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Cefazolin (INN)
Cefazolin ball-and-stick.png
Systematic (IUPAC) name
(6R,7R)-3-{[(5-methyl-1,3,4-thiadiazol-2-yl)thio]methyl}-8-oxo-7-[(1H-tetrazol-1-ylacetyl)amino]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid
Clinical data
Pronunciation /sɨˈfæzɵlɨn/
Trade names Ancef, Cefacidal, Cefamezin, Cefrina, Elzogram, Faxilen, Gramaxin, Kefzol, Kefol, Kefzolan, Kezolin, Novaporin, Reflin, Zinol Zolicef
AHFS/Drugs.com monograph
  • AU: B1
  • US: B (No risk in non-human studies)
Legal status
  • (Prescription only)
Routes of
Intravenous, intramuscular
Pharmacokinetic data
Bioavailability NA
Metabolism ?
Biological half-life 1.8 hours (given IV)
2 hours (given IM)
Excretion Renal, unchanged
CAS Number 25953-19-9 YesY
ATC code J01DB04 QJ51DB04
PubChem CID: 33255
DrugBank DB01327 YesY
ChemSpider 30723 YesY
KEGG D02299 YesY
ChEBI CHEBI:474053 YesY
Chemical data
Formula C14H14N8O4S3
Molecular mass 454.51 g/mol
 YesY (what is this?)  (verify)

Cefazolin, also known as cefazoline or cephazolin, is an antibiotic used for the treatment of a number of bacterial infections.[1] The drug is usually administered by either intramuscular injection (injection into a large muscle) or intravenous infusion (intravenous fluid into a vein).[2]

Due to possible cross-reactivity with penicillins, people who have experienced anaphylaxis to penicillins are not advised to receive cephalosporins.[1] Common side effects include nausea, vomiting, diarrhea, and rash.[3] Cefazolin is a first-generation cephalosporin antibiotic with broad spectrum antibiotic with activity against both gram-negative and gram-positive bacteria.

It was initially marketed by GlaxoSmithKline under the trade name Ancef, but is no longer available as brand name products.[2] It is on the World Health Organization's List of Essential Medicines the most important medications needed for a basic health system.[4]

Medical uses[edit]

Cefazolin is used in a variety of infections provided that susceptible organisms are involved. It is indicated for use in the following infections:[3]

It can also be used peri-operatively to prevent infections post-surgery, and is often the preferred drug for surgical prophylaxis.[3]

There is no penetration into the central nervous system and therefore cefazolin is not effective in treating meningitis.[1]

Cefazolin has been shown to be effective in treating methicillin-susceptible Staphylococcus aureus (MSSA) but does not work in cases of methicillin-resistant Staphylococcus aureus (MRSA).[3] In many instances of staphylococcal infections, such as bacteremia, cefazolin is an alternative to penicillin in patients who are allergic to penicillin.[1] However, there is still potential for a reaction to occur with cefazolin and other cephalosporins in patients allergic to penicillin.[3] Resistance to cefazolin is seen in several species of bacteria, such as Mycoplasma and Chlamydia, in which case different generations of cephalosporins may be more effective.[5] Cefazolin does not fight against Enterococcus, anaerobic bacteria or atypical bacteria among others.[1]

Bacterial susceptibility[edit]

As a first-generation cephalosporin antibiotic, cefazolin and other first-generation antibiotics are very active against gram-positive bacteria and some gram-negative bacteria.[3] Their broad spectrum of activity can be contributed to their improved stability to many bacterial beta-lactamases compared to penicillins.[1]

Spectrum of activity[edit]

Gram-positive aerobes:[1][3]

Gram-Negative Aerobes:

Non susceptible[edit]

The follow are not susceptible:[1][3]

Special populations[edit]


Cefazolin is pregnancy category B, indicating general safety for use in pregnancy. Caution should be used in breastfeeding as a small amount of cefazolin enters the breast milk.[3] Cefazolin can be used prophylactically against perinatal Group B streptococcal infection (GBS). Although penicillin and ampicillin are the standard of care for GBS prophylaxis, penicillin-allergic women with no history of anaphylaxis can be given cefazolin instead. These patients should be closely monitored as there is a small chance of an allergic reaction due to the similar structure of the antibiotics.[6]


There has been no established safety and effectiveness for use in premature infants and neonates.[3]


No overall differences in safety or effectiveness were observed in clinical trials comparing elderly and younger subjects, however the trials could not eliminate the possibility that some older individuals may have a higher level of sensitivity.[3]

Additional considerations[edit]

People with kidney disease and those on hemodialysis may need the dose adjusted.[3] Cefazolin levels are not significantly affected by liver disease.

As with other antibiotics, cefazolin may interact with other medications being taken. Some important drugs that may interact with cefazolin such as probenecid.[1]

Side effects[edit]

side effects associated with use of cefazolin therapy include:[3]

  • Common (1-10%): diarrhea, stomach pain or upset stomach, vomiting, and rash.
  • Uncommon (<1%): dizziness, headache, fatigue, itching, transient hepatitis[7]

Patients with penicillin allergies could experience a potential reaction to cefazolin and other cephalosporins.[3] As with other antibiotics, patients experiencing watery and/or bloody stools occurring up to three months following therapy should contact their prescriber.[3]

Like those of several other cephalosporins, the chemical structure of cefazolin contains an N-methylthiodiazole (NMTD or 1-MTD) side-chain. As the antibiotic is broken down in the body, it releases free NMTD, which can cause hypoprothrombinemia (likely due to inhibition of the enzyme vitamin K epoxide reductase) and a reaction with ethanol similar to that produced by disulfiram (Antabuse), due to inhibition of aldehyde dehydrogenase.[8]

Mechanism of action[edit]

Cefazolin inhibits cell wall biosynthesis by binding Penicillin binding proteins which stops peptidoglycan synthesis. Penicillin binding proteins are bacterial proteins that help to catalyze the last stages of peptidoglycan synthesis, which is needed to maintain the cell wall. They remove the D-alanine from the precursor of the peptidoglycan. The lack of synthesis causes the bacteria to lyse because they also continually break down their cell walls. Cefazolin is bactericidal, meaning it kills the bacteria rather than inhibiting their growth.[1]


  1. ^ a b c d e f g h i j Katzung, et. al., Bertram (2015). Basic & Clinical Pharmacology. New York: McGraw Hill Education. pp. 776–778. ISBN 978-0-07-182505-4. 
  2. ^ a b "Cefazolin Sodium Injection: MedlinePlus Drug Information". www.nlm.nih.gov. Retrieved 2015-11-05. 
  3. ^ a b c d e f g h i j k l m n o "DailyMed - CEFAZOLIN - cefazolin sodium injection, powder, for solution". dailymed.nlm.nih.gov. Retrieved 2015-11-05. 
  4. ^ "WHO Model List of Essential Medicines" (PDF). WHO Model List of Essential Medicines. August 2015. Retrieved November 4, 2015. 
  5. ^ "Cefazolin (Injection Route)". Mayo Clinic. 1 July 2015. 
  6. ^ "Prevention of Perinatal Group B Streptococcal Disease". www.cdc.gov. Retrieved 2015-11-05. 
  7. ^ "Cefazolin Prescribing Information" (PDF). FDA.  Check date values in: |date= (help)
  8. ^ Stork, CM (2006). Antibiotics, antifungals, and antivirals. New York: McGraw-Hill. p. 847. 

External links[edit]