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BSAVA CERT/BSAVA MANUAL > Ophthalmic drugs > Flashcards

Ophthalmic drugs Flashcards

1
Q

for a subconjunctival injection what volume of drug is usually injected and what gauge needle is used?

A

0.2-0.5ml with 25-27 gauge needle

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2
Q

what are the 2 possible routes of movement for drugs through the corneal epithelium?

A

transcellular and paracellular

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3
Q

what route do lipophilic drugs take through the corneal epithelium?

A

transcellular

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4
Q

what route do hydrophilic drugs take through the corneal epithelium?

A

paracellular

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5
Q

what are the 3 possible routes for a drug after permeation of the conjunctiva?

A

laterally movement into the corneal stroma
posteriorly across the sclera
absorbed into systemic circulation

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6
Q

is the sclera more or less permeable than the cornea and why? It is more permeable to hydrophilic or lipophilic molecules?

A

10 x more permeable because it has no epithelium

more permeable to hydrophilic molecules

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7
Q

name 3 substances used to modify osmolarity of a drug

A

sodium chloride, boric acid, dextrose

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8
Q

what pH is generally well tolerated for topical ocular drugs?

A

4.5-9

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9
Q

give 2 ways to improve the corneal penetration of a drug

A 
prodrugs (more lipophilic prodrug crosses epithelium and transforms into active drug egg, red acetate, latanoprost/travoprost)
penetration enhancers (EDTA, benzalkonium chloride)
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10
Q

are penicillins bactericidal or bacteristatic? what is there MOA?

A

bactericidal,

inhibit bacterial cell wall synthesis

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11
Q

name a first generation cephalosporin and a second generation cephalosporin

A

first: cephalexin
second: cefuroxime

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12
Q

name 5 antibiotic groups that affect bacterial protein synethesis

A

ahminoglycosides, tetracyclines, macrolides, lincosamides, chloramphenicol

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13
Q

name 2 amino glycoside antibiotics

A

2 from:

neomycin, gentamicin, tobramycin, kanamycin and amikacin

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14
Q

true or false: ahminoglycosides have poor gram negative activity and are mainly affected against staph aureus

A

false:
They have excellent gram-negative activity although neomycin is generally inactive against Pseudomonas aeruginosa. Their gram-positive activity is limited primarily to Staphylococcus aureus and they are inactive against anaerobes

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15
Q

are tetracyclines bactericidal or bacteriostatic?

A

bacteriostatic

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16
Q

give an example of a macrolide antibiotic

A

one from:

erythromycin, azithromycin and clarithromycin

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17
Q

what’s the more frequently used lincosamide antibiotic?

A

clindamycin

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18
Q

is chloramphenicol bactericidal or bacteriostatic?

A

bacteriostatic

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19
Q

true or false: chloramphenicol is useful for prophylaxis following intraocular surgery?

A

true:

owing to excellent corneal penetration (due to high lipophilicity of the drug)

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20
Q

give 2 examples of antibiotic groups that alter folic acid synthesis. Are they bactericidal or bacteriostatic?

A

sulphonamides and trimethoprim

both bacteriostatic

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21
Q

what is a possible risk of using TMS?

A

side effects of KCS

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22
Q

what is the MOA for fluoroquinolone? are they bacteriostatic or bactericidal?

A

inhibit bacterial DNA synthesis

bactericidal

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23
Q

true or false: enrofloxacin has good gram negative and gram positive activity

A

truew

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24
Q

what generation fluoroquinolone is ofloxacin?

A

second

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25
Q

what are the 3 anti-fungal classes most relevant to veterinary ophthalmology?

A

polyenes, pyrimidines, azoles

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26
Q

how what is the MOA for polyenes? are they fungicidal or fungistatic?

A

bind to ergosterol in the fungal cell membrane causing leakage of cell contents
fungicidal at high concentrations

27
Q

give 2 examples of polyene anti fungals

A

two from

amphotericin B, natamycin and nystatin

28
Q

are pyrimidines fungicidal or fungistatic?

A

fungistatic

29
Q

what is the MOA of azoles? and what classes are they divided into?

A

inhibit ergosterol synthesis.

imidazole and triazoles

30
Q

is ketoconazole a imidazole or triazole?

A

imidazole

31
Q

give 3 examples of triazoles

A

fluconazole, itraconazole, voriconazole

32
Q

In the absence of an authorised product for a specific indication in the dog in the UK, which of the following products should you consider prescribing first under the Cascade?

a. A veterinary medicinal product authorised for use in the dog but for a different indication
b. A medicinal product authorised for the same indication in man
c. A veterinary medicinal product authorised for use in another country
d. A medicinal product prepared extemporaneously by a pharmacist

A

a. A veterinary medicinal product authorised for use in the dog but for a different indication

33
Q

Which of the following statements regarding the topical ophthalmic application of drugs is TRUE?
Select one:
a. Solutions tend to have longer corneal retention times than ointments
b. The systemic route is usually preferred for treatment of ocular surface disease
c. Topically applied drugs usually achieve therapeutic concentrations in the posterior segment of the eye
d. In order to penetrate the intact cornea the agent must have lipophilic and hydrophilic properties

A

d. In order to penetrate the intact cornea the agent must have lipophilic and hydrophilic properties

34
Q 
Which of the following antibacterial agents is bacteriostatic?
Select one:
a. Cephalexin
b. Gentamycin
c. Chloramphenicol
d. Bacitracin
A

c. Chloramphenicol

35
Q

Put the following in decreasing order of in vitro efficacy against FHV-1 are:
Select one:
Acyclovir, ganciclovir, trifluorothymidine, cidofovir

A

Trifluorothymidine > ganciclovir > cidofovir > acyclovir

36
Q 
Which of the following topical ophthalmic corticosteroids is the most potent?
Select one:
a. Prednisolone acetate 1%
b. Betamethasone sodium phosphate 0.1%
c. Prednisolone sodium phosphate 0.1%
d. Fluoromethalone 0.1%
A

a. Prednisolone acetate 1%

37
Q 
Which of the following antibacterial agents is commonly used as prophylaxis against ocular surface infection in dogs?
Select one:
a. Polymyxin B
b. Gentamycin
c. Chloramphenicol
d. Doxycycline
A

c. Chloramphenicol

38
Q 
The main ocular side effect associated with topical ophthalmic use of corticosteroids in dogs is
Select one:
a. Corneal oedema
b. Ocular hypertension
c. Cataract formation
d. Lipid keratopathy
A

d. Lipid keratopathy

39
Q

Which of the following statements regarding ciclosporin is FALSE?
Select one:
a. Ciclosporin improves clinical signs in KCS through suppression of immune-mediated destruction of lacrimal tissue
b. Ciclosporin has excellent corneal penetration when applied topically, and thus may be used to treat intraocular immune-mediated disease
c. Ciclosporin is authorised for the treatment of canine KCS and chronic superficial keratitis as a 0.2% eye ointment
d. Ciclosporin is a calcineurin inhibit

A

b. Ciclosporin has excellent corneal penetration when applied topically, and thus may be used to treat intraocular immune-mediated disease

40
Q

Which of the following statements regarding mydriatic agents is TRUE?
Select one:
a. Mydriatics which do not induce cycloplegia are usually associated with an increase in IOP
b. Mydriasis is achieved by blockade of sympathetic-mediated iris muscle activity
c. Epinephrine has good corneal penetration and can be used topically to induce mydriasis
d. Mydriatics should be used in caution in patients with lens instability

A

d. Mydriatics should be used in caution in patients with lens instability

41
Q 
Place these ocular hypotensive agents in the appropriate drug group
Timolol
Latanoprost
Mannitol
Dorzolamide
Brinzolamide
A

Timolol - b blocker
Latanoprost - PG analogue
Mannitol - hyper osmotic agent
Dorzolamide and brinzolamide - carbonic anhydrase inhibitors

42
Q

true or false: only mydriatics which block the parasympathetic system can effect cycloplegia

A

true

43
Q

Name two parasiticides licensed for treatment of lungworm (Angiostrongylus vasorum) infection in dogs

A

two from:
fenbendazole
moxidectin
milbemycin praziquantel

44
Q

Does topical ciclosporin have good or bad corneal penetration? Why?

A

bad - it is lipophilic

45
Q

What is the normal rate of tear film turnover?

A

1ul/min

46
Q

Which enzyme is responsible for the degradation of cell membranes to release arachidonic acid?

A

phospholipase 2

47
Q

What are the ocular effects of prostaglandin release within the anterior segment of the eye?

A 
disruption of BAB
miosis
cell and protein exudation
conjunctival hyperaemia
hypotony
48
Q

Which factors influence bioavailability of topically applied corticosteroids?

A
  • Antiinflammatory potency of the base steroid
  • Concentration of the base steroid in the formulation
  • Type of formulation (solution, suspension or ointment)
  • Solubility characteristics of the base steroid
  • Patient factors (e.g. presence/absence of intact corneal epithelium)
49
Q

Arrange these corticosteroids in order of increasing potency: prednisolone, dexamethasone, hydrocortisone, triamcinolone

A

hydrocortisone < prednisolone < triamcinolone < dexamethasone

50
Q

Which has better corneal penetration – 1% prednisolone phosphate or 1% prednisolone acetate? Why?

A

acetate

more lipophilic

51
Q

Give two examples of direct-acting cholinergic agonists which may be used as ocular hypotensive agents.

A

pilocarpine

carbachol

52
Q

What are the postulated mechanisms of action of topical beta blockers in reducing IOP?

A
  1. Blockade of the β-receptors of the ciliary body epithelium results in reduced activation of adenylate cyclase which leads to a reduction in cAMP formation and ultimately in AH formation
  2. Inhibition of Na+/K+-ATPase activity leading to a reduction in AH formation
  3. They may exert a vasoactive effect and increase AH outflow
53
Q 
Which layer(s) does(do) carbomer 980 (polyacrylic
acid) mimic?
A

aqueous and mucin

54
Q

Name 2 ophthalmic uses of mitomycin C

A

to suppress formation of fibrous tissue around glaucoma implant devices
to reduce corneal scarring when used in eye drop formulation.

55
Q

What is the duration of mydriasis caused by topical 1%

tropicamide in the dog?

A

6-12 hours

56
Q

What is the duration range of mydriasis caused by topical 1% atropine in the normal canine eye?

A

96-120 hours

57
Q

what is the average volume of an eye drop?

A

50ul

58
Q

give 3 disadvantages of ointments

A

Toxic to anterior segment (contraindicated in corneal and scleral perforations)
Blurring of vision
more difficult to apply and achieve accurate dosing

59
Q

give 4 disadvantages of solutions/suspensions

A

Short contact time necessitates frequent application
Drainage via nasolacrimal appa􏰅at􏰈s is signi􏰄􏰆ant 􏰎it􏰃 potential for systemic absorption
Quickly diluted in irritated eyes by excess tear production
Negligible lubricant effect

60
Q

give 2 examples of collagenases

A

matrix metalloproteinases

serine protease

61
Q

name 3 types of cell that can release collagenases

A

neutrophils
bacteria (esp pseudomonas and b haemolytic strep)
keratocytes

62
Q

name 2 anti-collagenases found in serum

A

alpha2-macroglobulin

alpha2-antitrypsin

63
Q

what 3 components of serum help with epithelial growth, migration and differentiation?

A

epithelial growth factor
platelet-derived growth factor
vitamin A

64
Q

what dosage of TPA is associated with intraocular toxicity in the dog and cat?

A

> 50ug

BSAVA CERT/BSAVA MANUAL (19 decks)

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