Therapeutics

Question 1

what are common groups of antimicrobials used in equine medicine?

Answer 1

beta-lactams
cephalosporins
aminoglycosides
chloramphenicol
potentiated sulphonamides
tetracyclines
fluroquinolones
macrolides
rifampin
metronidazoles

Question 2

why are beta-lactams commonly used?

Answer 2

safety, efficacy and low cost

Question 3

what is the mechanism of action of beta-lactams?

Answer 3

interfere with bacterial cell wall production causing cell lysis

Question 4

what are the indications for beta-lactams?

Answer 4

gram positive bacteria
Streptococcal infections (horses)
most anaerobic infections

Question 5

what indication do beta-lactams have limited efficacy in?

Answer 5

abcesses

Question 6

what drugs do beta-lactams have a synergistic effect with?

Answer 6

aminoglycosides

Question 7

what drugs do beta-lactams have an additive effect with?

Answer 7

fluoroquinolone

Question 8

what is the main way beta-lactams are eliminated from the body?

Answer 8

via kidney

Question 9

what are the two types of beta-lactam penicillins?

Answer 9

Na and K (IV)

procaine (IM)

Question 10

what are the adverse effects of beta-lactams?

Answer 10

anaphylaxis (type I hypersensitivity)
haemolytic anaemia
thrombocytopenia

Question 11

what is the mechanism of action of cephalosporins?

Answer 11

interfere with bacterial cell wall production causing lysis (more resistant to bacterial defences than beta-lactams)

Question 12

how and where are cephalosporins excreted?

Answer 12

unchanged in urine

Question 13

what are the adverse effects of cephalosporins?

Answer 13

anaphylaxis (type I hypersensitivity)
haemolytic anaemia
thrombocytopenia

Question 14

why should cephalosporins never be used as a first line drug?

Answer 14

they are critically protected

Question 15

what is the mechanism of action of aminoglycosides?

Answer 15

penetrate bacteria and bind to 30S ribosomal subunit leading to misreading of genetic codes

Question 16

do aminoglycosides work best in gram positive or negative bacteria?

Answer 16

negative - only these have the ability to get the drugs inside of them

Question 17

are aminoglycosides bacteriocidal or bacteriostatic?

Answer 17

bacteriocidal

Question 18

how are aminoglycosides removed from the body?

Answer 18

glomerular filtration (kidneys)

Question 19

what are the adverse effects of aminoglycosides?

Answer 19

nephrotoxicity
endotoxaemia
ototoxicity
neuromuscular blockade

Question 20

what is the mechanism of action of chloramphenicol?

Answer 20

binds to 50S ribosomal subunit to inhibit protein synthesis

Question 21

is chloramphenicol bacteriostatic or bacteriocidal?

Answer 21

bacteriostatic

Question 22

what animal can chloramphenicol not be used in?

Answer 22

food producing animals

Question 23

where are chloramphenicols metabolised and excreted?

Answer 23

metabolised in liver

excreted renally

Question 24

why are chloramphenicols not commonly used?

Answer 24

painful IM injection

expensive

Question 25

what drugs should chloramphenicol not be used with? and why?

Answer 25

penicillin, aminoglycosides, fluoroquinolnes, macrocodes | shouldn't mix bacteriostatic and bacteriocidal drugs

Question 26

what is the mechanism of action of potentiated sulphonamides?

Answer 26

inhibit folic acid pathway to block bacterial nucleic acid synthesis

Question 27

why are potentiated sulphonamides very safe to use in mammals?

Answer 27

mammals don't create their own folic acid so will have no effect

Question 28

when are potentiated sulphonamides ineffective?

Answer 28

anaerobes | in pus and necrotic tissue

Question 29

where are potentiated sulphonamides metabolised and excreted?

Answer 29

liver metabolism | renal excretion

Question 30

what are the adverse effects of potentiated sulphonamides?

Answer 30

agranulocytosis, anaemia, thrombocytopenia diarrhoea crystalluria

Question 31

what is the mechanism of action of tetracyclines?

Answer 31

binds to 30S ribosomal subunit to inhibit protein synthesis

Question 32

is tetracycline bacteriocidal or bacteriostatic?

Answer 32

bacteriostatic

Question 33

why are tetracycline very safe to use in mammalian species?

Answer 33

mammalian cells cannot transport the drug into themselves

Question 34

what are the indication of tetracycline use?

Answer 34

broad spectrum gram positive and negative | contracted tendon in foals

Question 35

how and where are tetracyclines excreted?

Answer 35

unchanged in urine and bile

Question 36

what property of tetracyclines means they penetrate cells very well?

Answer 36

very lipid soluble

Question 37

what are the adverse effects of tetracyclines?

Answer 37

fatal colitis diarrhoea teeth discolouration collapse/death if given rapidly IV

Question 38

what is the mechanism of action of fluoroquinolones?

Answer 38

inhibits bacterial DNA gyrase leading to incomplete configuration of DNA

Question 39

are fluoroquinolone bacteriocidal or bacteriostatic?

Answer 39

bacteriocidal

Question 40

what are the indication of fluoroquinolone use?

Answer 40

``` broad spectrum (better against gram negative) very effective against gram negative enteric bacteria ```

Question 41

how and where are fluroquinolones excreted?

Answer 41

unchanged in the urine

Question 42

what are the adverse effects of fluoroquinolone?

Answer 42

cartilage lesions (foals)

Question 43

what types of drugs do fluoroquinolone antagonise?

Answer 43

antimicrobials that inhibit bacterial protein synthesis (chloramphenicol, rifampin)

Question 44

why should fluoroquinolone never be first line drugs?

Answer 44

they are critically protected

Question 45

what is the mechanism of action of macrolides?

Answer 45

binds to 50S ribosomal subunit to inhibit protein synthesis

Question 46

are macrolides bacteriostatic or bacteriocidal?

Answer 46

bacteriostatic

Question 47

when should macrolides never be used?

Answer 47

adult horses - diarrhoea and death

Question 48

when is the only time macrolides are used in equine medicine?

Answer 48

foals with Rhodococcus equi

Question 49

what is the mechanism of action of rifampin?

Answer 49

inhibit bacterial RNA polymerase leading to decrease RNA synthesis

Question 50

what are the main indications of rifampin use in horses?

Answer 50

staphylococcus rhodococcus equi mycobacteria

Question 51

where is rifampin excreted?

Answer 51

in the bile

Question 52

what is the main adverse effect of rifampin?

Answer 52

stains everything red - urine, tears, faeces, saliva

Question 53

what is the mechanism of action of metronidazole?

Answer 53

anaerobic bacteria take it up and break it into small free radicals leading to DNA damage

Question 54

what are the adverse effects of metronidazole?

Answer 54

mutagenic neurotoxicity depression decreased appetite

Question 55

what does therapeutics rely upon?

Answer 55

a correct diagnosis (better diagnosis means better treatment)

Question 56

why do turkeys have a higher amount of antibiotic usage than other poultry?

Answer 56

grown in high concentrations with high risk so are treated if there is any doubt

Question 57

what are the categories for the new EU antibiotic classification?

Answer 57

A - human critically important (not used in food producing animals) B - critically important in food producing animals C - may lead to resistance in category A/B so use cautiously D

Question 58

what is the sequence for the cascade for a non-food producing animal?

Answer 58

veterinary medicine authorised for use in another species or for different condition in same species medicine authorised for human us in UK or product authorised in another state medicine made up at the time on a one-off basis

Question 59

what are the rules that apply to the cascade for food producing animals?

Answer 59

restricted use to a single holding medicine imported must be authorised for food-producing species on other states active substance must be in Table 1 (regarding maximum residue limits (MRLs)) vet must specify appropriate withdrawal period

Question 60

what are some points that must be evaluated for prescribing therapeutics?

Answer 60

``` define what it wrong with the animal identify the targets for therapy critically evaluate the information what therapies are available and how does it work alternatives to therapy cost of treatment what are the risks how is it administered ```

Question 61

what are some alternative to prescribing therapeutics?

Answer 61

euthanasia | surgery

Question 62

what are some ways antibiotics work?

Answer 62

disrupt cell wall production DNA action inhibitors protein synthesis inhibitors effect cell membrane function

Question 63

what are some examples of antibiotics that disrupt cell wall production?

Answer 63

beta lactams penicillins cephalosporins

Question 64

what are some examples of antibiotics that inhibit DNA action?

Answer 64

potentiated sulphonamide | fluroroquinolones

Question 65

what are some examples of antibiotics that inhibit protein synthesis?

Answer 65

tetracyclines macrolides florphenicol streptomycin

Question 66

what is an example of an antibiotic that effects cell membrane function?

Answer 66

monensin