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LR Ophthalmology > Pharmacology > Flashcards

Pharmacology Flashcards

1
Q

List 5 routes of administration for eye drugs

A
  • Topical drops/ointment
  • Sub-conjunctival injection
  • Intra-vitreal injection
  • Oral
  • Intravenous
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2
Q

Topical drugs must be able to penetrate the cornea. Why can this pose a challenge?

A

The outer epithelial layer of the cornea is lipophilic so is penetrated by lipid soluble drugs

The inner stroma layer of the cornea is hydrophilic so is penetrated by water soluble drugs

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3
Q

Why is the antibiotic chloramphenicol able to penetrate the cornea easily?

A

It has both lipophilic and hydrophilic properties

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4
Q

Hydrophilic drugs are limited by the epithelium/stroma

Hydrophobic drugs are limited by the epithelium/stroma

A

Hydrophilic drugs are limited by the epithelium

Hydrophobic drugs are limited by the stroma

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5
Q

List one factor which can…

  • Reduce the hydrophobic nature of the endothelium
  • Increase the hydrophobic nature of the endothelium
A

Ocular surface inflammation can reduce the hydrophobic nature
Lipid layer formed by tears can increase the hydrophobic nature

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6
Q

Topical steroids need both hydrophobic and hydrophilic capabilities to have effect in the eye. This requires chemical modification.
Name a compound which can be added to the steroid to make it more…
-Hydrophobic
-Hydrophilic

A

Hydrophobic: alcohol or acetate

Hydrophilic: phosphate

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7
Q

When might prednisolone acetate be used? Why?

A

Acetate = hydrophobic

May be used post-op as it will have good penetration of the uninflamed cornea

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8
Q

When might prednisolone phosphate be used? Why?

A

Phosphate = hydrophilic

May be used for cornea disease or when only low dose steroid is required because penetration of the cornea is poor

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9
Q

Name a compound which can be added to some drugs to enhance corneal penetration

A

Benzalkonium

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10
Q

Name a drug which contains Benzalkonium preservative to enhance its corneal penetration

A

Bimatoprost (used to lower IOP in glaucoma)

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11
Q

Topical drugs which are applied to the cornea are often systemically absorbed by the conjunctiva or nasopharyngeal mucosa instead. How can this be minimised?

A

By pressing the fingers against the lacrimal lakes to block the nasolacrimal ducts

This punctal occlusion allows the drops to remain in the eye for longer and not be washed into the nasopharynx

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12
Q

Some steroids are administered by subconjunctival injection. What does this mean?

A

The drug is injected under the conjunctiva covering the sclera or the inner eyelids

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13
Q

Some anaesthetics are administered via subtenon injection. What does this mean?

A

The drug is injected between the sclera and the Tenon capsule (a layer of connective tissue surrounding the globe)

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14
Q

What is an intravitreal injection? Give 2 examples drugs being administered in this way

A

Intravitreal injection = injection into the vitreous humor in the posterior segment of the eye

  • Anti-VEGF drugs used to treat ‘wet’ macular degeneration can be administered in this way
  • Antibiotics in endophthalmitis can be administered this way
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15
Q

Some antibiotics (e.g., in endophthalmitis) are administered by intracameral injection. What does this mean?

A

The drug is injected into the anterior chamber of the eye (behind the cornea but before the iris)

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16
Q

What is the most common antibiotic used to treat eye infections? Why?

A

Chloramphenicol

  • It is a broad-spectrum antibiotic
  • It has hydrophilic and hydrophobic properties so has good corneal penetration
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17
Q

Ofloxacin (ExOcin) is often used to treat…

A

Contact lens ulcers

18
Q

List 4 anti-inflammatory agents that may be used in the eyes

A

Steroids
Topical NSAIDs
Anti-histamines
Mast cell stabilisers

19
Q

List 4 eye-related uses of topical steroids

A

Uveitis
Post-op cataracts
To prevent corneal graft rejection post-op
To prevent optic nerve ischaemia in temporal arteritis (high-dose steroid required)

20
Q

List 3 side effects of steroids which are local to the eye

A

Cataract
Glaucoma
Exacerbation of viral infection

21
Q

There are many systemic side effects of steroids. List 6

A 
Gastric ulcer
Immunosuppression
Osteoporosis
Weight gain
Diabetes
Neuropsychiatric effects
22
Q

What is the most commonly used topical steroid in the eye? Why?

A

Prednisolone acetate

  • It is the most potent topical steroid used for the eye
  • Addition of acetate makes it more hydrophobic which allows for better penetration of the outer epithelial layer of the cornea
23
Q

When might these other topical anti-inflammatory agents be used in the eyes:
Topical NSAIDs
Anti-histamines
Mast cell stabilisers

A

Topical NSAIDs: pain relief post-op

Anti-histamines + mast cell stabilisers: hayfever/allergic conjunctivitis

24
Q

Lowering intraocular pressure can slow the rate of progression of glaucoma. What are the 2 main ways that glaucoma eye drops work?

A
  • Increase drainage of aqueous humor

- Reduce production of aqueous humor

25
Q

Name 3 drug classes that increase drainage of aqueous humor that can be used to treat glaucoma

A

Prostaglandin analogues e.g., Bimatoprost, Latanoprost
Alpha adrenergic agonists e.g., Brimonidine
Parasympathomimetics e.g., Pilocarpine

26
Q

Name 2 drug classes that reduce production of aqueous humor that can be used to treat glaucoma

A

Beta blockers e.g., Timolol

Carbonic anhydrase inhibitors e.g., Dorzolamide

27
Q

Different types of glaucoma medications should not be combined into a single eye drop. T/F?

A

False

Combination drops are common e.g., Cosopt = Timolol + Dorzolamide

28
Q

How do local anaesthetic eye drops work?

A

They block sodium channels and delay nerve conduction

29
Q

List 5 uses of local anaesthetic drops in ophthalmology

A 
Foreign body removal
Tonometry (test of IOP)
Corneal scraping for taking samples
Pain relief
Cataract surgery
30
Q

Diagnostic drops are also used in ophthalmology. What is the most commonly used diagnostic dye?

A

Fluorescein

the orange dye

31
Q

List 6 uses of fluorescein

A
  • Shows corneal abrasion
  • Shows dendritic ulcer (often caused by herpes viral infection)
  • To identify leaks
  • In tonometry (IOP test)
  • Diagnosing nasolacrimal duct obstruction
  • Angiography
32
Q

What are the two actions of mydriatic drugs?

A

Dilate the pupil by blocking parasympathetic supply to the iris

Cause cycloplegia i.e., stop the lens from focusing by paralysing the ciliary body

33
Q

Give 2 uses of mydriatic drugs

A
  • To allow for more in-depth examination of the retina in eye examinations
  • To allow easier access into the eye during procedures e.g., cataract surgery
34
Q

Give 2 examples of mydriatic drugs

A

Atropine (most common)

Tropicamide

35
Q

List 2 side effects of mydriatics

A

Temporarily blurred vision

Acute angle-closure glaucoma (AACG)

36
Q

Sympathomimetics are a type of mydriatic drug. Describe their effect

A

They act on the sympathetic nervous system and cause the pupils to dilate via the dilator pupillae fibres

Some also cause cycloplegia (e.g., atropine) but others do not

37
Q

More than one sympathomimetic can be used at once if a large dilation is required. T/F?

A

True

38
Q

What is a miotic drug? Give an example of a drug class which has miotic properties

A

A drug which causes pupil constriction e.g., parasympathomimetics

39
Q

How to parasympathomimetics work?

A

They act on the parasympathetic nervous system and cause the pupils to constrict via the sphincter pupillae fibres

40
Q

Give an example of a parasympathomimetic and when it might be used

A

Pilocarpine

Can be used in the treatment of glaucoma
(as it also constricts the ciliary muscle which opens up the trabecular meshwork more, allowing increased outflow of aqueous humor)

41
Q

Give 8 examples of ocular side effects of common medications

A

Allergy to eye drops
Steroids can cause cataracts or glaucoma
Steroids can also cause corneal perforation if used in herpetic keratitis
Vigabatrin can constrict visual fields
Ethambutol (used in TB) can cause optic atrophy and loss of vision
Rifampicin (used in IE) can cause red tears
Hydroxychloroquine can cause “bulls-eye maculopathy”
Amiodarone can cause corneal verticullata

LR Ophthalmology (8 decks)

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