The US Food and Drug Administration has approved delafloxacin (Baxdela™, Melinta Therapeutics), a new antibacterial drug to treat acute bacterial skin and skin structure infections (ABSSSI).1 Available in both intravenous (IV) and oral formulations, delafloxacin is an anionic fluoroquinolone antibiotic that is active against both gram-positive and gram-negative pathogens, including methicillin-resistant Staphylococcus aureus (MRSA).

The new drug application approvals are based on results of 2 phase 3 multicenter, randomized, double-blind trials in which both the IV and oral delafloxacin monotherapy met the primary endpoint of noninferiority to a combination regimen of vancomycin plus aztreonam in patients with ABSSSI, reducing lesion size by at least 20% at the primary infection site within 48 to 72 hours.2

Of the 1500 individuals enrolled in the 2 trials, most were male (62%) and Caucasian (86%). The median age of patients treated with delafloxacin was 49 years (range, 18-94 years). The patient population included 11% with diabetes, 16% with renal impairment (calculated creatinine clearance less than 90 mL/min), 44% with obesity (body mass index, ≥30 kg/m2), and 15% older than 65 years.2

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In the first trial ( identifier: NCT01811732), 331 patients received delafloxacin 300 mg by IV infusion every 12 hours, and 329 patients received vancomycin 15 mg/kg plus aztreonam. In the delafloxacin group, 78.2% of patients were responders vs 80.9% in the vancomycin plus aztreonam group (treatment difference, −2.6; 2-sided 95% CI, −8.8 to 3.6).2

In the second trial ( identifier: NCT01984684), 423 patients received delafloxacin 300 mg via IV infusion every 12 hours for 6 doses and then made a mandatory switch to oral delafloxacin 450 mg every 12 hours, and 427 patients received vancomycin 15 mg/kg plus aztreonam. In the delafloxacin group, 83.7% of patients were responders vs 80.6% in the vancomycin plus aztreonam group (treatment difference, 3.1; 2-sided 95% CI, −2.0 to 8.3).2

The most common adverse reactions were nausea (8%), diarrhea (8%), headache (3%), transaminase elevations (3%), and vomiting (2%).1

The 450-mg tablet is bioequivalent to, and interchangeable with, the 300-mg IV dose and can be dosed without regard to food. There are no anticipated drug-drug interactions with delafloxacin other than coadministration with chelating agents, such as antacids.

Antibiotic resistance is a growing concern, and physicians need more tools in the fight against this threat to modern medicine. Approval of new therapies like Baxdela, which is effective against MRSA and other serious pathogens, provides physicians another option in addressing the challenges of ABSSSI patients,” said David Hooper, MD, chief of the Infection Control Unit and associate chief of the Division of Infectious Diseases at Massachusetts General Hospital, in a manufacturer’s news release.1

In an email interview with Infectious Disease Advisor, Sue Cammarata, MD, Melinta Therapeutics’ chief medical officer added that “we are currently enrolling a phase 3 study in community-acquired bacterial pneumonia, a serious and potentially life-threatening infection for which new treatment options are needed, that evaluates Baxdela vs moxifloxacin.” Enrollment for this study is slated to be completed in the second half of 2018.

Melinta Therapeutics is also planning to initiate a clinical trial in complicated urinary tract infections in 2018.

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