Pharmacology of the Eye Flashcards
When are topical steroids used?
Post cataract surgery
Uveitis/Iritis
Prevent graft rejection
What are the local side effects of steroid in the eye?
Cataracts
Exacerbation of viral infection
Glaucoma
What are the systemic effects of steroid use?
Osteoporosis Weight gain Immunosuppresion Moon face Truncal obesity Acne Gastric ulceration Hypertension
How can you make steroids more
a) Hydrophobic/lipophilic
b) Hydrophilic/lipophobic?
a) add acetate/alcohol
b) add phosphate
Why is benzalkonium added to topical treatments?
Preservative
Disrupts corneal lipid layer
Aids penetration
What drugs can be used in inflammation of the eye?
Steroids
NSAIDS
Anti-histamines
Mast call stabilisers
When are NSAIDS used?
Pain relief
Post refractive laser
When are anti-histamines used?
Hayfever
Allergic conjunctivitis
What are the routes of administration for drugs in the eye?
Topical Sub-conjunctival Intracorneal Sub-tenons Intravitreal
What are the problems with topical drugs?
Lipid layer of tear film impedes penetration
How does inflammation affect endothelium?
Makes it less hydrophobic
What drugs are given intravitreal?
Anti VEGF
Antibiotics for endophtalmitis
Intraocular steroids
Why are intravitreal injections good?
effective concentration to target site
Why may intravitreal injections potentially disadvantageous?
Retinal toxicity
What colour drops would you use diagnostically?
Flouriscene, orange
What can flouriscene be used for?
Diagnosis corneal abrasion
Diagnosis nasolacrimal gland obstruction
Tonometry
Angiography
Name 2 dilating drops
Tropicamide
Phenylephrine hydrochloride
How does tropicamide cause dilatation?
blocks parasympathetic supply
What are the local side effects of topicamide?
Blurred vision
Acute angle closure glaucoma
How does phenylephrine hydrochloride cause dilatation?
Acts on sympathetic supply
How do local anaesthetics work?
Block Na+ channels
Reduces nerve conduction
When are local anaesthetics used?
Foreign body removal
Tonometry
Corneal scraping
What is the route of administration in glaucoma medication?
Intravitreal
What is the aim of glaucoma medication?
Lower intra-ocular pressure
What medications are used in glaucoma?
Prostanoids (lantaprost, ie xalantan) Beta blockers Carbonic anhydrase inhibiters (dorcolamide) Alpha 2 agonists Parasympathomemetics (pilocarpine)
When are antivirals used in eye infections?
Dendritic ulcers
What should NOT be used with a dendritic ulcer?
Do not use steroids
Give an example of an antiviral used in eyes
Zovirax
What is the action of Quinolones?
Inhibits DNA gyrase
Unwinds supercoils
Causes bacterial death
Name a quinolone used in eyes
ofloxacin
What is the actoin of penicillins?
Has B-lactam ring
Inhibits cell wall producing enzyme
Causes cell death
What is the action of Chloramphenicol?
Inhibits peptidyl transferase
Stops proteins synthesis via ribosomes
What is the route of administration for chloramphenicol?
topical
How does chloramphenicol pass through the corneal layers? (Hydrophobic//Hydrophilic//Hydrophobic)
It is both hydrophobic and hydrophilic
When is chloramphenicol used?
Bacterocidal in Strep and Haemophilus
Bacterostatic in Staph
What are the side effects of Chloramphenicol?
Allergy
Aplastic anaemia (irreversible, rare)
Grey Baby Syndrome
What are the local side effects of
a) Vigabatrin
b) Steroids
c) Ethambutol
d) Chloroquine
a) constricts visual feilds
b) cataracts
c) optic neuropathy
d) maculopathy
