NCT07079761 · Massachusetts General Hospital
Facilitation of Extinction Retention and Reconsolidation Blockade by IV Allopregnanolone in PTSD.
(IV Allo PTSD)
What this study is about
Purpose: About 6.4% of the U.S. population suffers from posttraumatic stress disorder (PTSD). Trauma-focused psychotherapies are generally effective in PTSD, but responses vary greatly across individuals and PTSD subpopulations. Neurobiological factors impacted by life experiences, stress, and genetics can affect treatment responses.
View original scientific description
Purpose: About 6.4% of the U.S. population suffers from posttraumatic stress disorder (PTSD). Trauma-focused psychotherapies are generally effective in PTSD, but responses vary greatly across individuals and PTSD subpopulations. Neurobiological factors impacted by life experiences, stress, and genetics can affect treatment responses. These factors can alter brain capacities needed to reprocess traumatic memories prevent them from triggering intensely distressing, disruptive, out-of-place responses. For example, during psychotherapy for PTSD, trauma memory activation engages two competing brain processes that affect recovery: "extinction" versus "reconsolidation" of trauma-related emotional, physiological, and behavioral responses. This study tests whether a single intravenous (IV) dose of allopregnanolone (Allo) compared to placebo (which is non-active): promotes consolidation of extinction learning (sub-study 1) or blocks reconsolidation of physiological responses triggered by aversive memories (sub-study 2). The study also tests whether Allo compared to placebo affects retention of non-aversive memories.
Interventions
BEHAVIORAL
Experiment 1: Three-day aversive conditioning, extinction, and extinction retention testing paradigm
Day 1: Aversive conditioning will involve the pairing of a brief, noxious but not painful air blast to the neck (unconditioned stimulus; US) to a colored shape appearing on a computer monitor (conditioned stimulus). An auditory stimulus will serve as the startle probe. Day 2: Extinction training will occur followed by IV Allo administration. Day 3: The effects of IV Allo (administered on Day 2) on extinction retention as well as reinstatement of conditioned psychophysiological reactions will be assessed.
DRUG
Allopregnanolone (Allo) with 6% USP Dexolve (sulfobutyl ether-beta-cyclodextrin sodium salt) in 0.9% saline for IV infusion will be provided by the University of California, Davis, GMP manufacturer.
On Day 2 of Experiment 1, a 1.7 mcg/kg dose of IV Allo will be administered over 5 minutes at the completion of extinction training to raise resting plasma Allo plus pregnanolone (PA) levels by 1500 pg/ml. This will be followed by a 4-5-hour continuous infusion of IV Allo at 2.6 mcg/kg/hr to maintain resting plasma Allo levels at the target level.
BEHAVIORAL
Experiment 1. Three-day aversive conditioning, extinction, and extinction retention testing paradigm
Day 1: Aversive conditioning will involve the pairing of a brief, noxious but not painful air blast to the neck (unconditioned stimulus; US) to a colored shape appearing on a computer monitor (conditioned stimulus). An auditory stimulus will serve as the startle probe. Day 2: Extinction training will occur followed by IV Allo administration. Day 3: The effects of IV Allo (administered on Day 2) on extinction retention as well as reinstatement of conditioned psychophysiological reactions will be assessed.
OTHER
Matching IV Placebo
On Day 2 of Experiment 1, participants randomized to placebo will receive IV matching placebo over 5 minutes at the completion of extinction training followed by a continuous infusion of matching placebo over the next 4-5 hours. The matching IV placebo will be administered according to the same per kg dosing regimen as that for active drug.
BEHAVIORAL
Experiment 2. Three-day aversive conditioning, reconsolidation blockade, and testing paradigm
Day 1: Aversive conditioning will involve the pairing of a brief, noxious but not painful air blast to the neck (unconditioned stimulus; US) to a colored shape appearing on a computer monitor (conditioned stimulus). An auditory stimulus will serve as the startle probe. Day 2: Brief exposure to the conditioned stimulus will be followed by IV Allo administration. Day 3: The effects of IV Allo (administered on Day 2) on reconsolidation blockade and reinstatement of conditioned psychophysiological reactions will be assessed.
DRUG
Allopregnanolone (Allo) with 6% USP Dexolve (sulfobutyl ether-beta-cyclodextrin sodium salt) in 0.9% saline for IV infusion will be provided by the University of California, Davis, GMP manufacturer.
On Day 2 of Experiment 2, a 28 mcg/kg dose of IV Allo will be infused over 30 minutes following brief reactivation of aversively conditioned psychophysiological reactions, after which IV fluid only (0.9% normal saline) will be administered over 4-5 hours.
BEHAVIORAL
Experiment 2. Three-day aversive conditioning, reconsolidation blockade, and testing paradigm
Day 1: Aversive conditioning will involve the pairing of a brief, noxious but not painful air blast to the neck (unconditioned stimulus; US) to a colored shape appearing on a computer monitor (conditioned stimulus). An auditory stimulus will serve as the startle probe. Day 2: Brief exposure to the conditioned stimulus will be followed by IV Allo administration. Day 3: The effects of IV Allo (administered on Day 2) on reconsolidation blockade and reinstatement of conditioned psychophysiological reactions will be assessed.
OTHER
Matching IV Placebo
On Day 2 of Experiment 2, matching IV placebo will be infused over 30 minutes following brief reactivation of aversively conditioned psychophysiological reactions, after which IV fluid only (0.9% normal saline) will be administered over the 4-5 hours. The matching IV placebo will be administered according to the same per kg dosing regimen as that for active drug.
Primary outcome measures
Experiment 1: Extinction retention
Time frame: Day 3
Extinction retention is calculated as a) the difference between the average skin conductance response (SCR) to the first 4 aversively conditioned stimulus (CS+) trials and the average SCR to first 4 neutral conditioned stimulus (CS-) trials on Day 3 minus b) the difference between the average SCR to the last 4 CS+ trials and last 4 CS- trials on Day 2.
Experiment 2: Reconsolidation blockade
Time frame: Day 3
Reconsolidation blockade will be assessed by calculating the average fear potentiated startle (FPS) response to the first 4 CS+ trials on Day 3. Lower scores indicate better reconsolidation blockade.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Between the ages of 18 and 55 (at time of enrollment), reproductively mature, and English speaking.
- Meet criteria for chronic PTSD (i.e., CAPS-5 determined PTSD duration more than 3 months).
- Generally healthy and not on any prohibited medications (that could affect study outcomes).
- Willing to abstain from alcohol for 2 weeks and from nicotine, marijuana or illicit drugs for 4 weeks before experimental procedures and throughout the study.
- For biological females:
- Natural menstrual cycle.
- If of childbearing potential, female and partner must use 2 types of effective birth control (except for hormonal contraceptives, unless IUD or a device like Nuvaring) for a week before the IV Allo or placebo infusion, and for one month after.
Exclusion criteria
- Present an imminent risk to self or others or require clinical intervention to maintain safety
- Diagnosis of moderate or severe substance use disorder within three months of screening per administration of the DIAMOND substance abuse evaluation. Diagnosis of a mild substance use disorder within three months of screening will be allowed if the participant agrees to abstain from illicit drugs for one month and/or alcohol for 2 weeks prior to the experimental procedures, has a negative screening or follow-up urine toxicology and/or saliva alcohol test (if the screening test is positive), and tests negative for these substances on the morning of the experimental procedures.
- Bipolar I disorder, schizophreniform disorders, or clinically significant psychotic symptoms apart from the presence of trauma-related sensory hallucinations or negative beliefs.
- History of a suicide attempt within 1 year of enrolling.
- A history of severe TBI is exclusionary for the PK-1 and PK-2 studies. A history of moderate or severe TBI is exclusionary for the main studies (i.e., Expt. 1 and Expt. 2).
- Diagnosis of sleep apnea
- Awake resting O2 saturation \< 96%
- Severe renal failure with an eGFR \<30 ml/min
- Use of medications or substances (by report or toxicology testing) will be exclusionary under the following conditions:
- During screening for eligibility:
- Use of illicit substances, as well as prescribed opiates or benzodiazepines (either reported or detected on urine toxicology testing) will be exclusionary.
- Reported non-dependent use of cannabinoids or nicotine (indicated by a positive urine toxicology or cotinine test at screening) will not be exclusionary if the individual agrees to abstain from cannabinoids and nicotine for one month prior to the experimental procedures, has a follow-up negative screening test, and tests negative for these substances on the mornings of experimental procedures.
- A positive urine alcohol test at medical screening (which indicates uncontrolled alcohol use and likely moderate to severe alcohol dependence) will be exclusionary.
- A high serum gamma-glutamyl-transferase (GGT) test at screening (indicative of more remote recent drinking but not necessarily moderate to severe alcohol use or dependence) will not be exclusionary if the individual does not meet criteria for a moderate or severe alcohol use disorder within three months of screening, agrees to abstain from drinking for 2 weeks prior to the experimental procedures, and has normal follow-up urine alcohol and serum GGT tests.
- Use of non-illicit over the counter or prescribed medications that may increase the risk of IV Allo side effects or adversely affect the experimental results is exclusionary. Participants may agree to stop non-psychotropic medications used on a prn basis, such as acetaminophen, ibuprofen, or loratadine (a CYP3A inhibitor) for 5 half-lives of the parent drug or active metabolite (whichever is longer) before the experimental procedures. Regular psychotropic medications (including those used to treat non-psychiatric conditions, such as alpha1-antagonists prescribed for hypertension or urinary hesitancy) may be discontinued under the management of the potential participant's non-study prescriber for 3 months before evaluation for eligibility and participation in subsequent experimental procedures.
- On the mornings of the PK-1, PK-2, Expt. 1 or Expt. 2 experimental procedures:
- Use of any medications or substances that may increase the risk of IV Allo side effects or adversely affect the experimental results (indicated by report, urine toxicology, urine nicotine/cotinine testing, or urine alcohol testing) will be exclusionary.
- Systemic hormone therapy or contraception will be exclusionary \[Exception: Hormonal IUDs (e.g., Mirena, Kyleena, Liletta, and Skyla) or other contraceptive devices (e.g., Nuvaring)\] will be allowed if the participant still has normal menstrual periods and is found to ovulate using commercial urine test kits provided by study).
- Pregnancy (urine pregnancy tests given at each in-person session).
- Breast-feeding.
- Unable to tolerate IV placement or blood drawing by needle stick.
- Wear hearing aid(s) (For Expt. 1 and 2, not PK studies).
- Fail hearing test (For Expt. 1 and 2, not PK studies).
Where
- Boston, Massachusetts
Collaborators
National Institute of Mental Health (NIMH)
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Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Nov 5, 2025 · Source of record for eligibility and locations