Phase I randomised, double-blind IV infusion study in healthy volunteers (n=74): SAD (6 cohorts, 0.1–4.0 mg/kg single 40-min infusions), MAD (2 cohorts, 1.0–2.0 mg/kg on Days 1,4,7,10), plus CSF cohort; PK, qEEG and safety-focused assessments.
This Phase I study evaluates (2R,6R)-hydroxynorketamine hydrochloride in healthy adult volunteers using a slow 40-minute intravenous infusion across single ascending dose (SAD) cohorts, multiple ascending dose (MAD) cohorts, and a CSF capture cohort. Primary objectives are safety, tolerability, and pharmacokinetics including plasma and CSF sampling.
Safety assessments include AEs/SAEs, vitals, ECGs, clinical labs, ophthalmologic exams, C-SSRS, POMS, CADSS and MOAA/S. Pharmacodynamic measures include qEEG and serial PK sampling at multiple timepoints.
Study design incorporates sentinel dosing, placebo controls in each cohort, and predefined halting rules for dose escalation; MAD dosing occurs over four administrations with intensive safety monitoring.
Six SAD cohorts with single IV slow-infusion (40 min) doses across 0.1–4.0 mg/kg; sentinel dosing and placebo in each cohort.
SAD cohorts 0.1–4.0 mg/kg by 40-min IV infusion; 6 cohorts; sentinel dosing; placebo 2 per cohort.
Two MAD cohorts receiving 4 IV infusions (days 1,4,7,10) of 1.0 or 2.0 mg/kg.
MAD cohorts: 1.0 mg/kg and 2.0 mg/kg given on Days 1, 4, 7, 10 (40-min infusion).
Single-cohort CSF capture with IV slow-infusion and paired plasma/CSF sampling.
CSF cohort doses include 0.25 mg/kg and 2.0 mg/kg; CSF sampled preinfusion, ~1h and ~8h post-infusion; 40-min infusion.
Sterile saline placebo administered via slow IV infusion (40 minutes).
0.9% saline, 53 mL, 40-min slow IV infusion; placebo arms across SAD, MAD and CSF cohorts.
In a Phase 1 single- and multiple-ascending IV dosing study in healthy volunteers, (2R,6R)-hydroxynorketamine was well tolerated with minimal adverse events, showed no anesthetic or dissociative effects and demonstrated dose-proportional pharmacokinetics with confirmed CNS exposure in CSF. Quantitative EEG showed increases in gamma power in some participants, supporting progression of RR‑HNK into Phase 2 development.