Linezolid

1 INDICATIONS AND USAGE Linezolid injection is indicated for the treatment of infections caused by susceptible strains of the designated microorganisms in the specific conditions listed below. 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 ) ]. 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 ( 1.1 ); Complicated skin and skin structure infections, including diabetic foot infections, without concomitant osteomyelitis ( 1.2 ); Uncomplicated skin and skin structure infections ( 1.2 ); Vancomycin-resistant Enterococcus faecium infections. ( 1.3 ) To reduce the development of drug-resistant bacteria and maintain the effectiveness of linezolid 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. ( 1.4 ) 1.1 Pneumonia Nosocomial pneumonia caused by Staphylococcus aureus (methicillin-susceptible and -resistant isolates) or Streptococcus pneumoniae [ see Clinical Studies ( 14 ) ]. Community-acquired pneumonia caused by Streptococcus pneumoniae , including cases with concurrent bacteremia, or Staphylococcus aureus (methicillin-susceptible isolates only) [ see Clinical Studies ( 14 ) ]. 1.2 Skin and Skin Structure Infections 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 ) ]. Uncomplicated skin and skin structure infections caused by Staphylococcus aureus (methicillin-susceptible isolates only) or Streptococcus pyogenes [ see Clinical Studies ( 14 ) ]. 1.3 Vancomycin-resistant Enterococcus faecium Infections Vancomycin-resistant Enterococcus faecium infections , including cases with concurrent bacteremia [ see Clinical Studies ( 14 ) ]. 1.4 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. The safety and efficacy of linezolid injection given for longer than 28 days have not been evaluated in controlled clinical trials. 1.1 Pneumonia Nosocomial pneumonia caused by Staphylococcus aureus (methicillin-susceptible and -resistant isolates) or Streptococcus pneumoniae [ see Clinical Studies ( 14 ) ]. Community-acquired pneumonia caused by Streptococcus pneumoniae , including cases with concurrent bacteremia, or Staphylococcus aureus (methicillin-susceptible isolates only) [ see Clinical Studies ( 14 ) ]. 1.2 Skin and Skin Structure Infections 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 ) ]. Uncomplicated skin and skin structure infections caused by Staphylococcus aureus (methicillin-susceptible isolates only) or Streptococcus pyogenes [ see Clinical Studies ( 14 ) ]. 1.3 Vancomycin-resistant Enterococcus faecium Infections Vancomycin-resistant Enterococcus faecium infections , including cases with concurrent bacteremia [ see Clinical Studies ( 14 ) ]. 1.4 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. The safety and efficacy of linezolid injection given for longer than 28 days have not been evaluated in controlled clinical trials.

2 DOSAGE AND ADMINISTRATION Dosage, Route, and Frequency of Administration Infection Pediatric Patients Adults and Adolescents Duration (days ) Nosocomial pneumonia 10 mg/kg intravenous or oral every 8 hours 600 mg intravenous or oral 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 intravenous or oral every 8 hours 600 mg intravenous or oral every 12 hours 14 to 28 Uncomplicated skin and skin structure infections Less than 5 yrs: 10 mg/kg oral every 8 hours 5 to 11 yrs: 10 mg/kg oral every 12 hours Adults: 400 mg oral every 12 hours Adolescents: 600 mg oral every 12 hours 10 to 14 2.1 General Dosage and Administration The recommended dosage for linezolid formulations for the treatment of infections is described in Table 1. Table 1. Dosage Guidelines for Linezolid Infection* Dosage and Route of Administration Recommended Duration of Treatment (consecutive days) Pediatric Patients † (Birth through 11 Years of Age) Adults and Adolescents (12 Years and Older) Nosocomial pneumonia 10 mg/kg intravenously or oral ‡ every 8 hours 600 mg intravenously or oral ‡ 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 or oral ‡ every 8 hours 600 mg intravenously or oral ‡ every 12 hours 14 to 28 Uncomplicated skin and skin structure infections Less than 5 yrs: 10 mg/kg oral ‡ every 8 hours 5 to 11 yrs: 10 mg/kg oral ‡ every 12 hours Adults: 400 mg oral ‡ every 12 hours Adolescents: 600 mg oral ‡ every 12 hours 10 to 14 * Due to the designated pathogens [ see Indications and Usage ( 1 ) ]. † 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 ) ]. ‡ Oral dosing using either linezolid tablets or linezolid for oral suspension. No dose adjustment is necessary when switching from intravenous to oral administration. 2.2 Intravenous Administration Linezolid injection is supplied in single-use, ready-to-use flexible plastic containers. Parenteral drug products should be inspected visually for particulate matter prior to administration. Check for leakage by squeezing container firmly. If any leakage, discard solution as sterility may be impaired . Keep the infusion bag 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 flexible plastic 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. 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, 5% Dextrose Injection, and Lactated Ringer’s Injection. 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. 2.1 General Dosage and Administration The recommended dosage for linezolid formulations for the treatment of infections is described in Table 1. Table 1. Dosage Guidelines for Linezolid Infection* Dosage and Route of Administration Recommended Duration of Treatment (consecutive days) Pediatric Patients † (Birth through 11 Years of Age) Adults and Adolescents (12 Years and Older) Nosocomial pneumonia 10 mg/kg intravenously or oral ‡ every 8 hours 600 mg intravenously or oral ‡ 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 or oral ‡ every 8 hours 600 mg intravenously or oral ‡ every 12 hours 14 to 28 Uncomplicated skin and skin structure infections Less than 5 yrs: 10 mg/kg oral ‡ every 8 hours 5 to 11 yrs: 10 mg/kg oral ‡ every 12 hours Adults: 400 mg oral ‡ every 12 hours Adolescents: 600 mg oral ‡ every 12 hours 10 to 14 * Due to the designated pathogens [ see Indications and Usage ( 1 ) ]. † 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 ) ]. ‡ Oral dosing using either linezolid tablets or linezolid for oral suspension. No dose adjustment is necessary when switching from intravenous to oral administration. 2.2 Intravenous Administration Linezolid injection is supplied in single-use, ready-to-use flexible plastic containers. Parenteral drug products should be inspected visually for particulate matter prior to administration. Check for leakage by squeezing container firmly. If any leakage, discard solution as sterility may be impaired . Keep the infusion bag 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 flexible plastic 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. 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, 5% Dextrose Injection, and Lactated Ringer’s Injection. 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.

4 CONTRAINDICATIONS 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 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. 4.1 Hypersensitivity Linezolid 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.

5 WARNINGS AND PRECAUTIONS Myelosuppression: Monitor complete blood counts weekly. Consider discontinuation in patients who develop or have worsening myelosuppression. ( 5.1 ) Peripheral and optic neuropathy: Reported primarily in patients treated for longer than 28 days. If patients experience symptoms of visual impairment, prompt ophthalmic evaluation is recommended. ( 5.2 ) Serotonin syndrome: Patients taking serotonergic antidepressants should receive linezolid only if no other therapies are available. Discontinue serotonergic antidepressants and monitor patients for signs and symptoms of both serotonin syndrome and antidepressant discontinuation. ( 5.3 ) A mortality imbalance was seen in an investigational study in linezolid-treated patients with catheter-related bloodstream infections. ( 5.4 ) Clostridium difficile associated diarrhea: Evaluate if diarrhea occurs. ( 5.5 ) Potential interactions producing elevation of blood pressure: monitor blood pressure. ( 5.6 ) Hypoglycemia: Postmarketing cases of symptomatic hypoglycemia have been reported in patients with diabetes mellitus receiving insulin or oral hypoglycemic agents. ( 5.9 ) 5.1 Myelosuppression Myelosuppression (including anemia, leukopenia, pancytopenia, and thrombocytopenia) has been reported in patients receiving linezolid. In cases where the outcome is known, when linezolid was discontinued, the affected hematologic parameters have risen toward pretreatment levels. Complete blood counts should be monitored weekly in patients who receive linezolid, particularly in those who receive linezolid for longer than two weeks, those with pre-existing myelosuppression, those receiving concomitant drugs that produce bone marrow suppression, or those with a chronic infection who have received previous or concomitant antibiotic therapy. Discontinuation of therapy with linezolid should be considered in patients who develop or have worsening myelosuppression . 5.2 Peripheral and Optic Neuropathy Peripheral and optic neuropathies have been reported in patients treated with linezolid, primarily in those patients treated for longer than the maximum recommended duration of 28 days. In cases of optic neuropathy that progressed to loss of vision, patients were treated for extended periods beyond the maximum recommended duration. Visual blurring has been reported in some patients treated with linezolid for less than 28 days. Peripheral and optic neuropathy has also been reported in children. If patients experience symptoms of visual impairment, such as changes in visual acuity, changes in color vision, blurred vision, or visual field defect, prompt ophthalmic evaluation is recommended. Visual function should be monitored in all patients taking linezolid for extended periods (≥ 3 months) and in all patients reporting new visual symptoms regardless of length of therapy with linezolid. If peripheral or optic neuropathy occurs, the continued use of linezolid in these patients should be weighed against the potential risks. 5.3 Serotonin Syndrome Spontaneous reports of serotonin syndrome including fatal cases associated with the co-administration of linezolid and serotonergic agents, including antidepressants such as selective serotonin reuptake inhibitors (SSRIs), have been reported. Unless clinically appropriate and patients are carefully observed for signs and/or symptoms of serotonin syndrome or neuroleptic malignant syndrome-like (NMS-like) reactions, linezolid should not be administered to patients with carcinoid syndrome and/or patients taking any of the following medications: serotonin re-uptake inhibitors, tricyclic antidepressants, serotonin 5-HT1 receptor agonists (triptans), meperidine, bupropion, or buspirone [ see Drug Interactions ( 7 ) and Clinical Pharmacology ( 12.3 ) ]. In some cases, a patient already receiving a serotonergic antidepressant or buspirone may require urgent treatment with linezolid. If alternatives to linezolid are not available and the potential benefits of linezolid outweigh the risks of serotonin syndrome or NMS-like reactions, the serotonergic antidepressant should be stopped promptly and linezolid administered. The patient should be monitored for two weeks (five weeks if fluoxetine was taken) or until 24 hours after the last dose of linezolid, whichever comes first. Symptoms of serotonin syndrome or NMS-like reactions include hyperthermia, rigidity, myoclonus, autonomic instability, and mental status changes that include extreme agitation progressing to delirium and coma. The patient should also be monitored for discontinuation symptoms of the antidepressant (see package insert of the specified agent(s) for a description of the associated discontinuation symptoms). 5.4 Mortality Imbalance in an Investigational Study in Patients with Catheter-Related Bloodstream Infections, including those with catheter-site infections An imbalance in mortality was seen in patients treated with linezolid relative to vancomycin/dicloxacillin/oxacillin in an open-label study in seriously ill patients with intravascular catheter-related infections [78/363 (21.5%) vs. 58/363 (16%); odds ratio 1.426, 95% CI 0.970, 2.098]. While causality has not been established, this observed imbalance occurred primarily in linezolid-treated patients in whom either Gram-negative pathogens, mixed Gram-negative and Gram-positive pathogens, or no pathogen were identified at baseline, but was not seen in patients with Gram-positive infections only. Linezolid is not approved and should not be used for the treatment of patients with catheter-related bloodstream infections or catheter-site infections. Linezolid has no clinical activity against Gram-negative pathogens and 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 Indications and Usage ( 1 ) ]. 5.5 Clostridium difficile Associated Diarrhea Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including linezolid, 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 strains 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 antibiotic 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 antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile , and surgical evaluation should be instituted as clinically indicated. 5.6 Potential Interactions Producing Elevation of Blood Pressure Unless patients are monitored for potential increases in blood pressure, linezolid should not be administered to patients with uncontrolled hypertension, pheochromocytoma, thyrotoxicosis and/or patients taking any of the following types of medications: directly and indirectly acting sympathomimetic agents (e.g., pseudoephedrine), vasopressive agents (e.g., epinephrine, norepinephrine), dopaminergic agents (e.g., dopamine, dobutamine) [ see Drug Interactions ( 7 ) and Clinical Pharmacology ( 12.3 ) ]. 5.7 Lactic Acidosis Lactic acidosis has been reported with the use of linezolid. In reported cases, patients experienced repeated episodes of nausea and vomiting. Patients who develop recurrent nausea or vomiting, unexplained acidosis, or a low bicarbonate level while receiving linezolid should receive immediate medical evaluation. 5.8 Convulsions Convulsions have been reported in patients when treated with linezolid. In some of these cases, a history of seizures or risk factors for seizures was reported. 5.9 Hypoglycemia Postmarketing cases of symptomatic hypoglycemia have been reported in patients with diabetes mellitus receiving insulin or oral hypoglycemic agents when treated with linezolid, a reversible, nonselective MAO inhibitor. Some MAO inhibitors have been associated with hypoglycemic episodes in diabetic patients receiving insulin or hypoglycemic agents. While a causal relationship between linezolid and hypoglycemia has not been established, diabetic patients should be cautioned of potential hypoglycemic reactions when treated with linezolid. If hypoglycemia occurs, a decrease in the dose of insulin or oral hypoglycemic agent, or discontinuation of oral hypoglycemic agent, insulin, or linezolid may be required. 5.10 Development of Drug-Resistant Bacteria Prescribing linezolid in the absence of a 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. 5.1 Myelosuppression Myelosuppression (including anemia, leukopenia, pancytopenia, and thrombocytopenia) has been reported in patients receiving linezolid. In cases where the outcome is known, when linezolid was discontinued, the affected hematologic parameters have risen toward pretreatment levels. Complete blood counts should be monitored weekly in patients who receive linezolid, particularly in those who receive linezolid for longer than two weeks, those with pre-existing myelosuppression, those receiving concomitant drugs that produce bone marrow suppression, or those with a chronic infection who have received previous or concomitant antibiotic therapy. Discontinuation of therapy with linezolid should be considered in patients who develop or have worsening myelosuppression . 5.2 Peripheral and Optic Neuropathy Peripheral and optic neuropathies have been reported in patients treated with linezolid, primarily in those patients treated for longer than the maximum recommended duration of 28 days. In cases of optic neuropathy that progressed to loss of vision, patients were treated for extended periods beyond the maximum recommended duration. Visual blurring has been reported in some patients treated with linezolid for less than 28 days. Peripheral and optic neuropathy has also been reported in children. If patients experience symptoms of visual impairment, such as changes in visual acuity, changes in color vision, blurred vision, or visual field defect, prompt ophthalmic evaluation is recommended. Visual function should be monitored in all patients taking linezolid for extended periods (≥ 3 months) and in all patients reporting new visual symptoms regardless of length of therapy with linezolid. If peripheral or optic neuropathy occurs, the continued use of linezolid in these patients should be weighed against the potential risks. 5.3 Serotonin Syndrome Spontaneous reports of serotonin syndrome including fatal cases associated with the co-administration of linezolid and serotonergic agents, including antidepressants such as selective serotonin reuptake inhibitors (SSRIs), have been reported. Unless clinically appropriate and patients are carefully observed for signs and/or symptoms of serotonin syndrome or neuroleptic malignant syndrome-like (NMS-like) reactions, linezolid should not be administered to patients with carcinoid syndrome and/or patients taking any of the following medications: serotonin re-uptake inhibitors, tricyclic antidepressants, serotonin 5-HT1 receptor agonists (triptans), meperidine, bupropion, or buspirone [ see Drug Interactions ( 7 ) and Clinical Pharmacology ( 12.3 ) ]. In some cases, a patient already receiving a serotonergic antidepressant or buspirone may require urgent treatment with linezolid. If alternatives to linezolid are not available and the potential benefits of linezolid outweigh the risks of serotonin syndrome or NMS-like reactions, the serotonergic antidepressant should be stopped promptly and linezolid administered. The patient should be monitored for two weeks (five weeks if fluoxetine was taken) or until 24 hours after the last dose of linezolid, whichever comes first. Symptoms of serotonin syndrome or NMS-like reactions include hyperthermia, rigidity, myoclonus, autonomic instability, and mental status changes that include extreme agitation progressing to delirium and coma. The patient should also be monitored for discontinuation symptoms of the antidepressant (see package insert of the specified agent(s) for a description of the associated discontinuation symptoms). 5.4 Mortality Imbalance in an Investigational Study in Patients with Catheter-Related Bloodstream Infections, including those with catheter-site infections An imbalance in mortality was seen in patients treated with linezolid relative to vancomycin/dicloxacillin/oxacillin in an open-label study in seriously ill patients with intravascular catheter-related infections [78/363 (21.5%) vs. 58/363 (16%); odds ratio 1.426, 95% CI 0.970, 2.098]. While causality has not been established, this observed imbalance occurred primarily in linezolid-treated patients in whom either Gram-negative pathogens, mixed Gram-negative and Gram-positive pathogens, or no pathogen were identified at baseline, but was not seen in patients with Gram-positive infections only. Linezolid is not approved and should not be used for the treatment of patients with catheter-related bloodstream infections or catheter-site infections. Linezolid has no clinical activity against Gram-negative pathogens and 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 Indications and Usage ( 1 ) ]. 5.5 Clostridium difficile Associated Diarrhea Clostridium difficile associated diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including linezolid, 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 strains 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 antibiotic 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 antibiotic use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile , and surgical evaluation should be instituted as clinically indicated. 5.6 Potential Interactions Producing Elevation of Blood Pressure Unless patients are monitored for potential increases in blood pressure, linezolid should not be administered to patients with uncontrolled hypertension, pheochromocytoma, thyrotoxicosis and/or patients taking any of the following types of medications: directly and indirectly acting sympathomimetic agents (e.g., pseudoephedrine), vasopressive agents (e.g., epinephrine, norepinephrine), dopaminergic agents (e.g., dopamine, dobutamine) [ see Drug Interactions ( 7 ) and Clinical Pharmacology ( 12.3 ) ]. 5.7 Lactic Acidosis Lactic acidosis has been reported with the use of linezolid. In reported cases, patients experienced repeated episodes of nausea and vomiting. Patients who develop recurrent nausea or vomiting, unexplained acidosis, or a low bicarbonate level while receiving linezolid should receive immediate medical evaluation. 5.8 Convulsions Convulsions have been reported in patients when treated with linezolid. In some of these cases, a history of seizures or risk factors for seizures was reported. 5.9 Hypoglycemia Postmarketing cases of symptomatic hypoglycemia have been reported in patients with diabetes mellitus receiving insulin or oral hypoglycemic agents when treated with linezolid, a reversible, nonselective MAO inhibitor. Some MAO inhibitors have been associated with hypoglycemic episodes in diabetic patients receiving insulin or hypoglycemic agents. While a causal relationship between linezolid and hypoglycemia has not been established, diabetic patients should be cautioned of potential hypoglycemic reactions when treated with linezolid. If hypoglycemia occurs, a decrease in the dose of insulin or oral hypoglycemic agent, or discontinuation of oral hypoglycemic agent, insulin, or linezolid may be required. 5.10 Development of Drug-Resistant Bacteria Prescribing linezolid in the absence of a 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.

7 DRUG INTERACTIONS 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 ) ]. 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 ) ].

6 ADVERSE REACTIONS Most common adverse reactions (> 5% of adult and/or pediatric patients treated with linezolid) include: diarrhea, vomiting, headache, nausea, and anemia. ( 6 ) To report SUSPECTED ADVERSE REACTIONS, contact Fresenius Kabi USA, LLC, Vigilance & Medical Affairs 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. 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. Of the patients treated for uncomplicated skin and skin structure infections (uSSSIs), 25.4% of linezolid-treated and 19.6% of comparator-treated patients experienced at least one drug-related adverse event. For all other 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 (%) of Treatment–Emergent Adverse Reactions Occurring in > 1% of Adult Patients Treated with Linezolid in Comparator-Controlled Clinical Trials ADVERSE REACTIONS Uncomplicated Skin and Skin Structure Infections All Other Indications Linezolid 400 mg by mouth every 12 hours (n=548) Clarithromycin 250 mg by mouth every 12 hours (n=537) Linezolid 600 mg every 12 hours (n=1,498) All Other Comparators* (n=1,464) Headache 8.8 8.4 5.7 4.4 Diarrhea 8.2 6.1 8.3 6.4 Nausea 5.1 4.5 6.6 4.6 Vomiting 2 1.5 4.3 2.3 Dizziness 2.6 3 1.8 1.5 Rash 1.1 1.1 2.3 2.6 Anemia 0.4 0 2.1 1.4 Taste alteration 1.8 2 1 0.3 Vaginal moniliasis 1.8 1.3 1.1 0.5 Oral moniliasis 0.5 0 1.7 1 Abnormal liver function tests 0.4 0.2 1.6 0.8 Fungal infection 1.5 0.2 0.3 0.2 Tongue discoloration 1.3 0 0.3 0 Localized abdominal pain 1.3 0.6 1.2 0.8 Generalized abdominal pain 0.9 0.4 1.2 1 * 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. Of the patients treated for uSSSIs, 3.5% of linezolid-treated and 2.4% of comparator-treated patients discontinued treatment due to drug-related adverse events. For all other indications, 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% (13/215) in the linezolid arm and 3% (3/101) in the vancomycin arm. However, given the severe underlying illness in the patient population, no causality could be established. Of the pediatric patients treated for uSSSIs, 19.2% of linezolid-treated and 14.1% of comparator-treated patients experienced at least one drug-related adverse event. For all other 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 > 1% of Pediatric Patients (and > 1 Patient) in Either Treatment Group in Comparator-Controlled Clinical Trials ADVERSE REACTIONS Uncomplicated Skin and Skin Structure Infections* All Other Indications † Linezolid (n=248) Cefadroxil (n=251) Linezolid (n=215) Vancomycin (n=101) Diarrhea 7.8 8 10.8 12.1 Vomiting 2.9 6.4 9.4 9.1 Headache 6.5 4 0.9 0 Anemia 0 0 5.6 7.1 Thrombocytopenia 0 0 4.7 2 Nausea 3.7 3.2 1.9 0 Generalized abdominal pain 2.4 2.8 0.9 2 Localized abdominal pain 2.4 2.8 0.5 1 Loose stools 1.6 0.8 2.3 3 Eosinophilia 0.4 0.8 1.9 1 Pruritus at non-application site 0.8 0.4 1.4 2 Vertigo 1.2 0.4 0 0 * Patients 5 through 11 years of age received linezolid 10 mg/kg by mouth every 12 hours or cefadroxil 15 mg/kg by mouth every 12 hours. Patients 12 years or older received linezolid 600 mg by mouth every 12 hours or cefadroxil 500 mg by mouth every 12 hours. † Patients from birth through 11 years of age received linezolid 10 mg/kg intravenously by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6 to 24 hours, depending on age and renal clearance. Of the pediatric patients treated for uSSSIs, 1.6% of linezolid-treated and 2.4% of comparator-treated patients discontinued treatment due to drug-related adverse events. For all other 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%) with linezolid and 1.5% (range among studies: 0.4 to 7%) 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 Warning 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* Hematology Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Laboratory Assay Uncomplicated Skin and Skin Structure Infections All Other Indications Linezolid 400 mg every 12 hours Clarithromycin 250 mg every 12 hours Linezolid 600 mg every 12 hours All Other Comparators † Hemoglobin (g/dL) 0.9 0 7.1 6.6 Platelet count (x 10 3 /mm 3 ) 0.7 0.8 3 1.8 WBC (x 10 3 /mm 3 ) 0.2 0.6 2.2 1.3 Neutrophils (x 10 3 /mm 3 ) 0 0.2 1.1 1.2 * < 75% (< 50% for neutrophils) of Lower Limit of Normal (LLN) for values normal at baseline; < 75% (< 50% for neutrophils) of LLN and of baseline for values abnormal at baseline. † 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. Table 5. Percent of Adult Patients who Experienced at Least One Substantially Abnormal* Serum Chemistry Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Laboratory Assay Uncomplicated Skin and Skin Structure Infections All Other Indications Linezolid 400 mg every 12 hours Clarithromycin 250 mg every 12 hours Linezolid 600 mg every 12 hours All Other Comparators † AST (U/L) 1.7 1.3 5 6.8 ALT (U/L) 1.7 1.7 9.6 9.3 LDH (U/L) 0.2 0.2 1.8 1.5 Alkaline phosphatase (U/L) 0.2 0.2 3.5 3.1 Lipase (U/L) 2.8 2.6 4.3 4.2 Amylase (U/L) 0.2 0.2 2.4 2 Total bilirubin (mg/dL) 0.2 0 0.9 1.1 BUN (mg/dL) 0.2 0 2.1 1.5 Creatinine (mg/dL) 0.2 0 0.2 0.6 * > 2 x Upper Limit of Normal (ULN) for values normal at baseline; > 2 x ULN and > 2 x baseline for values abnormal at baseline. † 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. Table 6. Percent of Pediatric Patients who Experienced at Least One Substantially Abnormal* Hematology Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Laboratory Assay Uncomplicated Skin and Skin Structure Infections † All Other Indications ‡ Linezolid Cefadroxil Linezolid Vancomycin Hemoglobin (g/dL) 0 0 15.7 12.4 Platelet count (x 10 3 /mm 3 ) 0 0.4 12.9 13.4 WBC (x 10 3 /mm 3 ) 0.8 0.8 12.4 10.3 Neutrophils (x 10 3 /mm 3 ) 1.2 0.8 5.9 4.3 * < 75% (< 50% for neutrophils) of Lower Limit of Normal (LLN) for values normal at baseline; < 75% (< 50% for neutrophils) of LLN and < 75% (< 50% for neutrophils, < 90% for hemoglobin if baseline < LLN) of baseline for values abnormal at baseline. † Patients 5 through 11 years of age received linezolid 10 mg/kg by mouth every 12 hours or cefadroxil 15 mg/kg by mouth every 12 hours. Patients 12 years or older received linezolid 600 mg by mouth every 12 hours or cefadroxil 500 mg by mouth every 12 hours. ‡ Patients from birth through 11 years of age received linezolid 10 mg/kg intravenously by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6 to 24 hours, depending on age and renal clearance. Table 7. Percent of Pediatric Patients who Experienced at Least One Substantially Abnormal* Serum Chemistry Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Laboratory Assay Uncomplicated Skin and Skin Structure Infections † All Other Indications ‡ Linezolid Cefadroxil Linezolid Vancomycin ALT (U/L) 0 0 10.1 12.5 Lipase (U/L) 0.4 1.2 --- --- Amylase (U/L) --- --- 0.6 1.3 Total bilirubin (mg/dL) --- --- 6.3 5.2 Creatinine (mg/dL) 0.4 0 2.4 1 * > 2 x Upper Limit of Normal (ULN) for values normal at baseline; > 2 x ULN and > 2 (> 1.5 for total bilirubin) x baseline for values abnormal at baseline. † Patients 5 through 11 years of age received linezolid 10 mg/kg by mouth every 12 hours or cefadroxil 15 mg/kg by mouth every 12 hours. Patients 12 years or older received linezolid 600 mg by mouth every 12 hours or cefadroxil 500 mg by mouth every 12 hours. ‡ Patients from birth through 11 years of age received linezolid 10 mg/kg intravenously/by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6 to 24 hours, depending on age and renal clearance. 6.2 Postmarketing Experience The following adverse reactions have been identified during postapproval 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. Myelosuppression (including anemia, leukopenia, pancytopenia, and thrombocytopenia) has been reported during postmarketing use of linezolid [ see Warnings and Precautions ( 5.1 ) ]. Peripheral neuropathy, and optic neuropathy sometimes progressing to loss of vision, have been reported in patients treated with linezolid [ see Warnings and Precautions ( 5.2 ) ]. Lactic acidosis has been reported with the use of linezolid [ 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. Serotonin syndrome has been reported in patients receiving concomitant serotonergic agents, including antidepressants such as selective serotonin reuptake inhibitors (SSRIs) and linezolid [ see Warnings and Precautions ( 5.3 ) ]. Convulsions have been reported with the use of linezolid [ see Warnings and Precautions ( 5.8 ) ]. Anaphylaxis, angioedema, and bullous skin disorders such as those described as Stevens-Johnson syndrome have been reported. 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. Hypoglycemia, including symptomatic episodes, has been reported [ see Warnings and Precautions ( 5.9 ) ]. 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. Of the patients treated for uncomplicated skin and skin structure infections (uSSSIs), 25.4% of linezolid-treated and 19.6% of comparator-treated patients experienced at least one drug-related adverse event. For all other 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 (%) of Treatment–Emergent Adverse Reactions Occurring in > 1% of Adult Patients Treated with Linezolid in Comparator-Controlled Clinical Trials ADVERSE REACTIONS Uncomplicated Skin and Skin Structure Infections All Other Indications Linezolid 400 mg by mouth every 12 hours (n=548) Clarithromycin 250 mg by mouth every 12 hours (n=537) Linezolid 600 mg every 12 hours (n=1,498) All Other Comparators* (n=1,464) Headache 8.8 8.4 5.7 4.4 Diarrhea 8.2 6.1 8.3 6.4 Nausea 5.1 4.5 6.6 4.6 Vomiting 2 1.5 4.3 2.3 Dizziness 2.6 3 1.8 1.5 Rash 1.1 1.1 2.3 2.6 Anemia 0.4 0 2.1 1.4 Taste alteration 1.8 2 1 0.3 Vaginal moniliasis 1.8 1.3 1.1 0.5 Oral moniliasis 0.5 0 1.7 1 Abnormal liver function tests 0.4 0.2 1.6 0.8 Fungal infection 1.5 0.2 0.3 0.2 Tongue discoloration 1.3 0 0.3 0 Localized abdominal pain 1.3 0.6 1.2 0.8 Generalized abdominal pain 0.9 0.4 1.2 1 * 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. Of the patients treated for uSSSIs, 3.5% of linezolid-treated and 2.4% of comparator-treated patients discontinued treatment due to drug-related adverse events. For all other indications, 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% (13/215) in the linezolid arm and 3% (3/101) in the vancomycin arm. However, given the severe underlying illness in the patient population, no causality could be established. Of the pediatric patients treated for uSSSIs, 19.2% of linezolid-treated and 14.1% of comparator-treated patients experienced at least one drug-related adverse event. For all other 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 > 1% of Pediatric Patients (and > 1 Patient) in Either Treatment Group in Comparator-Controlled Clinical Trials ADVERSE REACTIONS Uncomplicated Skin and Skin Structure Infections* All Other Indications † Linezolid (n=248) Cefadroxil (n=251) Linezolid (n=215) Vancomycin (n=101) Diarrhea 7.8 8 10.8 12.1 Vomiting 2.9 6.4 9.4 9.1 Headache 6.5 4 0.9 0 Anemia 0 0 5.6 7.1 Thrombocytopenia 0 0 4.7 2 Nausea 3.7 3.2 1.9 0 Generalized abdominal pain 2.4 2.8 0.9 2 Localized abdominal pain 2.4 2.8 0.5 1 Loose stools 1.6 0.8 2.3 3 Eosinophilia 0.4 0.8 1.9 1 Pruritus at non-application site 0.8 0.4 1.4 2 Vertigo 1.2 0.4 0 0 * Patients 5 through 11 years of age received linezolid 10 mg/kg by mouth every 12 hours or cefadroxil 15 mg/kg by mouth every 12 hours. Patients 12 years or older received linezolid 600 mg by mouth every 12 hours or cefadroxil 500 mg by mouth every 12 hours. † Patients from birth through 11 years of age received linezolid 10 mg/kg intravenously by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6 to 24 hours, depending on age and renal clearance. Of the pediatric patients treated for uSSSIs, 1.6% of linezolid-treated and 2.4% of comparator-treated patients discontinued treatment due to drug-related adverse events. For all other 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%) with linezolid and 1.5% (range among studies: 0.4 to 7%) 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 Warning 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* Hematology Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Laboratory Assay Uncomplicated Skin and Skin Structure Infections All Other Indications Linezolid 400 mg every 12 hours Clarithromycin 250 mg every 12 hours Linezolid 600 mg every 12 hours All Other Comparators † Hemoglobin (g/dL) 0.9 0 7.1 6.6 Platelet count (x 10 3 /mm 3 ) 0.7 0.8 3 1.8 WBC (x 10 3 /mm 3 ) 0.2 0.6 2.2 1.3 Neutrophils (x 10 3 /mm 3 ) 0 0.2 1.1 1.2 * < 75% (< 50% for neutrophils) of Lower Limit of Normal (LLN) for values normal at baseline; < 75% (< 50% for neutrophils) of LLN and of baseline for values abnormal at baseline. † 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. Table 5. Percent of Adult Patients who Experienced at Least One Substantially Abnormal* Serum Chemistry Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Laboratory Assay Uncomplicated Skin and Skin Structure Infections All Other Indications Linezolid 400 mg every 12 hours Clarithromycin 250 mg every 12 hours Linezolid 600 mg every 12 hours All Other Comparators † AST (U/L) 1.7 1.3 5 6.8 ALT (U/L) 1.7 1.7 9.6 9.3 LDH (U/L) 0.2 0.2 1.8 1.5 Alkaline phosphatase (U/L) 0.2 0.2 3.5 3.1 Lipase (U/L) 2.8 2.6 4.3 4.2 Amylase (U/L) 0.2 0.2 2.4 2 Total bilirubin (mg/dL) 0.2 0 0.9 1.1 BUN (mg/dL) 0.2 0 2.1 1.5 Creatinine (mg/dL) 0.2 0 0.2 0.6 * > 2 x Upper Limit of Normal (ULN) for values normal at baseline; > 2 x ULN and > 2 x baseline for values abnormal at baseline. † 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. Table 6. Percent of Pediatric Patients who Experienced at Least One Substantially Abnormal* Hematology Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Laboratory Assay Uncomplicated Skin and Skin Structure Infections † All Other Indications ‡ Linezolid Cefadroxil Linezolid Vancomycin Hemoglobin (g/dL) 0 0 15.7 12.4 Platelet count (x 10 3 /mm 3 ) 0 0.4 12.9 13.4 WBC (x 10 3 /mm 3 ) 0.8 0.8 12.4 10.3 Neutrophils (x 10 3 /mm 3 ) 1.2 0.8 5.9 4.3 * < 75% (< 50% for neutrophils) of Lower Limit of Normal (LLN) for values normal at baseline; < 75% (< 50% for neutrophils) of LLN and < 75% (< 50% for neutrophils, < 90% for hemoglobin if baseline < LLN) of baseline for values abnormal at baseline. † Patients 5 through 11 years of age received linezolid 10 mg/kg by mouth every 12 hours or cefadroxil 15 mg/kg by mouth every 12 hours. Patients 12 years or older received linezolid 600 mg by mouth every 12 hours or cefadroxil 500 mg by mouth every 12 hours. ‡ Patients from birth through 11 years of age received linezolid 10 mg/kg intravenously by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6 to 24 hours, depending on age and renal clearance. Table 7. Percent of Pediatric Patients who Experienced at Least One Substantially Abnormal* Serum Chemistry Laboratory Value in Comparator-Controlled Clinical Trials with Linezolid Laboratory Assay Uncomplicated Skin and Skin Structure Infections † All Other Indications ‡ Linezolid Cefadroxil Linezolid Vancomycin ALT (U/L) 0 0 10.1 12.5 Lipase (U/L) 0.4 1.2 --- --- Amylase (U/L) --- --- 0.6 1.3 Total bilirubin (mg/dL) --- --- 6.3 5.2 Creatinine (mg/dL) 0.4 0 2.4 1 * > 2 x Upper Limit of Normal (ULN) for values normal at baseline; > 2 x ULN and > 2 (> 1.5 for total bilirubin) x baseline for values abnormal at baseline. † Patients 5 through 11 years of age received linezolid 10 mg/kg by mouth every 12 hours or cefadroxil 15 mg/kg by mouth every 12 hours. Patients 12 years or older received linezolid 600 mg by mouth every 12 hours or cefadroxil 500 mg by mouth every 12 hours. ‡ Patients from birth through 11 years of age received linezolid 10 mg/kg intravenously/by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6 to 24 hours, depending on age and renal clearance. 6.2 Postmarketing Experience The following adverse reactions have been identified during postapproval 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. Myelosuppression (including anemia, leukopenia, pancytopenia, and thrombocytopenia) has been reported during postmarketing use of linezolid [ see Warnings and Precautions ( 5.1 ) ]. Peripheral neuropathy, and optic neuropathy sometimes progressing to loss of vision, have been reported in patients treated with linezolid [ see Warnings and Precautions ( 5.2 ) ]. Lactic acidosis has been reported with the use of linezolid [ 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. Serotonin syndrome has been reported in patients receiving concomitant serotonergic agents, including antidepressants such as selective serotonin reuptake inhibitors (SSRIs) and linezolid [ see Warnings and Precautions ( 5.3 ) ]. Convulsions have been reported with the use of linezolid [ see Warnings and Precautions ( 5.8 ) ]. Anaphylaxis, angioedema, and bullous skin disorders such as those described as Stevens-Johnson syndrome have been reported. 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. Hypoglycemia, including symptomatic episodes, has been reported [ see Warnings and Precautions ( 5.9 ) ].

8.1 Pregnancy Teratogenic Effects – Pregnancy Category C Linezolid was not teratogenic in mice, rats, or rabbits at exposure levels 6.5-fold (in mice), equivalent to (in rats), or 0.06-fold (in rabbits) the expected human exposure level, based on AUCs. However, embryo and fetal toxicities were seen (see Non-teratogenic Effects). There are no adequate and well-controlled studies in pregnant women. Linezolid should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Non-teratogenic Effects In mice, embryo and fetal toxicities were seen only at doses that caused maternal toxicity (clinical signs and reduced body weight gain). A dose of 450 mg/kg/day (6.5-fold the estimated human exposure level based on AUCs) correlated with increased postimplantational embryo death, including total litter loss, decreased fetal body weights, and an increased incidence of costal cartilage fusion. In rats, mild fetal toxicity was observed at 15 and 50 mg/kg/day (exposure levels 0.22-fold to approximately equivalent to the estimated human exposure, respectively, based on AUCs). The effects consisted of decreased fetal body weights and reduced ossification of sternebrae, a finding often seen in association with decreased fetal body weights. Slight maternal toxicity, in the form of reduced body weight gain, was seen at 50 mg/kg/day. In rabbits, reduced fetal body weight occurred only in the presence of maternal toxicity (clinical signs, reduced body weight gain and food consumption) when administered at a dose of 15 mg/kg/day (0.06-fold the estimated human exposure based on AUCs). When female rats were treated with 50 mg/kg/day (approximately equivalent to the estimated human exposure based on AUCs) of linezolid during pregnancy and lactation, survival of pups was decreased on postnatal days 1 to 4. Male and female pups permitted to mature to reproductive age, when mated, showed an increase in preimplantation loss.