Human butyrylcholinesterase(DynPort Vaccine/Baxalta)

The purpose of this placebo-controlled study is to evaluate the safety, tolerability and pharmacokinetics of a single dose regimen of human butyrylcholinesterase (HuBChE) in healthy adults at 3 ascending dosage levels administered IV. HuBChE, which occurs naturally in human plasma, is being evaluated for prophylaxis and treatment in the event of exposure to chemical nerve agents (as employed during chemical warfare or as an act of terrorism). Volunteers in each dosage cohort will be randomized to treatment with HuBChE active drug or normal saline placebo in a 3:1 ratio. The volunteers will remain in the study for 90 (+/- 7) days. For the first 3 days following dose administration, they will remain at the clinical trial site as inpatients and will be closely monitored for patient safety. Afterwards, they will return to the trial site (at pre-determined intervals) as outpatients for 8 further visits, where patient safety will be assessed.