Carbapenems and Monobactams Flashcards

1
Q

What was the first carbapenem to come out (in late 1980s)?

A

imipenem (primaxin)

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2
Q

What is the root drug for all the carbapenems?

A

thienamycin

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3
Q

What are the four carbapenems?

A

imipenem, meropenem, ertapenem, doripenem

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4
Q

What do metalloenzymes utilize?

A

zinc

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5
Q

What are two beta-lactamases that have been observed to give resistance to carbapenems?

A

production of metalloenzymes, production of non-metalloenzymes

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6
Q

What is an example of an “old school” drug (that is highly nephrotoxic) that we might have to use if carbapenem treatment fails?

A

polymixin-B

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7
Q

What is the problem with using carbapenems as first-line agents for everything?

A

they are potent beta-lactamase inducers, so if resistance develops against them nothing else below their level (ie penicillins, cephalosporins, etc) will work either (better to use the least potent effective drug)

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8
Q

What are two situations where it might be necessary to use carbapenems?

A

Acinetobacter infections, presence of ESBLs (extended-spectrum beta lactamases)

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9
Q

What is the difference in the carbapenem structure and the penicillin structure?

A

carbapenems have an additional carbon instead of a sulfur in their five-membered ring

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10
Q

Why was it necessary to add cilastatin to thienamycin in imipenem?

A

because thienamycin by itself if hydrolyzed in the kidney to an inactive metabolite that is toxic; adding cilastatin blocks hydrolysis (restores antibiotic function, prevents renal toxicity)

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11
Q

Which carbapenem has the highest incidence of seizures (is most epileptogenic)?

A

imipenem

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12
Q

Are beta lactams concentration dependent or time dependent?

A

time dependent

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13
Q

Why is extended infusion often considered for carbapenems?

A

because they have short half-lives, so extended infusion improves their time above the MIC (imp because time-dependent drugs)

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14
Q

What is the only carbapenem that doesn’t cover pseudomonas?

A

ertapenem

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15
Q

What organisms does ertapenem (invanz) have good activity against?

A

gram positives (MSSA, etc.), enterobacteriaceae, anaerobes

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16
Q

Why is ertapenem a good choice for intra-abdominal infection treatment but a bad choic for Intensive Care hospital infections?

A

good for intra-abdominal because has anaerobic activity, bad for intensive care because has no pseudomonas activity

17
Q

What is the typical carbapenem extended infusion time?

A

4 hours

18
Q

What organisms does doripenem, imipenem, and meropenem have good activity against?

A

gram positive organisms (except MRSA), enterobacteriaceae, pseudomonas, anaerobes

19
Q

What side chain is present in aztreonam (monbactam)?

A

oxyimino

20
Q

What is the main advantage of aztreonam (azactam)?

A

it can be used safely (99% of the time) in people with penicillin allergies

21
Q

The monobactam aztreonam has a similar spectrum of activity as ________, but is not nephrotoxic.

A

aminoglycosides

22
Q

Why do you most always need to combine aztreonam with other drug therapies?

A

because it has a very narrow spectrum of action

23
Q

What organisms does aztreonam have good activity against?

A

gram negative aerobes (enterobacteriaceae), pseudomonas (but resistance a big problem)