Cephalosporins Gen 1-4 Flashcards
What is different between the structure of cephalosporins and the structure of penicllins?
cephalosporins have 6-membered ring attached to beta lactam (house w/ basement and garage), while penicllins have a 5-membered ring attached to the beta lactam ring (house w/ garage)
What organism are cephalosporins inherently active against that immediately attracted attention?
MSSA
Which cephalosporin is the parent compound of all modern cephalosporins?
Cephalosporin C
Side group at the ___ and ___ positions can be manipulated in cephalosporins.
3, 7
The N-methylthiotetrazole side chain is abbreviated as the…
NMTT chain
What does the NMTT chain block?
production of prothrombin (needed for clotting)
Cephalosporins with the NMTT side chain + alcohol results in the ________ reaction (so named because of an anti-alcoholic drug that caused intense nausea/vomiting when it came in contact with alcohol).
antabuse
When did the 1st generation cephalosporins come out?
late 1950s
Which company held the patent on Cefazolin (1st gen parenteral) and Cephalexin (1st gen oral)
Eli Lilly
Which three cephalosporins have oxyimino side chains in the 7 position, and what generation are they part of?
cefotaxime (parenteral), ceftriaxone (parenteral), ceftazidime (anti-pseudomonal, parenteral); 3rd generation
What does the oxyimino side chain hydrolyze?
extended-spectrum beta lactamases (to a point)
Which three cephalosporins cross the blood-brain barrier and so can be used to treat meningitis?
cefotaxime (3rd gen parenteral), ceftriaxone (3rd gen parenteral), ceftazidime (3rd gen parenteral, anti-pseudomonal)
Which common cephalosporin has an NMTT side chain in the 3 position and is therefore subject to the antabuse reaction and prothrombin inhibition?
cefpodoxime (3rd gen oral)
What is the only monobactam?
aztreonam
What differentiates a monobactam from the other beta lactams?
it has no side chains (just a beta lactam ring)
What are the four carbapenems?
imipenem, meropenem, ertapenem, doripenem
What are the two components of imipenem?
thienamycin, cilastatin
The 7-alpha-methoxy side chain gives cephalosporins…
anaerobic activity, AmpC (beta lactamase) hydrolysis ability
What is the most widely used of all the cephalosporins today?
cefazolin
What are the four first generation parenteral cephalosporins? Which is still popular today?
cefazolin, cephalothin (keflin), cephapirin (cephadyl), cephradine (velocef); cefazolin still popular
What are three first generation oral cephalosporins; which is still popular?
cephalexin (keflex), cephradine (velocef), cefadroxil (duracef); cephalexin still popular
What organisms do first generation cephalosporins have good activity against?
MSSA, streptococci
What organisms do first generation cephalosporins have moderate activity against?
Escherichia coli, Klebsiella pneumoniae, proteus mirabilis (some enteric GNRs)
What organisms do first generation cephalosporins have poor activity against?
enterococci, anaerobes, MRSA, pseudomonas
Why is cephalothin (1st gen parenteral) not good for prophylactic treatment, even though it has the best anti-staphylococcal activity?
it has a very short half-life (about 30 minutes)
Which 1st generation cephalosporin has the longest half-life (about 2 hours)?
cefazolin
Do any of the 1st generation cephalosporins enter the cerebral spinal fluid?
no
What is the likelihood of cross-reactivity between penicillin allergies and 1st generation cephalosporins?
3-5%
What are the six second generation parenteral cephalosporins? Which are still popular today?
cefamandole (mandol), cefoxitin (mefoxin), cefuroxime (ceftin), cefotetan (cefotan), cefonicid (monocid), cefmetazole (zefazone); cefoxitin, cefuroxime, cefotetan still popular
What are the four second generation oral cephalosporins? Which are still popular today?
cefaclor (ceclor), cefuroxime axetil, cefprozil (cefzil), lorcarbacef (lorabid); cefuroxime still popular
Which of the second generation cephalosporins are Cefamycins? What differentiates cefamycins from the other 2nd gen cephalosporins?
cefoxitin, cefotetan, cefmetazole; cefamycins have anaerobic coverage (moderate activity against B. fragilis although resistance increasing)
Which organisms do second generation cephalosporins have good activity against?
Haemophilus influenzae, Neisseria, some enteric GNRs
Which organisms do second generation cephalosporins have moderate activity against?
MSSA, streptococci, anaerobes (only for cefamycins)
Which organisms do second generation cephalosporins have poor activity against?
enterococci, MRSA, pseudomonas
What is the difference in organism coverage between the first and second generation cephalosporins?
2nd generation has more gram-negative coverage (because of enhanced beta lactamase stability) but less gram-positive coverage than 1st generation
Which two second generation cephalosporins are approved for use against H. influenzae, Strep pneumonia, and Moraxella catarrhalis?
cefamandole, cefuroxime
Which second generation cephalosporins have an NMTT side chain?
cefmetazole, cefotetan, cefamandole
Which of the second generation cephalosporins is designed to be dosed once daily because of its extended half life (about 3.5-4 hours)?
cefonicid
What is the first cephalosporin that was able to enter the cerebral spinal fluid? Is it still used today?
cefuroxime; not really used today because too many treatment failures
What does INR stand for and what does it refer to?
International normalized ratio, refers to clotting time
When might you be worried about giving a patient a cephalosporin?
if they have a true allergy to penicillin (anaphylaxis, hives, etc.)
What differentiates third generation cephalosporins from second generation cephalosporins?
3rd generation have enhanced beta lactamase stability, increased ability to penetrate gram-negative cell walls (even poorer gram-positive activity than 2nd)
What are the three subgroups of 3rd generation cephalosporins (parenteral)?
enterobacteriaceae activity, enterobacteriaceae plus anti-pseudomonal activity, enterobacteriaceae plus antianaerobic activity
What are the two 3rd generation parenteral cephalosporins in the enterobacteriaceae activity group?
cefotaxime (claforan), ceftriaxone (rocephin)
What is the 3rd generation parenteral cephalosporin in the enterobacteriaceae plus anti-pseudomonal activity group?
ceftazidime (ceftaz)
What is the 3rd generation parenteral cephalosporin in the enterobacteriaceae plus antianaerobic activity group?
ceftizoxime (cefizox)
What was the first cephalosporin to have anti-pseudomonal coverage?
ceftazidime
Which 3rd generation cephalosporins are approved for treating gram-negative meningitis?
ceftriaxone, cefotaxime
Why is ceftizoxime not good for prophylactic treatment even though it has anaerobic coverage?
it has very poor gram-positive coverage
What are the four oral 3rd generation cephalosporins?
cefixime (suprax), cefpodoxime (vantin), cefditoren (spectracef), cefdinir (omnicef)
Oral 3rd generation cephalosporins have been highly associated with what?
diarrhea from C. difficile
Before the 3rd generation cephalosporins (which had gram-negative coverage), what drugs had to be used for treating gram negative infections that had toxic side effects (including deafness, tinnitus, reversible kidney damage, etc.)?
aminoglycosides
What is the 4th generation cephalosporin?
cefepime (maxipime)
Which cephalosporin is a zwitterion (dipolar molecule with improved gram-negative cell wall penetration)?
cefepime
What characteristic other than improved cell wall penetration makes cefepime (4th gen) effective against gram-negative organisms?
it is a poor inducer of beta lactamases
What organisms does cefepime (4th gen) have good activity against?
enterobacteriaceae, pseudomonas aeruginosa, haemophilus influenzae, neisseria gonorrhea, neisseria meningitidis, gram-postiive organisms
What organisms does cefepime (4th gen) have poor (or no) activity against?
anaerobes, bacteroides fragilis, MRSA (no activity), enterococci (no activity)
Can cefepime (4th gen) cross the blood-brain barrier?
yes
The 4th generation cephalosporin was primarily intended to treat what?
hospital-acquired infections, meningitis
