Background: Recent interest in the clinical use of psychedelics has highlighted plant-derived medicines like ayahuasca showing rapid-acting and sustainable therapeutic effects in various psychiatric conditions. This traditional Amazonian plant decoction contains N,N-dimethyltryptamine (DMT) and β-carboline alkaloids such as harmine. However, its use is often accompanied by distressing effects like nausea, vomiting, and intense hallucinations, possibly due to complex pharmacokinetic/pharmacodynamic (PK-PD) interactions and lack of dose standardization.
Methods: This study addresses these limitations by testing a novel pharmaceutical formulation containing pure forms of DMT and harmine in a double-blind, randomized, placebo-controlled trial with 31 healthy male volunteers. We evaluated PK-PD by monitoring drug and metabolite plasma levels, subjective effects, adverse events, and cardiovascular parameters. Each participant received three randomized treatments: 1) 100 mg buccal harmine with 100 mg intranasal DMT, 2) 100 mg buccal harmine with intranasal placebo, and 3) full placebo; using a repeated-intermittent dosing scheme, such that 10 mg of DMT (or placebo) was administered every 15 minutes.
Results: DMT produced consistent PK profiles with Cmax values of 22.1 ng/ml and acute drug effects resembling the psychological effects of ayahuasca with a duration of 2-3 hours. Likewise, buccal harmine produced sustained-release PK profiles with Cmax values of 32.5 ng/ml, but lacked distinguishable subjective effects compared to placebo. All drug conditions were safe and well tolerated, indicating the formulation's suitability for clinical applications.
Conclusion: This study underscores the potential of a patient-oriented pharmaceutical formulation of DMT and harmine to reduce risks and improve therapeutic outcomes in treating mental health disorders.
Keywords: N; N-dimethyltryptamine; harmine; pharmacodynamics; pharmacokinetics; psychedelics.
© The Author(s) 2025. Published by Oxford University Press on behalf of CINP.