Phase I study assessing the safety, tolerability, and pharmacokinetics of avibactam and ceftazidime–avibactam in healthy Japanese volunteers

Avibactam is a novel non-β-lactam β-lactamase inhibitor that has been shown to restore the in vitro activity of ceftazidime against pathogens producing Ambler class A, C, and some class D β-lactamases. This study aimed to evaluate the safety, tolerability, and pharmacokinetics of single and multiple doses of avibactam alone or with ceftazidime in healthy Japanese subjects. In this Phase I, double-blind study (NCT01291602), 16 healthy Japanese males, mean age 28.8 years, were randomized in a 2:2:1 ratio to receive avibactam 500 mg (n = 6), ceftazidime 2000 mg plus avibactam 500 mg (n = 7), or placebo (n = 3), each administered as a 100 ml intravenous infusion over 2 h, once on Day 1, every 8 h on Days 3–6, and once on Day 7. There were no deaths or serious adverse events. Nine treatment-emergent adverse events were reported in three subjects in the avibactam group – including one elevation in transaminase levels, and three vital signs events (tachycardia, palpitations, and orthostatic hypotension) – and one in the ceftazidime–avibactam group. All events were considered mild. After single or multiple dosing, plasma concentrations of avibactam and ceftazidime declined in a multi-exponential manner. No plasma concentration accumulation was observed, and the majority of avibactam was excreted unchanged in urine within 24 h. No clinically relevant changes in intestinal bacterial flora were observed. In conclusion, avibactam alone and ceftazidime–avibactam were generally well tolerated in healthy male Japanese subjects, and avibactam pharmacokinetics were comparable whether administered alone or in combination with ceftazidime.