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

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What is this study about?

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.

Who Can Join the Study?

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 Study?

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.

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

No sites found in this category

Other Sites

Site Name	City	Country	Status
Tallaght Adult Mental Health Service	Dublin	Ireland
Wellcome HRB Clinical Research Facility	Dublin	Ireland

Trial status

Country	Status	Recruitment Start
Ireland	Not yet recruiting	01.02.2026

Trial locations

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.

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 ID:

2024-515147-32-02

Protocol code:

TRI-CRF-23-02

Trial Phase:

Therapeutic exploratory (Phase II)

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