Single Ascending Dose Study of NRS 033 in Healthy Volunteers

Subjects will provide written informed consent and undergo a screening visit within 28 days of receiving study drug. Eligible subjects must have a negative urine drug screen (UDS) and a negative naloxone challenge test at Screening and at the check-in visit (Day -1). Upon completion of screening, eligible subjects will be admitted to the clinical research unit (CRU) on Day -1 and remain confined in the CRU through completion of all scheduled procedures on Day 4 to allow for safety labs, pharmacokinetic (PK) blood draws, ECGs, injection site assessments, and adverse event monitoring.

Study medication dosing will occur in the morning on Day 1 and serial blood samples for plasma concentration determination for PK analysis will be taken during this time at pre-dose and 0.25, 0.50, 1, 1.5, 2, 4, 8, 10, 12, 24 (day 2), 48 (day 3), and 72 (day 4) hours post dose. Additional blood PK samples will be taken at follow-up visits. A Safety Review Committee (SRC) will review blinded, preliminary data from Cohort 1 to make recommendations regarding escalation to Cohorts 2 and 3.