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Dealing with Threats > Pharm - Cell Wall Inhibitors > Flashcards

Pharm - Cell Wall Inhibitors Flashcards

1
Q

What are the two types of B-lactam antibiotics?

A

Penicillins
Cephalosporins

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2
Q

Explain the mechanism of action for a B-lactam antibiotics

A

penetrate the outer cell wall and binds to and inhibits penicillin binding proteins (PBPs) which are transpeptidase enzymes required for cross-linking of cell wall precursors

ie by inhibiting PBPs, the abx interferes with the structure putting a hole in the cell wall allowing fluid in and eventually the rupturing and killing of the cell

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3
Q

Are B-lactam antibiotics considered bacteriocidal or bacteriostatic?

A

bacteriocidal

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4
Q

Explain the general principles of pharmokinetics associated with B-lactams

A
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5
Q

Are B-lactam antibiotics hydrophobic or hydrophilic? What does this mean?

A

Hydrophilic - water soluble
minimal intracellular concentrations
do NOT distribute well to protected sites

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6
Q

Do B-lactam antibiotics have a high or low plasma protein binding? Why is this significant?

A

Low
distribute well to the extracellular fluid in most tissues

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7
Q

Are B-lactam antibiotics metabolized?

A

minimally

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8
Q

How are B-lactam antibiotics eliminated?

A

glomerular filtration and tubular secretion

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9
Q

Why is the elimination of B-lactam antibiotics significant clinically?

A

very high conc. in urine so are very efficient at treating UTIs

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10
Q

What is the short life of B-lactams? How does this correlate with dosing?

A

short half life - frequent dosing

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11
Q

B-lactams are time dependent. If dosing for 12 hours, what will the time above MIC be?

A

6 hours

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12
Q

What bacteria are Benzylpenicillins effective against?

A

Streptococcus and anaerobes

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13
Q

What are penicillins inactivated by?

A

B-lactamases

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14
Q

Explain the varying routes of Penicillin G and which are the most effective

A

Oral - limited
IV - potassium or sodium - HUMAN PRODUCT SO EXPENSIVE
IM/SC - complexed with procaine or benzathine which have longer half lives and can be dosed less frequently

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15
Q

Why does Benzathine penicllin suck?

A

Sticks around for a long period of time but at subclinical concentrations

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16
Q

The old label on penicillin was 6600 IU/kg, what is it now and why?

A

22,000 IU/kg because it was used so frequently that now a higher dose is needed for it to be effective

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17
Q

What two drugs in the aminopeniciillin class are used very frequently in small animals

A

ampicillin
amoxicillin

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18
Q

Which aminopenicillin has a better oral absorption in small animals, although both have a considerably good absorption?

A

amoxicillin

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19
Q

Which drug is limited to NO ORAL ABSORPTION in large animals?

A

amimopenicillins

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20
Q

Aminopenicillin has an increased spectrum against gram _______ bacteria

A

negative

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21
Q

What two drugs are part of the anti-staphylococcal penicillins?

A

methicillin, oxacillin

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22
Q

What organisms do anti-staphylococcal penicillins have little activity against?

A

gram neg or anaerobes

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23
Q

Bacteria reported to be resistant to oxacillin should also be considered to be resistant against _____________

A

all other B-lactam antibiotics

24
Q

What are the classifications of Cephalosporins?

A

1st
2nd
3rd
4th
Generations

25
Q

What are 1st generation drugs active against?

A

gram-positive bacteria including some B-lactamase positive staphlococci

26
Q

What generation are cefazolin, cefadroxil, and cephalexin considered to be under?

A

1st generation

27
Q

Which of the 1st gen cephalosporin drugs have the most activity against gram-negative bacteria?

A

cefazolin

28
Q

What 1st gen cephalosporin drug is commonly prescribed for dogs?

A

Cephalexin

29
Q

What are 2nd generation drugs active against?

A

gram-negative bacteria

30
Q

What generation are the drugs cefoxitin, cefotetan, and cefaclor under?

A

2nd generation

31
Q

Which generation of Cephalosporins are often used before dental procedures as it has activity against anaerobes and dental disease?

A

2nd

32
Q

What are 3rd generation drugs active against?

A

gram-negative

33
Q

What generation is ceftiofur, cefovecin, cefpodoxime, and proxetil under?

A

3rd

34
Q

What generation are cefepime and cefquinone under?

A

4th generation

35
Q

As you go from 1st to 4th, which has more importance in human medicine? Which is more active against gram-negative while still retaining activity against gram positive

A

4th gen more important in human med
increasing activity against gram-neg from 1st to 4th

36
Q

What species is Cephalexin approved in, whats the preferred route, and what is it used to treat?

A

oral use in dogs and cats for dermatitis caused by non-methicillin/oxacillin resistant staphylococci

37
Q

What species is cefazolin approved in, whats the preferred route, and what is it used to treat?

A

IV use in dogs and cats (sometimes horses) for surgical prophylaxis

38
Q

What species is Cefpodoxime approved in, whats the preferred route, and what is it used to treat?

A

oral use dogs for skin and soft tissue infectious

39
Q

Besides dogs, which species has Cefpodoxime been safely used in?

A

cats and foals

40
Q

What is the half life of Cefpoxoxime? How does this relate to dosing?

A

longer half-life leading to a once daily dose

41
Q

What is Cefovecin and what species has it been approved for, what is the route of administration?

A

Convenia - SQ single dose approved for treatment of skin infections in dogs and cats providing therapeutic concentrations for up to 14 days

42
Q

Why can long-acting antibiotics be dangerous?

A

effects persist longer
adverse effects last longer
not fact acting - not useful for an emergency

43
Q

What is Ceftiofur, what species has it been approved for and what are the 3 formulations available?

A

Main Cephalosporin used systemically in LA but approved in dogs (mostly), horses, chickens, turkeys, cattle, goats, sheep, swine

three formulations
- ceftiofur sodium (Naxcel)
-ceftiofur hydrochloride (Excenel)
- ceftiofur crystalline free acid (Excede)

44
Q

Where is ceftiofur crystalline free acid (Excede) administered, in what species, and how long does it last?

A

long lasting administered in the base of the ear in cattle

45
Q

What are the species differences in the admin of ceftiofur crystalline free acid (Excede) in cattle, swine, and horses?

A

cattle - base of the ear
swine and horses- IM

46
Q

While in cattle and swine Ceftiofur crystalline free acid (Excede) are given as a single dose, which species requires a second dose? What is the timing of this second dose?

A

horses - repeated once in 4 days

47
Q

Extralabel use of cephalosporins is prohibited in ___________

A

major food producing species

48
Q

While adverse reactions of B-lactam antibiotics are rare, what are 5 different ways in which an adverse reaction can occur?

A

Hypersensitivity reactions
high concentrations inhibiting GABA
Procaine reactions
GI effects

49
Q

B-lactam antibiotics can rarely cause adverse effects such as GI effects which species is this prevalent to and what occurs?

A

dogs and cats - vomiting with high oral doses due to irritation of the gastric mucosa

horses and rabbits - high incidence of antibiotic associated colitis with oral admin

50
Q

What drug reactions are associated with B-lactam antibiotics?

A

aminoglycosides

51
Q

If having to give B-lactam antibiotics and aminoglycosides, should they be mixed in the same syringe or should the animal be given two injections, one with the B-lactam and the aminoglycoside in another?

A

separately

52
Q

What are the 3 mechanisms of resistance pertaining to B-lactam antibiotics?

A

methicillin resistance mediated by MecA gene which encodes for penicillin binding protein

reduced penetration of drug into bacteria due to gram-neg capsule or altered/reduced number of porins

enzyme mediated degradation by beta-lactamases, penicillinases, cephalosporinases, etc

53
Q

What are 3 B-lactamase inhibitors?

A

claculanic acid, sulbactam, and tazobactam

54
Q

What is the mechanism of action for b-lactamase inhibitors

A

combine w/ b-lactamase enzymes to form an inactive complex allowing for co-administered abx to exert its effect
can also bind to different PBPs to have bacteriocidal effects

55
Q

Amoxicillin + clavulanic acid –>

A

clavamox

56
Q

Ampicillin + sulbactam –>

A

Unasyn

Dealing with Threats (27 decks)

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