Zyvox (linezolid) is a synthetic antibacterial agent of the oxazolidinone class, specifically indicated for the treatment of infections caused by susceptible Gram-positive bacteria. It represents a critical therapeutic option, particularly for complicated skin and skin structure infections, hospital-acquired and community-acquired pneumonia, and vancomycin-resistant Enterococcus faecium (VRE) infections. Its unique mechanism of action inhibits bacterial protein synthesis at an early stage, a target site distinct from other antimicrobial classes, reducing the potential for cross-resistance. This profile provides a comprehensive overview for healthcare professionals considering its application in clinical practice.

Features

• Active Ingredient: Linezolid
• Pharmacologic Class: Oxazolidinone antibiotic
• Available Formulations: Film-coated tablets (600 mg), Oral suspension (100 mg/5 mL), Intravenous injection (2 mg/mL)
• Mechanism of Action: Binds to the 50S subunit of the bacterial ribosome, preventing the formation of a functional 70S initiation complex, a crucial early step in protein synthesis.
• Spectrum of Activity: Bacteriostatic against enterococci and staphylococci; bactericidal against most strains of streptococci.
• Bioavailability: Approximately 100% oral bioavailability, allowing for seamless transition from IV to oral therapy.

Benefits

• Provides a potent therapeutic option against multidrug-resistant Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE).
• Offers excellent oral bioavailability, facilitating early discharge from hospital settings and enabling effective outpatient treatment, which can improve patient quality of life and reduce healthcare costs.
• Features a unique mechanism of action that minimizes the risk of cross-resistance with other antibiotic classes, making it a valuable agent in the antimicrobial arsenal.
• Demonstrates reliable tissue penetration, achieving effective concentrations at the site of infection, including skin, soft tissue, and lungs.
• Supported by robust clinical trial data demonstrating efficacy in a range of severe infections where treatment options may be limited.

Common use

Zyvox is approved for the treatment of adults and specific pediatric populations with the following infections caused by susceptible strains of designated microorganisms:

• Complicated skin and skin structure infections (cSSSI): Including diabetic foot infections without concomitant osteomyelitis, caused by Staphylococcus aureus (methicillin-susceptible and -resistant strains), Streptococcus pyogenes, or Enterococcus faecalis (vancomycin-susceptible strains only).
• Vancomycin-resistant Enterococcus faecium (VRE) infections: Including cases with concurrent bacteremia.
• Hospital-acquired pneumonia (HAP): Caused by Staphylococcus aureus (methicillin-susceptible and -resistant strains) or Streptococcus pneumoniae.
• Community-acquired pneumonia (CAP): Including cases caused by Streptococcus pneumoniae (including multidrug-resistant strains [MDRSP]) or Staphylococcus aureus (methicillin-susceptible strains only). Its use should be reserved for situations where its specific spectrum is necessary, typically confirmed or strongly suspected resistant Gram-positive infections, to help preserve its efficacy and minimize the development of resistance.

Dosage and direction

The recommended dosage for most adult indications is 600 mg administered intravenously or orally every 12 hours. Treatment duration is typically 10 to 14 days, based on the site and severity of infection and clinical response.

• Adults: 600 mg IV or PO q12h.
• Pediatric Patients (Birth through 11 years): 10 mg/kg IV or PO q8h. For adolescents (12 years and older), the adult dosage is recommended.
• Oral Suspension: Must be inverted gently 3-5 times before use to mix suspension; not to be shaken. Does not require refrigeration.
• IV Administration: Must be administered over a period of 30 to 120 minutes. The IV solution is iso-osmotic and compatible with many common IV fluids. Dosage adjustment is not routinely required for patients with renal impairment or mild-to-moderate hepatic impairment. The oral formulation can be taken with or without food.

Precautions

• Myelosuppression: Zyvox has been associated with reversible myelosuppression (including anemia, leukopenia, pancytopenia, and thrombocytopenia). Complete blood counts (CBC) should be monitored weekly, especially in patients receiving therapy for longer than 2 weeks, those with pre-existing myelosuppression, those receiving concomitant drugs that may cause bone marrow suppression, or those with chronic infections who have received previous or concomitant antibiotic therapy.
• Peripheral and Optic Neuropathy: Cases of peripheral and optic neuropathy have been reported, primarily in patients treated for longer than the maximum recommended duration of 28 days. Patients should be monitored for visual function and questioned about visual changes. If symptoms of neuropathy occur, the continued use of Zyvox should be weighed against the potential risks.
• Serotonin Syndrome: Spontaneous reports of serotonin syndrome have been reported in patients receiving Zyvox concomitantly with serotonergic agents. Patients should be closely monitored for signs and symptoms such as cognitive dysfunction, hyperpyrexia, hyperreflexia, and incoordination, especially during concomitant use with SSRIs, SNRIs, tricyclic antidepressants, triptans, or other serotonergic drugs.
• Lactic Acidosis: Lactic acidosis has been reported with the use of Zyvox. Patients who develop recurrent nausea, vomiting, or unexplained acidosis should receive immediate medical evaluation.
• Clostridioides difficile-Associated Diarrhea (CDAD): CDAD has been reported with nearly all antibacterial agents and may range in severity from mild diarrhea to fatal colitis. This diagnosis should be considered in patients who present with diarrhea subsequent to antibiotic administration.

Contraindications

Zyvox is contraindicated in the following patient populations:

• Patients with known hypersensitivity to linezolid or any of the other product components.
• Patients taking any monoamine oxidase inhibitors (MAOIs) (e.g., phenelzine, isocarboxazid) or within two weeks of taking such drugs.
• Patients with uncontrolled hypertension, pheochromocytoma, thyrotoxicosis, and/or those taking directly and indirectly acting sympathomimetic agents (e.g., pseudoephedrine), vasopressive agents (e.g., epinephrine, norepinephrine), or dopaminergic agents (e.g., dopamine, dobutamine) due to the potential for pressor response, unless patients are closely monitored for changes in blood pressure.
• Patients with carcinoid syndrome and/or those taking serotonergic drugs without appropriate monitoring facilities for serotonin syndrome.

Possible side effect

The most common adverse reactions (≥5% of patients in clinical trials) include:

• Diarrhea
• Nausea
• Headache
• Vomiting
• Anemia Other important, but less common, side effects can include:
• Thrombocytopenia
• Leukopenia
• Tongue discoloration
• Oral moniliasis (thrush)
• Vaginal moniliasis
• Taste alteration
• Lactic acidosis
• Peripheral neuropathy
• Optic neuropathy (sometimes progressing to loss of vision)
• Seizures (reported postmarketing)
• Hypoglycemia (including symptomatic episodes)

Drug interaction

Zyvox is a weak, reversible, nonselective inhibitor of monoamine oxidase (MAO) and has the potential for interaction with adrenergic and serotonergic agents.

• Adrenergic Agents: May potentiate the pressor effect of sympathomimetic vasoconstrictors (e.g., pseudoephedrine, phenylpropanolamine) and dopaminergic agents (e.g., dopamine, dobutamine), potentially leading to significant increases in blood pressure.
• Serotonergic Agents: Concomitant use with serotonergic agents (e.g., SSRIs like sertraline, SNRIs, tricyclic antidepressants like amitriptyline, triptans) increases the risk of serotonin syndrome.
• Tyramine-Rich Foods: While a specialized tyramine-free diet is not required, patients should be advised to avoid consuming large amounts of tyramine-rich foods and beverages (e.g., aged cheeses, fermented meats, draft beers, soy sauces) due to the potential for a pressor response.

Missed dose

If a dose of Zyvox is missed, it should be taken as soon as it is remembered. However, if it is almost time for the next scheduled dose, the missed dose should be skipped, and the regular dosing schedule should be resumed. Patients should be instructed not to take a double dose to make up for a missed one.

Overdose

There is limited experience with Zyvox overdose. Reported cases have been associated with both doses higher than and within the recommended range. Adverse events reported in association with overdose were those reported with standard therapeutic doses, primarily gastrointestinal symptoms (nausea, vomiting) and neurological symptoms (dizziness, headache). Supportive care is advised, with maintenance of glomerular filtration. Hemodialysis may accelerate the removal of linezolid, with approximately 30% of the dose being removed over a 3-hour dialysis session.

Storage

• Tablets: Store at 25°C (77°F); excursions permitted to 15–30°C (59–86°F). Keep in original container.
• Oral Suspension: Store at 25°C (77°F); excursions permitted to 15–30°C (59–86°F). Keep bottle tightly closed. Use within 21 days after mixing.
• IV Injection: Store between 2°C and 8°C (36°F and 46°F). Protect from light. The IV solution may exhibit a yellow color that can intensify over time without adversely affecting potency.

Disclaimer

This information is intended for educational purposes for healthcare professionals and is a summary of the product’s characteristics. It is not exhaustive and does not replace the full Prescribing Information. The prescribing physician should be familiar with all the data contained in the official labeling before initiating therapy. Decisions regarding patient care must be based on the independent professional judgment of the clinician, considering all individual patient circumstances and the most current scientific evidence.

Reviews

(Clinical trial data and meta-analyses form the basis of expert consensus on Zyvox’s efficacy and safety profile.)

• Clinical Efficacy: Multiple randomized, controlled trials have demonstrated that Zyvox is non-inferior, and in some subpopulations superior, to vancomycin in the treatment of complicated skin and soft tissue infections and pneumonia caused by MRSA. Its efficacy in VRE infections is well-established.
• Safety Profile: Reviews consistently highlight the importance of hematologic and neurologic monitoring during therapy, especially for extended durations (>2 weeks). The manageable and generally reversible nature of most adverse effects, coupled with the benefit of oral bioavailability, is frequently cited as a significant advantage in appropriate patient populations.
• Place in Therapy: Expert reviews position Zyvox as a vital agent for resistant Gram-positive infections but emphasize the need for antimicrobial stewardship to prevent the development of resistance. Its role is often as a second-line or targeted therapy after susceptibility is confirmed or strongly suspected.