Skip to content
Clinical Trials – home

Rare diseases

Investigational molecules

Locations

Our offerNewsroom

Recruiting

A study of psilocybin and psychological support compared to diphenhydramine hydrochloride for people with cocaine addiction

Fast replyInvestigational
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

What is this trial about?

A plain-language summary of the goals, design and what participants do

This study focuses on Cocaine Use Disorder, a condition characterized by the inability to stop using cocaine despite harmful consequences. The research aims to evaluate the feasibility of using a substance called psilocybin (code name PEX010) combined with psychological support to treat this disorder. Psilocybin is a compound that can cause changes in perception and mood. Participants will be assigned to receive either the active substance or a placebo, which is an inactive substance, in the form of an oral capsule.

During the trial, individuals will undergo a process involving a single dose of the medication followed by six sessions of psychological support. The psychological support involves talking with trained professionals to assist with the treatment process. The study will monitor various aspects of the experience, including changes in mood, anxiety, and the ability to function in daily life, as well as the frequency of drug use. Safety will also be monitored through regular checks of heart health, such as an ECG, which is a test that records the electrical activity of the heart, and through laboratory tests to check blood and organ function.

The research process

The trial runs in 4 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    <b>randomisation</b>

    You are assigned to one of two groups to receive either the test substance or a placebo, which is an inactive substance used for comparison.

  2. Step 2

    <b>medication administration</b>

    You receive a single oral dose of one of two substances.

    If assigned to the test group, you take a 25 mg capsule of psilocybin.

    If assigned to the placebo group, you take a 100 mg capsule of diphenhydramine hydrochloride.

  3. Step 3

    <b>psychological support</b>

    You participate in 6 sessions of psychological support to assist with the treatment process.

  4. Step 4

    <b>monitoring and follow-up</b>

    Safety is monitored through electrocardiograms, which are tests that check the electrical activity of the heart, and blood tests to check liver, kidney, and general health.

    Blood pressure and heart rate are measured before the dose and at 1 hour, 3 hours, and 6 hours after taking the capsule.

    Ongoing assessments are conducted to track cocaine use, mood, anxiety, and overall functionality.

Who can join the trial?

13 criteria

  • You must have a diagnosis of cocaine use disorder, which is a medical condition where a person has difficulty controlling their use of cocaine, specifically when using the powder or intranasal form.
  • Your condition must be classified as moderate or more severe according to standard medical guidelines.
  • You must have used cocaine on at least 4 separate days during the past month.
  • You must score at least a 4 on the Severity of Dependence Scale, which is a tool used by doctors to measure how much a person relies on a substance.
  • You must have a negative urine test for cocaine at least one day before receiving the medication and on the day the medication is given.
  • You must be between the ages of 21 and 65 years old when you sign the agreement to join the study.
  • You must be able to speak English.
  • You must be able to provide informed written consent, which means you understand the study and agree to participate in writing.
  • You must be actively seeking treatment for your condition.
  • You must have a friend or family member available to take care of you and ensure you get home safely after your medication session.
  • If you are female, you must have a negative pregnancy test using blood (serum) during the initial screening and a urine test at the start of the study.
  • If you are a female of childbearing potential, you must agree to use an approved method of contraception, such as birth control pills, an intrauterine device (IUD), or having your fallopian tubes closed, from the start of the study until it is finished.
  • Your laboratory findings (results from blood or urine tests) and your ECG (a test that records the electrical activity of your heart) must be within a healthy or acceptable range.

Who cannot join the trial?

16 criteria

  • You have a diagnosis of bipolar affective disorder (a condition that causes extreme mood swings) or any psychotic disorder (a mental health condition that affects how a person thinks, feels, and perceives reality).
  • You have used psychedelics (drugs that change your perception, thoughts, and feelings) within the last 12 months.
  • You have used psychedelics 25 times or more in your lifetime.
  • Your personal situation or behavior makes it difficult to build a rapport (a relationship of trust and understanding) with the study staff or prevents you from being safe during the treatment.
  • You are facing legal problems that could lead to being sent to jail.
  • You have started new psychological or behavioral therapies (treatments like counseling or talk therapy) within the last 30 days, or if these therapies might change during the study.
  • You have dementia (a condition that causes a decline in memory and thinking skills).
  • You have a first-degree relative (a parent, sibling, or child) who has a psychotic disorder.
  • You are currently experiencing suicidal or homicidal ideation (thoughts of wanting to kill yourself or someone else).
  • You have shown a significant suicide risk, such as having thoughts of suicide or non-suicidal self-injury (hurting yourself without the intent to die) within the last six months.
  • You have stayed in a psychiatric inpatient facility (a hospital for mental health treatment) within the last six months.
  • You have a severe alcohol use disorder (a medical condition involving problematic alcohol consumption).
  • You are currently using heroin.
  • You are taking certain medications, including tricyclic antidepressants, lithium, MAO-Is (a type of antidepressant), or antipsychotics (medications used to manage psychosis) at doses higher than 25% of the maximum recommended amount.
  • You are taking Aldehyde dehydrogenase (ALDH) inhibitors, Alcohol dehydrogenase (ADH) inhibitors, or Uracil-DNA Glycosylase (UDG) (specific types of substances or drugs that affect how your body processes certain chemicals).
  • You meet any other general medical exclusion criteria (other health-related reasons for not being able to participate) listed in the study rules.
Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.

We usually reply within a few days

Verified sites

All sites with verified contact details – recruitment status may not be available; ask directly

Trial locations

Where you can join this trial

Countries are shaded by recruitment status. Click a recruiting country to ask about joining there.

Recruiting
Not finding your country?

Not sure what to do next?

Joining a clinical trial can seem overwhelming. We guide you step by step, so you know exactly what to expect and how we support you through the process.

See the full process and FAQ

Investigated drugs

Psilocybin is a substance derived from certain types of mushrooms that is being studied to see if it can help people who struggle with cocaine addiction when combined with professional mental health support.

What is already known about the treatment

  • Diphenhydramine hydrochloride

    This medication is taken as a pill by mouth and is commonly used to treat allergy symptoms or to help with sleep. While it is widely available in stores, in this study, it is being used as a placebo to compare against the test substance. It works by blocking certain natural chemicals in the brain and body that trigger allergic reactions and keep the body alert. It belongs to a group of drugs known as antihistamines.

  • Dry extract from Psilocybe cubensis

    This substance is administered orally in capsule form and is currently being extensively studied in medical literature for its potential to treat mental health conditions. It is primarily being investigated as a way to help people overcome addictions, such as cocaine use disorder. At a molecular level, it works by interacting with specific receptors in the brain that regulate mood and perception. It is classified as a psychedelic substance.

Investigated diseases

Cocaine use disorder - This is a condition characterized by a problematic pattern of cocaine use that leads to significant impairment or distress. It often begins with occasional use that can lead to a strong urge or compulsion to consume the substance. Over time, an individual may develop a high tolerance, requiring larger amounts to achieve the same effects. The disorder typically involves repeated use despite knowing the negative consequences. As it progresses, the brain's reward system changes, making it increasingly difficult to control the urge to use.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase IITrial ID2024-515147-32-02Protocol codeTRI-CRF-23-02Estimated enrolment24 patientsSponsorTrinity College Dublin

sourced from the EU Clinical Trials Register and site verification

Want to learn more about this trial or check if you can participate?

Clinical Trials Concierge

Prefer not to search? Our Concierge searches the trials for you.

Tell us about your condition – we search every trial in Europe and connect you with the right site.