SAGENT™

Rx only

To reduce the development of drug-resistant bacteria and maintain the effectiveness of CEFOXITIN FOR INJECTION, USP and other antibacterial drugs, CEFOXITIN FOR INJECTION, USP should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.

DESCRIPTION

CEFOXITIN FOR INJECTION, USP contains cefoxitin sodium a semi-synthetic, broad-spectrum cephalosporin antibiotic for parenteral administration. It is derived from cephalosporin C, which is produced by Cephalosporium Acremonium. It is the sodium salt of 3-(hydroxymethyl)-7-methoxy-8-oxo-7-[2-(2-thienyl)acetamido]-5-thia-1-azabicyclo [4.2.0] oct-2-ene-2-carboxylate carbamate (ester). The molecular formula is C16H16N3NaO7S2, and the structural formula is:

CEFOXITIN FOR INJECTION, USP contains approximately 53.8 mg (2.3 milliequivalents) of sodium per gram of cefoxitin activity. Solutions of CEFOXITIN FOR INJECTION, USP range from colorless to light amber in color. The pH of freshly constituted solutions usually ranges from 4.2 to 7.0.

Each conventional vial contains sterile cefoxitin sodium, USP equivalent to 1 or 2 g cefoxitin.

CLINICAL PHARMACOLOGY

Clinical Pharmacology

Following an intravenous dose of 1 gram, serum concentrations were 110 mcg/mL at 5 minutes, declining to less than 1 mcg/mL at 4 hours. The half-life after an intravenous dose is 41 to 59 minutes. Approximately 85 percent of cefoxitin is excreted unchanged by the kidneys over a 6-hour period, resulting in high urinary concentrations. Probenecid slows tubular excretion and produces higher serum levels and increases the duration of measurable serum concentrations.

Cefoxitin passes into pleural and joint fluids and is detectable in antibacterial concentrations in bile.

In a published study of geriatric patients ranging in age from 64 to 88 years with normal renal function for their age (creatinine clearance ranging from 31.5 to 174.0 mL/min), the half-life for cefoxitin ranged from 51 to 90 minutes, resulting in higher plasma concentrations than in younger adults. These changes were attributed to decreased renal function associated with the aging process.

Microbiology

The bactericidal action of cefoxitin results from inhibition of cell wall synthesis. Cefoxitin has in vitro activity against a wide range of gram-positive and gram-negative organisms. The methoxy group in the 7α position provides cefoxitin with a high degree of stability in the presence of beta-lactamases, both penicillinases and cephalosporinases, of gram-negative bacteria.

Cefoxitin has been shown to be active against most strains of the following microorganisms, both in vitro and in clinical infections as described in the INDICATIONS AND USAGE section.

Aerobic gram-positive microorganisms

 

Staphylococcus aureusa (including penicillinase-producing strains)

 

Staphylococcus epidermidisa

 

Streptococcus agalactiae

 

Streptococcus pneumoniae

 

Streptococcus pyogenes

 

a Staphylococci resistant to methicillin/oxacillin should be considered resistant to cefoxitin.

 

Most strains of enterococci, e.g., Enterococcus faecalis, are resistant.

Aerobic gram-negative microorganisms

 

Escherichia coli

 

Haemophilus influenzae

 

Klebsiella spp. (including K. pneumoniae)

 

Morganella morganii

 

Neisseria gonorrhoeae (including penicillinase-producing strains)

 

Proteus mirabilis

 

Proteus vulgaris

 

Providencia spp. (including Providencia rettgeri)

Anaerobic gram-positive microorganisms

 

Clostridium spp.

 

Peptococcus niger

 

Peptostreptococcus spp.

Anaerobic gram-negative microorganisms

 

Bacteroides distasonis

 

Bacteroides fragilis

 

Bacteroides ovatus

 

Bacteroides thetaiotaomicron

 

Bacteroides spp.

The following in vitro data are available, but their clinical significance is unknown.

Cefoxitin exhibits in vitro minimum inhibitory concentrations (MIC's) of 8 mcg/mL or less for aerobic microorganisms and 16 mcg/mL or less for anaerobic microorganisms against most (≥ 90%) strains of the following microorganisms; however, the safety and effectiveness of cefoxitin in treating clinical infections due to these microorganisms have not been established in adequate and well-controlled clinical trials.

Aerobic gram-negative microorganisms

 

Eikenella corrodens (non-β-lactamase producers)

 

Klebsiella oxytoca

Anaerobic gram-positive microorganisms

 

Clostridium perfringens

Anaerobic gram-negative microorganisms

 

Prevotella bivia (formerly Bacteroides bivius)

Cefoxitin is inactive in vitro against most strains of Pseudomonas aeruginosa and enterococci and many strains of Enterobacter cloacae.

Susceptibility Tests

Dilution Techniques:

Quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MIC's). These MIC's provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MIC's should be determined using a standardized procedure. Standardized procedures are based on a dilution method1 (broth or agar) or equivalent with sta