Pfizer's Novel Antibiotic Zyvox Receives FDA Approval for Treatment of Diabetic Foot Infections

NEW YORK -- Pfizer Inc said today that its novel antibiotic Zyvox (linezolid injection, tablets and for oral suspension) has been approved by the U.S. Food and Drug Administration (FDA) for the treatment of diabetic foot infections, without osteomyelitis, caused by Gram-positive bacteria, including resistant strains such as methicillin- resistant Staphylococcus aureus (MRSA). Zyvox is the first and only oral antibiotic approved for the treatment of MRSA infections.

Foot ulcer is a potentially serious complication that threatens an estimated 15 percent of the 17 million people with diabetes in the United States. Among diabetes patients who develop a foot ulcer or wound, approximately six percent will be hospitalized because of the infection or other ulcer-related complications. Serious infections can lead to long-term debilitation and, in the most severe cases, amputation. Diabetes is the leading cause of non-traumatic lower extremity amputations in the United States.

"It is critically important that healthcare professionals who treat people with diabetes be aware of their patients' risk for foot infections, especially those caused by resistant bacteria, and of available therapies," said Dr. David G. Armstrong, a member of the American Podiatric Medical Association's Diabetes Advisory Committee and the national board of directors of the American Diabetes Association.

The most commonly used antibiotics to treat diabetic foot infections are aminopenicillin/beta-lacatamase inhibitors such as ampicillin-sulbactam (IV) and amoxicillin-clavulanate. However, when MRSA is the suspected pathogen, vancomycin (IV) is usually added to the regimen.

"The approval of Zyvox for treatment of diabetic foot infections fills an unmet medical need for an oral treatment for these patients who are at an increased risk of getting an infection caused by MRSA," said Dr. Benjamin Lipsky, professor of medicine at the University of Washington School of Medicine. "The availability of an orally administered treatment is important because it may reduce the need for hospitalization as well as IV-related complications," he said.

The basis for the approval of Zyvox to treat diabetic foot infections was a clinical trial conducted at 30 U.S. and 15 European sites. Data demonstrated that Zyvox was as effective as two standard aminopenicillin therapies in treating diabetic foot infections caused by Gram-positive bacteria.

In the clinical trial, patients were randomly assigned to receive either Zyvox or an aminopenicillin/beta-lactamase inhibitor; vancomycin (IV) could be added to the aminopenicillin/beta lactamase inhibitor arm if the patient was thought to have an infection caused by MRSA. Most patients received appropriate adjunctive treatment such as debridement and off-loading as is typically required to treat diabetic foot infections.

Zyvox demonstrated clinical efficacy in the clinically evaluable population (n=293) for 83 percent (n=159/192) of patients treated, compared to 73 percent (n=74/101) on the comparator arm. Most patients in both arms were treated as outpatients with only oral therapy and with a single agent.

Zyvox was initially approved in the U.S. in April 2000 for the treatment of infections in adults with susceptible strains of designated organisms including complicated skin and skin structure infections and nosocomial pneumonia including those caused by MRSA. In December 2002 Zyvox was approved for use in pediatric patients. Since its introduction, Zyvox has proven to be an important treatment option for designated infections known or suspected to be caused by MRSA. To date, an estimated 450,000 patients worldwide have been treated with Zyvox for its approved indications.

Patients receiving Zyvox should have complete blood counts monitored weekly, since myelosuppression has been reported. This applies particularly to those who are given Zyvox for longer than two weeks, have pre-existing myelosuppression, are receiving concomitant drugs that produce bone marrow suppression, or have a chronic infection and have received previous or concomitant antibiotic therapy. Lactic acidosis has been reported with the use of Zyvox. 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 Zyvox should receive immediate medical evaluation. The most commonly reported adverse events in clinical trials in adults were diarrhea, nausea and headache.

Source: Pfizer Inc