*Anti gram negative drugs

Noreen Mohammed Naguib Mosaad

5212322G.11

Third Generation CephalosporinsExamples:Cefoperazone

The broadest spectrums of all cephalosporins

The lowest activities against G+ vebacteria

The highest resistance to β-lactamase

The best penetration into the CSF; almost no nephrotoxicity

Some of them are effective against pseudomonas and enteric bacilli

Fourth Generation Cephalosporins

•Examples : Cefepime

Similar to third generation

More resistant to hydrolysis by beta lactamase

It is cleared by the kidneys

It is useful in treatment of infections caused by enterobacter

AminoglycosidesMechanism of action:

•Aminoglycosides are irreversible inhibitors of bacterial protein synthesis.Antibacterial spectrum:

•All aminoglycosides are bactericidal. They are effective only against aerobic gram-negative organisms

They include:a)Streptomycin

b)Gentamicin

c)Neomycin

d)Tobramycin

Pharmacokinetic Properties•Aminoglycosides are poorly absorbed after

oraladministration, , because they are highly polar drugs. They must be given parenterally.

•Except Neomycinis neverused systemically

Concentrations in C.S.F are inadequate even when the meninges are inflammed.

•Aminoglycosides are cleared by the kidney

Adverse effects1-Ototoxicity

2-Nephrotoxicity.Binds tightly to renal tissue. Reduce dosage in patients with renal disease

3-Hypersensitivity

Contact dermatitis is a common reaction to topically applied neomycin.

Therapeutic usesUsed against gram-negative enteric bacteria

Used in combination with a beta-lactam antibiotic (e.g. penicillin) in order to extend coverage to include potential gram-positive pathogens.

Thank You