Pharmacology

Question 1

Is the epithelium lipophilic/phobic?

Answer 1

lipophilic

Question 2

Is the stroma lipophilic/phobic?

Answer 2

phobic

Question 3

Give an example of a drug which has both lipophilic and phobic properties, allowing it to easily penetrate the cornea.

Answer 3

chloramphenicol

Question 4

What can reduce the hydrophobic nature of endothelium?

Answer 4

ocular surface inflammation

Question 5

What makes a steroid more hydrophobic?

Answer 5

alcohol/acetate

Question 6

What makes a steroid more hydrophilic?

Answer 6

phosphate

Question 7

Is prednisolone acetate hydrophobic or philic?

Answer 7

hydrophobic

Question 8

Does prednisolone acetate have good or bad penetration in uninflamed cornea?

Answer 8

good penetration

Question 9

When is prednisolone acetate used?

Answer 9

post op

Question 10

What is Prednisolone phosphate used for?

Answer 10

for cornea disease or when want low dose steroids

Question 11

What is Benzalkonium?

Answer 11

Benzalkonium is a preservative.
Also disrupts lipid layer of tear film
Aids penetration of some drugs

Question 12

What is Bimatoprost?

Answer 12

Drug used to lower IOP in glaucoma

Question 13

What are the 3 broad categories of antibiotics used on the eye?

Answer 13

3 broad categories - all act on bacteria and either
Inhibit protein synthesis
Inhibit cell wall synthesis
Inhibit nucleic acid synthesis

Question 14

What is the most commonly used topical antibiotic?

Answer 14

chloramphenicol

Question 15

What are the side effects of chloramphenicol?

Answer 15

Allergy
Irreversible aplastic anaemia (rare : 1 in 40,000)
Grey baby syndrome

Question 16

Describe antibiotics that inhibit nucleic acid synthesis

Answer 16

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

Question 17

Describe antibiotics that inhibit cell wall synthesis.

Answer 17

Penicillins & cephalosporins have common B lactam ring
B lactam ring inhibits enzyme which makes bacterial cell wall
Without cell wall, bacteria die

Question 18

How does chlorampheniocol work?

Answer 18

inhibits bacterial protein synth via ribosomes

Question 19

Describe the antiviral drug zovirax and say what it is used for.

Answer 19

Zovirax inhibits viral DNA synthesis
Base analogue (mimics guanine)
Used for dendritic ulcers of the cornea

Question 20

List 4 anti inflammatory agents.

Answer 20

Steroids
Topical NSAIDs
Anti-histamines
Mast cell stabilisers

Question 21

What are steroids used in the eye for? (3 things)

Answer 21

1) post op cataracts
2) uveitis
3) to prevent corneal graft rejection

Question 22

List the local side effects of steroids.

Answer 22

cataract
glaucoma
exacerbation of viral infection

Question 23

What is intravitreal injections used for?

Answer 23

Used as method of administration of antibiotics in endophthalmitis
and used to deliver intra-ocular steroids

Question 24

How does local anaesthetic work?

Answer 24

Blocks sodium channels and impedes nerve conduction

Question 25

What is the most commonly used dye in the eye and what might it be used for.

Answer 25

fluorescein

1) seeing a corneal abrasion
2) tonometry
3) diagnosing nasolacrimal duct obstruction
4) angiography

Question 26

How do Mydriatics work?

Answer 26

Cause pupil dilation by blocking parasympathetic supply to iris

Question 27

Give examples of mydriatics.

Answer 27

tropicamide, cyclopentolate

Question 28

What are mydriatics side effects?

Answer 28

blurring, AACG (acute angle closure glaucoma)

Question 29

Describe how Sympathomimetics work and give examples.

Answer 29

Acts on sympathetic system
Causes pupil to dilate
Do not affect the ciliary muscle (accomodation)
E.g phenylephrine, atropine

Question 30

What treatments are used for glaucoma?

Answer 30

Prostanoids
Beta blockers
Carbonic anhydrase inhibitors
(‘Trusopt’) or systemic – acetazolamide (Diamox)
Alpha2 adrenergic agonist
Parasympathomimetic - pilocarpine
Combination - (dorzolamide and timolol - Cosopt ).

Question 31

What might Vigabatrin do?

Answer 31

constrict fields