This phase 2, randomized, 2-part, multicenter, dose-ranging, response-adaptive study with optional intravenous-oral switch evaluated the efficacy and safety of gepotidacin for the treatment of Gram-positive acute bacterial skin and skin structure infections in 122 adult patients in the United States. The study had a double-blind phase (part 1; intravenous [750 mg or 1,000 mg every 12 h {q12h}]) and an open-label phase (part 2; intravenous [750 mg q12h, 1,000 mg q12h, or 1,000 q8h]). The primary endpoint was a composite of efficacy and safety which consisted of the early cure rate and the withdrawal rate due to drug-related adverse events and utilized a clinical utility index for dose selection. At the early efficacy visit (48 to 72 h after the first dose), the 750-mg q12h and 1,000-mg q8h groups met prespecified success criteria for clinical utility in terms of efficacy and safety; however, the 1,000-mg q12h group did not meet these criteria due to observed lower efficacy rates.

The in vitro activities of gepotidacin were comparable against methicillin-susceptible and -resistant Staphylococcus aureus (MSSA and MRSA, respectively) isolates (MIC90, 0.5 μg/ml). The gepotidacin MIC90s were as follows (in micrograms per milliliter) for the indicated bacteria: Streptococcus pyogenes, 0.25; Escherichia coli, 2; Moraxella catarrhalis, ≤ 0.06; Streptococcus pneumoniae (0.25), Haemophilus influenzae, 1; Clostridium perfringens, 0.5; and Shigella spp., 1, including levofloxacin-resistant subsets.