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Pharm - Cell Wall Inhibitors Flashcards

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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 _____________

Study These Flashcards
A

all other B-lactam antibiotics

24
Q

What are the classifications of Cephalosporins?

Study These Flashcards
A

1st
2nd
3rd
4th
Generations

25
What are 1st generation drugs active against?
gram-positive bacteria including some B-lactamase positive staphlococci
26
What generation are cefazolin, cefadroxil, and cephalexin considered to be under?
1st generation
27
Which of the 1st gen cephalosporin drugs have the most activity against gram-negative bacteria?
cefazolin
28
What 1st gen cephalosporin drug is commonly prescribed for dogs?
Cephalexin
29
What are 2nd generation drugs active against?
gram-negative bacteria
30
What generation are the drugs cefoxitin, cefotetan, and cefaclor under?
2nd generation
31
Which generation of Cephalosporins are often used before dental procedures as it has activity against anaerobes and dental disease?
2nd
32
What are 3rd generation drugs active against?
gram-negative
33
What generation is ceftiofur, cefovecin, cefpodoxime, and proxetil under?
3rd
34
What generation are cefepime and cefquinone under?
4th generation
35
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
4th gen more important in human med increasing activity against gram-neg from 1st to 4th
36
What species is Cephalexin approved in, whats the preferred route, and what is it used to treat?
oral use in dogs and cats for dermatitis caused by non-methicillin/oxacillin resistant staphylococci
37
What species is cefazolin approved in, whats the preferred route, and what is it used to treat?
IV use in dogs and cats (sometimes horses) for surgical prophylaxis
38
What species is Cefpodoxime approved in, whats the preferred route, and what is it used to treat?
oral use dogs for skin and soft tissue infectious
39
Besides dogs, which species has Cefpodoxime been safely used in?
cats and foals
40
What is the half life of Cefpoxoxime? How does this relate to dosing?
longer half-life leading to a once daily dose
41
What is Cefovecin and what species has it been approved for, what is the route of administration?
Convenia - SQ single dose approved for treatment of skin infections in dogs and cats providing therapeutic concentrations for up to 14 days
42
Why can long-acting antibiotics be dangerous?
effects persist longer adverse effects last longer not fact acting - not useful for an emergency
43
What is Ceftiofur, what species has it been approved for and what are the 3 formulations available?
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
Where is ceftiofur crystalline free acid (Excede) administered, in what species, and how long does it last?
long lasting administered in the base of the ear in cattle
45
What are the species differences in the admin of ceftiofur crystalline free acid (Excede) in cattle, swine, and horses?
cattle - base of the ear swine and horses- IM
46
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?
horses - repeated once in 4 days
47
Extralabel use of cephalosporins is prohibited in ___________
major food producing species
48
While adverse reactions of B-lactam antibiotics are rare, what are 5 different ways in which an adverse reaction can occur?
Hypersensitivity reactions high concentrations inhibiting GABA Procaine reactions GI effects
49
B-lactam antibiotics can rarely cause adverse effects such as GI effects which species is this prevalent to and what occurs?
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
What drug reactions are associated with B-lactam antibiotics?
aminoglycosides
51
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?
separately
52
What are the 3 mechanisms of resistance pertaining to B-lactam antibiotics?
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
What are 3 B-lactamase inhibitors?
claculanic acid, sulbactam, and tazobactam
54
What is the mechanism of action for b-lactamase inhibitors
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
Amoxicillin + clavulanic acid -->
clavamox
56
Ampicillin + sulbactam -->
Unasyn

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