Pharmacology Flashcards
What is the sandwich that topical drugs have to penetrate to get into the cornea?
lipi:water:lipid
Is the epithelium lipophilic/phobic?
philic
Is the stroma lipophilic/phobic?
lipophobic
How far through the cornea do lipi soluble drugs penetrate?
epithelium
What do water soluble drugs penetrate in the cornea?
stroma
What is an example of a drug that has both liophilic and hydrophilic proerties and so can penetrate the cornea easily?
chloramphenicol
How does ocular surface inflammation affect the nature of the cornea epithelium?
reduces the hydrophobic nature
What can be added to a topical steroid to make it more hydrophobic?
alcohol or acetate
What can be added to a topical steroid to make it more hydrophilic?
phosphate
What is prednisolone phosphate used?
for cornea disease or when want low dose steroids (as hydrophilic)
What is benzalkonium?
a preservative
In addition to its preservative action, what else does benzalkonium do?
disrupts the lipi layer of the tear film, aiding penetration of hydrophilic drugs
How can the systemic absorption of topical drugs be prevented?
punctal occlusion
Where are intravitreal injections done?
after corneal limbus there is 3/4mm before the retina begins if hit retina can cause retinal detachment
What are the anti-inflammatory agents used in the eye?
steroids; topical NSAIDs; anti-histamines; mast cell stabilisers
When are topical steroids used?
post op cataracts; uveitis; to prevent corneal graft rejection
What are the local effects of steroids?
cataracts; glaucoma; exacerbation of viral infection
What is the only modifiable risk factor in glaucoma?
raised intra-ocular pressure
How do patients usually present with glaucoma?
usually asymptomatic- is screened for by optometrists- visual loss
What is LA used for?
FB removal; tonomtery(IOP); corneal scraping; comfort
How do LA wokr?
block sodium channels, impeding nerve conduction
What is the most commonly used diagnostic dye?
fluorescein
What are the uses of fluorescein?
shows corneal abrasions; tonometry; diagnosing nasolacrimal obstruction; angiography
How do mydriatics work?
pupil dilation by blocking parasympathetic supply to iris
What are the side effects of mydriatics?
blurring; AACG (acute glaucoma)
How do sympathomimetics work?
act of sympathetic system causing pupils to dilate
What can ethambutol cause?
optic neuropathy
How do drugs for glaucoma work?
by decreasing IOP by opening up drain or decreasing humour production
