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Zyvox

Zyvox

SIDE EFFECTS

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 ZYVOX formulations was evaluated in 2046 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 ZYVOX-treated and 19.6% of comparator-treated patients experienced at least one drug-related adverse event. For all other indications, 20.4% of ZYVOX -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 ZYVOX.

Table 2: Incidence (%) of Treatment–Emergent Adverse Reactions Occurring in > 1% of Adult Patients Treated with ZYVOX in Comparator-Controlled Clinical Trials

ADVERSE REACTIONS Uncomplicated Skin and Skin Structure Infections All Other Indications
ZYVOX 400 mg by mouth every 12 hours
(n=548)
Clarithromycin 250 mg by mouth every 12 hours
(n=537)
ZYVOX 600 mg every 12 hours
(n=1498)
All Other Comparators*
(n=1464)
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 ZYVOX -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 ZYVOX -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 ZYVOX 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.

Of the pediatric patients treated for uSSSIs, 19.2% of ZYVOX-treated and 14.1% of comparator-treated patients experienced at least one drug-related adverse event. For all other indications, 18.8% of ZYVOX-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†
ZYVOX
(n=248)
Cefadroxil
(n=251)
ZYVOX
(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 ZYVOX 10 mg/kg by mouth every 12 hours or cefadroxil 15 mg/kg by mouth every 12 hours. Patients 12 years or older received ZYVOX 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 ZYVOX 10 mg/kg intravenously by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6-24 hours, depending on age and renal clearance.

Of the pediatric patients treated for uSSSIs, 1.6% of ZYVOX-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 ZYVOX-treated and 6.1% of comparator-treated patients.

Laboratory Abnormalities

ZYVOX 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 ZYVOX 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 ZYVOX 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 ZYVOX and 0.4% with cefadroxil. Thrombocytopenia associated with the use of ZYVOX 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 ZYVOX; the role of linezolid in these events cannot be determined [see WARNINGS AND PRECAUTIONS].

Changes seen in other laboratory parameters, without regard to drug relationship, revealed no substantial differences between ZYVOX 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 ZYVOX

Laboratory Assay Uncomplicated Skin and Skin Structure Infections All Other Indications
ZYVOX 400 mg every 12 hours Clarithromycin 250 mg every 12 hours ZYVOX 600 mg every 12 hours All Other Comparators†
Hemoglobin (g/dL) 0.9 0 7.1 6.6
Platelet count (x 103/mm³) 0.7 0.8 3 1.8
WBC (x 103/mm³) 0.2 0.6 2.2 1.3
Neutrophils (x 103/mm³) 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 ZYVOX

Laboratory Assay Uncomplicated Skin and Skin Structure Infections All Other Indications
ZYVOX 400 mg every 12 hours Clarithromycin 250 mg every 12 hours ZYVOX 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 ZYVOX

Laboratory Assay Uncomplicated Skin and Skin Structure Infections† All Other Indications‡
ZYVOX Cefadroxil ZYVOX Vancomycin
Hemoglobin (g/dL) 0 0 15.7 12.4
Platelet count (x 103/mm³) 0 0.4 12.9 13.4
WBC (x 103/mm³) 0.8 0.8 12.4 10.3
Neutrophils (x 103/mm³) 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 ZYVOX 10 mg/kg by mouth every 12 hours or cefadroxil 15 mg/kg by mouth every 12 hours. Patients 12 years or older received ZYVOX 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 ZYVOX 10 mg/kg intravenously by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6-24 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 ZYVOX

Laboratory Assay Uncomplicated Skin and Skin Structure Infections† All Other Indications‡
ZYVOX Cefadroxil ZYVOX 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 ZYVOX 10 mg/kg by mouth every 12 hours or cefadroxil 15 mg/kg by mouth every 12 hours. Patients 12 years or older received ZYVOX 600 mg mouth every 12 hours or cefadroxil 500 mg by mouth every 12 hours.
‡ Patients from birth through 11 years of age received ZYVOX 10 mg/kg intravenously/by mouth every 8 hours or vancomycin 10 to 15 mg/kg intravenously every 6-24 hours, depending on age and renal clearance.

Postmarketing Experience

The following adverse reactions have been identified during postapproval use of ZYVOX. 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 ZYVOX [see WARNINGS AND PRECAUTIONS]. Peripheral neuropathy, and optic neuropathy sometimes progressing to loss of vision, have been reported in patients treated with ZYVOX [see WARNINGS AND PRECAUTIONS]. Lactic acidosis has been reported with the use of ZYVOX [see WARNINGS AND PRECAUTIONS]. 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 ZYVOX [see WARNINGS AND PRECAUTIONS]. Convulsions have been reported with the use of ZYVOX [see WARNINGS AND PRECAUTIONS]. 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].

Read the Zyvox (linezolid) Side Effects Center for a complete guide to possible side effects

DRUG INTERACTIONS

Monoamine Oxidase Inhibitors

Linezolid is a reversible, nonselective inhibitor of monoamine oxidase. [see CONTRAINDICATIONS and CLINICAL PHARMACOLOGY].

Adrenergic And Serotonergic Agents

Linezolid has the potential for interaction with adrenergic and serotonergic agents. [see WARNINGS AND PRECAUTIONS and CLINICAL PHARMACOLOGY].

Read the Zyvox Drug Interactions Center for a complete guide to possible interactions

Last reviewed on RxList: 2/6/2014
This monograph has been modified to include the generic and brand name in many instances.

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