week 2 pharamcology Flashcards
(31 cards)
hydrophobic + hydrophilic drugs administer topically to the eye limited by what?
Hydrophilic drugs limited by epithelium
Hydrophobic drugs limited by stroma
how are steroids modified to make for hydrophobic/phillic
Alcohol or acetate makes steroid more hydrophobic
Phosphate makes it more hydrophilic
give two examples of eye steroids and their uses
Prednisolone acetate:
- hydrophobic:
- Good penetration in uninflamed cornea
- Used post-operatively
Prednisolone phosphate
- hydrophilic
- poor penetration in uninflamed cornea
- Used for cornea disease or when want low dose steroids
what are the two functions of benzalkonium in eye drops?
Benzalkonium is a preservative.
Also disrupts lipid layer of tear film ( therefore; Aids penetration of some drugs)
how to limit systemic absorption of topical drugs?
punctal occlusion
-as tears are pumped out of lacrimal sac rapidly are drained by nasopharynx
when are topical steroids used?
1) post op cataracts
2) uveitis
3) to prevent corneal graft rejection
- work by suppressing inflammation, allergy and immune responses
what are the local side effects of steroid
cataract
glaucoma
exacerbation of viral infection
what are the systemic side effects of steroid
Gastric ulceration Immunosuppression Osteoporosis Weight gain Diabetes Neuropsychiatric effects
why can topical NSAIDs be used?
used for pain relief eg post refractive laser eye surgery
what can Antihistamines and mast cell stabilisers be used for?
used in hayfever / allergic conjunctivitis
what is glaucoma?
A group of diseases characterised by a progressive optic neuropathy resulting in characteristic fields defects. (reduced peripheral vision)
what is the only modifiable risk factor for glaucoma
raised IOP
how is glaucoma picked up?
Usually asymptomatic.
It is screened for by optometrists
Chronic disease
Usually slowly progressive
treatment for glaucoma?
Prostanoids eg Latanoprost (‘Xalatan’).
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 is the treatment for wet macular degeneration?
anti-VEGF [intravitreal]
how does local anaesthetic work?
Blocks sodium channels and impedes nerve conduction
when is local anaesthetic used?
1) FB removal
2) Tonometry (IOP measurement)
3) corneal scraping
4) comfort
(use in A+E if pain to examine bc treatment will probably require it anyways)
what is the most common diagnostic dye used?
fluorescein
why/when is fluorescein used?
1) shows corneal abrasion
2) tonometry
3) diagnosing nasolacrimal duct obstruction
4) angiography
5) dendrtiic ulcer
6) identify leak
give an example of a mydriatic
tropicamide, cyclopentolate
how do mydriatics work?
Cause pupil dilation by blocking parasympathetic supply to iris
side effects of mydraitics?
blurring, AACG (sudden onset headache, check eyes)
give an example of a sympathomimetic?
phenylephrine, atropine
how do Sympathomimetics work?
Acts on sympathetic system
Causes pupil to dilate
Do not affect the ciliary muscle (accomodation)
