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 pubished 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

Treatment

Cefoxitin for Injection and Dextrose Injection is indicated for the treatment of serious infections caused by susceptible strains of the designated microorganisms in the diseases listed below.

(1) Lower respiratory tract infections, including pneumonia and lung abscess, caused by Streptococcus pneumoniae, other streptococci (excluding enterococci, e.g., Enterococcus faecalis [formerly Streptococcus faecalis]), Staphylococcus aureus (including penicillinase-producing strains), Escherichia coli, Klebsiella species, Haemophilus influenzae, and Bacteroides species.

(2) Urinary tract infections caused by Escherichia coli, Klebsiella species, Proteus mirabilis, Morganella morganii, Proteus vulgaris and Providencia species (including P. rettgeri).

(3) Intra-abdominal infections, including peritonitis and intra-abdominal abscess, caused by Escherichia coli, Klebsiella species, Bacteroides species including Bacteroides fragilis, and Clostridium species.

(4) Gynecological infections, including endometritis, pelvic cellulitis, and pelvic inflammatory disease caused by Escherichia coli, Neisseria gonorrhoeae (including penicillinase-producing strains), Bacteroides species including B. fragilis, Clostridium species, Peptococcus niger, Peptostreptococcus species, and Streptococcus agalactiae. Cefoxitin, like cephalosporins, has no activity against Chlamydia trachomatis. Therefore, when cefoxitin is used in the treatment of patients with pelvic inflammatory disease and C. trachomatis is one of the suspected pathogens, appropriate anti-chlamydial coverage should be added.

(5) Septicemia caused by Streptococcus pneumoniae, Staphylococcus aureus (including penicillinase-producing strains), Escherichia coli, Klebsiella species, and Bacteroides species including B. fragilis.

(6) Bone and joint infections caused by Staphylococcus aureus (including penicillinase-producing strains).

(7) Skin and skin structure infections caused by Staphylococcus aureus (including penicillinase-producing strains), Staphylococcus epidermidis, Streptococcus pyogenes and other streptococci (excluding enterococci, e.g., Enterococcus faecalis [formerly Streptococcus faecalis]), Escherichia coli, Proteus mirabilis, Klebsiella species, Bacteroides species including B. fragilis, Clostridium species, Peptococcus niger, and Peptostreptococcus species.

Appropriate culture and susceptibility studies should be performed to determine the susceptibility of the causative organisms to cefoxitin. Therapy may be started while awaiting the results of these studies.

In randomized comparative studies, cefoxitin and cephalothin were comparably safe and effective in the management of infections caused by Gram-positive cocci and Gram-negative rods susceptible to the cephalosporins. Cefoxitin has a high degree of stability in the presence of bacterial beta-lactamases, both penicillinases and cephalosporinases.

Many infections caused by aerobic and anaerobic Gram-negative bacteria resistant to some cephalosporins respond to cefoxitin. Similarly, many infections caused by aerobic and anaerobic bacteria resistant to some penicillin antibiotics (ampicillin, carbenicillin, penicillin G) respond to treatment with cefoxitin. Many infections caused by mixtures of susceptible aerobic and anaerobic bacteria respond to treatment with cefoxitin.

Prevention

Cefoxitin is indicated for the prophylaxis of infection in patients undergoing uncontaminated gastrointestinal surgery, vaginal hysterectomy, abdominal hysterectomy, or cesarean section.

If there are signs of infection, specimens for culture should be obtained for identification of the causative organism so that appropriate treatment may be instituted.

General

Prescribing Cefoxitin for Injection and Dextrose Injection in the absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.

The total daily dose should be reduced when Cefoxitin for Injection and Dextrose Injection is administered to patients with transient or persistent reduction of urinary output due to renal insufficiency (see DOSAGE AND ADMINISTRATION), because high and prolonged serum antibiotic concentrations can occur in such individuals from usual doses.

Antibiotics (including cephalosporins) should be prescribed with caution in individuals with a history of gastrointestinal disease, particularly colitis.

As with other antibiotics, prolonged use of cefoxitin may result in overgrowth of nonsusceptible organisms. Repeated evaluation of the patient's condition is essential. If superinfection occurs during therapy, appropriate measures should be taken.

As with other dextrose-containing solutions, Cefoxitin for Injection and Dextrose Injection should be prescribed with caution in patients with overt or known subclinical diabetes mellitus or carbohydrate intolerance for any reason.

If administration is controlled by a pumping device, care must be taken to discontinue pumping action before the container runs dry or air embolism may result.

Use only if solution is clear and container and seals are intact.

Information for Patients

Diarrhea is a common problem caused by antibiotics which usually ends when the antibiotic is discontinued. Sometimes after starting treatment with antibiotics, patients can develop watery and bloody stools (with or without stomach cramps and fever) even as late as two or more months after having taken the last dose of the antibiotic. If this occurs, patients should contact their physician as soon as possible.

Patients should be counseled that antibacterial drugs including Cefoxitin for Injection and Dextrose Injection should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold). When Cefoxitin for Injection and Dextrose Injection is prescribed to treat a bacterial infection, patients should be told that although it is common to feel better early in the course of therapy, the medication should be taken exactly as directed. Skipping doses or not completing the full course of therapy may (1) decrease the effectiveness of the immediate treatment and (2) increase the likelihood that bacteria will develop resistance and will not be treatable by Cefoxitin for Injection and Dextrose Injection or other antibacterial drugs in the future.

Laboratory Tests

As with any potent antibacterial agent, periodic assessment of organ system functions, including renal, hepatic, and hematopoietic, is advisable during prolonged therapy.

Drug Interactions

Increased nephrotoxicity has been reported following concomitant administration of cephalosporins and aminoglycoside antibiotics.

Drug/Laboratory Test Interactions

As with cephalothin, high concentrations of cefoxitin (>100 mcg/mL) may interfere with measurement of serum and urine creatinine levels by Jaffé reaction, and produce false increases of modest degree in the levels of creatinine reported. Serum samples from patients treated with cefoxitin should not be analyzed for creatinine if withdrawn within 2 hours of drug administration.

High concentrations of cefoxitin in the urine may interfere with measurement of urinary 17-hydroxy-corticosteroids by the Porter-Silber reaction, and produce false increases of modest degree in the levels reported.

A false-positive reaction for glucose in the urine may occur. This has been observed with CLINITEST® reagent tablets.

Carcinogenesis, Mutagenesis, Impairment of Fertility

Long term studies in animals have not been performed with cefoxitin to evaluate carcinogenic or mutagenic potential. Studies in rats treated intravenously with 400 mg/kg of cefoxitin (approximately three times the maximum recommended human dose) revealed no effects on fertility or mating ability.

Pregnancy

Nursing Mothers

Cefoxitin is excreted in human milk in low concentrations. Caution should be exercised when cefoxitin is administered to a nursing woman.

Pediatric Use

Safety and efficacy in pediatric patients from birth to three months of age have not yet been established. In pediatric patients three months of age and older, higher doses of cefoxitin have been associated with an increased incidence of eosinophilia and elevated SGOT.

Geriatric Use

Of the 1,775 subjects who received cefoxitin in clinical studies, 424 (24%) were 65 and over, while 124 (7%) were 75 and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out (see CLINICAL PHARMACOLOGY).

This drug is known to be substantially excreted by the kidney, and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function (see DOSAGE AND ADMINISTRATION and PRECAUTIONS).

Local Reactions

Thrombophlebitis has occurred with intravenous administration.

Allergic Reactions

Rash (including exfoliative dermatitis and toxic epidermal necrolysis), urticaria, flushing, pruritus, eosinophilia, fever, dyspnea, and other allergic reactions including anaphylaxis, interstitial nephritis and angioedema have been noted.

Cardiovascular

Hypotension.

Gastrointestinal

Diarrhea, including documented pseudomembranous colitis which can appear during or after antibiotic treatment. Nausea and vomiting have been reported rarely.

Neuromuscular

Possible exacerbation of myasthenia gravis.

Blood

Eosinophilia, leukopenia including granulocytopenia, neutropenia, anemia, including hemolytic anemia, thrombocytopenia, and bone marrow depression. A positive direct Coombs test may develop in some individuals, especially those with azotemia.

Liver Function

Transient elevation in SGOT, SGPT, serum LDH, and serum alkaline phosphatase; and jaundice have been reported.

Renal Function

Elevations in serum creatinine and/or blood urea nitrogen levels have been observed. As with the cephalosporins, acute renal failure has been reported rarely. The role of cefoxitin in changes in renal function tests is difficult to assess, since factors predisposing to prerenal azotemia or to impaired renal function usually have been present.

In addition to the adverse reactions listed above which have been observed in patients treated with cefoxitin, the following adverse reactions and altered laboratory test results have been reported for cephalosporin class antibiotics:

Urticaria, erythema multiforme, Stevens-Johnson syndrome, serum sickness-like reactions, abdominal pain, colitis, renal dysfunction, toxic nephropathy, false-positive test for urinary glucose, hepatic dysfunction including cholestasis, elevated bilirubin, aplastic anemia, hemorrhage, prolonged prothrombin time, pancytopenia, agranulocytosis, superinfection, vaginitis including vaginal candidiasis.

Several cephalosporins have been implicated in triggering seizures, particularly in patients with renal impairment when the dosage was not reduced. (See DOSAGE AND ADMINISTRATION.) If seizures associated with drug therapy occur, the drug should be discontinued. Anticonvulsant therapy can be given if clinically indicated.

TREATMENT

PREVENTION

Effective prophylactic use depends on the time of administration. Cefoxitin for Injection and Dextrose Injection usually should be given one-half to one hour before the operation, which is sufficient time to achieve effective levels in the wound during the procedure. Prophylactic administration should usually be stopped within 24 hours since continuing administration of any antibiotic increases the possibility of adverse reactions but, in the majority of surgical procedures, does not reduce the incidence of subsequent infection.

For prophylactic use in uncontaminated gastrointestinal surgery, vaginal hysterectomy, or abdominal hysterectomy, the following doses are recommended:

ADMINISTRATION

The intravenous route is preferable for patients with bacteremia, bacterial septicemia, or other severe or life-threatening infections, or for patients who may be poor risks because of lowered resistance resulting from such debilitating conditions as malnutrition, trauma, surgery, diabetes, heart failure, or malignancy, particularly if shock is present or impending.

Cefoxitin for Injection and Dextrose Injection may be administered through the tubing system by which the patient may be receiving other intravenous solutions. However, during infusion of the solution containing Cefoxitin for Injection and Dextrose Injection, it is advisable to temporarily discontinue administration of any other solutions at the same site.

Solutions of Cefoxitin for Injection and Dextrose Injection, like those of most beta-lactam antibiotics, should not be added to aminoglycoside solutions (e.g., gentamicin sulfate, tobramycin sulfate, amikacin sulfate) because of potential interaction. However, Cefoxitin for Injection and Dextrose Injection and aminoglycosides may be administered separately to the same patient.

CAUTION: Do not use plastic containers in series connections. Such use would result in air embolism due to residual air being drawn from the primary container before administration of the fluid from the secondary container is complete.

NOTE: Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration.

DUPLEX® Drug Delivery System Directions for Use

• To avoid inadvertent activation, DUPLEX® Container should remain in the folded position until activation is intended.

Patient Labeling and Drug Powder/Diluent Inspection

• Apply patient-specific label on foil side of container. USE CARE to avoid activation. Do not cover any portion of foil strip with patient label.
• Unlatch side tab and unfold Duplex® Container. (See Diagram 1.)
  
  
• Visually inspect diluent chamber for particulate matter.
• Use only if container and seals are intact.
• To inspect the drug powder for foreign matter or discoloration, peel foil strip from drug chamber. (See Diagram 2.)
  
  
• Protect from light after removal of foil strip.

Note: If foil strip is removed, product must be used within 7 days, but not beyond the labeled expiration date.

• The product should be re-folded and the side tab latched until ready to activate.

Reconstitution (Activation)

• Do not use directly after storage by refrigeration, allow the product to equilibrate to room temperature before patient use.
• Unfold the DUPLEX® Container and point the set port in a downward direction. Starting at the hanger tab end, fold the DUPLEX® Container just below the diluent meniscus trapping all air above the fold. To activate, squeeze the folded diluent chamber until the seal between the diluent and powder opens, releasing diluent into the drug powder chamber. (See Diagram 3.)
  
  
• Agitate the liquid-powder mixture until the drug powder is completely dissolved.

Note: Following reconstitution (activation), product must be used within 12 hours if stored at room temperature or within 7 days if stored under refrigeration.

Administration

• Visually inspect the reconstituted solution for particulate matter.
• Point the set port in a downwards direction. Starting at the hanger tab end, fold the DUPLEX® Container just below the solution meniscus trapping all air above the fold. Squeeze the folded DUPLEX® Container until the seal between reconstituted drug solution and set port opens, releasing liquid to set port. (See Diagram 4.)
  
  
• Prior to attaching the IV set, check for minute leaks by squeezing container firmly. If leaks are found, discard container and solution as sterility may be impaired.
• Using aseptic technique, peel foil cover from the set port and attach sterile administration set. (See Diagram 5.)
   
  
• Refer to Directions for Use accompanying the administration set.

Precautions

• As with other cephalosporins, reconstituted Cefoxitin for Injection and Dextrose Injection tends to darken depending on storage conditions, within the stated recommendations. However, product potency is not adversely affected.
• Use only if prepared solution is clear and free from particulate matter.
• Do not use in series connection.
• Do not introduce additives into the DUPLEX® Container.
• Do not freeze.

Store the unactivated unit at 20–25°C (68–77°F). Excursions permitted to 15–30°C (59–86°F). [See USP Controlled Room Temperature.]