NCT07565493 · Johns Hopkins University
Psilocybin Administration With 5-HT1a Blockade
(PsilBlock1)
What this study is about
The purpose of this study is to assess the effects of 5-HT1A receptor blockade on the acute subjective effects of psilocybin, as measured through subjective survey measures and acute electroencephalography (EEG). Further, the investigators will assess the effects of psilocybin on post-acute sleep and dreaming through the use of sleep EEG and sleep and dream diaries.
View original scientific description
The purpose of this study is to assess the effects of 5-HT1A receptor blockade on the acute subjective effects of psilocybin, as measured through subjective survey measures and acute electroencephalography (EEG). Further, the investigators will assess the effects of psilocybin on post-acute sleep and dreaming through the use of sleep EEG and sleep and dream diaries.
Interventions
DRUG
Pindolol
Pindolol is a 5-HT1A antagonist drug that will be used as a pharmacological probe for the mechanism of acute subjective effects in the altered state of consciousness induced by psilocybin.
DRUG
Placebo
Microcrystalline cellulose capsules, identical in appearance to the active treatment, containing no pharmacologically active ingredients, will be administered as an inert placebo comparator.
DRUG
Psilocybin
Psilocybin is a tryptamine psychedelic with 5-HT2A agonist activity. The psilocybin-induced altered state of consciousness is characterized by changes in sensory perception, cognition, and induction of mystical-type experiences. These subjective effects will be assessed in each dosing session.
Primary outcome measures
Mystical Experiences Questionnaire
Time frame: From the first dosing session to the end of the second dosing session, approximately 10 days
Assess changes in intensity of the subjective effects induced by psilocybin with co-administration of a 5-HT1A antagonist, pindolol as measured through the mystical experience questionnaire. Scores can range from 0-150 with a higher score indicating a more intense mystical-type experience.
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
- 21 - 60 years old
- Must give written or electronic informed consent
- Must have at least a high-school level of education or equivalent (e.g. GED) and are fluent in English
- Must be healthy and psychologically stable as determined by screening for medical and psychiatric problems via a personal interview, a medical questionnaire, a physical examination, an electrocardiogram (ECG), and routine medical blood and urinalysis laboratory tests
- Must agree not to take any as needed (PRN) medications on the mornings of drug sessions
- Must agree not to take sildenafil (Viagra®), tadalafil, or similar medications within 72 hours of each drug administration.
- Must agree to refrain from using all psychoactive substances within 24 hours or 5 elimination half-lives (whichever is greater) before psilocybin administration. Caffeine is the exception.
- Must have a negative urine toxicology report on the same day as drug dosing.
- Who are female and of child-bearing potential and are sexually active, must agree to use highly effective means of birth control (i.e. implants, injectables, combined oral contraceptives, progestin-containing intrauterine device (IUD) or vasectomized partner) for the duration of this study.
- Who are male and sexually active, must agree to use contraception and refrain from sperm donation within 90 days of completing dosing sessions. Effective methods of contraception are barrier, hormonal, and sterilization methods.
Exclusion criteria
- Are currently taking a medication with any significant pharmacokinetic or pharmacodynamic interactions with pindolol (e.g. beta-blockers or other anti-hypertensive medications).
- Have a history of orthostatic hypotension or low blood-pressure.
- Have elevated transaminases (2x the upper limit of normal)
- Have a Child-Pugh score that falls within classes B or C.
- Are pregnant (as indicated by a positive urine pregnancy test assessed at intake and before each drug session) or nursing.
- Have cardiovascular conditions: coronary artery disease, stroke, angina, uncontrolled hypertension, a clinically significant ECG abnormality (e.g. atrial fibrillation, corrected QT interval (QTc) \> 450 msec), artificial heart valve, symptomatic valvopathy, history of pulmonary hypertension or transient ischemic attack (TIA) in the past year; systolic blood pressure \> 139, diastolic blood pressure \> 89
- Have epilepsy or a history of seizures
- Have insulin-dependent diabetes; if taking oral hypoglycemic agent, then no history of hypoglycemia
- Are currently taking on a regular (e.g. daily) basis any medications having a centrally acting serotonergic effect, including monoamine oxidase inhibitors (MAOIs). For individuals who have intermittent or PRN use of such medications, psilocybin sessions will not be conducted until at least five half-lives of the agent have elapsed after the last dose.
- Have a current diagnosis of schizophrenia spectrum disorders
- Have a current diagnosis of bipolar spectrum disorders
- Have a current diagnosis of major depressive disorder or Generalized Anxiety Disorder
- Have a current diagnosis or history of substance induced psychotic disorder
- Have a current DSM-5 moderate or severe alcohol or drug use disorder (excluding caffeine and nicotine)
- Have a first degree relative with bipolar I disorder, or schizophrenia spectrum disorder.
- Have a psychiatric condition judged to be incompatible with establishment of safe exposure to psilocybin.
- Have a BMI ≥ 40
- Report a known history of sleep apnea, symptoms indicative of sleep apnea, or have an Apnea-Hypopnea Index (AHI) \> 15, or STOP BANG \>5
- Taking prescribed hypnotics or other medications known to alter sleep physiology: i.e., Z-drugs, Benzodiazepines, Orexin Agonists or Antagonist, Beta Blockers.
- Regularly taking over-the-counter sleep aids (inc. melatonin and diphenhydramine) and unwilling to abstain during the study.
- Insomnia Severity Index ≥ 10
Where
- Baltimore, Maryland
Related conditions & keywords
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 Jun 25, 2026 · Source of record for eligibility and locations