Group of semisynthetic antibiotics derived from cephalosprin -C obtained from fungus Cephalosporium
Chemically related to Pn, the nucleus consist of beta lactam ring fused to dihydrothiazine ring
Divided into four generation on the basis of chronological sequence, potency & antibacterial spectrum
First generation cephalosporins
Developed in 1960s
High activity against gram positive but weaker against gram negative bacteria
Mainly used for surgical prophylaxis
Oral: Cephalexin, Cephradine, Cefadroxil
Parenteral: Cefazolin, Cephalothin
Second generation cephalosporins
Developed subsequent to first generation
More active against gram negative organism, some members active against anaerobes but none inhibit P.aeruginosa
Oral: Cefaclor, Cefuroxim axetil
Parenteral: Cefuroxim, Cefoxitin
Third generation cephalosporins
Augmented activity against gram negative enterobacteriacae, some inhibit Pseudomonas as well
Highly resistant to beta lactamases from gram negative bacteria
Oral: Cefixime, Cefdinir,
Parenteral: Ceftriaxone, Cefotaxim, Cefoperazone,
Fourth generation cephalosporins
Developed in 1990s, antibacterial spectrum similar to 3rd generation , but is highly resistant to beta lactamases
Active against P. aeruginosa & S. aureus
Used for serious hospital acquired infections
Only parenteral
Cefepime
Cefpirome
Properties
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