Safety, tolerability, and pharmacokinetics of allopregnanolone as a regenerative therapeutic for Alzheimer’s disease: A single and multiple ascending dose phase 1b/2a clinical trial

Gerson D. Hernandez, Christine M. Solinsky, Wendy J. Mack, Naoko Kono, Kathleen E. Rodgers, Chun Yi Wu, Ana R. Mollo, Claudia M. Lopez, Sonia Pawluczyk, Gerhard Bauer, Dawn Matthews, Yonggang Shi, Meng Law, Michael A. Rogawski, Lon S. Schneider, Roberta D. Brinton

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Introduction: Allopregnanolone is an endogenous neurosteroid with the potential to be a novel regenerative therapeutic for Alzheimer’s disease (AD). Foundations of mechanistic understanding and well-established preclinical safety efficacy make it a viable candidate. Methods: A randomized, double-blinded, placebo-controlled, single and multiple ascending dose trial was conducted. Intravenous allopregnanolone or placebo was administered once-per-week for 12weeks with a 1-month follow-up. Participants with early AD(mild cognitive impairment due toAD or mildAD), aMini-Mental State Examination score of 20–26 inclusive, and age ≥55 years were randomized (6:2 to three allopregnanolone dosing cohorts or one placebo cohort). Primary endpoint was safety and tolerability. Secondary endpoints included pharmacokinetic (PK) parameters and maximally tolerated dose (MTD). Exploratory endpoints included cognitive and imaging biomarkers. Results: A total of 24 participants completed the trial. Allopregnanolone was safe and well tolerated in all study participants. No differences were observed between treatment arms in the occurrence and severity of adverse events (AE). Most common AE were mild to moderate in severity and included rash (n = 4 [22%]) and fatigue (n = 3 [17%]). A single non-serious AE, dizziness, was attributable to treatment. There was one serious AE not related to treatment. Pharmacokinetics indicated a predictable linear dose-response in plasma concentration of allopregnanolone after intravenous administration over 30 minutes. The maximum plasma concentrations for the 2 mg, 4mg, 6mg, and 10mg dosages were 14.53 ng/mL (+/−7.31), 42.05 ng/mL (+/−14.55), 60.07 ng/mL (+/−12.8), and 137.48 ng/mL (+/−38.69), respectively. The MTD was established based on evidence of allopregnanolone-induced mild sedation at the highest doses; a sex difference in the threshold for sedation was observed (males 10 mg; females 14 mg). No adverse outcomes on cognition or magnetic resonance imaging– based imaging outcomes were evident. Conclusions: Allopregnanolone was well tolerated and safe across all doses in persons with early AD. Safety,MTD, and PK profiles support advancement of allopregnanolone as a regenerative therapeutic for AD to a phase 2 efficacy trial.

Original languageEnglish (US)
Article numbere12107
JournalAlzheimer's and Dementia: Translational Research and Clinical Interventions
Issue number1
StatePublished - 2020


  • Alzheimer’s disease
  • allopregnanolone
  • maximally tolerated dose
  • neurogenesis
  • pharmacokinetics
  • phase 1 clinical trial
  • regenerative therapeutic
  • translational research

ASJC Scopus subject areas

  • Clinical Neurology
  • Psychiatry and Mental health


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