indication

Mainly used to treat bacterial infections of the skin. It can also be used to treat moderately severe bacterial infections involving the lung, bone, joint, stomach, blood, heart valve, and urinary tract. It is clinically effective against infections caused by staphylococci and streptococci species of Gram positive bacteria. May be used for surgical prophylaxis; if required metronidazole may be added to cover B. fragilis.

pharmacology

Cefazolin (also known as cefazoline or cephazolin) is a semi-synthetic first generation cephalosporin for parenteral administration. Cefazolin has broad-spectrum antibiotic action due to inhibition of bacterial cell wall synthesis. It attains high serum levels and is excreted quickly via the urine.

mechanism of action

In vitro tests demonstrate that the bactericidal action of cephalosporins results from inhibition of cell wall synthesis. By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, it inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins.

biotransformation

Not metabolized.

absorption

Not absorbed from GI tract. Must be administered parenterally. Peak serum concentrations attained 1-2 hours post intramuscular injection.

half life

The serum half-life is approximately 1.8 hours following IV administration and approximately 2.0 hours following IM administration.

route of elimination

Cefazolin is present in very low concentrations in the milk of nursing mothers. Cefazolin is excreted unchanged in the urine. In the first six hours approximately 60% of the drug is excreted in the urine and this increases to 70%-80% within 24 hours.

drug interactions

Amikacin: Increased risk of nephrotoxicity

Gentamicin: Increased risk of nephrotoxicity

Netilmicin: Increased risk of nephrotoxicity

Probenecid: Probenecid may increase the serum level of cefazolin.

Tobramycin: Increased risk of nephrotoxicity