Ophthalmic drugs

Question 1

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

Answer 1

0.2-0.5ml with 25-27 gauge needle

Question 2

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

Answer 2

transcellular and paracellular

Question 3

what route do lipophilic drugs take through the corneal epithelium?

Answer 3

transcellular

Question 4

what route do hydrophilic drugs take through the corneal epithelium?

Answer 4

paracellular

Question 5

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

Answer 5

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

Question 6

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

Answer 6

10 x more permeable because it has no epithelium

more permeable to hydrophilic molecules

Question 7

name 3 substances used to modify osmolarity of a drug

Answer 7

sodium chloride, boric acid, dextrose

Question 8

what pH is generally well tolerated for topical ocular drugs?

Answer 8

4.5-9

Question 9

give 2 ways to improve the corneal penetration of a drug

Answer 9

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

Question 10

are penicillins bactericidal or bacteristatic? what is there MOA?

Answer 10

bactericidal,

inhibit bacterial cell wall synthesis

Question 11

name a first generation cephalosporin and a second generation cephalosporin

Answer 11

first: cephalexin
second: cefuroxime

Question 12

name 5 antibiotic groups that affect bacterial protein synethesis

Answer 12

ahminoglycosides, tetracyclines, macrolides, lincosamides, chloramphenicol

Question 13

name 2 amino glycoside antibiotics

Answer 13

2 from:

neomycin, gentamicin, tobramycin, kanamycin and amikacin

Question 14

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

Answer 14

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

Question 15

are tetracyclines bactericidal or bacteriostatic?

Answer 15

bacteriostatic

Question 16

give an example of a macrolide antibiotic

Answer 16

one from:

erythromycin, azithromycin and clarithromycin

Question 17

what’s the more frequently used lincosamide antibiotic?

Answer 17

clindamycin

Question 18

is chloramphenicol bactericidal or bacteriostatic?

Answer 18

bacteriostatic

Question 19

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

Answer 19

true:

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

Question 20

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

Answer 20

sulphonamides and trimethoprim

both bacteriostatic

Question 21

what is a possible risk of using TMS?

Answer 21

side effects of KCS

Question 22

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

Answer 22

inhibit bacterial DNA synthesis

bactericidal

Question 23

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

Answer 23

truew

Question 24

what generation fluoroquinolone is ofloxacin?

Answer 24

second

Question 25

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

Answer 25

polyenes, pyrimidines, azoles

Question 26

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

Answer 26

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

Question 27

give 2 examples of polyene anti fungals

Answer 27

two from | amphotericin B, natamycin and nystatin

Question 28

are pyrimidines fungicidal or fungistatic?

Answer 28

fungistatic

Question 29

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

Answer 29

inhibit ergosterol synthesis. | imidazole and triazoles

Question 30

is ketoconazole a imidazole or triazole?

Answer 30

imidazole

Question 31

give 3 examples of triazoles

Answer 31

fluconazole, itraconazole, voriconazole

Question 32

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

Answer 32

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

Question 33

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

Answer 33

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

Question 34

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

Answer 34

c. Chloramphenicol

Question 35

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

Answer 35

Trifluorothymidine > ganciclovir > cidofovir > acyclovir

Question 36

``` 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% ```

Answer 36

a. Prednisolone acetate 1%

Question 37

``` 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 ```

Answer 37

c. Chloramphenicol

Question 38

``` 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 ```

Answer 38

d. Lipid keratopathy

Question 39

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

Answer 39

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

Question 40

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

Answer 40

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

Question 41

``` Place these ocular hypotensive agents in the appropriate drug group Timolol Latanoprost Mannitol Dorzolamide Brinzolamide ```

Answer 41

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

Question 42

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

Answer 42

true

Question 43

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

Answer 43

two from: fenbendazole moxidectin milbemycin praziquantel

Question 44

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

Answer 44

bad - it is lipophilic

Question 45

What is the normal rate of tear film turnover?

Answer 45

1ul/min

Question 46

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

Answer 46

phospholipase 2

Question 47

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

Answer 47

``` disruption of BAB miosis cell and protein exudation conjunctival hyperaemia hypotony ```

Question 48

Which factors influence bioavailability of topically applied corticosteroids?

Answer 48

* 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)

Question 49

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

Answer 49

hydrocortisone < prednisolone < triamcinolone < dexamethasone

Question 50

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

Answer 50

acetate | more lipophilic

Question 51

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

Answer 51

pilocarpine | carbachol

Question 52

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

Answer 52

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

Question 53

``` Which layer(s) does(do) carbomer 980 (polyacrylic acid) mimic? ```

Answer 53

aqueous and mucin

Question 54

Name 2 ophthalmic uses of mitomycin C

Answer 54

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

Question 55

What is the duration of mydriasis caused by topical 1% | tropicamide in the dog?

Answer 55

6-12 hours

Question 56

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

Answer 56

96-120 hours

Question 57

what is the average volume of an eye drop?

Answer 57

50ul

Question 58

give 3 disadvantages of ointments

Answer 58

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

Question 59

give 4 disadvantages of solutions/suspensions

Answer 59

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

Question 60

give 2 examples of collagenases

Answer 60

matrix metalloproteinases | serine protease

Question 61

name 3 types of cell that can release collagenases

Answer 61

neutrophils bacteria (esp pseudomonas and b haemolytic strep) keratocytes

Question 62

name 2 anti-collagenases found in serum

Answer 62

alpha2-macroglobulin | alpha2-antitrypsin

Question 63

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

Answer 63

epithelial growth factor platelet-derived growth factor vitamin A

Question 64

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

Answer 64

>50ug