NCT04558294 (L-Ket) is a Phase 1 clinical trial of Lysergic Acid Diethylamide in Healthy, sponsored by University Hospital, Basel, Switzerland.

Who is sponsoring NCT04558294?

NCT04558294 is sponsored by University Hospital, Basel, Switzerland.

What drugs are being tested in NCT04558294?

Interventions in NCT04558294: Lysergic Acid Diethylamide, Ketanserin Placebo, Ketanserin.

Is NCT04558294 still recruiting?

NCT04558294 is currently completed. Last updated 21 October 2021.

Last reviewed 2021-10-21 · How we verify

NCT04558294: L-Ket

Name: Drug Landscape Pharmaceutical Database
Creator: Drug Landscape
Published: 2026-01-01
License: https://creativecommons.org/licenses/by/4.0/

Effect of Ketanserin After LSD Administration

Completed Phase 1 Last updated 21 October 2021

What this trial tests

Phase 1 trial testing Lysergic Acid Diethylamide in Healthy in 24 participants. Completed in 29 September 2021.

Timeline

16 October 2020

Primary endpoint
28 August 2021

29 September 2021

Quick facts

Lead sponsor	University Hospital, Basel, Switzerland
Phase	Phase 1
Status	Completed
Study type	INTERVENTIONAL
Allocation	randomized
Design	crossover
Masking	triple
Primary purpose	basic science
Enrollment	24
Start date	16 October 2020
Primary completion	28 August 2021
Estimated completion	29 September 2021
Sites	1 location across Switzerland

Drugs / interventions tested

Lysergic Acid Diethylamide
Ketanserin Placebo — full drug profile →
Ketanserin (KETANSERIN) — full drug profile →

Conditions studied

Healthy — all drugs for Healthy →

Sponsor

University Hospital, Basel, Switzerland

Who can join

Adults 25 to 65, any sex, with Healthy. Patients with the condition only — healthy volunteers not accepted.

Sponsor's own description

LSD (lysergic acid diethylamide) is a serotonergic (5-HT) hallucinogen widely used for recreational and/or ethnomedical purposes. LSD is thought to induce its prototypical psychedelic effects primarily via stimulation of the 5-HT2A receptor. This study investigates whether an LSD experience can be attenuated and shortened using 5-HT2A receptor antagonist ketanserin administration after LSD once the psychedelic effects have established.

Publications & conference data

3 peer-reviewed publications reference this trial (live from Europe PMC):

Ketanserin Reverses the Acute Response to LSD in a Randomized, Double-Blind, Placebo-Controlled, Crossover Study in Healthy Participants.
Becker AM, Klaiber A, Holze F, Istampoulouoglou I, et al · · 2023 · cited 71× · PMID 36342343 · DOI 10.1093/ijnp/pyac075
Pharmacological and non-pharmacological predictors of the LSD experience in healthy participants.
Vizeli P, Studerus E, Holze F, Schmid Y, et al · · 2024 · cited 9× · PMID 39231959 · DOI 10.1038/s41398-024-03074-9
Motivation and retrospective appraisal of psychedelic study participation: a qualitative study in healthy volunteers.
Ley L, Liechti ME, Becker AM, Straumann I, et al · · 2025 · PMID 40140019 · DOI 10.1007/s00213-025-06772-4

Verify or expand the search:

Other trials of Lysergic Acid Diethylamide

Trials testing the same drug.

NCT05175430 — Effects of SERT Inhibition on the Subjective Response to LSD in Healthy Subjects · Phase 1 · completed
NCT05177419 — Effects of LSD on Neuroplasticity in Healthy Subjects · Phase 1 · completed
NCT04516902 — Effects of MDMA Co-administration on the Response to LSD in Healthy Subjects · Phase 1 · completed
NCT03790358 — Mood Effects of Serotonin Agonists · Phase 1 · completed

Other recruiting trials for Healthy

Currently open trials in the same condition.

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NCT07496697 — Effects of Electroacupuncture at NP82 and SP15 on Bowel Motility in Healthy Subjects · NA · recruiting
NCT06431932 — Pilot Trial of Fisetin in Healthy Volunteers and Older Patients With Multimorbidity · Phase 1, PHASE2 · recruiting

Other University Hospital, Basel, Switzerland trials

Trials by the same sponsor.

NCT07444788 — Acute Effects of Intravenous 5-MeO-DMT in Healthy Participants · Phase 1 · recruiting
NCT07494214 — Acute Analgesic Effects of MDMA on Experimentally Induced Acute Pain, Hyperalgesia and Allodynia in Healthy Participants · Phase 1 · recruiting
NCT07419048 — Artificial Intelligence or Human Hand? Evaluating Inferior Vena Cava Imaging for Hydration Status · recruiting
NCT06978777 — Effect of Caffeine on Cold-stimulated Brown Adipose Tissue Activity · NA · recruiting
NCT07273630 — Effect of Protein Supplementation and Fluid Restriction on Plasma Sodium Levels in Patients Undergoing Pituitary Surgery · NA · recruiting

Verify against primary sources

ClinicalTrials.gov — authoritative US registry record
WHO ICTRP — international registry index
EU Clinical Trials Register
Sponsor press releases (Google)

Data sources for this page

Trial protocol + status: ClinicalTrials.gov NCT04558294 (US National Library of Medicine, public domain)
Publications: Europe PMC API search by NCT ID, retrieved 10 June 2026
Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
Sponsor: as reported to ClinicalTrials.gov by University Hospital, Basel, Switzerland
Last refreshed: 21 October 2021

Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT04558294.

Primary sources · FDA · ClinicalTrials.gov · EMA · SEC EDGAR · ChEMBL · Wikidata · full sourcing