Primaxin I.V. (Imipenem / Cilastatin Sodium) - Indications and Dosage

INDICATIONS AND USAGE

PRIMAXIN I.V. is indicated for the treatment of serious infections caused by susceptible strains of the designated microorganisms in the conditions listed below:

1. Lower respiratory tract infections. Staphylococcus aureus (penicillinase-producing strains), Acinetobacter species, Enterobacter species, Escherichia coli, Haemophilus influenzae, Haemophilus parainfluenzae *, Klebsiella species, Serratia marcescens
2. Urinary tract infections (complicated and uncomplicated). Enterococcus faecalis, Staphylococcus aureus (penicillinase-producing strains) *, Enterobacter species, Escherichia coli, Klebsiella species, Morganella morganii *, Proteus vulgaris *, Providencia rettgeri *, Pseudomonas aeruginosa
3. Intra-abdominal infections. Enterococcus faecalis, Staphylococcus aureus (penicillinase-producing strains) *, Staphylococcus epidermidis, Citrobacter species, Enterobacter species, Escherichia coli, Klebsiella species, Morganella morganii *, Proteus species, Pseudomonas aeruginosa, Bifidobacterium species, Clostridium species, Eubacterium species, Peptococcus species, Peptostreptococcus species, Propionibacterium species *, Bacteroides species including B. fragilis, Fusobacterium species
4. Gynecologic infections. Enterococcus faecalis, Staphylococcus aureus (penicillinase-producing strains) *, Staphylococcus epidermidis, Streptococcus agalactiae (Group B streptococci), Enterobacter species*, Escherichia coli, Gardnerella vaginalis, Klebsiella species *, Proteus species, Bifidobacterium species *, Peptococcus species *, Peptostreptococcus species, Propionibacterium species *, Bacteroides species including B. fragilis *
5. Bacterial septicemia. Enterococcus faecalis, Staphylococcus aureus (penicillinase-producing strains), Enterobacter species, Escherichia coli, Klebsiella species, Pseudomonas aeruginosa, Serratia species *, Bacteroides species including B. fragilis *
6. Bone and joint infections. Enterococcus faecalis, Staphylococcus aureus (penicillinase-producing strains), Staphylococcus epidermidis, Enterobacter species, Pseudomonas aeruginosa
7. Skin and skin structure infections. Enterococcus faecalis, Staphylococcus aureus (penicillinase-producing strains), Staphylococcus epidermidis, Acinetobacter species, Citrobacter species, Enterobacter species, Escherichia coli, Klebsiella species, Morganella morganii, Proteus vulgaris, Providencia rettgeri *, Pseudomonas aeruginosa, Serratia species, Peptococcus species, Peptostreptococcus species, Bacteroides species including B. fragilis, Fusobacterium species *
8. Endocarditis. Staphylococcus aureus (penicillinase-producing strains)
9. Polymicrobic infections. PRIMAXIN I.V. is indicated for polymicrobic infections including those in which S. pneumoniae (pneumonia, septicemia), S. pyogenes (skin and skin structure), or nonpenicillinase-producing S. aureus is one of the causative organisms. However, monobacterial infections due to these organisms are usually treated with narrower spectrum antibiotics, such as penicillin G.

PRIMAXIN I.V. is not indicated in patients with meningitis because safety and efficacy have not been established.

For Pediatric Use information, See PRECAUTIONS, Pediatric Use, and DOSAGE AND ADMINISTRATION sections.

Because of its broad spectrum of bactericidal activity against gram-positive and gram-negative aerobic and anaerobic bacteria, PRIMAXIN I.V. is useful for the treatment of mixed infections and as presumptive therapy prior to the identification of the causative organisms.

Although clinical improvement has been observed in patients with cystic fibrosis, chronic pulmonary disease, and lower respiratory tract infections caused by Pseudomonas aeruginosa, bacterial eradication may not necessarily be achieved.

As with other beta-lactam antibiotics, some strains of Pseudomonas aeruginosa may develop resistance fairly rapidly during treatment with PRIMAXIN I.V. During therapy of Pseudomonas aeruginosa infections, periodic susceptibility testing should be done when clinically appropriate.

Infections resistant to other antibiotics, for example, cephalosporins, penicillin, and aminoglycosides, have been shown to respond to treatment with PRIMAXIN I.V.

To reduce the development of drug-resistant bacteria and maintain the effectiveness of PRIMAXIN I.V. and other antibacterial drugs, PRIMAXIN I.V. 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.

*Efficacy for this organism in this organ system was studied in fewer than 10 infections.

DOSAGE AND ADMINISTRATION

ADULTS

The dosage recommendations for PRIMAXIN I.V. represent the quantity of imipenem to be administered. An equivalent amount of cilastatin is also present in the solution. Each 125 mg, 250 mg, or 500 mg dose should be given by intravenous administration over 20 to 30 minutes. Each 750 mg or 1000 mg dose should be infused over 40 to 60 minutes. In patients who develop nausea during the infusion, the rate of infusion may be slowed.

The total daily dosage for PRIMAXIN I.V. should be based on the type or severity of infection and given in equally divided doses based on consideration of degree of susceptibility of the pathogen(s), renal function, and body weight. Adult patients with impaired renal function, as judged by creatinine clearance 2, require adjustment of dosage as described in the succeeding section of these guidelines.

INTRAVENOUS DOSAGE SCHEDULE FOR ADULTS WITH NORMAL RENAL FUNCTION AND BODY WEIGHT >/=70 KG

Doses cited in Table I are based on a patient with normal renal function and a body weight of 70 kg. These doses should be used for a patient with a creatinine clearance of >/=71 mL/min/1.73 m² and a body weight of >/=70 kg. A reduction in dose must be made for a patient with a creatinine clearance 2 and/or a body weight less than 70 kg. (See Tables II and III.)

Dosage regimens in column A of Table I are recommended for infections caused by fully susceptible organisms which represent the majority of pathogenic species. Dosage regimens in column B of Table I are recommended for infections caused by organisms with moderate susceptibility to imipenem, primarily some strains of P. aeruginosa.

Due to the high antimicrobial activity of PRIMAXIN I.V., it is recommended that the maximum total daily dosage not exceed 50 mg/kg/day or 4.0 g/day, whichever is lower. There is no evidence that higher doses provide greater efficacy. However, patients over twelve years of age with cystic fibrosis and normal renal function have been treated with PRIMAXIN I.V. at doses up to 90 mg/kg/day in divided doses, not exceeding 4.0 g/day.

REDUCED INTRAVENOUS DOSAGE SCHEDULE FOR ADULTS WITH IMPAIRED RENAL FUNCTION AND/OR BODY WEIGHT <70 KG

Patients with creatinine clearance of 2 and/or body weight less than 70 kg require dosage reduction of PRIMAXIN I.V. as indicated in the tables below. Creatinine clearance may be calculated from serum creatinine concentration by the following equation:

To determine the dose for adults with impaired renal function and/or reduced body weight:

1. Choose a total daily dose from Table I based on infection characteristics.
2. a) If the total daily dose is 1.0 g, 1.5 g, or 2.0 g, use the appropriate subsection of Table II and continue with step 3.
   b) If the total daily dose is 3.0 g or 4.0 g, use the appropriate subsection of Table III and continue with step 3.
3. From Table II or III:
   a) Select the body weight on the far left which is closest to the patient's body weight (kg).
   b) Select the patient's creatinine clearance category.
   c) Where the row and column intersect is the reduced dosage regimen.

Patients with creatinine clearances of 6 to 20 mL/min/1.73 m² should be treated with PRIMAXIN I.V. 125 mg or 250 mg every 12 hours for most pathogens. There may be an increased risk of seizures when doses of 500 mg every 12 hours are administered to these patients.

Patients with creatinine clearance 2 should not receive PRIMAXIN I.V. unless hemodialysis is instituted within 48 hours. There is inadequate information to recommend usage of PRIMAXIN I.V. for patients undergoing peritoneal dialysis.

HEMODIALYSIS

When treating patients with creatinine clearances of ²who are undergoing hemodialysis, use the dosage recommendations for patients with creatinine clearances of 6-20 mL/min/1.73 m². (See Reduced Intravenous Dosage Schedule for Adults with Impaired Renal Function and/or Body Weight <70 kg.) Both imipenem and cilastatin are cleared from the circulation during hemodialysis. The patient should receive PRIMAXIN I.V. after hemodialysis and at 12 hour intervals timed from the end of that hemodialysis session. Dialysis patients, especially those with background CNS disease, should be carefully monitored; for patients on hemodialysis, PRIMAXIN I.V. is recommended only when the benefit outweighs the potential risk of seizures. (See PRECAUTIONS.)

PEDIATRIC PATIENTS

HOW SUPPLIED

PRIMAXIN I.V. is supplied as a sterile powder mixture in single dose containers including vials, infusion bottles, ADD-Vantage® vials, and MONOVIAL® vials containing imipenem (anhydrous equivalent) and cilastatin sodium as follows:

No. 3514--250 mg imipenem equivalent and 250 mg cilastatin equivalent and 10 mg sodium bicarbonate as a buffer

NDC 0006-3514-58 in trays of 25 vials.

No. 3516--500 mg imipenem equivalent and 500 mg cilastatin equivalent and 20 mg sodium bicarbonate as a buffer

NDC 0006-3516-59 in trays of 25 vials.

No. 3517--500 mg imipenem equivalent and 500 mg cilastatin equivalent and 20 mg sodium bicarbonate as a buffer

NDC 0006-3517-75 in trays of 10 infusion bottles.

No. 3551 --250 mg imipenem equivalent and 250 mg cilastatin equivalent and 10 mg sodium bicarbonate as a buffer

NDC 0006-3551-58 in trays of 25 ADD-Vantage® vials.

No. 3552 --500 mg imipenem equivalent and 500 mg cilastatin equivalent and 20 mg sodium bicarbonate as a buffer

NDC 0006-3552-59 in trays of 25 ADD-Vantage® vials.

No. 3666 --500 mg imipenem equivalent and 500 mg cilastatin equivalent and 20 mg sodium bicarbonate as a buffer

NDC 0006-3666-59 in trays of 25 MONOVIAL® vials.