To reduce the development of drug-resistant bacteria and maintain the effectiveness of cefoxitin for injectionand other antibacterial drugs, cefoxitin for injection should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria.
DESCRIPTION
Cefoxitin for injection is a semi-synthetic, broad-spectrum cepha antibiotic sealed under nitrogen for intravenous administration. It is derived from cephamycinC, which is produced by Streptomyces lactamdurans. Its chemical name is sodium (6R,7S)-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, USPcontains cefoxitin sodium equivalent to 1 or 2 gram cefoxitin. Cefoxitin for injection contains approximately 53.8mg (2.3 milliequivalents) of sodium per gram of cefoxitin activity.Sterile Cefoxitin for injection is a dry white to off-white powder. Solutions of cefoxitinfor injection range from colorless to light amber in color. The pH of freshly constituted solutions usually ranges from 4.2 to 7.0
CLINICAL PHARMACOLOGY
Clinical Pharmacology
Following an intravenous dose of 1gram, serum concentrations were 110mcg/mL at 5minutes, declining to less than 1mcg/mL at 4hours. The half-life after an intravenous dose is 41 to 59minutes. 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 aureus1(including penicillinase-producing strains)
Staphylococcus epidermidis1
Streptococcus agalactiae
Streptococcus pneumoniae
Streptococcus pyogenes
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 gonorr
