3. Cephalosporins

Question 1

Cephalosporin

• structure

Answer 1

• B-lactam ring : 6 member ring!! (Penicillin 5-member!)
• B-lactamase can not break this bond because of the COOH group

Question 2

Cephalosporum

• mechanism of effect

Answer 2

• same as penicillin
• Bactericidal, time dependent, PAE
• cell wall syntehsis inhibitors
• PBP

Question 3

Cephalosporins

• resistance

Answer 3

• Ab Ovo:
• bacterium: Mycoplasma, Rickettsia, Chlamydia, Pseudomonoas
• –> AB: Cephoperazon, Cefazitine
• B-lactamase production
• Bacterium: staph., pesudomonas
• in this case the cephalosporins will be used against staph.
• PBP-mutaion: MRSA, MRSP

Question 4

Cephalosporins

• Antibacterial spectrum

Answer 4

4 Generations

• down the generations: more lipophilic, better penetration, eg: BBB

Question 5

Cephalosporins

• 1st. generation

Answer 5

• pronounced activity against Gram + bacteria (staph.) –> Penicillinase stable!
• Gram -: NOT against lactamase producers

Question 6

Cephalosporins

• 2nd. generation

Answer 6

• less pronounced activity against Gram +
• Gram -: active against several lactamase producers: E.coli, Salmonella spp., Klebsiella spp. etc

Question 7

Cephalosporins

• 3rd. generation

Answer 7

• weak activity against Gram +
• Gram -: active against most lactamase producers!
• • pesudomonas aeruginosa
• Cefoperazone, ceftazidime!

Question 8

Cephalosporins

• 4th. generation

Answer 8

• good activity against Gram+
• Gram- : most lactamase producers
• • more active (MICs are lower)
• GI-infection, resp. infection
• CIA: ABs only used in emergency and life treathening conditions., eg: Cepquimoe

Question 9

Cephalosporins

• pharmacokinetics

Answer 9

• Absorption: Oral <-> parenteral
• Distribution: varies between generations
• Metabolism: Liver
• Excretion: Kidney (some in bile: Cefoperazone)
• in case of kidney failure: Cefachlor, cefatriofur

Cefovecin: T1/2

• dermatitis, oral cavity inf., UTI in small animals
• 3rd generation cephalosporin
• SC
• Dose: 8mg/kg
• half life: dogs 5 days, cats 7 days
• duration of action: 2 weeks
• they have a post-antibitoic effect (therefore half-life 5-7 days)

Ceftiofur:

• large animals: Cattle (SC), Swine (IM)
• Dose: 8mg/kg
• Respiratory (1st choice), GI-tract (2nd choice)
• 3 forms exists: Ceftiofur Na (short acting, BID), Ceftiofur hydrochloride (longer acting, SID), Ceftiofur crystalline free acid form (CCFA) (acting for 3 days), –> Desfuroyl ceftiofur: the common metabolite of all, excreted with urine.

Question 10

Cephalosporins

• Side effects

Answer 10

Mild toxicity

• allergy (ca 5% cross allergy with penicillin, NB: never use this combination in Eq!)
• dysbacteriosis
• haematological: increased thrombocyte and RBC count
• tissue irritation
• mild nephrotoxiciy: not a big problem, can be used in UTI. If it is combined with aminoglycosides = BIG problem!

Question 11

Cephalosporins

• ex of all the 4 generations

Answer 11

Question 12

Cephalosporins

• Indications

Answer 12

• mastitis
• Cephapirin, Cefacetril, Cephalotin
• dermatitis, soft tissue infections
• Cephalexin
• –> also otitis externa and UTI in case of Staph., NOT in case of E.coli
• respiratory infections
• Cefquinome (GI, resp., UTI), mainly large animals
• UTI
• Cephalexin, Cefquinome
• Ceficime: in case of E.coli
• meningitis, encephalitis
• Cefotaxime
• Ceftriaxone (excreted by bile)
• praeoperative, intraoperative prophylaxis
• Cephazoline