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Ophthalmology > Pharmacology > Flashcards

Pharmacology Flashcards

1
Q

What must a topical drug be able to do?

A

Act on the surface and penetrate the cornea

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2
Q

Describe the structure of the cornea in terms of solubility

A

Consists of two lipophilic epithelium with hydrophilic stroma in between

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3
Q

Name a drug that is both lipid and water soluble

A

Chloramphenicol

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4
Q

What is the consequence of ocular inflammation on solubility?

A

Reduces the hydrophobic nature of the epithelium

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5
Q

How are steroids made more hydrophobic?

A

Add alcohol or acetate (prednisolone acetate)

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6
Q

How are steroids made more hydrophilic?

A

Add phosphate (prednisolone phosphate)

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7
Q

Describe predisolone acetate

A

Hydrophobic, allows good penetration in an uninflammed cornea and is used post-op

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8
Q

Describe prednisolone phosphate

A

Hydrophilic, has poor penetration in an uninflammed cornea but is used in corneal disease where low doses are required

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9
Q

What chemical can be added to drugs to aid penetration?

A

Benzalkonium Chloride

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10
Q

Other than aiding penetration what else does benzalkonium chloride do?

A

It is a preservative emollient that depletes the lipid tear film and kills some microbes

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11
Q

What are the side effects of benzalkonium chloride?

A

Some patients are allergic and some experience dry eyes

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12
Q

How does systemic absorption of topical drugs occur?

A

Excess tears go through the nasopharynx and can enter the GI tract

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13
Q

What advice can be given to patients experiencing GI side effects of topical drugs?

A

Occlude the puncta to limit systemic absorption

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14
Q

Name four other routes of administration (apart from topical)

A
  • subconjunctival (acts like a deposit)
  • subtenous (into posterior orbital space)
  • intravitreal injection
  • intracameral injection
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15
Q

What drugs are often given subconjunctivally?

A

Steroids and antibiotics

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16
Q

Name four drugs given to patients with ocular inflammation

A
  • Steroids
  • NSAIDs
  • Anti-histamines
  • Mast cell stabilisers
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17
Q

How do steroids work?

A

Suppress the immune inflammatory response

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18
Q

When are steroids used?

A

Post op cataracts
Uveitis
Prevent corneal graft rejection
Temporal arterities

19
Q

What are the signs of uveitis?

A

Circumcorneal injection - enlargement of ciliary and conjunctival vessels
Keratic precipitates
Yellow/white dots in chorioretinitis with ischaemia

20
Q

Why are steroids used in temporal arterities?

A

IV steroids are used as it can cause optic nerve infarction, anterior ischaemic neuropathy and blindness

21
Q

What are the ocular side effects of steroids?

A

Cataract
Glaucoma
Exacerbation of virus

22
Q

What is the only clinically modifiable risk factor for glaucoma?

A

Raised intraocular pressure

23
Q

What kind of vision do patients with glaucoma have?

A

Tunnel vision

24
Q

What does the treatment of glaucoma aim to do?

A

Slow the disease down and prevent loss of vision

25
Q

Name five medications used in glaucoma

A
  • prostanoids
  • beta blockers
  • carbonic anhydrase inhibitors
  • alpha 2 adrenergic agonists
  • parasympathomimetics
26
Q

What is the mechanism of action of prostanoids?

A

Open the drain

27
Q

What is the mechanism of action of beta blockers?

A

Turns off the tap

28
Q

What is the mechanism of action of carbonic anhydrase inhibitors and how can they be administered?

A

Turn off the tap can be given orally or IV in an acute situation

29
Q

How do alpha 2 adrenergic agonists work?

A

Turn off the tap and open the drain by vasodilation

30
Q

How do parasympathomimetics work?

A

Open the drain by pulling on the iris

31
Q

What drugs are absolutely contraindicated in children?

A

Alpha 2 agonists due to fatigue and sleep apnoea, they can also cause an allergic reaction

32
Q

Describe intravitreal administration

A

Delivers effective concentrations of drug at site but they may be toxic to the retina

33
Q

When are intravitreal drugs given?

A

Antibiotics in endophthalmitis

Steroids and anti-VEGF in wet ARMD

34
Q

What is the mechanism of action of local anaesthetic?

A

Blocks sodium channels and impedes nerve conduction

35
Q

When is local anaesthetic used?

A 
Foreign body removal 
Tonometry 
Corneal scraping 
Comfort 
Cataract surgery
36
Q

What does tonometry do?

A

Measure intra-ocular pressure

37
Q

What is the most common diagnostic dye?

A

Fluorescein

38
Q

What are diagnostic dyes used for?

A

Corneal abrasion, dendritic ulcer, identifying leaks, tonometry, nasolacrimal duct obstruction and angiography

39
Q

What do some mydriatics do to the ciliary muscles?

A

Paralyse them

40
Q

When are parasympathomimetics used?

A

To decrease pressure

41
Q

What TB drug can cause ocular side effects?

A

Ethambutol - optic neuropathy

42
Q

What ocular side effect can hydroxychloroquine cause?

A

Bulls Eye Maculopathy

43
Q

Which heart drug can cause disturbance to colour vision?

A

Digoxin

44
Q

When must steroids never be given?

A

Hepatic Keratitis

Ophthalmology (12 decks)

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