36.cephalosporins

Question 1

definition of cephalosporins

Answer 1

semi-synthetic derivatives of 7-amino- cefalosporanic acid

Question 2

spectrum of activity of cephalosporins

Answer 2

wide spectrum
stable to beta lactamases

Question 3

excretion of cephalosporins

Answer 3

urine
some have bile excretion

Question 4

what can happen when cephalosporins are injected?

Answer 4

1.local irritation
2.phlebitogenic effect

Question 5

how many generations of cephalosporins are there?

Answer 5

5

Question 6

name drugs in the 1st gen cs

Answer 6

1.cefazolin - flac.1g
2.cefalotin - flac 1g
3.cefapirin - flac.1g

Question 7

name drugs in the 2nd gen cs

Answer 7

1.Cefaclor - caps.250mg
2.Cefoxitin - flac.1g
3.Cefotenan - flac.1g

Question 8

name drugs in the 3rd generation cs

Answer 8

1.Cefotaxime - flac.1g
2.Ceftibuten - caps.400mg
3.Ceftriaxone - flac.1g

Question 9

name drugs in the 4th gen. cs

Answer 9

1. cefepime - flac.1g
2. cefpirom - flac.1g

Question 10

name drugs in the 5th generation cs

Answer 10

1.ceftobiprole -flac 1g
2.ceftaroline

Question 11

antibacterial spectrum of ceftobiprole

Answer 11

i.v administration

1. Gram (-),
2. MRSA,
3. coagulase- negative Staph.,
4. Str. pneumoniae,
5. Enterococcus faecalis, but not Enterococcus faecium and Ps. aeruginosa.

Question 12

distribution of cephalosporins

Answer 12

1.penetrate well into tissues and body fluids
2.only extracellular distibution
3.1st gen are the least penetrating the eye and prostate
4.all cross the placenta
4. 1st and 2nd gen don’t cross BBB - only cefuroxime
5. 3rd and 4th pass HEB in inflammed meninges

Question 13

excretion of cephalosporins

Answer 13

1. Most are excreted in the urine.
2. Some are also excreted in the bile:
   Cefazoline (I gen.),
   Cefamadole (II gen.)
   Ceftriaxone (III gen.)
3. Double elimination:
   Ceftriaxone - 60% urinary and 40% biliary excretion.

Question 14

ADRs of cephalosporins

Answer 14

1. All types allergic reactions – cross-allergy with penicillins!
2. Dysbacteriosis
3. GIT disorders: nausea, vomiting, diarrhea, candidiasis.
4. Pseudomembranous colitis – in oral and parenteral drugs with biliary excretion.
5. Nephrotoxicity – only 1-st gen.
6. Contraindicated at first 3 months of pregnancy, some of them during breast feeding also.
7. disulfiram reaction - in drugs with biliary excretion
8. local irritation
9. false positive urine glucose test

Question 15

drug interactions of cephalosporins

Answer 15

1. In vitro incompatibility with aminoglycosides.
2. Synergism with penicillins.
3. Loop diuretics and nephrotoxic antibiotics
   increase the risk of 1-st-gen. renal impairment.
4. Drugs with bile excretion lower the prothrombin
   index and enhance the action of
   anticoagulants.
5. They combine with β-lactams.

Question 16

pharmacokinetics of cephalosporins
a,d,m,e

Answer 16

• A- oral (acid stable), parenteral (acid unstable)
  
  • Cefuroxime can be given both ways (it is an exception)
  • Oral absorption is normally poor
• D- 3-5th gen can cross BBB in meningitis
• M- no metabolism
• E- urine
  
  • 2nd generation eliminated with bile!

Question 17

pharmacodynamics of cephalosporins

Answer 17

-bactericidal
work via their beta-lactam rings.
- The beta-lactam rings bind to the penicillin-binding protein and inhibit its normal activity.
- Unable to synthesize a cell wall, the bacteria die!

Question 18

spectrum of activity of cephalosporins

Answer 18

broad

Question 19

Contraindications of cephalosporins

Answer 19

1- Allergies
2- Neonates with hyperbilirubinemia
- Ceftriaxone is contraindicated here!
3- Kidney impairment
4- Liver impairment