Cefazolin sodium clinical pharmacology
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sheng Shi, M.D. [2]
Clinical Pharmacology
Mechanism of Action
Cefazolin is an antibacterial drug [see Microbiology (12.4)].
Pharmacodynamics
The pharmacokinetic/pharmacodynamic relationship for cefazolin has not been evaluated in patients.
Pharmacokinetics
Studies have shown that following intravenous administration of cefazolin to normal volunteers, mean serum concentrations peaked at approximately 185 mcg/mL and were approximately 4 mcg/mL at 8 hours for a 1 gram dose.
The serum half-life for cefazolin is approximately 1.8 hours following intravenous administration.
In a study, using normal volunteers, of constant intravenous infusion with dosages of 3.5 mg/kg for 1 hour (approximately 250 mg) and 1.5 mg/kg the next 2 hours (approximately 100 mg), cefazolin produced a steady serum concentration at the third hour of approximately 28 mcg/mL.
Plasma pharmacokinetic parameters of cefazolin in normal volunteers (N=12) following a single 15-minute intravenous infusion of 2 grams of Cefazolin for Injection, USP are summarized in Table below.
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Studies in patients hospitalized with infections indicate that cefazolin produces mean peak serum concentrations approximately equivalent to those seen in normal volunteers.
Bile concentrations in patients without obstructive biliary disease can reach or exceed serum concentrations by up to five times; however, in patients with obstructive biliary disease, bile concentrations of cefazolin are considerably lower than serum concentrations (< 1 mcg/mL).
In synovial fluid, the cefazolin concentration becomes comparable to that reached in serum at about 4 hours after drug administration.
Studies of cord blood show prompt transfer of cefazolin across the placenta. Cefazolin is present in very low concentrations in the milk of nursing mothers.
Cefazolin is excreted unchanged in the urine. In the first 6 hours approximately 60% of the drug is excreted in the urine and this increases to 70% to 80% within 24 hours.[1]
References
- ↑ "http://www.accessdata.fda.gov/drugsatfda_docs/label/2004/50461slr139_ancef_lbl.pdf" (PDF). External link in
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Adapted from the FDA Package Insert.