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Cephalosporins are a class of ____________.
B-lactam antibiotics
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cephalosporins are _________ to penicillins.
similar
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Cephalosporins are _____________ compared to many bacterial B-lactamases
more stable
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Cephalosporins have a ____________ of activity.
broad spectrum
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What is a potential problem with cephalosporins?
strains that express extended-spectrum B-lactamasees can hydrolyze most cephalosporins
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Chephalosporins not active against?
- enterococci
- L monocytogenes
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What is the nucelus of cephalosporins?
- 7-aminocephalosporanic acid
- (closely resembles nucleus of penicillins)
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The intrinsic antimicrobial activity of natural cephalosporins is ________, but adding an R group yields hundreds of ________ compounds with _____________.
- low
- potent compounds
- low toxicity
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What was the first synthetic cephalosporin?
cephalothin (cefalothin)
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Cephalosporin Mechanism of action?
- same mode of action as other B-lactam antibiotics
- less susceptible to penicillinases
- bactericidal
- disrupt synthesis of peptidoglycan layer of bacterial cell wall.
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First generation Cephalosporins active against ______________ and not generally active against ____________
- gram+ cocci(pneumococci,streptococci,staphylococci)
- methicillin-resistant strains of staphylococci (new compounds developed for this though)
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What are the 1st gen oral cephalosporins?
cephalexin, cephradine, cefadroxil
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After oral doses of 500mg of 1st gen serum levels are
15-20 mcg/ml
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After oral dose of 1st gen urine conc are usually __________ but in tissue they are variable and generally __________ than in serum
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Excretion of 1st gen oral cephalosporins is done by
- glomerular filtration
- tubular secretion (drugs that block this (probenecid) may increase serum levels)
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What is the only 1st gen ceph for parenteral use still in use? and whats its dose?
- cefazolin
- for adults 0.5-2g IV q 8 hr
- (excretion by kidney and dose adjustments required for renal impaired)
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What is the indication for 1st gen oral cephalosporins? What are they not indicated for?
- UTI
- streptococcal infections (cellulitis and soft tissue abscess)
not used for serious systemic infection
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What is the indications for cefazolin (parenteral 1st gen)? what is it not used for?
- Drug of choice for surgical prophylaxis
- staphylococcal or streptococccal infection for people who have pen allergy
- alternate for antistaphylococcal penicillin if pt allergic to pen
not for meningitis cuz it doesn't penetrate CNS
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What are the 2nd generation cephalosporins?
- cefamandole
- cefonicid
- cefuroxime
- cefaclor
- cefprozil
- Structurally related cephamycins, cefoxitin, cefmetazole, cefotetan have activity against anaerobes
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What are 2nd gen ceph active against? and not active against?
- active against organisms inhibited by 1st generation drugs
- greater gram neg spectrum
- more resistant to B-lactamase
Not active against enterococci or P. aeruginosa
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