Placebo-Controlled Study Finds Psilocybin Formulation is Safe and Well-Tolerated in Healthy Volunteers

The study used an investigational psilocybin formulation called COMP360 developed and produced by COMPASS Pathways.


COMPASS Pathways and King’s College London have announced the results of their placebo-controlled phase 1 clinical trial of psilocybin in 89 healthy volunteers. The results were presented at the 58th Annual Meeting of the American College of Neuropsychopharmacology held December 8-11, 2019.

The study used synthetic psilocybin in an investigational formulation called COMP360 which was developed and produced by COMPASS.

In the December 2019 issue of COMPASS Pathway News, COMPASS co-founder and Chief Innovation Officer Dr. Ekaterina Malievskaia summed up the study by saying,

In addition to creating regulatory quality data on the short-and long-term safety of psilocybin, we explored the safety and feasibility of 1:1 therapeutic support with several simultaneous sessions.

The highlights of the study were:

  • The volunteers experienced no serious adverse events.
  • The majority of adverse events seen were of the expected psychedelic nature.
  • The most frequent were changes in sensory perception and positive mood alteration.
  • COMP360 had no negative effects on cognitive and emotional functioning
  • The study demonstrated the feasibility of administering COMP360 in a controlled setting to healthy participants with 1:1 therapist support.
  • The study used up to six sessions running simultaneously.

Looking to the future, Dr. Malievskaia said,

If further supported by regulators, this model could expedite research and eventually improve patient access to innovative treatments.

In 2018, the US Food and Drug Administration granted breakthrough therapy designation to COMPASS for psilocybin in treating treatment-resistant depression.

Barb Bauer Headshot

Barb is the former Editor and one of the founders of Psychedelic Science Review. She is currently a contributing writer. Her goal is making accurate and concise psychedelic science research assessable so that researchers and private citizens can make informed decisions.


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Francis Hemeter
2 years ago

I postulate that are two effects Pharmacodynamic one and insight mystical experience Conscious Cognitive. You could design an experiment with psilocybin administration under general anaesthesia (or a memory blocking drug) vs conscious. I expect you will still get a pharmacodynamic effect on say depression in the Anaesthetise group still but better long term outcomes Conscious cognitive group that have a mystical experience. This is on the basis that substances like high dose smoked DMT are often other worldly short and confusing with no or little conscious cognitive insights are gained but short term mood shift next day up to 2… Read more »