DISCUSSION
psychiatric, nasal congestion, hypotension, neuroregeneration
ADVERSE EFFECTS
The present study demonstrated that the 5-HTPsilocybin is the most commonly investigated psychedelic in psychiatric research. It is currently preferred over LSD, partly because of its shorter duration of action. The duration of action of 20–25 mg psilocybin, a dose equivalent to the 100-µg dose of LSD used in the present study (Ketanserin has known adverse effects, including sedation, hypotension, and nasal congestion (Psychedelics induce neuroplastogenic effects and increase markers of neuroregeneration, including BDNF (The present study also described the pharmacokinetics of an oral LSD solution in healthy individuals. The parameters were consistent with previous studies that used the same formulation (The fact that ketanserin persistently blocked the LSD response despite its shorter half-life is notable. Ketanserin is typically used in preclinical research in competitive binding assays or to antagonize effects of psychedelics. Assuming that ketanserin competitively displaces LSD at the receptor, similar or higher effect-site concentrations as LSD would be needed. Plasma ketanserin concentrations reached a maximum of 129 ng/mL (327 nM) within 2.3 hours, consistent with its rapid absorption (The present study has several strengths. First, we used a blinded, placebo-controlled, randomized, balanced design. The crossover design allowed well-powered within-participant comparisons. Second, the pharmaceutical formulation of LSD was produced according to Good Manufacturing Practices, including content definition and stability.The present study also has limitations. First, the study design did not include a placebo condition for LSD. However, the study validly tested the effects of ketanserin compared with placebo on the non-blinded acute subjective LSD effects reflecting the clinical situation in patients in LSD-assisted treatment where LSD is administered open-label. The acute effects of the dose and formulation of LSD used in the present study have repeatedly been described in previous placebo-controlled studies (In conclusion, the present study supports the view that LSD produces its subjective and autonomic effects in humans predominantly via a primary interaction with the 5-HT