Ocular Pharmacology Flashcards
Describe the problem with drug administration through the cornea
•Epithelium is lipophilic/hydrophobic
•Stroma is lipophobic/hydrophilic
What are the two blood-ocular barriers
•Blood–aqueous barrier – iris and ciliary body
•Blood-retinal barrier – retinal tight junctions
What four factors increases drug absorption of drops across the cornea/conjunctiva
- Higher concentration
- Lipophilic
- Preservatives to alter cell membrane & ^ permeability
- pH of ~7.4 to avoid tear reflex
Punctual occlusion can be used when administer drugs to the eye through drops/topically. Why does this help?
Limits the amount of drug being pumped into the lacrimal sac with tears instead of being absorbed
What other routes of administration (other than drops/topical) exist for the eye
•Subconjunctival
•Subtenons
•Intravitreal
•Intracameral
Why do systemic drugs have poor ocular absorption
Blood-ocular barrier (esp the retinal tight junctions)
Antibiotics can be used to treat eye infections. How would the route of administration differ between different types of infection
Topical/drops - conjunctivitis/ keratitis
Periorbital cellulitis - orally
Orbital cellulitis - IV
Endophthalmitis - Intravitreal
Topical antiviral (gel) uses
Adenovirus conjunctivitis/keratitis
Herpetic conjunctivitis/ keratitis
Acute retinal necrosis (HSV/HZV chorioretinitis)
Topical antifungal (drops) uses
- Candida keratitis
- Candida endogenous chorioretinitis
Topical steroid (drops) uses
- Post op cataracts
- Uveitis
- Post corneal transplant
Eye side effects of steroids (systemic or topical)
Cataracts
Glaucoma
Exacerbation of viral infection e.g. Herpetic keratitis
Raised intraocular pressure
Intravitreal injection uses
- antibiotics in endophthalmitis
- intraocular steroids
- anti-VEGF in wet AMD
Wet AMD (age related macular degeneration) treatment
Anti-VEGF (Vado-endothelial growth factor)
Name two types of dilating drops & name 2 examples of each
- Mydriatics e.g. tropicamide, cyclopentolate
- Sympathomimetics e.g. atropine, phenylephrine
Mydriatics MOA
blocks parasympathetic supply to iris to dilate the pupil
Sympathomimetic MOA
Acts on sympathetic system to dilate pupil
Dilating drop side effects
cycloplegia
Local anaesthetic MOA
Blocks sodium channels and impedes nerve conduction
Local anaesthetic uses
•1) FB removal
•2) Tonometry (IOP measurement)
•3) corneal scraping
•4) comfort
•5) Cataract surgery
What is the most common dye used in opthalmology
Fluorescein
Diagnostic dye uses
•corneal epithelial defects and ulcers
•Tonometry– checking eye pressure
•seidels test – concentrated dye
•jones dye test – assessing lacrimal passage
•fundus fluoroscein angiography
•tear film break up time
What drug types are used in glaucoma
- beta blockers
- prostaglandin inhibitors
- carbonic anhydrase inhibitors
- miotics
- sympatomimetics (alpha2 adrenergic agonist)
Beta blockers in glaucoma MOA
Reduce aqueous humour production
Prostaglandin analogues in glaucoma MOA
Increased aqueous humour drainage
Carbonic Anhydrase inhibitors in glaucoma MOA
Reduce aqueous humour production (from ciliary body)
Mitotics in glaucoma MOA
Either decrease aqueous production OR
Increase aqueous outflow
Sympatomimetics (Alpha2 adrenergic agonist) in glaucoma MOA
Cause pupil constriction which opens the aqueous humour drainage angle
Beta blockers systemic side effects (if absorbed into bloodstream)
Bradycardia, hypotension
Alpha agonists systemic side effects (if absorbed into bloodstream)
Dry mouth, sedation
Prostaglandin analogues local side effects
Hypertrichosis around eyelids e.g. eyelash growth
Chloroquine side effect in eye
Bullseye maculopathy
Ethambutol side effects in eye
Optic neuropathy
Amoidarone side effects in eye
Vortex keratopathy
