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
Trade names Ancef, Kefzol
Pregnancy cat.
Legal status
  • Prescription only
Routes Intravenous, intramuscular
Pharmacokinetic data
Bioavailability NA
Metabolism ?
Half-life 1.8 hours (given IV)
2 hours (given IM)
Excretion Renal, unchanged
CAS number  YesY
ATC code J01 QJ51
ChemSpider  YesY
Chemical data
Formula C14H14N8O4S3 
Mol. mass 454.51 g/mol

Cefazolin (INN), also known as cefazoline or cephazolin is an antibiotic useful for the treatment of a number of bacterial infections.

It is a first-generation cephalosporin antibiotic. Cephalosporins fall into the category of β-Lactam (beta-lactam) antibiotics. Other antibiotics that fall into this category are penicillin derivatives, monobactams and carbapenems. This group of antibiotics works by inhibiting cell wall synthesis of the bacteria by binding to penicillin-binding proteins. These groups of antibiotics are known as bactericidal, meaning that they kill the targeted bacteria (as opposed to inhibiting reproduction as bacteriostatic antibiotics do).

The drug is usually administered by either intramuscular injection (injection into a large muscle) or intravenous infusion (health system.[1]

Medical uses

Cefazolin is mainly used to treat bacterial infections of the skin (cellulitis). 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 which are Gram-positive bacteria commonly found on human skin. Cefazolin has been shown to be very effective in treating Methicillin-susceptible Staphylococcus aureus (MSSA) but does not work in cases of Methicillin-resistant Staphylococcus aureus (MRSA). In many instances of MSSA, the use of cefazolin is preferred over the use of other antibiotics such as vancomycin.[2]

Cefazolin also has coverage against some Gram-negative bacteria such as Escherichia coli and Klebsiella pneumoniae.[3] Resistance to cefazolin is seen in several species of bacteria in which case different generations of cephalosporins may be more effective. Cefazolin does not fight against Enterococcus, anaerobic bacteria or atypical bacteria among others.

Surgery Prophylaxis

Cefazolin is often used as a prophylactic antibiotic before a wide range of surgical operations due to being one of the most widely studied antibiotics with proven efficacy. The antibiotic is ideally given within the 60 minutes before the start of the surgical procedure. In procedures lasting longer than 4 hours, additional doses of cefazolin should be given every 4 hours until the procedure has finished. As with many other antibiotics, the amount of cefazolin given to each patient varies by weight. The standard amount for adult patients is 2 grams per dosing. In cases of obese patients weighing >120 kg, this dose should be increased to 3 grams. In pediatric (children) cases, the amount given is determined by giving 30 mg of the antiobitic for each kilogram the child weighs (30 mg/kg).

Bacterial susceptibility

Cefazolin is a broad spectrum antibiotic that is often used to treat different types of infections including urinary tract, skin, and bone infections. In order to kill the targeted bacteria, antibiotics must reach a certain level in the blood. Studies are done in a laboratory to determine the Minimum inhibitory concentration (MIC) for each antibiotic and bacteria. The following represents MIC susceptibility data for a few medically significant bacteria.

  • Escherichia coli: 0.5 μg/mL - >412.8 μg/mL
  • Staphylococcus aureus: <0.2 μg/mL - >344 μg/mL
  • Streptococcus pyogenes: 0.125 μg/mL - 0.25 μg/mL



Cefazolin is a pregnancy category B drug and is therefore usually safe to use. It is also safe to breastfeed while taking cefazolin.[5][6] Cefazolin also has some use in prophylaxis 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.[7]

Additional considerations

People with kidney disease and those on hemodialysis should make sure their physician is aware of such conditions. Cefazolin is cleared by the kidneys and those with decreased kidney function will need their dosages adjusted.[8] Cefazolin levels are not significantly affected by liver disease.

As with many other antibiotics, there is a chance that cefazolin will interact with other drugs/antibiotics that a person is taking. Some important drugs that may interact with cefazolin include phenytoin, probenecid and warfarin. All persons should inform the prescribing physician of all other medications (prescribed, over the counter, etc.) they are taking.[9]

Adverse effects

Adverse drug reactions from cefazolin are not common. Possible side effects include diarrhea, stomach pain or upset stomach, vomiting, and rash. Patients with penicillin allergies may also have a reaction to cefazolin and other cephalosporins and therefore this information should be disclosed to the prescribing physician.

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.[10]


Cefazolin is marketed under the following brand names: Ancef, Cefacidal, Cefamezin, Cefrina, Elzogram, Faxilen, Gramaxin, Kefzol, Kefol, Kefzolan, Kezolin, Novaporin, Reflin, Zinol and Zolicef.


  1. ^ "WHO Model List of EssentialMedicines". World Health Organization. October 2013. Retrieved 22 April 2014. 
  2. ^ Schweizer, ML; Furuno, JP; Harris, AD; Johnson, JK; Shardell, MD; McGregor, JC; Thom, KA; Cosgrove, SE; Sakoulas, G; Perencevich, EN (Oct 19, 2011). "Comparative effectiveness of nafcillin or cefazolin versus vancomycin in methicillin-susceptible Staphylococcus aureus bacteremia.". BMC infectious diseases 11: 279.  
  3. ^ http://www.antimicrobe.org/drugpopup/Cefazolin.pdf
  4. ^ http://www.toku-e.com/Assets/MIC/Cefazolin%20sodium%20USP.pdf
  5. ^ http://www.mayoclinic.org/drugs-supplements/cefazolin-injection-route/before-using/drg-20073267
  6. ^ http://pediatrics.aappublications.org.proxy1.lib.tju.edu/content/108/3/776.long
  7. ^ http://www.cdc.gov/mmwr/preview/mmwrhtml/rr5910a1.htm
  8. ^ http://cid.oxfordjournals.org.proxy1.lib.tju.edu/content/41/8/1159.long
  9. ^ http://reference.medscape.com/drug/kefzol-cefazolin-342492#3
  10. ^ Stork CM (2006). "Antibiotics, antifungals, and antivirals". In Nelson LH, Flomenbaum N, Goldfrank LR, Hoffman RL, Howland MD, Lewin NA (eds.). Goldfrank's toxicologic emergencies. New York: McGraw-Hill. p. 847.  

External links

  • MedlinePlus Drug Information: Cefazolin Sodium Injection.