LINEZOLID

Linezolid injection contains linezolid, which is a synthetic antibacterial agent of the oxazolidinone class. The chemical name for linezolid is ( S )- N -[[3-[3-Fluoro-4-(4-morpholinyl)phenyl]-2-oxo-5-oxazolidinyl] methyl]-acetamide. The empirical formula is C 16 H 20 FN 3 O 4 . Its molecular weight is 337.35, and its chemical structure is represented below: Linezolid injection is supplied as a ready-to-use sterile isotonic solution for intravenous infusion. Each container contains 600 mg of linezolid in 300 mL of a clear, colorless to slightly yellow aqueous solution. Inactive ingredients include: citric acid anhydrous USP 1.92 mg/mL, sodium chloride USP 9 mg/mL, sodium hydroxide NF 0.76 mg/mL, and water for injection USP. Sodium hydroxide NF and/or hydrochloric acid NF are used to adjust the pH. The sodium (Na + ) content is 3.98 mg/mL (52 mEq/300 mL container). Chemical Structure

Linezolid injection is an oxazolidinone-class antibacterial indicated in adults and children for the treatment of the following infections caused by susceptible Gram-positive bacteria: Nosocomial pneumonia ( 1.1 ); Community-acquired pneumonia ( 1.2 ); Complicated skin and skin structure infections, including diabetic foot infections, without concomitant osteomyelitis ( 1.3 ); Vancomycin-resistant Enterococcus faecium infections. ( 1.4 ) Limitations of Use: ( 1.5 ) • Linezolid injection is not indicated for the treatment of Gram-negative infections. • The safety and efficacy of Linezolid formulations given for longer than 28 days have not been evaluated in controlled clinical trials. To reduce the development of drug-resistant bacteria and maintain the effectiveness of Linezolid injection formulations and other antibacterial drugs, Linezolid injection should be used only to treat or prevent infections that are proven or strongly suspected to be caused by bacteria. ( 1.6 ) 1.1 Nosocomial Pneumonia Linezolid injection is indicated for the treatment of nosocomial pneumonia caused by Staphylococcus aureus (methicillin-susceptible and -resistant isolates) or Streptococcus pneumoniae [ see Clinical Studies (14) ]. 1.2 Community-acquired Pneumonia Linezolid injection is indicated for the treatment of community-acquired pneumonia caused by Streptococcus pneumoniae , including cases with concurrent bacteremia, or Staphylococcus aureus (methicillin-susceptible isolates only) [ see Clinical Studies (14) ]. 1.3 Complicated Skin and Skin Structure Infections Linezolid injection is indicated for the treatment of complicated skin and skin structure infections, including diabetic foot infections, without concomitant osteomyelitis, caused by Staphylococcus aureus (methicillin-susceptible and -resistant isolates), Streptococcus pyogenes , or Streptococcus agalactiae . Linezolid injection has not been studied in the treatment of decubitus ulcers [ see Clinical Studies (14) ]. 1.4 Vancomycin-resistant Enterococcus faecium Infections Linezolid injection is indicated for the treatment of vancomycin-resistant Enterococcus faecium infections, including cases with concurrent bacteremia [ see Clinical Studies (14) ]. 1.5 Limitations of Use • Linezolid injection is not indicated for the treatment of Gram-negative infections. It is critical that specific Gram-negative therapy be initiated immediately if a concomitant Gram-negative pathogen is documented or suspected [ see Warnings and Precautions (5.4) ]. • The safety and efficacy of Linezolid formulations given for longer than 28 days have not been evaluated in controlled clinical trials [ see Clinical Studies (14) ]. 1.6 Usage To reduce the development of drug-resistant bacteria and maintain the effectiveness of Linezolid injection and other antibacterial drugs, Linezolid 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.

Dosage, Route, and Frequency of Administration Infection Pediatric Patients (Birth through 11 Years of Age) Adults and Adolescents (12 Years and Older) Duration (days) Nosocomial pneumonia ( 1.1 ) 10 mg/kg intravenously every 8 hours 600 mg intravenously every 12 hours 10 to 14 Community-acquired pneumonia, including concurrent bacteremia ( 1.2 ) Complicated skin and skin structure infections ( 1.3 ) Vancomycin-resistant Enterococcus faecium infections, including concurrent bacteremia ( 1.4 ) 10 mg/kg intravenously every 8 hours 600 mg intravenously every 12 hours 14 to 28 • Pediatric Patients-The recommended dose is 10 mg per kg intravenously every 8 hours. Linezolid injection in a single-dose container should be used only in pediatric patients who require the entire 600 mg dose and not any fraction thereof. ( 2.1 ) 2.1 General Dosage and Administration The recommended dosage for Linezolid injection for the treatment of infections is described in Table 1. No dose adjustment is necessary when switching from intravenous to oral administration. Table 1. Dosage Guidelines for Linezolid Injection Dosage, Route, and Frequency of Administration Recommended Duration of Treatment (consecutive days) Infection Due to the designated pathogens [ see Indications and Usage (1) ] Pediatric Patients Neonates less than 7 days : Most pre-term neonates less than 7 days of age (gestational age less than 34 weeks) have lower systemic linezolid clearance values and larger AUC values than many full-term neonates and older infants. These neonates should be initiated with a dosing regimen of 10 mg/kg every 12 hours. Consideration may be given to the use of 10 mg/kg every 8 hours regimen in neonates with a sub-optimal clinical response. All neonatal patients should receive 10 mg/kg every 8 hours by 7 days of life [ see Use in Specific Populations (8.4) and Clinical Pharmacology (12.3) ] . (Birth through 11 Years of Age) Adults and Adolescents (12 Years and Older) Nosocomial pneumonia 10 mg/kg intravenously every 8 hours 600 mg intravenously every 12 hours 10 to 14 Community-acquired pneumonia, including concurrent bacteremia Complicated skin and skin structure infections Vancomycin-resistant Enterococcus faecium infections , including concurrent bacteremia 10 mg/kg intravenously every 8 hours 600 mg intravenously every 12 hours 14 to 28 The maximum dose for pediatric patients should not exceed the recommended adult dose. The recommended dose is 10 mg per kg intravenously every 8 hours. Linezolid injection in a single-dose container should be used only in pediatric patients who require the entire 600 mg dose and not any fraction thereof. 2.2 Intravenous Administration Linezolid injection is supplied in single-dose, ready-to-use container [ see How Supplied/Storage and Handling (16) ]. Parenteral drug products should be inspected visually for particulate matter prior to administration. Check for minute leaks by firmly squeezing the bag. If leaks are detected, discard the solution, as sterility may be impaired . Keep the containers in the overwrap until ready to use. Store at room temperature. Protect from freezing. Linezolid injection may exhibit a yellow color that can intensify over time without adversely affecting potency. Linezolid injection should be administered by intravenous infusion over a period of 30 to 120 minutes. Do not use this intravenous container in series connections . Additives should not be introduced into this solution. If Linezolid injection is to be given concomitantly with another drug, each drug should be given separately in accordance with the recommended dosage and route of administration for each product. Discard unused portion. If the same intravenous line is used for sequential infusion of several drugs, the line should be flushed before and after infusion of Linezolid injection with an infusion solution compatible with Linezolid injection and with any other drug(s) administered via this common line. 2.3 Compatibilities Compatible intravenous solutions include 0.9% Sodium Chloride Injection, USP, 5% Dextrose Injection, USP, and Lactated Ringer's Injection, USP. 2.4 Incompatibilities Physical incompatibilities resulted when Linezolid injection was combined with the following drugs during simulated Y-site administration: amphotericin B, chlorpromazine HCl, diazepam, pentamidine isothionate, erythromycin lactobionate, phenytoin sodium, and trimethoprim-sulfamethoxazole. Additionally, chemical incompatibility resulted when Linezolid injection was combined with ceftriaxone sodium.

• Known hypersensitivity to linezolid or any of the other product components. ( 4.1 ) • Patients taking any monoamine oxidase inhibitors (MAOI) or within two weeks of taking an MAOI. ( 4.2 ) 4.1 Hypersensitivity Linezolid injection is contraindicated for use in patients who have known hypersensitivity to linezolid or any of the other product components . 4.2 Monoamine Oxidase Inhibitors Linezolid should not be used in patients taking any medicinal product which inhibits monoamine oxidases A or B (e.g., phenelzine, isocarboxazid) or within two weeks of taking any such medicinal product.

The following clinically significant adverse reactions are described elsewhere in the labeling: • Myelosuppression [ see Warnings and Precautions (5.1) ] • Peripheral and Optic Neuropathy [ see Warnings and Precautions (5.2) ] • Serotonin Syndrome [ see Warnings and Precautions (5.3) ] • Clostridioides difficile -Associated Diarrhea [ see Warnings and Precautions (5.5) ] • Lactic Acidosis [ see Warnings and Precautions (5.7) ] • Convulsions [ see Warnings and Precautions (5.8) ] • Rhabdomyolysis [ see Warnings and Precautions (5.9) ] • Hypoglycemia [ see Warnings and Precautions (5.10) ] • Hyponatremia and/or Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) [ see Warnings and Precautions (5.11) ] Most common adverse reactions (>5% of adult and pediatric patients treated with Linezolid injection) include: diarrhea, vomiting, headache, nausea, and anemia. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Pfizer Inc. at 1-800-438-1985, 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. Adults The safety of linezolid formulations was evaluated in 2,046 adult patients enrolled in seven Phase 3 comparator-controlled clinical trials, who were treated for up to 28 days. For all indications, 20.4% of linezolid-treated and 14.3% of comparator-treated patients experienced at least one drug-related adverse event. Table 2 shows the incidence of all-causality, treatment-emergent adverse reactions reported in at least 1% of adult patients in these trials by dose of linezolid. Table 2. Incidence (%) Treatment-Emergent Adverse Reactions Occurring in greater than 1% of Adult Patients Treated with Linezolid in Comparator-Controlled Clinical Trials ADVERSE REACTIONS Linezolid 600 mg every 12 hours (n = 1498) All Other Comparators Comparators included cefpodoxime proxetil 200 mg by mouth every 12 hours; ceftriaxone 1 g intravenously every 12 hours; dicloxacillin 500 mg by mouth every 6 hours; oxacillin 2 g intravenously every 6 hours; vancomycin 1 g intravenously every 12 hours. (n = 1464) Headache 5.7 4.4 Diarrhea 8.3 6.4 Nausea 6.6 4.6 Vomiting 4.3 2.3 Dizziness 1.8 1.5 Rash 2.3 2.6 Anemia 2.1 1.4 Taste alteration 1.0 0.3 Vaginal moniliasis 1.1 0.5 Oral moniliasis 1.7 1.0 Abnormal liver function tests 1.6 0.8 Fungal infection 0.3 0.2 Tongue discoloration 0.3 0 Localized abdominal pain 1.2 0.8 Generalized abdominal pain 1.2 1.0 Discontinuations due to drug-related adverse events occurred in 2.1% of linezolid-treated and 1.7% of comparator-treated patients. The most common reported drug-related adverse events leading to discontinuation of treatment were nausea, headache, diarrhea, and vomiting. Pediatric Patients The safety of linezolid formulations was evaluated in 215 pediatric patients ranging in age from birth through 11 years, and in 248 pediatric patients aged 5 through 17 years (146 of these 248 were age 5 through 11 and 102 were age 12 to 17). These patients were enrolled in two Phase 3 comparator-controlled clinical trials and were treated for up to 28 days. In the study of hospitalized pediatric patients (birth through 11 years) with Gram-positive infections, who were randomized 2 to 1 (linezolid: vancomycin), mortality was 6.0% (13/215) in the linezolid arm and 3.0% (3/101) in the vancomycin arm. However, given the severe underlying illness in the patient population, no causality could be established. For all indications, 18.8% of linezolid-treated and 34.3% of comparator-treated patients experienced at least one drug-related adverse event. Table 3 shows the incidence of all-causality, treatment-emergent adverse reactions reported in more than 1% of pediatric patients (and more than 1 patient) in either treatment group in the comparator-controlled Phase 3 trials. Table 3. Incidence (%) of Treatment-Emergent Adverse Reactions Occurring in greater than 1% of Pediatric Patients (and greater than 1 Patient) in Either Treatment Group in Comparator-Controlled Clinical Trials Patients from birth through 11 years of age received linezolid 10 mg/kg intravenously and/or by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6–24 hours, depending on age and renal clearance. ADVERSE REACTIONS Linezolid (n = 215) Vancomycin (n = 101) Diarrhea 10.8 12.1 Vomiting 9.4 9.1 Headache 0.9 0 Anemia 5.6 7.1 Thrombocytopenia 4.7 2.0 Nausea 1.9 0 Generalized abdominal pain 0.9 2.0 Localized abdominal pain 0.5 1.0 Loose stools 2.3 3.0 Eosinophilia 1.9 1.0 Pruritus at non-application site 1.4 2.0 Vertigo 0 0 For all indications, discontinuations due to drug-related adverse events occurred in 0.9% of linezolid-treated and 6.1% of comparator-treated patients. Laboratory Abnormalities Linezolid has been associated with thrombocytopenia when used in doses up to and including 600 mg every 12 hours for up to 28 days. In Phase 3 comparator-controlled trials, the percentage of adult patients who developed a substantially low platelet count (defined as less than 75% of lower limit of normal and/or baseline) was 2.4% (range among studies: 0.3 to 10.0%) with linezolid and 1.5% (range among studies: 0.4 to 7.0%) with a comparator. In a study of hospitalized pediatric patients ranging in age from birth through 11 years, the percentage of patients who developed a substantially low platelet count (defined as less than 75% of lower limit of normal and/or baseline) was 12.9% with linezolid and 13.4% with vancomycin. In an outpatient study of pediatric patients aged from 5 through 17 years, the percentage of patients who developed a substantially low platelet count was 0% with linezolid and 0.4% with cefadroxil. Thrombocytopenia associated with the use of linezolid appears to be dependent on duration of therapy (generally greater than 2 weeks of treatment). The platelet counts for most patients returned to the normal range/baseline during the follow-up period. No related clinical adverse events were identified in Phase 3 clinical trials in patients developing thrombocytopenia. Bleeding events were identified in thrombocytopenic patients in a compassionate use program for linezolid; the role of linezolid in these events cannot be determined [ see Warnings and Precautions (5.1) ]. Changes seen in other laboratory parameters, without regard to drug relationship, revealed no substantial differences between linezolid and the comparators. These changes were generally not clinically significant, did not lead to discontinuation of therapy, and were reversible. The incidence of adult and pediatric patients with at least one substantially abnormal hematologic or serum chemistry value is presented in Tables 4, 5, 6, and 7. Table 4. Percent of Adult Patients who Experienced at Least One Substantially Abnormal Less than 75% (less than 50% for neutrophils) of Lower Limit of Normal (LLN) for values normal at baseline; less than 75% (less than 50% for neutrophils) of LLN and of baseline for values abnormal at baseline. Hematology Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Laboratory Assay Linezolid 600 mg every 12 hours All Other Comparators Comparators included cefpodoxime proxetil 200 mg by mouth every 12 hours; ceftriaxone 1 g intravenously every 12 hours; dicloxacillin 500 mg by mouth every 6 hours; oxacillin 2 g intravenously every 6 hours; vancomycin 1 g intravenously every 12 hours. Hemoglobin (g/dL) 7.1 6.6 Platelet count (× 10 3 /mm 3 ) 3.0 1.8 WBC (× 10 3 /mm 3 ) 2.2 1.3 Neutrophils (× 10 3 /mm 3 ) 1.1 1.2 Table 5. Percent of Adult Patients who Experienced at Least One Substantially Abnormal Greater than 2× Upper Limit of Normal (ULN) for values normal at baseline; greater than 2× ULN and greater than 2× baseline for values abnormal at baseline. Serum Chemistry Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Laboratory Assay Linezolid 600 mg every 12 hours All Other Comparators Comparators included cefpodoxime proxetil 200 mg by mouth every 12 hours; ceftriaxone 1 g intravenously every 12 hours; dicloxacillin 500 mg by mouth every 6 hours; oxacillin 2 g intravenously every 6 hours; vancomycin 1 g intravenously every 12 hours. AST (U/L) 5.0 6.8 ALT (U/L) 9.6 9.3 LDH (U/L) 1.8 1.5 Alkaline phosphatase (U/L) 3.5 3.1 Lipase (U/L) 4.3 4.2 Amylase (U/L) 2.4 2.0 Total bilirubin (mg/dL) 0.9 1.1 BUN (mg/dL) 2.1 1.5 Creatinine (mg/dL) 0.2 0.6 Table 6. Percent of Pediatric Patients who Experienced at Least One Substantially Abnormal Less than 75% ( less than 50% for neutrophils) of Lower Limit of Normal (LLN) for values normal at baseline; less than 75% (less than 50% for neutrophils) of LLN and less than 75% (less than 50% for neutrophils, less than 90% for hemoglobin if baseline less than LLN) of baseline for values abnormal at baseline. Hematology Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Patients from birth through 11 years of age received linezolid 10 mg/kg intravenously and/or by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6–24 hours, depending on age and renal clearance. Laboratory Assay Linezolid Vancomycin Hemoglobin (g/dL) 15.7 12.4 Platelet count (× 10 3 /mm 3 ) 12.9 13.4 WBC (× 10 3 /mm 3 ) 12.4 10.3 Neutrophils (× 10 3 /mm 3 ) 5.9 4.3 Table 7. Percent of Pediatric Patients who Experienced at Least One Substantially Abnormal Greater than 2 × Upper Limit of Normal (ULN) for values normal at baseline; greater than 2× ULN and greater than 2 (greater than 1.5 for total bilirubin) × baseline for values abnormal at baseline. Serum Chemistry Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Patients from birth through 11 years of age received linezolid 10 mg/kg intravenously and/or by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6–24 hours, depending on age and renal clearance. Laboratory Assay Linezolid Vancomycin ALT (U/L) 10.1 12.5 Lipase (U/L) --- --- Amylase (U/L) 0.6 1.3 Total bilirubin (mg/dL) 6.3 5.2 Creatinine (mg/dL) 2.4 1.0 6.2 Postmarketing Experience The following adverse reactions have been identified during post-approval use of linezolid. 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: • Anaphylaxis, angioedema, bullous skin disorders including severe cutaneous adverse reactions (SCAR) such as toxic epidermal necrolysis and Stevens-Johnson syndrome, and hypersensitivity vasculitis. • Myelosuppression (including anemia, leukopenia, pancytopenia, and thrombocytopenia). Thrombocytopenia has been reported more often in patients with severe renal impairment and in patients with moderate to severe hepatic impairment [ see Warnings and Precautions (5.1) ]; sideroblastic anemia. • Peripheral neuropathy, and optic neuropathy sometimes progressing to loss of vision [ see Warnings and Precautions (5.2) ]. • Serotonin syndrome has been reported in patients receiving concomitant serotonergic agents, including antidepressants such as selective serotonin reuptake inhibitors (SSRIs) and opioids, and linezolid [ see Warnings and Precautions (5.3) ]. • Lactic acidosis [ see Warnings and Precautions (5.7) ]. Although these reports have primarily been in patients treated for longer than the maximum recommended duration of 28 days, these events have also been reported in patients receiving shorter courses of therapy. • Convulsions [ see Warnings and Precautions (5.8) ]. • Rhabdomyolysis [ see Warnings and Precautions (5.9) ]. • Hypoglycemia, including symptomatic episodes [ see Warnings and Precautions (5.10) ]. • Hyponatremia and/or Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) [ see Warnings and Precautions (5.11) ]. • Superficial tooth discoloration and tongue discoloration have been reported with the use of linezolid. The tooth discoloration was removable with professional dental cleaning (manual descaling) in cases with known outcome.

Monoamine oxidase inhibitors and potential for interaction with adrenergic and serotonergic agents. ( 4.2 , 5.3 , 5.6 , 7 , 12.3 ) 7.1 Monoamine Oxidase Inhibitors Linezolid is a reversible, nonselective inhibitor of monoamine oxidase [ see Contraindications (4.2) and Clinical Pharmacology (12.3) ]. 7.2 Adrenergic and Serotonergic Agents Linezolid has the potential for interaction with adrenergic and serotonergic agents [ see Warnings and Precautions (5.3 , 5.6) and Clinical Pharmacology (12.3) ].

Store at 20 to 25°C (68 to 77°F), excursions permitted to 15 to 30°C (59 to 86°F) [see USP Controlled Room Temperature]. Protect from light. It is recommended that the containers be kept in the overwrap until ready to use. Protect containers from freezing.