Ophth - Special senses pharmacology

Question 1

What are some inherent ocular defences?

Answer 1

Lacrimal functional unit
Internal ocular homeostasis

Question 2

What is the name for increased tearing?

Answer 2

Epiphora

Question 3

What is the nmae for increased blinking?

Answer 3

Blepharospasm

Question 4

What is the function of the functional lacrimal unit?

Answer 4

Physical and chemical barrier to infectious agents

Question 5

What makes up the functional lacrimal unit?

Answer 5

Normal eyelids
Normal tear film
Corneal epithelium
Functional tear drainage
Conjunctival associated lymphoid tissue

Question 6

What is conjunctival associated lymphoid tissue?

Answer 6

Very diffuse lymph gland under epithelium
Recruits immune cells with chemical mediators to remove foreign substances by WBCs

Question 7

What makes up the ocular surface response?

Answer 7

Epiphora
Mucoid discharge
Purulent discharge
Blepharospasm

Question 8

What is the function of internal ocular homeostasis?

Answer 8

Maintains the clarity of ocular media (aqueous and vitreous humour) for vision

Question 9

What helps to maintain the internal ocular homeostasis?

Answer 9

Blood ocular barrier
immune priveliged site
Intraocular pressure maintained locally

Question 10

What is the blood ocular barrier?

Answer 10

Second line physical and chemical barrier - tight junctions that act as a filter to keep drugs and infectious agents out of eye

Question 11

What does it mean that the eye is an immune privileged site?

Answer 11

No immune cells are in the eye as they can damage the eye
There is no lymphatic drainage

Question 12

What is the general rule for treating the eye with drugs?

Answer 12

Surface and anterior segment - topical drugs needed
Posterior segment - systemic drugs needed

Question 13

What are the barriers to topical penetration?

Answer 13

Tear dilution
Blinking
Lacrimal drainage
Permeability of tissues - cornea, conjunctiva, sclera

Question 14

What is the best pH for drugs used in the eye?

Answer 14

pH 7.4 - same as normal tears so non-irritant
Between 4.5 and 9 for comfort

Question 15

What are the two main routes of penetration?

Answer 15

Transcellular - across the corneal epithelial cell
Paracellular - between individual cells

Question 16

What is the structure of the cornea? What are the layers?

Answer 16

Corneal epithelium - lipophilic barrier
Corneal stroma - hyprophilic
Descemet’s membrane (endothelium) - lipophilic barrier

Question 17

What is required for a drug to be able to go the transcellular route for topical eye treatment?

Answer 17

Lipophilic-hydrophilic balance of the drug

Question 18

What is required for a drug to be able to go the paracellular route for topical eye treatment?

Answer 18

Small molecular weight - to pass between the tight junctions

Question 19

What is an example of a drug that go via the transcellular route?

Answer 19

Chloramphenicol

Question 20

How do topical solutions for eye treatment work?

Answer 20

Treat the ocular surface without needing to penetrate deeply

Question 21

What is an example of an optical topical solution?

Answer 21

Prednisolone sulphate

Question 22

How can you improve topical penetration?

Answer 22

Combine drugs with organic salts
Add preservatives that disrupt the corneal epithelial barrier
Use suspension

Question 23

How do topical suspensions aid with drug absorption?

Answer 23

They improve tear retention by micronizing the particles to prevent irritation

Question 24

Why are topical ointments good for drug retention and absorption?

Answer 24

Have a lipophilic character so are retained in the tearfilm

Question 25

What is the topical dose/drop volume to use

Answer 25

1 drop! Palpebral fissure can hold max 25/30 ul

Question 26

How often do you need to give topical eye treatments?

Answer 26

As often as possible - 1 drop cleared in 10 mins Wait 10 mins in between applications of different drops or will dilute each other

Question 27

What order should you put different eye treatments in?

Answer 27

Aqueous drop>suspension>gel>ointment

Question 28

What periocular injections can you give?

Answer 28

Subconjunctival injection - for absrobing across the sclera Retrobulbar injection - for removing an eye

Question 29

When do you use sustained release implants in eyes?

Answer 29

For immun emediated conditions

Question 30

What do systemic medications need to penetrate the eye?

Answer 30

Lipid solubility Low molecular weight molecules Protein binding

Question 31

What are the most commonly used systemic drugs for eyes?

Answer 31

Chloramphenicol, doxycycline

Question 32

What anti-inflammatory drugs are used for eyes?

Answer 32

Corticosteroids NSAIDs

Question 33

What are the contraindications for corticosteroids?

Answer 33

Dont use in infections - immunosuppressive Dont use in corneal ulceration

Question 34

What are the antiglaucoma drugs?

Answer 34

Prostaglandin analogues Carbonic anhydrase inhibitors Beta blockers

Question 35

How do prostaglandin analogues act as anti-glaucoma drugs?

Answer 35

The increase the outflow of aqueous humour so reduce the pressure in the eye

Question 36

When do prostaglandin analogues not work to prevent glaucoma?

Answer 36

In cats

Question 37

What is a side effect of prostaglandin analogues as anti-glaucoma drugs?

Answer 37

Cause a profound myosis - small pupil

Question 38

How do carbonic anhydrase inhibitors and beta blockers act as anti-glaucoma drugs?

Answer 38

They decrease aqueous humour production

Question 39

What are the two main mydriatic drugs?

Answer 39

Atropine Tropicamide

Question 40

What are the features of atropine and when should it be used?

Answer 40

Atropine has a slower onset but longer duration So use for clinical indication to dilate the pupil eg. spasming Tastes bitter

Question 41

When should you not use atropine?

Answer 41

In glaucoma or keratoconjunctivitis secca cases

Question 42

What are the main features of tropicamide and when should it be used?

Answer 42

Rapid onset, quicker wear off Reduces tears in cats

Question 43

What local anaesthetics can be used in the eye?

Answer 43

Proxymetacaine

Question 44

What should you use for tear replacement?

Answer 44

Hyaluronic acid (clinitas) - holds water well, good lubricant Lipid based substitutes Aqueous based substitutes

Question 45

What are anti-collagenases used for in the eyes?

Answer 45

They stop the cornea melting from collagenase enzymes produced by bacteria

Question 46

What are the best anti-collagenases?

Answer 46

Serum and plasma from the patients own blood Acetylcysteine Tetracyclines