ADVERSE REACTIONS SECTION.

ADVERSE REACTIONS. The following reactions have been reported:. Gastrointestinal. Diarrhea, oral candidiasis (oral thrush), vomiting, nausea, stomach cramps, anorexia, and pseudomembranous colitis. Onset of pseudomembranous colitis symptoms may occur during or after antibiotic treatment (see WARNINGS). Nausea and vomiting have been reported rarely.. Allergic. Anaphylaxis, eosinophilia, itching, drug fever, skin rash, Stevens-Johnson syndrome.. Hematologic. Neutropenia, leukopenia, thrombocytopenia, thrombocythemia.. Hepatic. Transient rise in SGOT, SGPT, and alkaline phosphatase levels has been observed. As with other cephalosporins, reports of hepatitis have been received.. Renal. As with other cephalosporins, reports of increased BUN and creatinine levels, as well as renal failure, have been received.. Local Reactions. Rare instances of phlebitis have been reported at site of injection. Some induration has occurred.. Other Reactions. Genital and anal pruritus (including vulvar pruritus, genital moniliasis, and vaginitis).To report SUSPECTED ADVERSE EVENTS, contact Baxter Healthcare Corporation at 1-866-888-2472 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

CLINICAL PHARMACOLOGY SECTION.

CLINICAL PHARMACOLOGY. Studies have shown that following intravenous administration of cefazolin to normal volunteers, mean serum concentrations peaked at approximately 185 mcg/mL and were approximately mcg/mL at hours for 1-gram dose.The serum half-life for cefazolin is approximately 1.8 hours following intravenous administration.In study (using normal volunteers) of constant intravenous infusion with dosages of 3.5 mg/kg for hour (approximately 250 mg) and 1.5 mg/kg the next hours (approximately 100 mg), cefazolin produced steady serum level at the third hour of approximately 28 mcg/mL.Studies in patients hospitalized with infections indicate that cefazolin produces mean peak serum levels approximately equivalent to those seen in normal volunteers.Bile levels in patients without obstructive biliary disease can reach or exceed serum levels by up to times; however, in patients with obstructive biliary disease, bile levels of cefazolin are considerably lower than serum levels (<1.0 mcg/mL).In synovial fluid, the level of cefazolin becomes comparable to that reached in serum at about 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 hours approximately 60% of the drug is excreted in the urine and this increases to 70% to 80% within 24 hours.In patients undergoing peritoneal dialysis (2 L/hr.), cefazolin produced mean serum levels of approximately 10 and 30 mcg/mL after 24 hours instillation of dialyzing solution containing 50 mg/L and 150 mg/L, respectively. Mean peak levels were 29 mcg/mL (range 13 to 44 mcg/mL) with 50 mg/L (3 patients), and 72 mcg/mL (range 26 to 142 mcg/mL) with 150 mg/L (6 patients). Intraperitoneal administration of cefazolin is usually well tolerated.Controlled studies on adult normal volunteers, receiving gram times day for 10 days, monitoring CBC, SGOT, SGPT, bilirubin, alkaline phosphatase, BUN, creatinine, and urinalysis, indicated no clinically significant changes attributed to cefazolin.. Microbiology. Mechanism of Action. Cefazolin is bactericidal agent that acts by inhibition of bacterial cell wall synthesis.. Resistance. Predominant mechanisms of bacterial resistance to cephalosporins include the presence of extended-spectrum beta-lactamases and enzymatic hydrolysis.. Antimicrobial Activity. Cefazolin has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections as described in INDICATIONS AND USAGE. Gram-Positive BacteriaStaphylococcus aureus Staphylococcus epidermidisStreptococcus agalactiaeStreptococcus pneumoniaeStreptococcus pyogenesMethicillin-resistant staphylococci are uniformly resistant to cefazolin.Gram-Negative BacteriaEscherichia coliProteus mirabilisMost isolates of indole positive Proteus (Proteus vulgaris), Enterobacter spp., Morganella morganii, Providencia rettgeri, Serratia spp., and Pseudomonas spp. are resistant to cefazolin.. Susceptibility Test Methods. For specific information regarding susceptibility test interpretive criteria and associated text methods and quality control standards recognized by FDA for this drug, please see: http://www.fda.gov/STIC.

DESCRIPTION SECTION.

DESCRIPTION. Cefazolin Injection, USP is semi-synthetic cephalosporin for parenteral administration. It is the sodium salt of (6R,7R)-3-[[(5-methyl-1,3,4-thiadiazol-2-yl)thio]methyl]-8-oxo-7-[2-(1H-tetrazol-1-yl)acetamido]-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid.Structural Formula:The sodium content is 46 mg per gram of cefazolin.Dextrose Hydrous, USP structural (molecular) formula:The molecular weight of Dextrose Hydrous, USP is 198.17.The chemical name is D-Glucose, Monohydrate.Cefazolin Injection, USP is frozen, premixed, iso-osmotic, sterile, nonpyrogenic 50 mL solution containing cefazolin sodium equivalent to g of Cefazolin, USP. Dextrose, USP has been added to adjust osmolality (2 as dextrose hydrous).The pH of Cefazolin Injection, USP has been adjusted with sodium bicarbonate. The solution is intended for intravenous use after thawing to room temperature.This GALAXY container (PL 2040 Plastic) is fabricated from 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. However, the suitability of the plastic has been confirmed in tests in animals according to the USP biological tests for plastic containers, as well as by tissue culture toxicity studies.. Image of Structural Formula for Cefazolin Injection, USP. Dextrose Hydrous, USP structural (molecular) formula.

DOSAGE & ADMINISTRATION SECTION.

DOSAGE AND ADMINISTRATION. Note: Cefazolin Injection, USP in GALAXY Container (PL 2040 Plastic) is intended for intravenous infusion.Usual Adult Dosage:Type of InfectionDoseFrequencyModerate to severe infections500 mg to gramevery to hrs. Mild infections caused by susceptible gram-positive cocci250 mg to 500 mgevery hoursAcute, uncomplicated urinary tractinfections1 gramevery 12 hoursPneumococcal pneumonia500 mgevery 12 hoursSevere, life-threatening infections (e.g., endocarditis, septicemia)In rare instances, doses of up to 12 grams of cefazolin per day have been used. gram to 1.5 gramsevery hours. Perioperative Prophylactic Use. To prevent postoperative infection in contaminated or potentially contaminated surgery, recommended doses are:a.1 gram intravenously administered 1/2 hour to hour prior to start of surgery.b.For lengthy operative procedures (e.g., hours or more), 500 mg to gram intravenously administered during surgery (administration modified depending on the duration of the operative procedure).c.500 mg to gram intravenously administered every to hours for 24 hours postoperatively.It is important that (1) the preoperative dose be given just 1/2 to hour) prior to start of surgery so that adequate antibiotic levels are present in the serum and tissues at the time of initial surgical incision; and (2) cefazolin be administered, if necessary, at appropriate intervals during surgery to provide sufficient levels of the antibiotic at the anticipated moments of greatest exposure to infective organisms.In surgery where the occurrence of infection may be particularly devastating (e.g., open-heart surgery and prosthetic arthroplasty), the prophylactic administration of cefazolin may be continued for to days following the completion of surgery.. a.1 gram intravenously administered 1/2 hour to hour prior to start of surgery.. b.For lengthy operative procedures (e.g., hours or more), 500 mg to gram intravenously administered during surgery (administration modified depending on the duration of the operative procedure).. c.500 mg to gram intravenously administered every to hours for 24 hours postoperatively.. Dosage Adjustment for Patients With Reduced Renal Function. Cefazolin may be used in patients with reduced renal function with the following dosage adjustments: Patients with creatinine clearance of 55 mL/min. or greater or serum creatinine of 1.5 mg or less can be given full doses. Patients with creatinine clearance rates of 35 to 54 mL/min. or serum creatinine of 1.6 to 3.0 mg can also be given full doses but dosage should be restricted to at least hour intervals. Patients with creatinine clearance rates of 11 to 34 mL/min. or serum creatinine of 3.1 to 4.5 mg should be given 1/2 the usual dose every 12 hours. Patients with creatinine clearance rates of 10 mL/min. or less or serum creatinine of 4.6 mg or greater should be given 1/2 the usual dose every 18 to 24 hours. All reduced dosage recommendations apply after an initial loading dose appropriate to the severity of the infection. Patients undergoing peritoneal dialysis: See CLINICAL PHARMACOLOGY.. Pediatric Dosage In pediatric patients, total daily dosage of 25 to 50 mg per kg (approximately 10 to 20 mg per pound) of body weight, divided into or equal doses, is effective for most mild to moderately severe infections. Total daily dosage may be increased to 100 mg per kg (45 mg per pound) of body weight for severe infections. Since safety for use in premature infants and in neonates has not been established, the use of cefazolin in these patients is not recommended.Pediatric Dosage GuideWeight25 mg/kg/dayDivided into Doses25 mg/kg/dayDivided into DosesLbsKgApproximate Single Dose mg/q8hVol. (mL) needed with dilution of 125 mg/mLApproximate Single Dose mg/q6hVol. (mL) needed with dilution of 125 mg/mL104.540 mg0.35 mL30 mg0.25 mL209.075 mg0.60 mL55 mg0.45 mL3013.6115 mg0.90 mL85 mg0.70 mL4018.1150 mg1.20 mL115 mg0.90 mL5022.7190 mg1.50 mL140 mg1.10 mLWeight50 mg/kg/dayDivided into Doses50 mg/kg/dayDivided into DosesLbsKgApproximateSingle Dosemg/q8hVol. (mL) needed with dilution of 225 mg/mLApproximate Single Dose mg/q6hVol. (mL) needed with dilution of 225 mg/mL104.575 mg0.35 mL55 mg0.25 mL209.0150 mg0.70 mL110 mg0.50 mL3013.6225 mg1.00 mL170 mg0.75 mL4018.1300 mg1.35 mL225 mg1.00 mL5022.7375 mg1.70 mL285 mg1.25 mLIn pediatric patients with mild to moderate renal impairment (creatinine clearance of 70 to 40 mL/min.), 60 percent of the normal daily dose given in equally divided doses every 12 hours should be sufficient. In patients with moderate impairment (creatinine clearance of 40 to 20 mL/min.), 25 percent of the normal daily dose given in equally divided doses every 12 hours should be adequate. Pediatric patients with severe renal impairment (creatinine clearance of 20 to mL/min.) may be given 10 percent of the normal daily dose every 24 hours. All dosage recommendations apply after an initial loading dose.

GENERAL PRECAUTIONS SECTION.

General. Prolonged use of cefazolin may result in the overgrowth of nonsusceptible organisms. Careful clinical observation of the patient is essential.When cefazolin is administered to patients with low urinary output because of impaired renal function, lower daily dosage is required (see DOSAGE AND ADMINISTRATION).As with other beta-lactam antibiotics, seizures may occur if inappropriately high doses are administered to patients with impaired renal function (see DOSAGE AND ADMINISTRATION).Cefazolin, as with all cephalosporins, should be prescribed with caution in individuals with history of gastrointestinal disease, particularly colitis.Cephalosporins may be associated with fall in prothrombin activity. Those at risk include patients with renal or hepatic impairment or poor nutritional state, as well as patients receiving protracted course of antimicrobial therapy, and patients previously stabilized on anticoagulant therapy. Prothrombin time should be monitored in patients at risk and exogenous vitamin administered as indicated.As with other dextrose-containing solutions, Cefazolin Injection, USP should be prescribed with caution in patients with overt or known subclinical diabetes mellitus or carbohydrate intolerance for any reason.Prescribing cefazolin in the absence of proven or strongly suspected bacterial infection or prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.

INDICATIONS & USAGE SECTION.

INDICATIONS AND USAGE. Cefazolin Injection, USP is indicated in the treatment of the following infections due to susceptible organisms:. Respiratory Tract Infections:. Due to S. pneumoniae, Klebsiella species, H. influenzae, S. aureus (penicillin sensitive and penicillin resistant), and group beta-hemolytic streptococci.Injectable benzathine penicillin is considered to be the drug of choice in treatment and prevention of streptococcal infections, including the prophylaxis of rheumatic fever. Cefazolin is effective in the eradication of streptococci from the nasopharynx; however, data establishing the efficacy of cefazolin in the subsequent prevention of rheumatic fever are not available.. Urinary Tract Infections:. Due to E. coli, P. mirabilis, Klebsiella species, and some strains of enterobacter and enterococci.. Skin and Skin Structure Infections:. Due to S. aureus (penicillin sensitive and penicillin-resistant), group beta-hemolytic streptococci, and other strains of streptococci.. Biliary Tract Infections:. Due to E. coli, various strains of streptococci, P. mirabilis, Klebsiella species, and S. aureus.. Bone and Joint Infections:. Due to S. aureus.. Genital Infections:. (i.e., prostatitis, epididymitis) due to E. coli, P. mirabilis, Klebsiella species, and some strains of enterococci.. Septicemia:. Due to S. pneumoniae, S. aureus (penicillin sensitive and penicillin resistant), P. mirabilis, E. coli, and Klebsiella species.. Endocarditis:. Due to S. aureus (penicillin sensitive and penicillin resistant), and group beta-hemolytic streptococci.. Perioperative Prophylaxis:. The prophylactic administration of cefazolin preoperatively, intraoperatively, and postoperatively may reduce the incidence of certain postoperative infections in patients undergoing surgical procedures which are classified as contaminated or potentially contaminated (e.g., vaginal hysterectomy, and cholecystectomy in high-risk patients such as those older than 70 years, with acute cholecystitis, obstructive jaundice, or common duct bile stones).The perioperative use of cefazolin may also be effective in surgical patients in whom infection at the operative site would present serious risk (e.g., during open-heart surgery and prosthetic arthroplasty).The prophylactic administration of cefazolin should usually be discontinued within 24-hour period after the surgical procedure. In surgery where the occurrence of infection may be particularly devastating (e.g., open-heart surgery and prosthetic arthroplasty), the prophylactic administration of cefazolin may be continued for to days following the completion of surgery.If there are signs of infection, specimens for cultures should be obtained for the identification of the causative organism so that appropriate therapy may be instituted (see DOSAGE AND ADMINISTRATION).To reduce the development of drug-resistant bacteria and maintain the effectiveness of cefazolin and other antibacterial drugs, cefazolin should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

MICROBIOLOGY SECTION.

Microbiology. Mechanism of Action. Cefazolin is bactericidal agent that acts by inhibition of bacterial cell wall synthesis.. Resistance. Predominant mechanisms of bacterial resistance to cephalosporins include the presence of extended-spectrum beta-lactamases and enzymatic hydrolysis.. Antimicrobial Activity. Cefazolin has been shown to be active against most isolates of the following microorganisms, both in vitro and in clinical infections as described in INDICATIONS AND USAGE. Gram-Positive BacteriaStaphylococcus aureus Staphylococcus epidermidisStreptococcus agalactiaeStreptococcus pneumoniaeStreptococcus pyogenesMethicillin-resistant staphylococci are uniformly resistant to cefazolin.Gram-Negative BacteriaEscherichia coliProteus mirabilisMost isolates of indole positive Proteus (Proteus vulgaris), Enterobacter spp., Morganella morganii, Providencia rettgeri, Serratia spp., and Pseudomonas spp. are resistant to cefazolin.. Susceptibility Test Methods. For specific information regarding susceptibility test interpretive criteria and associated text methods and quality control standards recognized by FDA for this drug, please see: http://www.fda.gov/STIC.

PACKAGE LABEL.PRINCIPAL DISPLAY PANEL.

PACKAGE LABEL PRINCIPAL DISPLAY PANEL. Container LabelBaxter logo1 gCefazolin Injection, USPGALAXYSingle Dose Container50 mLIso-osmoticNDC 0338-3503-41Code 2G3503Sterile Nonpyrogenic Each 50 mL contains: Cefazolin Sodium equivalent to g Cefazolin, USPwith approx. g Dextrose Hydrous, USP added to adjust osmolality.pH adjusted with sodium bicarbonate.Usual Dosage: For I.V. use only. See insert.Cautions: Do not add supplementary medication or additives. Must not beused in series connections. Check for minute leaks and solution clarity.See insert.Rx onlyStore at or below -20C/-4F. Thaw at room temperature (25C/77F) or underrefrigeration (5C/41F). DO NOT FORCE THAW BY IMMERSION IN WATERBATHS OR BY MICROWAVE IRRADIATION. Thawed solution is stable for 30days under refrigeration and 48 hours at room temperature. Do not refreeze. Baxter and Galaxy are registered trademarks ofBaxter International Inc.Manufactured by Baxter Healthcare Corporation Deerfield, IL 60015 USAMade in USAPL 2040 Plastic07-34-63-671BAR CODE POSITIONONLY 303383503411Carton Label Carton Label Thaw at room temperature (25C/77F) or under refrigeration (5C/41F). DO NOT FORCETHAW BY IMMERSION IN WATER BATHS OR BY MICROWAVE IRRADIATION. Thawedsolution is stable for 30 days under refrigeration (5C/41F) and 48 hours at room temperature(25C/77F). Do not refreeze. Handle frozen product containers with care. Product containers may be fragile in thefrozen state.Baxter and Galaxy are registered trademarks of Baxter International Inc.PL 2040 Plastic07-04-65-178Baxter logoCefazolin Injection, USP12 50 mL Single Dose Containers Iso-osmoticStore at or below -20C/-4F. Do not refreeze.1 gBaxter Healthcare Corporation Deerfield, IL 60015 USANDC 0338-3503-41Code 2G3503FOR BAR CODE POSITION ONLY(01) 20303383503415GALAXY ContainerSterile NonpyrogenicEach 50 mL contains: Cefazolin Sodium equivalent to g of Cefazolin, USP with approx. gDextrose Hydrous, USP added to adjust osmolality. pH adjusted with sodium bicarbonate.Usual Dosage: For I.V. use only. See insert.Cautions: Do not add supplementary medications or additives. Must not be used in seriesconnections. Check for minute leaks by squeezing thawed bag firmly. If leaks are found,discard bag as sterility may be impaired. Do not use unless solution is clear. Rx only CODE: 2G3503LOT: XXXXXXXXXEXP: DD MMM YYQTY: QQSN: BAR CODE FOR PLACEMENT ONLY(01)X XXXXXXXX XXXXX X(21)XXXXXXXXX(17)XXXXXX(10)XXXXXXXXX. Representative Cefazolin Container Label 0338-3503-41 of 2. Representative Cefazolin Container Label 0338-3503-41 of 2. Representative Cefazolin Carton Label 0338-3503-41 of 2. Representative Cefazolin Carton Label 0338-3503-41 of 2. Cefazolin 1g Representative Serialized Lbl.

PRECAUTIONS SECTION.

PRECAUTIONS. General. Prolonged use of cefazolin may result in the overgrowth of nonsusceptible organisms. Careful clinical observation of the patient is essential.When cefazolin is administered to patients with low urinary output because of impaired renal function, lower daily dosage is required (see DOSAGE AND ADMINISTRATION).As with other beta-lactam antibiotics, seizures may occur if inappropriately high doses are administered to patients with impaired renal function (see DOSAGE AND ADMINISTRATION).Cefazolin, as with all cephalosporins, should be prescribed with caution in individuals with history of gastrointestinal disease, particularly colitis.Cephalosporins may be associated with fall in prothrombin activity. Those at risk include patients with renal or hepatic impairment or poor nutritional state, as well as patients receiving protracted course of antimicrobial therapy, and patients previously stabilized on anticoagulant therapy. Prothrombin time should be monitored in patients at risk and exogenous vitamin administered as indicated.As with other dextrose-containing solutions, Cefazolin Injection, USP should be prescribed with caution in patients with overt or known subclinical diabetes mellitus or carbohydrate intolerance for any reason.Prescribing cefazolin in the absence of proven or strongly suspected bacterial infection or prophylactic indication is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria.. Drug Interactions. Probenecid may decrease renal tubular secretion of cephalosporins when used concurrently, resulting in increased and more prolonged cephalosporin blood levels.. Drug/Laboratory Test Interactions. false positive reaction for glucose in the urine may occur with Benedicts solution, Fehlings solution or with CLINITEST tablets, but not with enzyme-based tests such as CLINISTIX Kit.Positive direct and indirect antiglobulin (Coombs) tests have occurred; these may also occur in neonates whose mothers received cephalosporins before delivery.. Information for Patients. Patients should be counseled that antibacterial drugs including cefazolin should only be used to treat bacterial infections. They do not treat viral infections (e.g., the common cold). When cefazolin is prescribed to treat 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 cefazolin or other antibacterial drugs in the future.. Carcinogenesis/Mutagenesis. Mutagenicity studies and long-term studies in animals to determine the carcinogenic potential of cefazolin have not been performed.. Pregnancy. Teratogenic Effects. Reproduction studies have been performed in rats, mice, and rabbits at doses up to 25 times the human dose and have revealed no evidence of impaired fertility or harm to the fetus due to cefazolin. 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.. Labor and Delivery. When cefazolin has been administered prior to caesarean section, drug levels in cord blood have been approximately one quarter to one third of maternal drug levels. The drug appears to have no adverse effect on the fetus.. Nursing Mothers. Cefazolin is present in very low concentrations in the milk of nursing mothers. Caution should be exercised when cefazolin is administered to nursing woman.. Pediatric Use. Safety and effectiveness for use in premature infants and neonates have not been established. See DOSAGE AND ADMINISTRATION for recommended dosage in pediatric patients older than month.. Geriatric Use. Of the 920 subjects who received cefazolin in clinical studies, 313 (34%) were 65 years and over, while 138 (15%) were 75 years and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects. 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.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 PRECAUTIONS, General and DOSAGE AND ADMINISTRATION).

WARNINGS SECTION.

WARNINGS BEFORE THERAPY WITH CEFAZOLIN IS INSTITUTED, CAREFUL INQUIRY SHOULD BE MADE TO DETERMINE WHETHER THE PATIENT HAS HAD PREVIOUS HYPERSENSITIVITY REACTIONS TO CEFAZOLIN, CEPHALOSPORINS, PENICILLINS, OR OTHER DRUGS. IF THIS PRODUCT IS GIVEN TO PENICILLIN-SENSITIVE PATIENTS, CAUTION SHOULD BE EXERCISED BECAUSE CROSS-HYPERSENSITIVITY AMONG BETA-LACTAM ANTIBIOTICS HAS BEEN CLEARLY DOCUMENTED AND MAY OCCUR IN UP TO 10% OF PATIENTS WITH HISTORY OF PENICILLIN ALLERGY. IF AN ALLERGIC REACTION TO CEFAZOLIN OCCURS, DISCONTINUE TREATMENT WITH THE DRUG. SERIOUS ACUTE HYPERSENSITIVITY REACTIONS MAY REQUIRE TREATMENT WITH EPINEPHRINE AND OTHER EMERGENCY MEASURES, INCLUDING OXYGEN, INTRAVENOUS FLUIDS, INTRAVENOUS ANTIHISTAMINES, CORTICOSTEROIDS, PRESSOR AMINES, AND AIRWAY MANAGEMENT, AS CLINICALLY INDICATED.Pseudomembranous colitis has been reported with nearly all antibacterial agents, including cefazolin, and may range in severity from mild to life-threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhea subsequent to the administration of antibacterial agents.Treatment with antibacterial agents alters the normal flora of the colon and may permit overgrowth of clostridia. Studies indicate that toxin produced by Clostridium difficile is primary cause of antibiotic associated colitis.After the diagnosis of pseudomembranous colitis has been established, 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 oral antibacterial drug clinically effective against C. difficile colitis.