Could Oritavancin Be a Safe Alternative to Vancomycin for ABSSSIs?

A single dose of the antibiotic oritavancin could save patients and health services time and money when treating acute bacterial skin and skin structure infections (ABSSSIs) according to new findings recently published in Open Forum Infectious Diseases.

According to US Healthcare Cost and Utilization Project National Inpatient Sample data, ABSSSIs are the leading causes of infection-related emergency room visits and hospital admissions. This is, in part, because treating these infections often requires patients to be admitted to the hospital in order to receive multi-day intravenous antibiotic treatment. At present, the most common treatment for ABSSSIs involves 10 days of vancomycin administered twice a day, which makes it very difficult to treat these infections without hospital admission.

According to lead author on the Open Forum study, Thomas Lodise, PharmD, PhD, and colleagues, in many cases, those patients with ABSSSIs do not have existing comorbidities, systemic signs of infection, or evident symptoms of infection other than the site of the infection itself. This makes them good candidates for an effective outpatient treatment method. In addition, treating ABSSSIs on an outpatient basis could save as much as $6,500 per patient.

Oritavancin, which only requires a single dose to treat infections, was recently deemed “noninferior” to the vancomycin regimen. However, the treatment brings new viability to outpatient treatment options thanks to the much shorter timeframe for dosing and treatment. Therefore, the researchers sought to determine if oritavancin could be a safe alternative to vancomycin in treating ABSSSIs.

For their study, the team of scientists used subgroups of patients from two separate but identical multicenter, double-blind, randomized phase 3 trials. The patients received either a single 1200-mg dose of intravenous oritavancin or a week-long (up to 10 days) regimen of intravenous vancomycin.

A total of 392 patients received the single dose of oritavancin, and 400 patients received the multi-day vancomycin treatment. The mean age of the patients in both subgroups was 42 years, and most were Caucasian and male. A number of patients also said that they used IV drugs, and about a third were diagnosed with hepatitis. Nine percent had diabetes mellitus.

The most common type of ABSSSI found in the patients in the study was caused by Staphylococcus aureus (74%), followed by methicillin-resistant Staphylococcus aureus (MRSA), which was present in 254 of 461 of the S. aureus patients.

The team followed up and assessed patients’ ongoing health and safety (defined as not needing “rescue antibiotics” or experiencing negative side effects or exacerbated infections) until 60 days after the treatment regimen had ended. They focused particularly on health events that occurred during the vancomycin treatment regimen or shortly after the first dose of oritavancin.

At seven to 14 days after treatment, primary efficacy outcomes were defined as “cessation of spread or reduction in size of the baseline lesion, absence of fever, and no rescue antibiotic at early clinical evaluation (ECE) at 48 to 72 hours.” Secondary outcomes included “investigator-assessed clinical cure” at two weeks or less, and “20% or greater reduction in lesion area at ECE.” The team conducted these evaluations based on assessment of “vital signs, electrocardiograms, clinical chemistry and hematologic assessments, rate of adverse events (AEs), and rates of serious adverse events (SAEs),” they said.

According to the scientists, both drugs produced similar results at the point of ECE, with oritavancin performing slightly better than vancomycin (80.4% vs. 77.5%). In addition, both medications had low incidences of adverse events such as hospitalization or “rescue antibiotic treatments,” with 1.3% of orativancin patients (five) requiring hospital admission and 2.3% of vancomycin patients (nine) requiring hospital admission.

The authors suggested that the results of the study indicate that oritavancin could provide a safe and effective means of shifting ABSSSI treatment from an inpatient setting to an outpatient one given the few number of patients that required inpatient post-outpatient treatment after the oritavancin dose. “The drug was generally well-tolerated, with lower incidences of hypersensitivity reactions and pruritus relative to vancomycin,” they added.

Disclosures: The Medicines Company collaborated with the authors of the study and supported the research. In addition, the authors disclosed all potential conflicts of interest in advance of publication.