Safety and Psychological Effects of Psilocybin and D-Serine Formulation in Healthy Volunteers

This Phase I, open-label, dose-escalation trial (n=10) will evaluate the safety and psychological effects of a combined psilocybin and D-Serine formulation; cohort 1 will receive psilocybin 15 mg with D-Serine 5 g, and if safe cohort 2 will receive psilocybin 25 mg with D-Serine 7 g.

The trial is a first-in-human, exploratory study run by Hadassah Medical Organization in Jerusalem (Principal Investigator: Bernard Lerer, MD). It recruits 10 medically and psychiatrically healthy adults aged 25–60 with no recent psychedelic use or family history of psychotic disorders. The investigators aim to see whether D-Serine (an amino acid that acts as a co-agonist at the NMDA receptor — a brain receptor involved in learning and plasticity) can modulate or reduce the acute psychedelic effects of psilocybin while preserving potential neuroplastic or therapeutic actions. The design is sequential: a small first cohort receives the lower dose and an interim safety report is provided to the ethics committee before the higher-dose cohort is enrolled. Participants undergo screening and preparation, a single administration day, and follow-ups on Day 2, Day 7, Day 28 and Day 84.

The primary outcome is the incidence and severity of treatment-emergent adverse events (TEAEs) through Day 84 (TEAEs = side-effects that start after treatment). Secondary measures assess subjective altered states (5D-ASC — a 5-dimension questionnaire of altered consciousness), mood (Profile of Mood States), acute distress (SUDS), depression (BDI-II), anxiety (STAI), EEG and blood biomarkers (plasma D-serine, inflammatory markers, BDNF [brain-derived neurotrophic factor], glutamate). Sponsor: Hadassah Medical Organization. Estimated start: November 2025; primary completion: November 2026; study completion: February 2027.

Topic Safety Neuroscience Healthy Subjects
Compound Psilocybin
Country Israel
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Trial Details



Trial Number

Sponsors & Collaborators

Hadassah Medical Organization
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Measures Used

Beck Depression Inventory
The Beck Depression Inventory (BDI) contains 21 self-report items, completed using a multiple-choice format. Scores range from 0-63 with higher scores associated with more severe depression.

State-Trait Anxiety Inventory
The State-Trait Anxiety Inventory (STAI) is a commonly used measure of trait and state anxiety. The STAI measures two types of anxiety – state anxiety, anxiety about an event, and trait anxiety, anxiety level as a personal characteristic.

Profile of Mood States
The Profile of Mood States (POMS) is a scale used to assess transient, distinct mood states. The questionnaire contains 65 words/statements that describe the feelings people have. It measures six different dimensions of mood swings over a period of time including tension or anxiety, anger or hostility, vigour or activity, fatigue or inertia, depression or dejection, confusion or bewilderment. Each item is marked on a five-point scale from "not at all" to "extremely."

5-Dimensional Altered States of Consciousness Questionnaire
The 5D-ASC scale measures altered states of consciousness and contains 94 items (visual analog scales).

Data attribution

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