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Pharmacology > Lecture 11 2/22/24 > Flashcards

Lecture 11 2/22/24 Flashcards

1
Q

Which antibiotics need to have a certain concentration above MIC to be effective?

A

-aminoglycosides
-ketolides

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2
Q

Which antibiotics need to have a certain time above MIC to be effective?

A

-beta-lactams
-cephalosporins
-macrolides
-lincosamides
-sulfonamides
-tetracyclines
-‘amphenicols

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3
Q

Which antibiotics need to have a certain AUC above MIC to be effective?

A

fluoroquinolones

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4
Q

Which antibiotics are bactericidal?

A

-beta-lactams
-aminoglycosides
-nitrofurans
-nitroimidazoles
-fluoroquinolones

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5
Q

Which antibiotics are bacteriostatic?

A

-sulfonamides
-tetracyclines
-macrolides
-chloramphenicol

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6
Q

What is the mechanism of action for beta-lactams?

A

-inhibit bacterial cell wall synthesis
-prevent cell wall components from cross-linking

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7
Q

Which antibiotics fall into the beta-lactams class?

A

-penicillins
-aminopenicillins
-antipseudomonal penicillins
-antistaphylococcal penicillins
-cephalosporins
-carbepenems
-monobactems

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8
Q

What are the penicillin-binding proteins?

A

the bacterial proteins that penicillins target

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9
Q

What are the characteristics of penicillin pharmacokinetics?

A

-weak acid w/ pKa around 2.7
-mostly ionized in plasma/intestine
-unstable at gastric pH
-low volume of distribution
-generally not orally bioavailable
-renal elimination via glomerular filtration and tubular secretion
-short half-life
-concentrated in urine

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10
Q

What are the characteristics of penicillin G pharmacokinetics?

A

-not orally bioavailable
-inactivated at low pH

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11
Q

What are the characteristics of procaine penicillin G?

A

-formulated for IM administration
-absorbed more slowly after IM injection compared to sodium penicillin G

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12
Q

Why is frequent dosing of penicillin G required?

A

penicillin G is rapidly excreted

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13
Q

Why are slow release formulations useful in the case of beta-lactams?

A

-beta-lactams have short half-lives
-beta-lactams exhibit time-dependent pharmacodynamic behavior

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14
Q

What is the general rule regarding beta-lactam efficacy?

A

penicillins are more effective with frequent administration for the same total daily dose

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15
Q

How does efficacy change with time above MIC?

A

efficacy increases as time above MIC approaches 100% of the dose interval

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16
Q

Why should a longer infusion time be used when infusing beta-lactams?

A

-longer infusion times allow for more time above MIC
-the concentration reached does not matter as much as the time spent at a concentration above MIC

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17
Q

What are the characteristics of beta-lactamase production as a way to resist beta-lactams?

A

-major mechanism of resistance
-enzymes capable of hydrolyzing the cyclic amide bond
-can be inherent or acquired
-can inactivate penicillins, cephalosporins, or both

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18
Q

What is inherent beta-lactamase resistance?

A

gram neg. bacteria inherently express low levels of chromosomally-mediated beta-lactamases within the periplasmic space

19
Q

What are some examples of gram neg. bacteria with inherent beta-lactamases?

A

-Klebsiella spp.
-Pseudomonas spp.
-Bacteroides fragilis

20
Q

What is acquired beta-lactamase resistance?

A

gram pos. bacteria secrete beta-lactamases extracellularly as inducible exoenzymes that are plasmid mediated

21
Q

Which species is known for acquired beta-lactamase resistance?

A

Staphylococcus aureus

22
Q

What are beta-lactamase inhibitors?

A

inhibitors that bind irreversibly to beta-lactamases and improve the efficacy of the beta-lactam with which they are combined

23
Q

What is an example of a beta-lactamase inhibitor?

A

clavulanate

24
Q

What must occur in order for antibiotics to reach the cell wall in gram neg. bacteria?

A

they must penetrate the outer membrane layer via a porin protein

25
Q

Why are gram pos. bacteria more susceptible to beta-lactams than gram neg. bacteria?

A

it is easier to reach the site of action in gram pos. bacteria due to the lack of outer membrane

26
Q

Which type of resistance is seen in MRSA, MRSP, and Enterococcus faecium?

A

production of PBPs with low affinity for beta-lactams

27
Q

What are L-forms?

A

bacterial variants that lack a cell wall

28
Q

What are some of the challenges involved with penicillin compliance?

A

-anaphylaxis in veterinary staff/owners administering the drug
-injections sting

29
Q

What are the characteristics of penicillin adverse effects and toxicity?

A

-acute toxicity is minimal
-diarrhea may occur with oral doses
-procaine reaction when given IV in horses

30
Q

Which animals often experience diarrheal reactions to penicillin?

A

horses and other animals with a large cecum

31
Q

What are the main examples of gram pos. bacteria that are susceptible to penicillin G?

A

-all beta-hemolytic Streptococci
-Actinomyces spp.
-Clostridium spp.

32
Q

What are the main examples of bacteria that are resistant to penicillin G?

A

-Enterobacteriaeceae
-Bacteroides fragilis
-Staphylococcus spp.
-Pseudomonas aeruginosa

33
Q

Which bacteria are treated with penicillin G?

A

-most gram pos. bacteria
-Haemophilus spp.
-Pasteurella spp.
-many anaerobes

34
Q

What are the advantages of penicillin G?

A

-potent
-bactericidal activity
-wide margin of safety

35
Q

What are the disadvantages of penicillin G?

A

-must be given as injection
-narrow-spectrum
-widespread resistance
-low ability to cross biological membranes

36
Q

What is the spectrum for penicillin G?

A

-high susceptibility of gram pos. aerobes and anaerobes
-some susceptibility of gram neg. aerobes and anaerobes
-no susceptibility of gram pos. or neg. facultative anaerobes

37
Q

What are the characteristics of aminopenicillins?

A

-addition of side chains
-extended gram pos. and gram neg. spectrum
-increased acid stability

38
Q

What is the spectrum of aminopenicillins?

A

-high susceptibility of gram pos. aerobes and anaerobes
-decent susceptibility of gram neg. aerobes
-some susceptibility of gram neg. anaerobes
-no susceptibility of gram pos. or neg. FAs

39
Q

What are potentiated penicillins?

A

penicillins mixed with a beta-lactamase inhibitor

40
Q

What is the spectrum of potentiated penicillins?

A

-high susceptibility of gram pos. aerobes and anaerobes
-decent susceptibility of gram pos. FAs and gram neg. aerobes, anaerobes, and FAs

41
Q

What are the characteristics of antistaphylococcal penicillins?

A

-increased resistance to Staph. beta-lactamase
-oral and parenteral formulations available

42
Q

What is the spectrum of antistaphylococcal penicillins?

A

-some susceptibility of gram pos. aerobes and anaerobes
-high susceptibility of gram. pos. FAs/Staph.
-no susceptibility of any gram neg.

43
Q

What are the characteristics of antipseudomonal penicillins?

A

-increased penetration in gram neg. bacteria
-increased resistance to beta-lactamases
-multiplicity of PBP targets
-expensive
-parenterally administered
-used in serious gram neg. infections

44
Q

What is the spectrum of antipseudomonal penicillins?

A

-decent susceptibility of gram pos. aerobes and anaerobes
-no susceptibility of gram pos. FAs
-some susceptibility of gram neg. aerobes and anaerobes
-high susceptibility of gram neg. FAs

Pharmacology (27 decks)

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