthen other eye
why dont systemic drugs reach the eye
inner and outer retinal blood brain barrier
what do miotics do
constrict the pupil (pilocarpine)
what can alcohol and ethambutol (TB) cause
optic atrophy
what can rifampicin cause
red tears, stain contact lenses
what can digoxin cause
changes in colour appreciation
what can chloroquine cause
maculopathy
what can amiodarone cause
corneal verticullata
what do you never give steroids to
herpetic keratitis
