Pharmacology of Cephalosporins:General Overview

Bawoh. M PhD.

mohamedbawoh@yahoo.com

β- lactams: cell wall inhibitors

β-lactam ring

•The β-lactam ring is a common structure for:•Penicillins•Cephalosporins•Monobactams•Carbapenems

• Bacteria will target this ring to gain resistance.

Cell wall inhibitors: important features

• Cell wall inhibitors have bacericidal effect.

• They act sinergistically with amynoglycosides

• Time-dependent kinetics: the more time the drug binds the bacteria, the more effective it is.

Mechanism of action 1

•Some PBP have transpeptidase activity.• Transpeptidase activity is essential in cell wall synthesis.

•Beta-lactams bind PBP (Penicillin Binding Proteins).

Mechanism of action 2

Cephalosporins

Cephalosporins: characteristics

Chemical structure of cephalosporins

• Derived from 7-aminocephalosporanic acid.

• They suffer the “attack” of bacteria at their beta-lactam ring.

First gen. cephalosporins.:

1st Generation cephalosporins: antibacterial coverage

Active mainly against Gram positive cocci. Less active against Gram negative.

Clinical uses of first gen. cephalosporins

2nd generation cephalosporins

2nd generation cephalosporins. Antibiotic coverage

Increased coverage against Gram negatives, while keeping coverage against Gram +.

3rd generation cephalosporins

3rd generation cephalosporinsCoverage

Increased coverage against Gram negatives.Decreased coverage against Gram +

3rd generation cephalosporinsClinical uses

Ceftriaxone and meningitis

4th generation cephalosporins

4th generation cephalosporinsAntibacterial coverage

Coverage against Gram + and Gram -, good activity against β-lactamase producing bacteria.