Carbapenems and Monobactams Flashcards
What was the first carbapenem to come out (in late 1980s)?
imipenem (primaxin)
What is the root drug for all the carbapenems?
thienamycin
What are the four carbapenems?
imipenem, meropenem, ertapenem, doripenem
What do metalloenzymes utilize?
zinc
What are two beta-lactamases that have been observed to give resistance to carbapenems?
production of metalloenzymes, production of non-metalloenzymes
What is an example of an “old school” drug (that is highly nephrotoxic) that we might have to use if carbapenem treatment fails?
polymixin-B
What is the problem with using carbapenems as first-line agents for everything?
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)
What are two situations where it might be necessary to use carbapenems?
Acinetobacter infections, presence of ESBLs (extended-spectrum beta lactamases)
What is the difference in the carbapenem structure and the penicillin structure?
carbapenems have an additional carbon instead of a sulfur in their five-membered ring
Why was it necessary to add cilastatin to thienamycin in imipenem?
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)
Which carbapenem has the highest incidence of seizures (is most epileptogenic)?
imipenem
Are beta lactams concentration dependent or time dependent?
time dependent
Why is extended infusion often considered for carbapenems?
because they have short half-lives, so extended infusion improves their time above the MIC (imp because time-dependent drugs)
What is the only carbapenem that doesn’t cover pseudomonas?
ertapenem
What organisms does ertapenem (invanz) have good activity against?
gram positives (MSSA, etc.), enterobacteriaceae, anaerobes