Cephalosporins

Question 1

What effect do the two side chains on Cephalosporins have?

Answer 1

R1 - Spectrum of activity, PBP affinity, B-lactamase

R2 - Longer half life (allows for infrequent dosing)

Question 2

Which drug is available as prodrug?

Cephalosporins

Answer 2

Cefuroxime axetile

gets hydrolyzed in the intestines

Question 3

Mechanism of action

Cephalosporins

Answer 3

binds PBPs - inhibits crosslinking of peptidoglycan strands

Question 4

How do cephalosporins vary in their efficacy?

Answer 4

Affinity to PBP

Question 5

Distribution? when is CSF penetration possible?

Cephalosporins

Answer 5

well distributed

CSF penetration with inflamed meninges - 3rd generation - Ceftriaxone
- High dose required

Question 6

main route of excretion

Cephalosporins

Answer 6

renal

Question 7

Adverse effects

Cephalosporins

Answer 7

hypersensitivity
Bleeding
Disulfiram-like intolerance 
GI - diarrhea, pseudomembranous colitis
Renal - IN (rare)
Immunologic - serum sickness in children

Question 8

What is the structure that causes Bleeding?

Cephalosporins

Answer 8

NMTT side chain

Question 9

Which drugs cause bleeding? how?

Cephalosporins

Answer 9

cefamandole and cefoperazone

disturbance in Vit K dependent clotting factors - hypoprothrombinemia

Question 10

What can induce disulfiram-like intolerance?

Cephalosporins

Answer 10

Consuming alcohol while on agents with NMTT side chain - Cefamandole and cefaperazone

Question 11

Which cephalosporin causes serum sickness in children?

Answer 11

Cefaclor (Ceclor - 2nd generation)

Question 12

What is the result of drug interaction with warfarin?

Cephalosporins

Answer 12

potentiation of anticoagulant effects

Question 13

Drug interaction with probenecid?

Cephalosporins

Answer 13

prolongs excretion in cephalosporins that have tubular secretion

Question 14

What happens to the spectrum of activity as generations increase?
(Cephalosporins)

Answer 14

Gram negative coverage increases

Question 15

What are generally NOT covered by cephalosporins?

Answer 15

Enterococcus
MRSA
Chlamydia, Mycoplasma, Legionella (Atypicals)
Listeria monocytogenes

Question 16

Uses:
Community acquired Pneumonia
(Cephalosporins)

Answer 16

3rd generations (no atypical pathogen coverage)
- ceftriaxone, cefotaxime (SACE, strep)

Question 17

Uses:
Nosocomial pneumonia
(Cephalosporins)

Answer 17

Ceftazidime (3rd - antipseudomonal), cefepime (4th -strep, staph, SPACE)
double coverage for SPACE bugs

Question 18

Uses:
Meningitis
(Cephalosporins)

Answer 18

ceftriaxone

3rd generations/use higher doses

Question 19

Uses:
Skin soft tissue
(Cephalosporins)

Answer 19

1st generation - staph/strep (simple cellulitis/Non-DM)

3rd/4th /Cephamycins - severe cases or diabetic patients (G +/-, anaerobes)

Question 20

Surgical prophylaxis

Answer 20

cefazolin 
cephamycins (Abdomina/GI surgeries)

Question 21

why is cefazolin good for surgical prophylaxis?

Answer 21

long half life
covers staph

convenient dosing for osteomyelitis/MSSA sepsis

Question 22

How is cephalosporin used in neutropenic patient with fever?

Answer 22

Cefepime or ceftaz with Vancomycin

• but, cefepime covers staph/strep that ceftaz doesn’t
• Vanc covers staph and MRSA/strep/enterococcus