Zyvox (Linezolid)

Brand Name Drug: Zyvox
Active Ingredient Drug: linezolid
Indication: Treatment of nosocomial pneumonia, community-acquired pneumonia, complicated and uncomplicated skin and skin structure infections, and vancomycin-resistant Enterococcus faecium infections caused by indicated bacteria, in adults.
Company Name: Pharmacia & Upjohn
Availability: Approved by the FDA on April 18, 2000

Introduction

Infections due to the bacteria Enterococcus faecium and methicillin-resistant Staphylococcus aureus (MRSA) pose a particular problem in hospitalized patients and in those with depressed immune systems. These organisms are often resistant to multiple antibiotics. The antibiotic vancomycin has, for many years, served as the treatment of last resort for these infections.

But in 1989, the first case of vancomycin-resistant Enterococcus faecium (VREF) was reported in this country. Since then, there has been a rapid increase in the incidence of VREF infections, as well as a dramatic increase in the incidence of MRSA infections. There have been limited treatment options available for patients with these infections.

A new antibiotic, approved by the FDA in April, will help doctors make substantial advances in this battle. It’s called Zyvox (linezolid), and it’s a member of the “oxazolidinone” drug class, the first new class of antibiotics to be introduced in more than 30 years. Zyvox has a unique mechanism of action: It attacks bacteria at a much earlier point in their growth cycle than other antibiotics by halting the production of proteins that bacteria need to multiply.

Zyvox (linezolid), which is manufactured by Pharmacia & Upjohn, was approved for the treatment of patients with infections caused by “Gram-positive” bacteria, which can be notoriously difficult to treat. The drug is indicated for the treatment of hospital-acquired pneumonia, community-acquired pneumonia, skin infections, and VREF infections in adults.

Zyvox (linezolid) is available in both intravenous and oral (tablet) formulations, and will be used first primarily in hospital or institutional care settings. Physicians can use the IV and tablet forms interchangeably without adjusting the dose. The ability to complete treatment with an oral form of Zyvox may enable some patients to leave the hospital sooner.

Zyvox: Clinical Study Results

Zyvox’s approval was supported by clinical trials in more than 4,000 patients. The approval for VREF infections was based on a study in which 145 patients were treated with Zyvox (either 600 mg or 200 mg) every 12 hours for VREF infection for 7-28 days. Types of VREF infections studied included complicated abdominal and skin infections, urinary tract infections, and bacteremia (infection of the bloodstream) of unknown cause. The cure rate for Zyvox was 67% in the high-dose (600 mg) group and 52% in the low-dose (200 mg) group.

Zyvox (600 mg twice a day) was also found to be as effective as vancomycin (1 g twice a day) for treatment of hospital-acquired pneumonia, including cases due to MRSA, in a clinical trial involving nearly 400 patients treated for 7-21 days. The cure rates were 57% for patients treated with Zyvox and 60% for patients treated with vancomycin. The approval for complicated skin infections, including those caused by MRSA, was based on a clinical trial of some 800 patients that compared Zyvox (600 mg injected twice daily followed by Zyvox 600 mg tablets twice daily) with the antibiotic combination oxacillin/dicloxacillin (oxacillin 2 g every 6 hours IV followed by dicloxacillin 500 mg every 6 hours orally); treatment lasted 10-21 days. The cure rates were 90% for patients treated with Zyvox and 85% for those treated with oxacillin/dicloxacillin.

“Zyvox has a profile that makes it truly unique,” said Robert Moellering, MD, Professor of Medicine at Harvard Medical School. “It represents an important discovery in the treatment of Gram-positive infections.”

What You Should Know

Side effects you may experience while taking Zyvox (linezolid) include headache, nausea, diarrhea, and vomiting. Zyvox may interact with certain other drugs, including over-the-counter cold remedies that contain pseudoephedrine or phenylpropanolamine, and cause an increase in blood pressure. If you are taking such medications and receiving Zyvox, you should let your physician know.

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Jennifer Bowles

Jennifer is a clinical pharmacologist. She helps doctors of all medical specialties choose medications. Jennifer consults about drug dosage, interactions, and side effects.