Cefoxitin sodium is a semi-synthetic, broad-spectrum cepha antibiotic for intravenous administration. It is derived from cephamycin C, which is produced by Streptomyces lactamdurans. Its chemical name is sodium (6 R ,7 S )-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 empirical formula is C 16 H 16 N 3 NaO 7 S 2 , and the molecular weight is 449.44. The structural formula is:
Cefoxitin sodium contains approximately 53.8 mg (2.3 milliequivalents) of sodium per gram of cefoxitin activity.
Premixed Intravenous Solution MEFOXIN* (Cefoxitin Sodium Injection) is supplied as a sterile, nonpyrogenic, frozen, iso-osmotic solution of cefoxitin sodium. Each 50 mL contains cefoxitin sodium equivalent to either 1 gram or 2 grams cefoxitin. Dextrose hydrous USP has been added to the above dosages to adjust osmolality (approximately 2 grams and 1.1 grams to 1 gram and 2 gram dosages, respectively). The pH is adjusted with sodium bicarbonate and may have been adjusted with hydrochloric acid. The pH is approximately 6.5. After thawing, the solution is intended for intravenous use only. Solutions of MEFOXIN range from colorless to light amber.
The plastic container is fabricated from a specially designed multilayer plastic (PL 2040). Solutions are in contact with the polyethylene layer of this container and can leach out certain chemical components of the plastic in very small amounts within the expiration period. The suitability and safety of the plastic have been confirmed in tests in animals according to the USP biological tests for plastic containers, as well as by tissue culture toxicity studies.
*Registered trademark of MERCK & CO., INC.
Following an intravenous dose of 1 gram of cefoxitin, 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.
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 7(alpha) position provides MEFOXIN with a high degree of stability in the presence of beta-lactamases, both penicillinases and cephalosporinases, of gram-negative bacteria. While in vitro studies have demonstrated the susceptibility of most strains of the following organisms, clinical efficacy for infections other than those included in the section is unknown.
Staphylococcus aureus, including penicillinase and non-penicillinase producing strains
Beta-hemolytic and other streptococci (most strains of enterococci, e.g., Enterococcus faecalis [formerly Streptococcus faecalis ], are resistant)
Eikenella corrodens (beta-lactamase negative strains)
Klebsiella species (including K. pneumoniae )
Neisseria gonorrhoeae, including penicillinase and non-penicillinase producing strains
Providencia species, including Providencia rettgeri
Bacteroides species, including the B. fragilis group (includes B. fragilis, B. distasonis, B. ovatus, B. thetaiotaomicron )
MEFOXIN is inactive in vitro against most strains of Pseudomonas aeruginosa and enterococci and many strains of Enterobacter cloacae.
Methicillin-resistant staphylococci are almost uniformly resistant to MEFOXIN.
For fast-growing aerobic organisms, quantitative methods that require measurements of zone diameters give the most precise estimates of antibiotic susceptibility. One such procedure** has been recommended for use with discs to test susceptibility to cefoxitin. Interpretation involves correlation of the diameters obtained in the disc test with minimal inhibitory concentration (MIC) values for cefoxitin.
Reports from the laboratory giving results of the standardized single disc susceptibility test** using a 30 mcg cefoxitin disc should be interpreted according to the following criteria:
Organisms producing zones of 18 mm or greater are considered susceptible, indicating that the tested organism is likely to respond to therapy.
Organisms of intermediate susceptibility produce zones of 15 to 17 mm, indicating that the tested organism would be susceptible if high dosage is used or if the infection is confined to tissues and fluids (e.g., urine) in which high antibiotic levels are attained.
Resistant organisms produce zones of 14 mm or less, indicating that other therapy should be selected.
The cefoxitin disc should be used for testing cefoxitin susceptibility.
Cefoxitin has been shown by in vitro tests to have activity against certain strains of Enterobacteriaceae found resistant when tested with the cephalosporin class disc. For this reason, the cefoxitin disc should not be used for testing susceptibility to cephalosporins, and cephalosporin discs should not be used for testing susceptibility to cefoxitin.
Dilution methods, preferably the agar plate dilution procedure, are most accurate for susceptibility testing of obligate anaerobes.
A bacterial isolate may be considered susceptible if the MIC value for cefoxitin*** is not more than 16 mcg/mL. Organisms are considered resistant if the MIC is greater than 32 mcg/mL.
**Bauer, A. W.; Kirby, W. M. M.; Sherris, J. C.; Turck, M.: Antibiotic susceptibility testing by a standardized single disc method, Amer. J. Clin. Path. 45 : 493-496, Apr. 1966. Standardized disc susceptibility test, Federal Register 37 : 20527-20529, 1972. National Committee for Clinical Laboratory Standards: Performance Standards for Antimicrobial Disc Susceptibility Tests--Fifth Edition; Approved Standard, NCCLS Document M2-A5, Vol 13, No. 24, NCCLS, Villanova, PA, December 1993.
***Determined by the ICS agar dilution method (Ericsson and Sherris, Acta Path. Microbiol. Scand. [B] Suppl. No. 217, 1971) or any other method that has been shown to give equivalent results.
MEFOXIN, supplied as a premixed solution in plastic containers, is intended for intravenous use only.
MEFOXIN is indicated for the treatment of serious infections caused by susceptible strains of the designated microorganisms in the diseases listed below.
Appropriate culture and susceptibility studies should be performed to determine the susceptibility of the causative organisms to MEFOXIN. 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. MEFOXIN 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 MEFOXIN. Similarly, many infections caused by aerobic and anaerobic bacteria resistant to some penicillin antibiotics (ampicillin, carbenicillin, penicillin G) respond to treatment with MEFOXIN. Many infections caused by mixtures of susceptible aerobic and anaerobic bacteria respond to treatment with MEFOXIN.
MEFOXIN 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.
**** B. fragilis, B. distasonis, B. ovatus, B. thetaiotaomicron.
MEFOXIN is contraindicated in patients who have shown hypersensitivity to cefoxitin and the cephalosporin group of antibiotics.
BEFORE THERAPY WITH `MEFOXIN' IS INSTITUTED, CAREFUL INQUIRY SHOULD BE MADE TO DETERMINE WHETHER THE PATIENT HAS HAD PREVIOUS HYPERSENSITIVITY REACTIONS TO CEFOXITIN, CEPHALOSPORINS, PENICILLINS, OR OTHER DRUGS. THIS PRODUCT SHOULD BE GIVEN WITH CAUTION TO PENICILLIN-SENSITIVE PATIENTS. ANTIBIOTICS SHOULD BE ADMINISTERED WITH CAUTION TO ANY PATIENT WHO HAS DEMONSTRATED SOME FORM OF ALLERGY, PARTICULARLY TO DRUGS. IF AN ALLERGIC REACTION TO `MEFOXIN' OCCURS, DISCONTINUE THE DRUG. SERIOUS HYPERSENSITIVITY REACTIONS MAY REQUIRE EPINEPHRINE AND OTHER EMERGENCY MEASURES.
Treatment with antibacterial agents alters the normal flora of the colon and may permit overgrowth of clostridia. Studies indicate that a toxin produced by Clostridium difficile is one primary cause of "antibiotic-associated colitis."
After the diagnosis of pseudomembranous colitis has been established, appropriate therapeutic measures should be initiated. Mild cases of pseudomembranous colitis usually respond to drug discontinuation alone. In moderate to severe cases, consideration should be given to management with fluids and electrolytes, protein supplementation, and treatment with an antibacterial drug clinically effective against Clostridium difficile colitis
The total daily dose should be reduced when MEFOXIN is administered to patients with transient or persistent reduction of urinary output due to renal insufficiency (see DOSAGE AND ADMINISTRATION , TREATMENT ), 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 MEFOXIN may result in overgrowth of nonsusceptible organisms. Repeated evaluation of the patient' condition is essential. If superinfection occurs during therapy, appropriate measures should be taken.
Do not use unless solution is clear and seal is intact.
As with any potent antibacterial agent, periodic assessment of organ system functions, including renal, hepatic, and hematopoietic, is advisable during prolonged therapy.
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 micrograms/mL) may interfere with measurement of serum and urine creatinine levels by the 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.
** Registered trademark of Ames Company, Division of Miles Laboratories, Inc.
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 Category B. Reproduction studies performed in rats and mice at parenteral doses of approximately one to seven and one-half times the maximum recommended human dose did not reveal teratogenic or fetal toxic effects, although a slight decrease in fetal weight was observed.
There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.
In the rabbit, cefoxitin was associated with a high incidence of abortion and maternal death. This was not considered to be a teratogenic effect but an expected consequence of the rabbit's unusual sensitivity to antibiotic-induced changes in the population of the microflora of the intestine.
Cefoxitin is excreted in human milk in low concentrations. Caution should be exercised when MEFOXIN is administered to a nursing woman.
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.
The potential for toxic effects in pediatric patients from chemicals that may leach from the single-dose I.V. preparation in plastic has not been determined.
Cefoxitin is generally well tolerated. The most common adverse reactions have been local reactions following intravenous injection. Other adverse reactions have been encountered infrequently.
Thrombophlebitis has occurred with intravenous administration.
Rash (including exfoliative dermatitis and toxic epidermal necrolysis), pruritus, eosinophilia, fever, dyspnea, and other allergic reactions including anaphylaxis, interstitial nephritis and angioedema have been noted.
Diarrhea, including documented pseudomembranous colitis which can appear during or after antibiotic treatment. Nausea and vomiting have been reported rarely.
Possible exacerbation of myasthenia gravis.
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.
Transient elevations in SGOT, SGPT, serum LDH, and serum alkaline phosphatase; and jaundice have been reported.
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 MEFOXIN 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 MEFOXIN, 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.
The acute intravenous LD 50 in the adult female mouse and rabbit was about 8.0 g/kg and greater than 1.0 g/kg respectively. The acute intraperitoneal LD 50 in the adult rat was greater than 10.0 g/kg.
NOTE: MEFOXIN® in Galaxy *** container is for intravenous infusion only.
The usual adult dosage range is 1 gram to 2 grams every six to eight hours. Dosage should be determined by susceptibility of the causative organisms, severity of infection, and the condition of the patient (see Table 1 for dosage guidelines).
If C. trachomatis is a suspected pathogen, appropriate anti-chlamydial coverage should be added, because cefoxitin sodium has no activity against this organism.
MEFOXIN may be used in patients with reduced renal function with the following dosage adjustments:
In adults with renal insufficiency, an initial loading dose of 1 gram to 2 grams may be given. After a loading dose, the recommendations for maintenance dosage (Table 2) may be used as a guide.
When only the serum creatinine level is available, the following formula (based on sex, weight, and age of the patient) may be used to convert this value into creatinine clearance. The serum creatinine should represent a steady state of renal function.
In patients undergoing hemodialysis, the loading dose of 1 to 2 grams should be given after each hemodialysis, and the maintenance dose should be given as indicated in Table 2.
Antibiotic therapy for group A beta-hemolytic streptococcal infections should be maintained for at least 10 days to guard against the risk of rheumatic fever or glomerulonephritis. In staphylococcal and other infections involving a collection of pus, surgical drainage should be carried out where indicated.
The recommended dosage in pediatric patients three months of age and older is 80 to 160 mg/kg of body weight per day divided into four to six equal doses. The higher dosages should be used for more severe or serious infections. The total daily dosage should not exceed 12 grams.
At this time no recommendation is made for pediatric patients from birth to three months of age (see PRECAUTIONS ).
In pediatric patients with renal insufficiency, the dosage and frequency of dosage should be modified consistent with the recommendations for adults (see Table 2).
Effective prophylatic use depends on the time of administration. MEFOXIN 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:
2 grams administered intravenously just prior to surgery (approximately one-half to one hour before the initial incision) followed by 2 grams every 6 hours after the first dose for no more than 24 hours.
Pediatric Patients (3 months and older):
30 to 40 mg/kg doses may be given at the times designated above.
Cesarean section patients:
For patients undergoing cesarean section, either a single 2 gram dose administered intravenously as soon as the umbilical cord is clamped OR a 3-dose regimen consisting of 2 grams given intravenously as soon as the umbilical cord is clamped followed by 2 grams 4 and 8 hours after the initial dose is recommended. (See CLINICAL STUDIES .)
This premixed solution is for intravenous use only. Premixed Intravenous Solution MEFOXIN in Galaxy® containers (PL 2040 Plastic) is to be administered either as a continuous or intermittent infusion using sterile equipment. Scalp vein-type needles are preferred for this type of infusion. It is recommended that the intravenous administration apparatus be replaced at least once every 48 hours.
The intravenous route is preferred 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.
Thaw frozen container at room temperature, 25°C (77°F), or under refrigeration, 2-8°C (36-46°F). DO NOT FORCE THAW BY IMMERSION IN WATER BATHS OR BY MICROWAVE IRRADIATION.
After thawing, check for minute leaks by squeezing container firmly. If leaks are detected, discard solution as sterility may be impaired.
The container should be visually inspected for particulate matter and discoloration prior to administration. Components of the solution may precipitate in the frozen state and will dissolve upon reaching room temperature with little or no agitation. Agitate after solution has reached room temperature.
Do not use if the solution is cloudy or a precipitate has formed. If any seals or outlet ports are not intact, the container should be discarded. Solutions of MEFOXIN tend to darken depending on storage conditions; product potency, however, is not adversely affected.
Additives should not be introduced into this solution.
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.
MEFOXIN may be administered through the tubing system by which the patient may be receiving other intravenous solutions. However, during infusion of the solution containing MEFOXIN, it is advisable to temporarily discontinue administration of any other solutions at the same site.
Solutions of MEFOXIN, 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, MEFOXIN and aminoglycosides may be administered separately to the same patient.
MEFOXIN, supplied as frozen, premixed, iso-osmotic solution in Galaxy® containers (PL 2040 Plastic), maintains satisfactory potency after thawing for 24 hours at a room temperature of 25°C (77°F) or 21 days under refrigeration, 2-8°C (36-46°F). After these periods, any unused solutions should be discarded.
DO NOT REFREEZE.
*** Galaxy® is a registered trademark of Baxter International Inc.
Premixed Intravenous Solution MEFOXIN is supplied in single dose Galaxy® containers (PL 2040 Plastic) containing cefoxitin sodium as follows:
No. 2G3506--1 gram cefoxitin equivalent, iso-osmotic in 50 mL diluent containing approximately 2 grams dextrose hydrous USP
NDC 0006-3545-24 in boxes of 24
(6505-01-380-3410, 1 g 24's).
No. 2G3507--2 gram cefoxitin equivalent, iso-osmotic in 50 mL diluent containing approximately 1.1 grams dextrose hydrous USP
NDC 0006-3547-25 in boxes of 24
(6505-01-379-9245, 2 g 24's).
Special storage instructions
Store at or below -20°C (-4°F). [See Directions for Use of Galaxy® container (PL 2040 Plastic)].
MEFOXIN is also available in dry powder form in vials and infusion bottles containing sterile cefoxitin sodium equivalent to either 1 gram or 2 grams of cefoxitin, and in vials for pharmacy bulk use containing sterile cefoxitin sodium equivalent to 10 grams of cefoxitin, for constitution and intravenous administration (see appropriate product circular).
A prospective, randomized, double-blind, placebo-controlled clinical trial was conducted to determine the efficacy of short-term prophylaxis with MEFOXIN in patients undergoing cesarean section who were at high risk for subsequent endometritis because of ruptured membranes. Patients were randomized to receive either three doses of placebo (n=58), a single dose of MEFOXIN (2 g) followed by two doses of placebo (n=64), or a three-dose regimen of MEFOXIN (each dose consisting of 2 g) (n=60), given intravenously, usually beginning at the time of clamping of the umbilical cord, with the second and third doses given 4 and 8 hours post-operatively. Endometritis occurred in 16/58 (27.6%) patients given placebo, 5/63 (7.9%) patients given a single dose of MEFOXIN, and 3/58 (5.2%) patients given three doses of MEFOXIN. The differences between the two groups treated with MEFOXIN and placebo with respect to endometritis were statistically significant (p<0.01) in favor of MEFOXIN. The differences between the one-dose and three-dose regimens of MEFOXIN were not statistically significant.
Two double-blind, randomized studies compared the efficacy of a single 2 gram intravenous dose of MEFOXIN to a single 2 gram dose of cefotetan in the prevention of surgical site-related infection (major morbidity) and non-site-related infections (minor morbidity) in patients following cesarean section. In the first study, 82/98 (83.7%) patients treated with MEFOXIN and 71/95 (74.7%) patients treated with cefotetan experienced no major or minor morbidity. The difference in the outcomes in this study (95% CI: -0.03, +0.21) was not statistically significant. In the second study, 65/75 (86.7%) patients treated with MEFOXIN and 62/76 (81.6%) patients treated with cefotetan experienced no major or minor morbidity. The difference in the outcomes in this study (95% CI: -0.08, +0.18) was not statistically significant.
In clinical trials of patients with intra-abdominal infections due to Bacteroides fragilis group microorganisms, eradication rates at 1 to 2 weeks posttreatment for isolates were in the range of 70% to 80%. Eradication rates for individual species are listed below:
Bacteroides distasonis 7/10 (70%)
Bacteroides fragilis 26/33 (79%)
Bacteroides ovatus 10/13 (77%)
B. thetaiotaomicron 13/18 (72%)
MERCK & CO., INC., WEST POINT, PA 19486, USA
BAXTER HEALTHCARE CORPORATION
Deerfield, Illinois 60015, USA
7948521 Issued October 1996
COPYRIGHT © MERCK & CO., INC., 1985, 1996
All rights reserved