pharmacology Flashcards
what are 4 routes of eye administration
topical, subconjunctival, subtenons and ocular injection
are the ocular epithelium of the cornea (outside) and the ocular stroma of the cornea (middle) hydrophobic/ hydrophilic respectively
ocular epithelium = hydrophobic/ lipophilic (lipophillic drugs penetrate
ocular stroma = hydrophilic/ lipophobic (hydrophillic drugs penetrate)
inflammation reduces the hydrophobic/ hydrophilic nature of the endothelium
inflamm reduces the hydrophobic nature of endothelium
what can the lipid tear layer do to drug penetration
reduce it
what drug is both lipophilic and hydrophilic and so can penetrate both layers of the cornea well
chloramphenicol
what is added to a steroid to make it hydrophobic? what are they used for and give an example
alcohol or acetate / passes through cornea so good for cataracts or post op in uniflammed eye / prednisolone acetate
what is added to a steroid to make it hydrophillic? what are they used for and give an example
phosphate / stays on surface of eye - good in inflamed eye and cornea disease / prednisolone phosphate
what strengths of ocular steroids are there (mild –> strong)
FML –> predsol (pred phosphate) –> betamethasone –> dexamthasone/ pred acetate
when are topical steroids used (3)
post op cataracts, uveitis, protect corneal graft rejection
what are local and systemic side effects of steroids
cataract, glaucoma, exac viral infection - GI upset, osteoporosis, weight gain, diabetes
when must topical steroids NEVER be given and why
viral keratitis as can cause corneal melting
what agents can be added to drugs to enhance corneal penetration
benzalkonium (disrupts teat film) and Bimatoprost (glaucoma)
what antibiotics are used in eye infections
chloramphenicol, gent, ofloxacin
what antiviral is used in eye infections
zorivax
what is the aim of glaucoma treatment and by what mechanisms fo they work
reduce IOP - decreased production of fluid AND/ OR increase fluid outflow/ drainage from trabecular network
what main drug classes are used in glaucoma (5)
prostanoids, B blockers, carbonic anhydrase inhibitors, A2 agonist, parasympathetics/ miotics
what is the first line drug for glaucoma and what does it do
prostanoids eg latanoprost (xalatan) - opens uvea-scleral outflow (drainage)
give an example of a betablocker and how they work in glaucoma
timolol - block ciliary body (decrease fluid production)
give an example of a carbonic anhydrase inhibitor and how they work in glaucoma
dorzolamide - reduce production of aqueous humour (side effects)
give an example of a parasympathetic/ miotic and how they work in glaucoma
contracts pupil to increase drainage - used in closed angle
what drug is commonly used in open angle glaucoma and how does it work
A2 agonist eg brimonidine - makes vessels leakier to increase drainage
when would intravitreal administration be used and why is it dangerous
antibiotics in endophthalmitis and intra-ocular steroids - many drugs toxic to retina
how does local anaesthetic work in the eye and when is it used
blocks Na channels to stop nerve conduction - FB removal / tonometry/ corneal scraping/ surgert
what diagnostic eye is used in ophthalmology and what is it used for
fluorescein - corneal abrasion/ dentritic ulcer/ leaks/ tonometry
what effects to mydriatics have on the eye and what are some side effects
cause pupil dilation by blocking parasympathetic supply to iris - blurring and acute glaucoma
name 2 mydriatics
tropicamide and cyclopentolate
what drug causes colour blindness as a side effect
digoxin
what drug causes white streaks across pupil as a side effect
amiodarone
what drug causes red tears as a side effect
rifampicin
what drug causes maculopathy as a side effect
chloroquine
what drug causes optic atrophy as a side effect
alcohol
