Pharmacology Flashcards
what drugs are suitable for corneal penetration and why
Lipid soluble drugs penetrate the epithelium as it is lipophilic/hydrophobic
Water soluble drugs penetrate stroma as it is lipophobic/hydrophilic
why does Chloramphenical penetrate the cornea easily
has both lipophilic and hydrophilic properties
what can reduce the hydrophobic nature of the endothelium
ocular surface inflammation
features of Prednisolone acetate
hydrophobic
Good penetration in uninflamed cornea
Used post-operatively
features of prednisolone phosphate
Hydrophilic
Poor penetration in uninflamed cornea
Used for cornea disease or when want low dose steroids
what makes a steroid more hydrophobic
alcohol or acetate
what makes a steroid more hydrophilic
phosphate
what preservative aids the penetration of some drugs
Benzalkonium
drugs used in Tx of infection of the eye
Chloramphenicol
Olfloxacin
Aciclovir
drugs used in Tx of inflammation of the eye
Dexamethasone
Betamethasone
Predsol
Steroids
Topical NSAIDs
Anti-histamines
Mast cell stabilisers
what are the actions of steroids
suppress inflammation, allergy and immune responses
when are steroids used in the eye
1) post op cataracts
2) uveitis - inflammation of middle eye
3) to prevent corneal graft rejection
what are side effects of the steroids in the eye
cataract
glaucoma
exacerbation of viral infection
when should steroids never be given
in a patient with red eye
what are glaucomas
A group of diseases characterised by a progressive optic neuropathy resulting in characteristic fields defects.
what is the only modifiable risk factor in glaucomas
raised intra ocular pressure
what is the gold standard drug treatment of glaucoma
Prostanoids eg Latanoprost (‘Xalatan’)
what are other drugs used in treatment of glaucoma
Beta blockers (timolol, betaxolol, levobunolol carteolol etc)
Carbonic anhydrase inhibitors eg Dorzolamide (‘Trusopt’) or systemic – acetazolamide (Diamox)
Alpha2 adrenergic agonist -Brimonidine (‘Alphagan’)
Parasympathomimetic - pilocarpine
how do beta blockers and Carbonic anhydrase inhibitors work in the treatment of glaucoma
turn off the tap/block the ciliary bodies
how do alpha2 adrenergic agonist inhibitors work in the treatment of glaucoma
make eye blood vessels more leaky
how do Parasympathomimetic work and what is a possible side effect
pulls iris tight and opens up trabecular meshwork.
Can cause patients to have difficulty seeing in the dark
when is intravitreal used as a method of transport of a drug
antibiotics in endophthalmitis
deliver intra-ocular steroids
anti-VEGF therapy
what are diagnostic drops
Fluorescein
what are dilating drops
Cyclopentolate
Tropicamide
how do local anaesthetics work
Blocks sodium channels and impedes nerve conduction
when are local anaesthetics used
1) FB removal
2) Tonometry (IOP measurement)
3) corneal scraping
4) comfort (put cannot let patient take home as it stops epithelium from regeneration)
what are uses of diagnostic drops
1) shows corneal abrasion
2) tonometry
3) diagnosing nasolacrimal duct obstruction
4) angiography
how do Mydriatics work
Cause pupil dilation by blocking parasympathetic supply to iris
how do Sympathomimetics work
Acts on sympathetic system
Causes pupil to dilate
Do not affect the ciliary muscle (accommodation)
E.g phenylephrine, atropine
what TB drug can cause optic neuropathy
Ethambutol
what eye side effect can Chloroquine cause
Maculopathy
