Pharmacology Flashcards
Is the epithelium lipophilic/phobic?
lipophilic
Is the stroma lipophilic/phobic?
phobic
Give an example of a drug which has both lipophilic and phobic properties, allowing it to easily penetrate the cornea.
chloramphenicol
What can reduce the hydrophobic nature of endothelium?
ocular surface inflammation
What makes a steroid more hydrophobic?
alcohol/acetate
What makes a steroid more hydrophilic?
phosphate
Is prednisolone acetate hydrophobic or philic?
hydrophobic
Does prednisolone acetate have good or bad penetration in uninflamed cornea?
good penetration
When is prednisolone acetate used?
post op
What is Prednisolone phosphate used for?
for cornea disease or when want low dose steroids
What is Benzalkonium?
Benzalkonium is a preservative.
Also disrupts lipid layer of tear film
Aids penetration of some drugs
What is Bimatoprost?
Drug used to lower IOP in glaucoma
What are the 3 broad categories of antibiotics used on the eye?
3 broad categories - all act on bacteria and either
Inhibit protein synthesis
Inhibit cell wall synthesis
Inhibit nucleic acid synthesis
What is the most commonly used topical antibiotic?
chloramphenicol
What are the side effects of chloramphenicol?
Allergy
Irreversible aplastic anaemia (rare : 1 in 40,000)
Grey baby syndrome
Describe antibiotics that inhibit nucleic acid synthesis
Quinolones e.g. ofloxacin, inhibit DNA gyrase, an enzyme that compresses bacterial DNA into supercoils
Inhibition of DNA gyrase leads to unwinding of supercoils and cell death
Describe antibiotics that inhibit cell wall synthesis.
Penicillins & cephalosporins have common B lactam ring
B lactam ring inhibits enzyme which makes bacterial cell wall
Without cell wall, bacteria die
How does chlorampheniocol work?
inhibits bacterial protein synth via ribosomes
Describe the antiviral drug zovirax and say what it is used for.
Zovirax inhibits viral DNA synthesis
Base analogue (mimics guanine)
Used for dendritic ulcers of the cornea
List 4 anti inflammatory agents.
Steroids
Topical NSAIDs
Anti-histamines
Mast cell stabilisers
What are steroids used in the eye for? (3 things)
1) post op cataracts
2) uveitis
3) to prevent corneal graft rejection
List the local side effects of steroids.
cataract
glaucoma
exacerbation of viral infection
What is intravitreal injections used for?
Used as method of administration of antibiotics in endophthalmitis
and used to deliver intra-ocular steroids
How does local anaesthetic work?
Blocks sodium channels and impedes nerve conduction
What is the most commonly used dye in the eye and what might it be used for.
fluorescein
1) seeing a corneal abrasion
2) tonometry
3) diagnosing nasolacrimal duct obstruction
4) angiography
How do Mydriatics work?
Cause pupil dilation by blocking parasympathetic supply to iris
Give examples of mydriatics.
tropicamide, cyclopentolate
What are mydriatics side effects?
blurring, AACG (acute angle closure glaucoma)
Describe how Sympathomimetics work and give examples.
Acts on sympathetic system
Causes pupil to dilate
Do not affect the ciliary muscle (accomodation)
E.g phenylephrine, atropine
What treatments are used for glaucoma?
Prostanoids
Beta blockers
Carbonic anhydrase inhibitors
(‘Trusopt’) or systemic – acetazolamide (Diamox)
Alpha2 adrenergic agonist
Parasympathomimetic - pilocarpine
Combination - (dorzolamide and timolol - Cosopt ).
What might Vigabatrin do?
constrict fields
