1.1 Respiratory Tract Infections

Cefazolin for Injection and Dextrose Injection is indicated for the treatment of respiratory tract infections due to Streptococcus pneumoniae, Staphylococcus aureus and Streptococcus pyogenes in adults and pediatric patients for whom appropriate dosing with this formulation can be achieved [see Dosage and Administration (2.1, 2.2, 2.4, 2.5) and Use in Specific Populations (8.4)].

Limitations of Use

Injectable benzathine penicillin is considered the drug of choice in treatment and prevention of streptococcal infections, including the prophylaxis of rheumatic fever.

Cefazolin for Injection and Dextrose Injection is indicated for the eradication of streptococci from the nasopharynx; however, data establishing the efficacy of cefazolin in the subsequent prevention of rheumatic fever are not available.

1.2 Urinary Tract Infections

Cefazolin for Injection and Dextrose Injection is indicated for the treatment of urinary tract infections due to Escherichia coli, and Proteus mirabilis in adults and pediatric patients for whom appropriate dosing with this formulation can be achieved [see Dosage and Administration (2.1, 2.2, 2.4, 2.5) and Use in Specific Populations (8.4)].

1.3 Skin and Skin Structure Infections

Cefazolin for Injection and Dextrose Injection is indicated for the treatment of skin and skin structure infections due to S. aureus, S. pyogenes, and Streptococcus agalactiae in adults and pediatric patients for whom appropriate dosing with this formulation can be achieved [see Dosage and Administration (2.1, 2.2, 2.4, 2.5) and Use in Specific Populations (8.4)].

1.4 Biliary Tract Infections

Cefazolin for Injection and Dextrose Injection is indicated for the treatment of biliary infections due to E. coli, various isolates of streptococci, P. mirabilis, and S. aureus in adults and pediatric patients for whom appropriate dosing with this formulation can be achieved [see Dosage and Administration (2.1, 2.2, 2.4, 2.5) and Use in Specific Populations (8.4)].

1.5 Bone and Joint Infections

Cefazolin for Injection and Dextrose Injection is indicated for the treatment of bone and joint infections due to S. aureus in adults and pediatric patients for whom appropriate dosing with this formulation can be achieved [see Dosage and Administration (2.1, 2.2, 2.4, 2.5) and Use in Specific Populations (8.4)].

1.6 Genital Infections

Cefazolin for Injection and Dextrose Injection is indicated for the treatment of genital infections due to E. coli, and P. mirabilis in adults and pediatric patients for whom appropriate dosing with this formulation can be achieved [see Dosage and Administration (2.1, 2.2, 2.4, 2.5) and Use in Specific Populations (8.4)].

1.7 Septicemia

Cefazolin for Injection and Dextrose Injection is indicated for the treatment of septicemia due to S. pneumoniae, S. aureus, P. mirabilis, and E. coli in adults and pediatric patients for whom appropriate dosing with this formulation can be achieved [see Dosage and Administration (2.1, 2.2, 2.4, 2.5) and Use in Specific Populations (8.4)].

1.8 Endocarditis

Cefazolin for Injection and Dextrose Injection is indicated for the treatment of endocarditis due to S. aureus and S. pyogenes in adults and pediatric patients for whom appropriate dosing with this formulation can be achieved [see Dosage and Administration (2.1, 2.2, 2.4, 2.5) and Use in Specific Populations (8.4)].

1.9 Perioperative Prophylaxis

Cefazolin for Injection and Dextrose Injection is indicated for perioperative prophylaxis in adults and pediatric patients aged 10 to 17 years old for whom appropriate dosing with this formulation can be achieved [see Dosage and Administration (2.1, 2.3, 2.4, 2.5) and Use in Specific Populations (8.4)].

The perioperative use of Cefazolin for Injection and Dextrose Injection is indicated in adult and pediatric (aged 10 to 17 years old) surgical patients in whom infection at the operative site would present a serious risk (e.g., during open-heart surgery and prosthetic arthroplasty).

The prophylactic administration of Cefazolin for Injection and Dextrose Injection 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).

1.10 Usage

To reduce the development of drug-resistant bacteria and maintain the effectiveness of Cefazolin for Injection and Dextrose Injection and other antibacterial drugs, Cefazolin for Injection and Dextrose Injection 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.

2.1 Important Administration Instructions

If a dose of Cefazolin for Injection and Dextrose Injection is required that does not equal 1 gram or 2 grams, this product is not recommended for use and an alternative formulation of cefazolin should be considered.

Administer Cefazolin for Injection and Dextrose Injection intravenously over approximately 30 minutes.

2.2 Dosage for the Treatment of Infections

Dosage for the Treatment of Infections in Adults with Creatinine Clearance (CLcr) Equal to 55 mL/min or Greater 

The recommended adult dosages for the treatment of infections [see Indications and Usage (1.1 to 1.8)] are outlined in Table 1 below. Administer Cefazolin for Injection and Dextrose Injection intravenously over approximately 30 minutes.

Dosage for the Treatment of Infections in Pediatric Patients with CLcr Equal to 70 mL/min or Greater 

The recommended pediatric dosages for the treatment of infections [see Indications and Usage (1.1 to 1.8)] are outlined in Table 2 below. Administer Cefazolin for Injection and Dextrose Injection intravenously over approximately 30 minutes.

If a dose of Cefazolin for Injection and Dextrose Injection is required that does not equal 1 gram or 2 grams, this product is not recommended for use and an alternative formulation of cefazolin should be considered [see Use in Specific Populations (8.4)].

2.3  Dosage for Perioperative Prophylaxis

Dosage for Perioperative Prophylaxis in Adults with CLcr Equal to 55 mL/min or Greater

To prevent postoperative infection in contaminated or potentially contaminated surgery, recommended dosages are described in Table 3 below.

If a dose of Cefazolin for Injection and Dextrose Injection is required that does not equal 1 gram or 2 grams, this product is not recommended and an alternative formulation of cefazolin should be considered.

It is important that (i) the preoperative dose be given just prior (1/2 hour to 1 hour) to the start of surgery so that adequate antibacterial concentrations are present in the serum and tissues at the  time of initial surgical incision; and (ii) cefazolin be administered, if necessary, at appropriate  intervals during surgery to provide sufficient concentrations of the antibacterial drug at the anticipated moments of greatest exposure to infective organisms. 

The perioperative prophylactic administration of cefazolin should usually be discontinued within a 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 3 days to 5 days following the completion of surgery.

Dosage for Perioperative Prophylaxis in Pediatric Patients Aged 10 to 17 Years Old with CLcr 70 mL/min or Greater

To prevent postoperative infection in contaminated or potentially contaminated surgery, recommended doses are described in Table 4 below.

* If a dose of Cefazolin for Injection and Dextrose Injection is required that does not equal 1 gram or 2 grams, this product is not recommended for use and an alternative formulation of cefazolin should be considered.

It is important that (i) the preoperative dose be given just prior (1/2 hour to 1 hour) to the start of surgery so that adequate antibacterial concentrations are present in the serum and tissues at the time of initial surgical incision; and (ii) cefazolin be administered, if necessary, at appropriate intervals during surgery to provide sufficient concentrations of the antibacterial drug at the anticipated moments of greatest exposure to infective organisms.

The administration of Cefazolin for Injection and Dextrose Injection for perioperative prophylaxis should usually be discontinued within a 24-hour period after the surgical procedure. In surgery where the occurrence of infection may be particularly devastating the administration of Cefazolin for Injection and Dextrose Injection for perioperative prophylaxis may be continued for 3 days to 5 days following the completion of surgery.

2.4  Dosage Recommendations in Adult and Pediatric Patients with Renal Impairment

Dosage Recommendations in Adult Patients with CLcr less than 55 mL/min

The dosage recommendation for Cefazolin for Injection and Dextrose Injection in adult patients with renal impairment (CLcr less than 55 mL/min)  is outlined in Table 5 below.

Dosage Recommendations in Pediatric Patients with CLcr less than 70 mL/min

The dosage recommendation for Cefazolin for Injection and Dextrose Injection in pediatric patients with renal impairment (CLcr less than 70 mL/min)  is outlined in Table 6 below.

*If a dose of Cefazolin for Injection and Dextrose Injection is required that does not equal 1 gram or 2 grams, this product is not recommended for use and an alternative formulation of cefazolin should be considered.

2.5 Preparation for Use of Cefazolin for Injection and Dextrose Injection in DUPLEX® Container

This reconstituted solution of Cefazolin for Injection and Dextrose Injection is for intravenous use only.

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. 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.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior
to administration. Use only if solution is clear and container and seals are intact.

DUPLEX® Container Storage

• To avoid inadvertent activation, the 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, the container should be re-folded and the side tab latched until ready to activate. The product must then be used within 7 days, but not beyond the labeled expiration date.

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 24 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 compromised.
• 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.

Important Administration Instructions

• Do not use in series connections.
• Do not introduce additives into the DUPLEX® Container.
• Administer Cefazolin for Injection and Dextrose Injection intravenously over approximately 30 minutes.

4.1 Hypersensitivity to Cefazolin or the Cephalosporin Class of Antibacterial Drugs, Penicillins, or Other Beta-lactams

Cefazolin for Injection and Dextrose Injection is contraindicated in patients who have a history of immediate hypersensitivity reactions (e.g., anaphylaxis, serious skin reactions) to cefazolin or the cephalosporin class of antibacterial drugs, penicillins, or other beta-lactams [see Warnings and Precautions (5.1)].

5.1 Hypersensitivity Reactions to Cefazolin, Cephalosporins, Penicillins, or Other Beta-lactams

Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving beta-lactam antibacterial drugs. Before therapy with Cefazolin for Injection and Dextrose Injection is instituted, careful inquiry should be made to determine whether the patient has had previous immediate hypersensitivity reactions to cefazolin, cephalosporins, penicillins, or carbapenems. Exercise caution if this product is to be given to penicillin-sensitive patients because cross-hypersensitivity among beta-lactam antibacterial drugs has been clearly documented and may occur in up to 10% of patients with a history of penicillin allergy. If an allergic reaction to Cefazolin for Injection and Dextrose Injection occurs, discontinue the drug.

5.2 Seizures in Patients with Renal Impairment

Seizures may occur with the administration of Cefazolin for Injection and Dextrose Injection, particularly in patients with renal impairment when the dosage is not reduced appropriately. Discontinue Cefazolin for Injection and Dextrose Injection if seizures occur or make appropriate dosage adjustments in patients with renal impairment [see Dosage and Administration (2.4)].  Anticonvulsant therapy should be continued in patients with known seizure disorders.

5.3 Clostridioides difficile-associated Diarrhea

Clostridioides difficile-associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including cefazolin, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile.

C. difficile produces toxins A and B, which contribute to the development of CDAD. Hypertoxin-producing isolates of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibacterial drug use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents.

If CDAD is suspected or confirmed, ongoing antibacterial drug use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibacterial drug treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.

5.4 Hypersensitivity to Dextrose-containing Products

Hypersensitivity reactions, including anaphylaxis, have been reported with administration of dextrose-containing products. These reactions have been reported in patients receiving high concentrations of dextrose (i.e. 50% dextrose)1.  The reactions have also been reported when corn-derived dextrose solutions were administered to patients with or without a history of hypersensitivity to corn products.2

5.5 Risk of Development of Drug-resistant Bacteria

Prescribing cefazolin for injection and dextrose injection in the absence of 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.

As with other antimicrobials, prolonged use of Cefazolin for Injection and Dextrose Injection may result in overgrowth of nonsusceptible microorganisms. Repeated evaluation of the patient's condition is essential. Should superinfection occur during therapy, appropriate measures should be taken.

5.6 Drug/Laboratory Test Interactions

5.7 Patients with Overt or Known Subclinical Diabetes Mellitus or Carbohydrate Intolerance

As with other dextrose-containing solutions, Cefazolin 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.

6.1 Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.

The following adverse reactions were reported from clinical trials:

Gastrointestinal: Diarrhea, oral candidiasis (oral thrush), mouth ulcers, vomiting, nausea, stomach cramps, epigastric pain, heartburn, flatus, anorexia and pseudomembranous colitis. Onset of pseudomembranous colitis symptoms may occur during or after antibacterial treatment [see Warnings and Precautions (5.3)].

Allergic: Anaphylaxis, eosinophilia, urticaria, 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. Reports of hepatitis have been received.

Renal: Reports of increased BUN and creatinine levels, as well as renal failure, have been received.

Local Reactions: Instances of phlebitis have been reported at site of injection. Some induration has occurred.

Other Reactions: Pruritus (including genital, vulvar and anal pruritus, genital moniliasis, and vaginitis). Dizziness, fainting, lightheadedness, confusion, weakness, tiredness, hypotension, somnolence and headache.

Adverse Reactions in Pediatric Patients for Perioperative Prophylaxis

Two studies (Study 1: NCT 3231228 and Study 2: NCT 01904357) were conducted to assess the safety and pharmacokinetics of a single 30-minute infusion of either 1 gram or 2 grams (based on weight) of Cefazolin for Injection and Dextrose Injection for perioperative prophylaxis in pediatric patients.

Study 1 was a multicenter, open-label, non-comparative, parallel group study to evaluate the safety and pharmacokinetics of a single 30-minute infusion of either 1 gram or 2 grams (based on weight) of Cefazolin for Injection and Dextrose Injection for perioperative prophylaxis in 61 pediatric patients 10 to 17 years of age. Thirty-three subjects with a weight of at least 25 kg but less than 60 kg received a single dose of 1 gram of cefazolin and 28 subjects with a weight of at least 60 kg received a single dose of 2 grams of cefazolin. The mean age of the safety population was 14 years and ranged from 10 to 17 years. There were no adverse reactions leading to study discontinuation or deaths reported during the study. The most frequently reported adverse reactions were nausea (14.8%), infusion site pain (6.6%), and headache (4.9%).  

Study 2 was a multicenter, non-comparative study that evaluated the safety and pharmacokinetics of a single 30-minute infusion of either 1 gram or 2 grams (based on weight) of Cefazolin for Injection and Dextrose Injection for perioperative prophylaxis in 12 pediatric patients 10 to 12 years of age. Subjects weighing at least 25 kg to less than 50 kg received a single dose of 1 gram of Cefazolin for Injection and Dextrose Injection and subjects weighing at least 50 kg to less than 85 kg received a single dose of 2 grams of Cefazolin for Injection and Dextrose Injection.

The safety findings in Study 2 in pediatric patients aged 10 to 12 years old  were similar to those observed in adult patients and the pediatric patients aged 10 to 17 years old in Study 1.

6.2 Postmarketing Experience

The following adverse reactions have been identified during post approval use of cefazolin.  Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

Immune system disorders: Serum sickness-like reaction

Renal and urinary disorders: Acute tubulointerstitial nephritis (ATIN)

Skin and subcutaneous tissue disorders: Acute generalized exanthematous pustulosis (AGEP)

6.3 Cephalosporin-class Adverse Reactions

In addition to the adverse reactions listed above that have been observed in patients treated with cefazolin, the following adverse reactions and altered laboratory tests have been reported for cephalosporin-class antibacterials:

Stevens-Johnson syndrome, erythema multiforme, toxic epidermal necrolysis, renal impairment, toxic nephropathy, aplastic anemia, hemolytic anemia, hemorrhage, hepatic impairment including cholestasis, and pancytopenia.

8.1 Pregnancy

8.2 Lactation

Data from published literature report that cefazolin is present in human milk, but is not expected to accumulate in a breastfed infant. There are no data on the effects of cefazolin on the breastfed child or on milk production.

The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for Cefazolin for Injection and Dextrose Injection and any potential adverse effects on the breastfed child from Cefazolin for Injection and Dextrose Injection or from the mother’s underlying condition.

8.4 Pediatric Use

Cefazolin for Injection and Dextrose Injection is indicated for the treatment of respiratory tract infections, urinary tract infections, skin and skin structure infections, biliary tract infections, bone and joint infections, genital infections, septicemia, and endocarditis in pediatric patients for whom appropriate dosing with this formulation can be achieved, and for perioperative prophylaxis in pediatric patients aged 10 to 17 years old [see Indications and Usage (1.1 to 1.9)].

Safety and effectiveness of Cefazolin for Injection and Dextrose Injection in premature infants and neonates have not been established and is not recommended for use in this age group of pediatric patients. Dosing for cefazolin in pediatric patients younger than one month old has not been established.

Because of the limitations of the available strengths and administration requirements (i.e., administration of fractional doses is not recommended) of Cefazolin for Injection and Dextrose Injection, and to avoid unintentional overdose, this product is not recommended for use if a dose of Cefazolin for Injection and Dextrose Injection that does not equal 1 gram or 2 grams is required and an alternative formulation of cefazolin should be considered [see Dosage and Administration (2.2, 2.3, 2.4 and 2.5)].

The safety and effectiveness of Cefazolin for Injection and Dextrose Injection for perioperative prophylaxis have been established in pediatric patients aged 10 to 17 years old. Use of Cefazolin for Injection and Dextrose Injection in these age groups is supported by evidence from adults with additional safety and pharmacokinetic data in pediatric patients aged 10 to 17 years old. Safety and pharmacokinetics were evaluated in two multicenter, non-comparative studies (Study 1 and Study 2). These studies were conducted to assess the safety and pharmacokinetics of a single 30-minute infusion of either 1 gram or 2 grams (based on weight) of Cefazolin for Injection and Dextrose Injection for perioperative prophylaxis in pediatric patients. Study 1 evaluated the safety and pharmacokinetics of 1 g of Cefazolin for Injection and Dextrose Injection in pediatric patients aged 10 to 17 years old scheduled for surgery with a weight of at least 25 kg but less than 60 kg and, 2 g in pediatric patients with a weight of at least 60 kg. Study 2 evaluated 1 g of Cefazolin for Injection and Dextrose Injection in pediatric patients aged 10 to 12 years old scheduled for surgery with a weight of at least 25 kg but less than 50 kg and, 2 g in pediatric patients with a weight of at least 50 kg to less than 85 kg [see Dosage and Administration (2.3), Adverse Reactions (6.1) and Clinical Pharmacology (12.3)].

The safety and effectiveness of Cefazolin for Injection and Dextrose Injection for perioperative prophylaxis have not been established in pediatric patients younger than 10 years old.

8.5 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 Dosage and Administration (2.4) and Warnings and Precautions (5.2)].

8.6 Patients with Renal Impairment

When Cefazolin for Injection and Dextrose Injection is administered to adult and pediatric patients with low urinary output because of impaired renal function (creatinine clearance less than 55 mL/min and 70 mL/min for adults and pediatric patients, respectively), lower daily dosage is required [see Dosage and Administration (2.4) and Warnings and Precautions (5.2)].

12.1 Mechanism of Action

Cefazolin is an antibacterial drug [see Microbiology (12.4)].

12.2 Pharmacodynamics

The pharmacokinetic/pharmacodynamic relationship for cefazolin has not been evaluated in patients.

12.3 Pharmacokinetics

Studies have shown that following intravenous administration of cefazolin to normal volunteers, mean serum concentrations peaked at approximately 185 mcg/mL and were approximately 4 mcg/mL at 8 hours for a 1 gram dose.

The serum half-life for cefazolin is approximately 1.8 hours following IV administration.

In a study of constant intravenous infusion with dosages of 3.5 mg/kg for 1 hour (approximately 250 mg) and 1.5 mg/kg the next 2 hours (approximately 100 mg) in healthy volunteers, cefazolin serum concentrations at the third hour were approximately 28 mcg/mL.

Plasma pharmacokinetic parameters of cefazolin in healthy volunteers (N=12) following a single 15-minute IV infusion of 2 grams of Cefazolin for Injection and Dextrose Injection are summarized in Table 7.

N= number of subjects observed;  Cmax = maximum plasma concentration;  Tmax = time to maximum plasma concentration;  AUC0-inf = area under the plasma concentration-time curve extrapolated to infinity;   t1/2 = apparent plasma terminal elimination half-life;  CL = total clearance;  Vz = volume of distribution

Studies in patients hospitalized with infections indicate that cefazolin mean peak serum concentrations were approximately equivalent to those seen in healthy volunteers.

Bile concentrations in patients without obstructive biliary disease can reach or exceed serum concentrations by up to five times; however, in patients with obstructive biliary disease, bile concentrations of cefazolin are considerably lower than serum concentrations (less than 1.0 mcg/mL).

In synovial fluid, the cefazolin concentration becomes comparable to that reached in serum at about 4 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 6 hours, approximately 60% of the drug is excreted in the urine and this increases to 70% to 80% within 24 hours.

Specific Populations

Pediatric Patients for Perioperative Prophylaxis

A simulation based on pharmacokinetic data from healthy adults (n=24), pediatric patients aged 10 to 17 years (n=26: Study 1 [see Adverse Reactions (6.1)]), and pediatric patients aged 10 to 12 years (n=12: Study 2 [see Adverse Reactions (6.1)] indicate that the administration of a 1 gram cefazolin dose for pediatric patients weighing less than 50 kg and a 2 grams cefazolin dose for those weighing 50 kg or greater will provide comparable exposures between pediatric patients aged 10 to 17 years and healthy adults receiving 2 grams Cefazolin for Injection and Dextrose Injection [see Dosage and Administration (2.2 and 2.3) and Use in Specific Populations (8.4)].

12.4 Microbiology

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility