Imipenem And Cilastatin Sodium

1 INDICATIONS AND USAGE Imipenem and Cilastatin for Injection, USP for intravenous use is a combination of imipenem, a penem antibacterial, and cilastatin, a renal dehydropeptidase inhibitor, indicated for the treatment of the following serious infections caused by designated susceptible bacteria: Lower respiratory tract infections. ( 1.1 ) Urinary tract infections. ( 1.2 ) Intra-abdominal infections. ( 1.3 ) Gynecologic infections. ( 1.4 ) Bacterial septicemia. ( 1.5 ) Bone and joint infections. ( 1.6 ) Skin and skin structure infections. ( 1.7 ) Endocarditis. ( 1.8 ) Limitations of Use : Imipenem and Cilastatin for Injection, USP (I.V.) is not indicated in patients with meningitis because safety and efficacy have not been established ( 1.9 ). Imipenem and Cilastatin for Injection, USP (I.V.) is not recommended in pediatric patients with CNS infections because of the risk of seizures ( 1.9 ). Imipenem and Cilastatin for Injection, USP (I.V.) is not recommended in pediatric patients weighing less than 30 kg with impaired renal function ( 1.9 ). Usage : To reduce the development of drug resistant bacteria and maintain the effectiveness of Imipenem and Cilastatin for Injection, USP (I.V.) and other antibacterial drugs, Imipenem and Cilastatin for Injection, USP (I.V.) should be used only to treat infections that are proven or strongly suspected to be caused by bacteria ( 1.10 ). 1.1 Lower Respiratory Tract Infections Imipenem and Cilastatin for Injection, USP (I.V.) for intravenous use is indicated for the treatment of lower respiratory tract infections caused by susceptible strains of Staphylococcus aureus (penicillinase-producing isolates), Acinetobacter species, Enterobacter species, Escherichia coli , Haemophilus influenzae , Haemophilus parainfluenzae , Klebsiella species, Serratia marcescens . 1.2 Urinary Tract Infections (complicated and uncomplicated) Imipenem and Cilastatin for Injection, USP (I.V.) is indicated for the treatment of urinary tract infections (complicated and uncomplicated) caused by susceptible strains of Enterococcus faecalis , Staphylococcus aureus (penicillinase-producing isolates), Enterobacter species, Escherichia coli , Klebsiella species, Morganella morganii , Proteus vulgaris , Providencia rettgeri , Pseudomonas aeruginosa . 1.3 Intra-Abdominal Infections Imipenem and Cilastatin for Injection, USP (I.V.) is indicated for the treatment of intra-abdominal infections caused by susceptible strains of Enterococcus faecalis , Staphylococcus aureus (penicillinase-producing isolates), 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. 1.4 Gynecologic Infections Imipenem and Cilastatin for Injection, USP (I.V.) is indicated for the treatment of gynecologic infections caused by susceptible strains of Enterococcus faecalis , Staphylococcus aureus (penicillinase-producing isolates), 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 . 1.5 Bacterial Septicemia Imipenem and Cilastatin for Injection, USP (I.V.) is indicated for the treatment of bacterial septicemia caused by susceptible strains of Enterococcus faecalis , Staphylococcus aureus (penicillinase-producing isolates), Enterobacter species, Escherichia coli , Klebsiella species, Pseudomonas aeruginosa , Serratia species, Bacteroides species including B. fragilis . 1.6 Bone and Joint Infections Imipenem and Cilastatin for Injection, USP (I.V.) is indicated for the treatment of bone and joint infections caused by susceptible strains of Enterococcus faecalis , Staphylococcus aureus (penicillinase-producing isolates), Staphylococcus epidermidis , Enterobacter species, Pseudomonas aeruginosa . 1.7 Skin and Skin Structure Infections Imipenem and Cilastatin for Injection, USP (I.V.) is indicated for the treatment of skin and skin structure infections caused by susceptible strains of Enterococcus faecalis , Staphylococcus aureus (penicillinase-producing isolates), 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. 1.8 Endocarditis Imipenem and Cilastatin for Injection, USP (I.V.) is indicated for the treatment of endocarditis caused by susceptible strains of Staphylococcus aureus (penicillinase-producing isolates). 1.9 Limitations of Use Imipenem and Cilastatin for Injection, USP (I.V.) is not indicated in patients with meningitis because safety and efficacy have not been established. Imipenem and Cilastatin for Injection, USP (I.V.) is not recommended in pediatric patients with CNS infections because of the risk of seizures [see Dosage and Administration ( 2.2 ), Warnings and Precautions ( 5.2 ), and Use in Specific Populations ( 8.4 )] . Imipenem and Cilastatin for Injection, USP (I.V.) is not recommended in pediatric patients less than 30 kg with impaired renal function, as no data are available [see Use in Specific Populations ( 8.4 ), and Dosage and Administration ( 2.2 )] . Periodic assessment of organ system functions, including renal, hepatic and hematopoietic, is advisable during prolonged therapy. 1.10 Usage To reduce the development of drug-resistant bacteria and maintain the effectiveness of Imipenem and Cilastatin for Injection, USP (I.V.) and other antibacterial drugs, Imipenem and Cilastatin for Injection, USP (I.V.) should be used only to treat 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 DOSAGE AND ADMINISTRATION The dosage of Imipenem and Cilastatin for Injection (I.V.) in adult patients should be based on suspected or confirmed pathogen susceptibility ( 2.1 ). For adult patients with normal renal function (creatinine clearance of greater than or equal to 90 mL/min), the recommended dosage regimens are: 500 mg every 6 hours OR 1,000 mg every 8 hours OR 1,000 mg every 6 hours ( 2.1 ). See full prescribing information for dosage recommendations in pediatric patients ( 2.2 ). A reduction in dose must be made for a patient with a creatinine clearance of less than 90 mL/min ( 2.3 ). Patients with creatinine clearances of less than 15 mL/min should not receive Imipenem and Cilastatin for Injection (I.V.) unless hemodialysis is instituted within 48 hours ( 2.4 ). Reconstitute Imipenem and Cilastatin for Injection, USP (I.V.) vial with appropriate diluent and dilute the reconstituted suspension with an appropriate infusion solution before administering by intravenous infusion ( 2.5 ). 2.1 Dosage in Adults For Intravenous Injection Only The dosage of Imipenem and Cilastatin for Injection (I.V.) in adult patients should be based on suspected or confirmed pathogen susceptibility as shown in Table 1 below. The dosage recommendations for Imipenem and Cilastatin for Injection (I.V.) represent the quantity of imipenem to be administered. An equivalent amount of cilastatin is also present in the solution. These doses should be used for patients with creatinine clearance of greater than or equal to 90 mL/min. A reduction in dose must be made for patients with creatinine clearance less than 90 mL/min as shown in Table 3 [see Dosage and Administration ( 2.3 )] . Recommend that the maximum total daily dosage not exceed 4 g/day. Administer 500 mg by intravenous infusion over 20 to 30 minutes. Administer 1,000 mg by intravenous infusion over 40 to 60 minutes. In patients who develop nausea during the infusion, the rate of infusion may be slowed. Table 1: Dosage of Imipenem and Cilastatin for Injection (I.V.) in Adult Patients with Creatinine Clearance Greater than or Equal to 90 mL/min Suspected or Proven Pathogen Susceptibility Dosage of Imipenem and Cilastatin for Injection (I.V.) If the infection is suspected or proven to be due to a susceptible bacterial species 500 mg every 6 hours OR 1,000 mg every 8 hours If the infection is suspected or proven to be due to bacterial species with intermediate susceptibility [see Microbiology ( 12.4 )] 1,000 mg every 6 hours 2.2 Dosage in Pediatric Patients Imipenem and Cilastatin for Injection (I.V.) is not recommended in pediatric patients with CNS infections because of the risk of seizures [see Use in Specific Populations ( 8.4 )] . Imipenem and Cilastatin for Injection (I.V.) is not recommended in pediatric patients < 30 kg with renal impairment, as no data are available [see Use in Specific Populations ( 8.4 )] . Based on studies in adults, the maximum total daily dose in pediatric patients should not exceed 4 g/day [see Dosage and Administration ( 2.1 )] . The recommended dosage for pediatric patients with non-CNS infections is shown in Table 2 below: Table 2: Recommended Imipenem and Cilastatin for Injection (I.V.) Dosage in Pediatric Patients for Non-CNS Infections * Doses less than or equal to 500 mg should be given by intravenous infusion over 20 to 30 minutes † Doses greater than 500 mg should be given by intravenous infusion over 40 to 60 minutes Age Dose (mg/kg) *, † Frequency (hours) Greater than or equal to 3 Months of Age 15-25 mg/kg Every 6 hours Less than or equal to 3 months of age (Greater than or equal to 1,500 g body weight) 4 weeks to 3 months of age 25 mg/kg Every 6 hours 1 to 4 weeks of age 25 mg/kg Every 8 hours Less than 1 week of age 25 mg/kg Every 12 hours Recommend that the maximum total daily dosage not exceed 4 g/day 2.3 Dosage in Adult Patients with Renal Impairment Patients with creatinine clearance less than 90 mL/min require dosage reduction of Imipenem and Cilastatin for Injection (I.V.) as indicated in Table 3 . The serum creatinine should represent a steady state of renal function. Use the Cockcroft-Gault method described below to calculate the creatinine clearance: Males: (weight in kg) x (140-age in years) (72) x serum creatinine (mg/100 mL) Females: (0.85) x (value calculated for males) Table 3: Dosage of Imipenem and Cilastatin for Injection (I.V.) for Adult Patients in Various Renal Function Groups Based on Estimated Creatinine Clearance (CLcr) * Administer doses less than or equal to 500 mg by intravenous infusion over 20 to 30 minutes. Discard unused portion of the infusion solution. † Administer doses greater than 500 mg by intravenous infusion over 40 to 60 minutes. In patients who develop nausea during the infusion, the rate of infusion may be slowed. Creatinine clearance (mL/min) Greater than or equal to 90 Less than 90 to greater than or equal to 60 Less than 60 to greater than or equal to 30 Less than 30 to greater than or equal to 15 Dosage of Imipenem and Cilastatin for Injection (I.V.)*, † If the infection is suspected or proven to be due to a susceptible bacterial species: 500 mg every 6 hours 400 mg every 6 hours 300 mg every 6 hours 200 mg every 6 hours OR 1,000 mg every 8 hours 500 mg every 6 hours 500 mg every 8 hours 500 mg every 12 hours Dosage of Imipenem and Cilastatin for Injection (I.V.)*, † If the infection is suspected or proven to be due to bacterial species with intermediate susceptibility [see Microbiology ( 12.4 )] : 1,000 mg every 6 hours 750 mg every 8 hours 500 mg every 6 hours 500 mg every 12 hours In patients with creatinine clearances of less than 30 to greater than or equal to 15 mL/min, there may be an increased risk of seizures [see Warnings and Precautions ( 5.2 ) and Use in Specific Populations ( 8.6 )] . Patients with creatinine clearance less than 15 mL/min should not receive Imipenem and Cilastatin for Injection (I.V.) unless hemodialysis is instituted within 48 hours. There is inadequate information to recommend usage of Imipenem and Cilastatin for Injection (I.V.) for patients undergoing peritoneal dialysis. 2.4 Dosage in Hemodialysis Patients When treating patients with creatinine clearances of less than 15 mL/min who are undergoing hemodialysis , use the dosage recommendations for patients with creatinine clearances of less than 30 to greater than or equal to 15 mL/min in Table 3 above [see Dosage and Administration ( 2.3 )]. Both imipenem and cilastatin are cleared from the circulation during hemodialysis. The patient should receive Imipenem and Cilastatin for Injection (I.V.) after hemodialysis and at 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, Imipenem and Cilastatin for Injection (I.V.) is recommended only when the benefit outweighs the potential risk of seizures [see Warnings and Precautions ( 5.2 )]. 2.5 Reconstitution and Preparation of Imipenem and Cilastatin for Injection (I.V.) Solution for Intravenous Administration Imipenem and Cilastatin for Injection (I.V.) Vials Do not use diluents containing benzyl alcohol to reconstitute Imipenem and Cilastatin for Injection (I.V.) for administration to neonates because it has been associated with toxicity in neonates. While toxicity has not been demonstrated in pediatric patients greater than three months of age, small pediatric patients in this age range may also be at risk for benzyl alcohol toxicity. Contents of the vials must be reconstituted by adding approximately 10 mL of the appropriate diluent to the vial. List of appropriate diluents are as follows: 0.9% Sodium Chloride Injection 5% Dextrose Injection 5% Dextrose and 0.9% Sodium Chloride Injection 5% Dextrose Injection with 0.225% or 0.45% saline solution Reconstituted Solutions of Imipenem and Cilastatin for Injection (I.V.) range from colorless to yellow. Variations of color within this range do not affect the potency of the product. The reconstituted suspension must not be administered by direct Intravenous Infusion. After reconstitution, shake vial well and transfer the resulting suspension to 100 mL of an appropriate infusion solution before administering by intravenous infusion. Repeat transfer of the resulting suspension with an additional 10 mL of infusion solution to ensure complete transfer of vial contents to the infusion solution. Agitate the resulting mixture until clear. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Discard unused portion of the infusion solution where applicable. 2.6 Storage of Reconstituted Solutions Vials (After Reconstitution) Imipenem and Cilastatin for Injection (I.V.), as supplied in single dose vials and reconstituted with the appropriate diluents [see Dosage and Administration ( 2.5 )] , maintains satisfactory potency for 4 hours at room temperature or for 24 hours under refrigeration (5°C). Do not freeze solutions of Imipenem and Cilastatin for Injection (I.V.). 2.7 Incompatibility and Compatibility of Imipenem and Cilastatin for Injection (I.V.) with other Antibacterial Drugs Do not mix Imipenem and Cilastatin for Injection (I.V.) with, or physically add to, other antibacterial drugs. Imipenem and Cilastatin for Injection (I.V.) may be administered concomitantly with other antibacterial drugs, such as aminoglycosides.

6 ADVERSE REACTIONS The following serious adverse reactions are described in greater detail in the Warnings and Precautions section. Hypersensitivity Reactions [see Warnings and Precautions ( 5.1 )] Seizure Potential [see Warnings and Precautions ( 5.2 )] Increased Seizure Potential Due to Interaction with Valproic Acid [see Warnings and Precautions ( 5.3 )] Clostridioides difficile -Associated Diarrhea (CDAD) [see Warnings and Precautions ( 5.4 )] Development of Drug-Resistant Bacteria [see Warnings and Precautions ( 5.5 )] The most frequently occurring adverse reactions (≥ 0.2%) in adults were phlebitis, nausea, diarrhea, vomiting, rash, pain injection site, fever, hypotension, seizures, erythema at injection site, dizziness, pruritus, vein induration, urticaria, somnolence ( 6.1 ). The most frequently occurring adverse reactions (> 1%) in pediatric patients greater than or equal to 3 months of age were diarrhea, rash, phlebitis, gastroenteritis, vomiting, IV site irritation, urine discoloration ( 6.1 ). The most frequently occurring adverse reactions (> 1%) in neonates to 3 months of age were convulsions, diarrhea, oliguria/anuria, oral candidiasis, rash, tachycardia ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Fresenius Kabi USA, LLC at 1-800-551-7176 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 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. Adult Patients During clinical investigations 1,723 patients were treated with Imipenem and Cilastatin for Injection (I.V.). Table 4 shows the incidence of adverse reactions reported during the clinical investigations of adult patients treated with Imipenem and Cilastatin for Injection (I.V.). Table 4: Incidence (%)* of Adverse Reactions Reported During Clinical Investigations of Adult Patients Treated with Imipenem and Cilastatin for Injection (I.V.) * Adverse reactions with an incidence ≥ 0.2% of Imipenem and Cilastatin for Injection (I.V.) -treated adult patients. Body System Adverse Reactions Frequency (%) Local Administration site Phlebitis/ thrombophlebitis 3.1% Pain at the injection site 0.7% Erythema at the injection site 0.4% Vein induration 0.2% Gastrointestinal Nausea 2% Diarrhea 1.8% Vomiting 1.5% Skin Rash 0.9% Pruritus 0.3% Urticaria 0.2% Vascular Hypotension 0.4% Body as a Whole Fever 0.5% Nervous system Seizures 0.4% Dizziness 0.3% Somnolence 0.2% Additional adverse reactions reported in less than 0.2% of the patients or reported since the drug was marketed are listed within each body system in order of decreasing severity [see Table 5 ]. Table 5: Additional Adverse Reactions Occurring in Less than 0.2% of Adult Patients Listed within Each Body System in Order of Decreasing Severity Body System Adverse Reactions Gastrointestinal Pseudomembranous Colitis (the onset of Pseudomembranous colitis symptoms), Hemorrhagic Colitis Gastroenteritis Abdominal Pain Glossitis Tongue Papillar Hypertrophy Heartburn Pharyngeal Pain Increased Salivation CNS Encephalopathy Confusion Myoclonus Paresthesia Vertigo Headache Special Senses Hearing Loss Tinnitus Respiratory Chest Discomfort Dyspnea Hyperventilation Thoracic Spine Pain Cardiovascular Palpitations Tachycardia Skin Erythema Multiforme Angioneurotic Edema Flushing Cyanosis Hyperhidrosis Skin Texture Changes Candidiasis Pruritus Vulvae Local Administration site Infused vein infection Body as a Whole Polyarthralgia Asthenia/Weakness Renal Oliguria/Anuria Polyuria Adverse Laboratory Changes The following adverse laboratory changes were reported during clinical trials: Hepatic: Increased alanine aminotransferase (ALT or SGPT), aspartate aminotransferase (AST or SGOT), alkaline phosphatase, bilirubin, and lactate dehydrogenase (LDH) Hemic: Increased eosinophils, positive Coombs test, increased WBC, increased platelets, decreased hemoglobin and hematocrit, increased monocytes, abnormal prothrombin time, increased lymphocytes, increased basophils Electrolytes: Decreased serum sodium, increased potassium, increased chloride Renal: Increased BUN, creatinine Urinalysis: Presence of urine protein, urine red blood cells, urine white blood cells, urine casts, urine bilirubin, and urine urobilinogen. Pediatric Patients Table 6: Incidence (%)* of Adverse Reactions Reported During Clinical Investigations of Pediatric Patients Greater Than or Equal to 3 Months of Age Treated with Imipenem and Cilastatin for Injection (I.V.) * Adverse reactions that occurred in > 1 % of Imipenem and Cilastatin for Injection (I.V.)-treated pediatric patients (greater than or equal to 3 months of age) Body System Adverse Reactions Frequency (%) Local Administration Site Phlebitis 2.2% Intravenous Site Irritation 1.1% Gastrointestinal Diarrhea 3.9% Gastroenteritis 1.1% Vomiting 1.1% Skin Rash 2.2% Renal Urine Discoloration 1.1% Table 7: Incidence (%)* of Adverse Reactions Reported During Clinical Investigations of Pediatric Patients Neonates to 3 Months of Age Treated with Imipenem and Cilastatin for Injection (I.V.) * Adverse reactions that occurred in > 1 % of Imipenem and Cilastatin for Injection (I.V.)-treated pediatric patients (neonates to 3 months of age) Body System Adverse Reactions Frequency (%) Gastrointestinal Diarrhea 3% CNS Convulsions 5.9% Cardiovascular Tachycardia 1.5% Skin Rash 1.5% Body as a Whole Oral Candidiasis 1.5% Renal Oliguria/Anuria 2.2% Adverse Laboratory Changes The following adverse laboratory changes were reported in studies of 178 pediatric patients 3 months of age: increased AST (SGOT), decreased hemoglobin/hematocrit, increased platelets, increased eosinophils, increased ALT (SGPT), increased urine protein, decreased neutrophils. The following adverse laboratory changes were reported in studies of 135 patients (neonates to 3 months of age): increased eosinophils, increased AST (SGPT), increased serum creatinine, increased/decreased platelet count, increased/decreased bilirubin, increased ALT (SGPT), increased alkaline phosphatase, increased/decreased hematocrit. 6.2 Postmarketing Experience The following adverse reactions have been identified during post-approval use of Imipenem and Cilastatin for Injection (I.V.). 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. Table 8: Adverse Reactions Identified During Post Approval Use of Imipenem and Cilastatin for Injection (I.V.) Body System Adverse Reactions Gastrointestinal Hepatitis (including fulminant hepatitis) Hepatic failure Jaundice Staining of the teeth and/or tongue Hematologic Pancytopenia Bone marrow depression Thrombocytopenia Neutropenia Leukopenia Hemolytic anemia CNS Tremor Psychic disturbances including hallucinations Dyskinesia Agitation Special Senses Taste perversion Skin Stevens-Johnson syndrome Toxic epidermal necrolysis Body as a whole Drug fever Renal Acute renal failure Urine discoloration Adverse Laboratory Changes Adverse laboratory changes reported since the drug was marketed were: Hematologic: agranulocytosis. Examination of published literature and spontaneous adverse reactions reports suggested a similar spectrum of adverse reactions in adult and pediatric patients.

12.3 Pharmacokinetics Intravenous infusion of Imipenem and Cilastatin for Injection (I.V.) over 20 minutes results in peak plasma levels of imipenem antimicrobial activity that range from 21 to 58 mcg/mL for the 500 mg dose, and from 41 to 83 mcg/mL for the 1,000 mg dose. At these doses, plasma levels of imipenem antimicrobial activity decline to below 1 mcg/mL or less in 4 to 6 hours. Peak plasma levels of cilastatin following a 20-minute intravenous infusion of Imipenem and Cilastatin for Injection (I.V.) range from 31 to 49 mcg/mL for the 500 mg dose, and from 56 to 88 mcg/mL for the 1,000 mg dose. Distribution The binding of imipenem to human serum proteins is approximately 20% and that of cilastatin is approximately 40%. Imipenem has been shown to penetrate into human tissues, including vitreous humor, aqueous humor, lung, peritoneal fluid, CSF, bone, interstitial fluid, skin, and fascia. As there are no adequate and well-controlled studies of imipenem treatment in these additional body sites, the clinical significance of these tissue concentration data is unknown. After a 1 gram dose of Imipenem and Cilastatin for Injection (I.V.), the following average levels of imipenem were measured (usually at 1 hour post dose except where indicated) in the tissues and fluids listed in Table 9 : Table 9: Average Levels of Imipenem Tissue or Fluid N Imipenem Level mcg/mL or mcg/g Range Vitreous Humor 3 3.4 (3.5 hours post dose) 2.88 to 3.6 Aqueous Humor 5 2.99 (2 hours post dose) 2.4 to 3.9 Lung Tissue 8 5.6 (median) 3.5 to 15.5 Sputum 1 2.1 — Pleural 1 22 — Peritoneal 12 23.9 S.D.±5.3 (2 hours post dose) — Bile 2 5.3 (2.25 hours post dose) 4.6 to 6 CSF (uninflamed) 5 1 (4 hours post dose) 0.26 to 2 CSF (inflamed) 7 2.6 (2 hours post dose) 0.5 to 5.5 Fallopian Tubes 1 13.6 — Endometrium 1 11.1 — Myometrium 1 5 — Bone 10 2.6 0.4 to 5.4 Interstitial Fluid 12 16.4 10 to 22.6 Skin 12 4.4 NA Fascia 12 4.4 NA Metabolism Imipenem, when administered alone, is metabolized in the kidneys by dehydropeptidase I, resulting in relatively low levels in urine. Cilastatin, an inhibitor of this enzyme, effectively prevents renal metabolism of imipenem so that when imipenem and cilastatin sodium are given concomitantly, adequate antibacterial levels of imipenem are achieved in the urine. Elimination The plasma half-life of each component is approximately 1 hour. Approximately 70% of the administered imipenem is recovered in the urine within 10 hours after which no further urinary excretion is detectable. Urine concentrations of imipenem in excess of 10 mcg/mL can be maintained for up to 8 hours with Imipenem and Cilastatin for Injection (I.V.) at the 500 mg dose. Approximately 70% of the cilastatin sodium dose is recovered in the urine within 10 hours of administration of Imipenem and Cilastatin for Injection (I.V.). Imipenem and Cilastatin for Injection (I.V.) is hemodialyzable [see Overdosage ( 10 )] . No accumulation of imipenem/cilastatin in plasma or urine is observed with regimens administered as frequently as every 6 hours in patients with normal renal function. Specific Populations Geriatric Patients In healthy elderly volunteers (65 to 75 years of age with normal renal function for their age), the pharmacokinetics of a single dose of imipenem 500 mg and cilastatin 500 mg administered intravenously over 20 minutes are consistent with those expected in subjects with slight renal impairment for which no dosage alteration is considered necessary. The mean plasma half-lives of imipenem and cilastatin are 91 ± 7 minutes and 69 ± 15 minutes, respectively. Multiple dosing has no effect on the pharmacokinetics of either imipenem or cilastatin, and no accumulation of imipenem/cilastatin is observed. Pediatric Patients Doses of 25 mg/kg/dose in patients 3 months to < 3 years of age, and 15 mg/kg/dose in patients 3 to 12 years of age were associated with mean trough plasma concentrations of imipenem of 1.1±0.4 mcg/mL and 0.6±0.2 mcg/mL following multiple 60-minute infusions, respectively; trough urinary concentrations of imipenem were in excess of 10 mcg/mL for both doses. These doses have provided adequate plasma and urine concentrations for the treatment of non-CNS infections. In a dose-ranging study of smaller premature infants (670 to 1,890 g) in the first week of life, a dose of 20 mg/kg q12h by 15 to 30 minutes infusion was associated with mean peak and trough plasma imipenem concentrations of 43 mcg/mL and 1.7 mcg/mL after multiple doses, respectively. However, moderate accumulation of cilastatin in neonates may occur following multiple doses of Imipenem and Cilastatin for Injection (I.V.). The safety of this accumulation is unknown.