A Phase 1, Open-label, Single Cohort Study to Evaluate the Safety and Pharmacokinetics (PK) of a Single Intravenous (IV) Infusion of TRP-8803 [Psilocin Besylate formulation] in Healthy Adult Participants

This Phase I, open-label trial (n=4) will assess the safety and pharmacokinetics of a single intravenous dose of psilocin (TRP-8803; 5 mg loading over 20 minutes followed by 5 mg maintenance over 120 minutes) in healthy adults undergoing psychedelic-assisted psychotherapy.

The study is being conducted as a follow-up to a previous trial and focuses on evaluating psilocin (the active metabolite of psilocybin) delivered intravenously.

Participants will receive preparatory psychotherapy prior to dosing, followed by two integration sessions after dosing. The psychotherapy will be facilitated by a consistent pair of trained therapists, with at least one being medically qualified. This structure aims to ensure safety and support before, during, and after the psychedelic experience.

Primary outcomes include assessing safety via adverse events and physiological measures, while secondary outcomes focus on understanding the drug’s pharmacokinetics, psychological effects (e.g. mystical or emotional breakthroughs), and changes in brain activity using EEG. This trial exclusively includes healthy participants with no current or recent psychiatric diagnoses, substance use issues, or personal histories deemed incompatible with the safe use of psychedelics.

Trial Details

INTERVENTIONAL: This is a phase 1 open label uncontrolled trial of TRP-8803 (Psilocin Besylate) administered intravenously in conjunction with psychedelic-assisted psychotherapy. PSYCHEDELIC-ASSISTED PSYCHOTHERAPY: The study is a combined pharmacological and psychological treatment, and as such, each individual participant will receive psychotherapy before, during, and after each dosing session. All participants will be seen by the same two therapists from baseline through to the completion of the study. The trial therapists are qualified and experienced mental health professionals (i.e., psychiatrists, psychologists) with specialty training in empirically based therapeutic modalities and psychedelic-assisted psychotherapy. The therapist dyad will typically consist of one male and one female therapist. In every dyad, at least one therapist will be a medically qualified healthcare practitioner. This ensures appropriately qualified staff are able to administer trial medication, both the study drug and any medical interventions if required (i.e., anti-anxiety medication due to persistent psychological distress), and manage any medical events that emerge. The psychotherapy focuses on three distinct phases of this approach: (1) Preparation: emphasising therapeutic alliance, non-avoidance training, psychological and practical preparation for dosing sessions, nature of and relationship to distress, anxiety management strategies, the importance of set and setting, and intention formation; (2) Dosing session: establishing suitable set and setting, and providing non-directive support when necessary; (3) Integration: focus on sustaining the change, emotion and body-focused therapy, meaning-centred integration into wider context, mindfulness training, ongoing peer- and professional support, and facilitating contextual changes to support outcomes. Therapy guides will ensure trial fidelity. The intervention scheduled for all participants will commence with two hours of preparatory psychotherapy session (week 1). In week 2, the investigational medical product (IMP) will be administered, followed by two, 1 hour sessions of integration psychotherapy; the first within 24 hours after the dosing session (week 2) and the second 2 weeks later (week 4). Treatment will be delivered to individual participants separately. Adherence to trial protocol (i.e., session attendance) will be documented. TRP-8803 (Psilocin Besylate) ADMINISTRATION: TRP-8803 will be administered via an intravenous (IV) infusion once (1) to each participant in week 2. During the single dosing session, participants will receive an initial 5 mg loading dose infused over the first 20 minutes to provide a therapeutic/psychoactive dose of psilocin that will be maintained by infusing the maintenance dose of 5 mg over the following 120 minutes. Participant dosing will be staggered with at least a 48-hour interval scheduled between the start of psilocin administration for the first and remaining participants, with no more than one participant being dosed on a single day. The nature and severity of any adverse events related to the dosing of the first participant will be reviewed by the investigators and the Data Safety Monitoring Board (DSMB) to determine whether to proceed with the remaining dosing, modify the study, pause the study, or stop the study in accordance with pre-defined discontinuation rules. Adherence to the study intervention will be monitored by the therapist dyad facilitating the dosing session, essential documentation (i.e., IMP accountability records), and audiovisual recording of dosing session.

Trial Number ACTRN12625000403437p

Data attribution

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