CXA-101 is a novel, broad-spectrum cephalosporin with excellent antipseudomonal activity. A Phase 1 study was performed to determine the safety, tolerability, and pharmacokinetics of CXA-101 after single- and multiple-dose intravenous administration over 1 h to healthy male and female subjects. In part 1 of the study, five cohorts of eight subjects each (six receiving CXA-101 and two receiving a placebo) received single ascending doses of 250, 500, 1,000, 1,500, and 2,000 mg. In part 2, cohorts 1 and 2 received 500 mg and 1,000 mg, respectively, every 8 h, and cohort 3 received 1,500 mg every 12 h; each cohort received dosing for 10 days. Standard safety and tolerability assessments were performed. Blood and urine pharmacokinetic samples were assayed by a validated bioanalytical method and analyzed using standard noncompartmental methodology. All 64 subjects completed dosing; none withdrew from the study. Drug-related systemic adverse events were infrequent and mild. Mild, non-treatment-limiting infusion site events occurred during multiple-dose administration. No clinically significant laboratory or electrocardiographic finding or dose-limiting toxicity was observed. CXA-101 exhibited dose-linear pharmacokinetics; the mean plasma half-life was approximately 2.3 h. More than 90% of the administered dose was eliminated unchanged through renal excretion. In summary, CXA-101 administered as a 1-hour infusion was generally safe and well tolerated in single doses up to 2,000 mg and in multiple doses up to 3 g daily over 10 days. The favorable safety and predictable pharmacokinetic profile of CXA-101 support its continuing clinical development for the treatment of serious bacterial infections.