pharmacology Flashcards
what are the requirements for a topical eye drop to work?
needs to act on surface
requires corneal penetration
which drug penetrates the epithelium?
Lipid soluble drugs penetrate epithelium
which drugs penetrate the stroma?
Water soluble drugs penetrate stroma
what are the features of prednisolone acetate?
hydrophobic
Good penetration in uninflamed cornea
Used post-operatively
what are the features of prednisolone phosphate?
hydrophilic
Poor penetration in uninflamed cornea
Used for cornea disease or when want low dose steroids
how is corneal penetration enhancement achieved?
Benzalkonium is a preservative.
Also disrupts lipid layer of tear film
Aids penetration of some drugs
what other routes of administration for eye meds are there
Subconjunctival
Subtenons
Intravitreal
Intracameral
what do opthalmic drugs treat?
Treatment of Infections
Treatment of Inflammation
Treatment of Glaucoma
Diagnostic eye drops
Intraocular injections
Ocular toxicity
when are topical steroids commonly used?
post op cataracts
uveitis
to prevent corneal graft rejection
what are some local side effects steroids?
cataract
glaucoma
exacerbation of viral infection
what are some systemic side effects of steroids?
Gastric ulceration
Immunosuppression
Osteoporosis
Weight gain
Diabetes
Neuropsychiatric effects
what is a key feature of uveitis?
photophobia
what is used in hayfever/ allergic conjunctivitis?
Antihistamines and mast cell stabilisers
what is glaucoma?
A group of diseases characterised by a progressive optic neuropathy resulting in characteristic fields defects.
Raised intra ocular pressure is currently the only modifiable risk factor
what are the features for glaucoma?
Usually asymptomatic.
It is screened for by optometrists
Chronic disease
Usually slowly progressive
what is the most common glaucoma medication?
Prostanoids eg Latanoprost (‘Xalatan’).
what are some other examples of glaucoma medications?
Beta blockers (timolol, betaxolol, levobunolol carteolol etc)
Carbonic anhydrase inhibitors eg topical eg Dorzolamide (‘Trusopt’) or systemic – acetazolamide (Diamox)
Alpha2 adrenergic agonist Brimonidine (‘Alphagan’).
Parasympathomimetic - pilocarpine
Combination - (dorzolamide and timolol - Cosopt ).
what are the features of intravitreal drugs
Delivers effective concentration of drug at target site instantly BUT many drugs toxic to retina
Used as method of administration of antibiotics in endophthalmitis
Used to deliver intra-ocular steroids
Anti-VEGF
what is endopthalmitis?
a purulent inflammation of the intraocular fluids (vitreous and aqueous) usually due to infection. Serious intraocular inflammatory disorder resulting from infection of the vitreous cavity.
Progressive vitritis is the hallmark of any form of endophthalmitis.
sight threatening
what does a local anaesthetic do?
Blocks sodium channels and impedes nerve conduction
what is the treatment for wet AMD
vaso-endothelial growth factor
monoclonal antibody fragment to VEGF
intravitreal injections
whan are diagnostic dyes used (fluorescein)?
shows corneal abrasion
dendritic ulcer
identify leaks
tonometry
when is local anaesthetic used in opthalmology?
FB removal
Tonometry (IOP measurement)
corneal scraping
comfort
Cataract surgery
what are some examples of mydriatics?
tropicamide, cyclopentolate
what are the features of mydriatics?
Cause pupil dilation by blocking parasympathetic supply to iris
Cause cycloplegia ie stop lens from focus
Side effects – blurring, AACG
what are some features of sympathomimetics?
Acts on sympathetic system
Causes pupil to dilate
Some cause cycloplegia eg atropine
Some do not eg phenylephrine
do you give steroids to herpetic keratitis?
no
