Psychopharmacology

, Volume 219, Issue 4, pp 1039–1053 | Cite as

Pharmacology of ayahuasca administered in two repeated doses

  • Rafael G. dos Santos
  • Eva Grasa
  • Marta Valle
  • Maria Rosa Ballester
  • José Carlos Bouso
  • Josep F. Nomdedéu
  • Rosa Homs
  • Manel J. Barbanoj
  • Jordi Riba
Original Investigation

Abstract

Rationale

Ayahuasca is an Amazonian tea containing the natural psychedelic 5-HT2A/2C/1A agonist N,N-dimethyltryptamine (DMT). It is used in ceremonial contexts for its visionary properties. The human pharmacology of ayahuasca has been well characterized following its administration in single doses.

Objectives

To evaluate the human pharmacology of ayahuasca in repeated doses and assess the potential occurrence of acute tolerance or sensitization.

Methods

In a double-blind, crossover, placebo-controlled clinical trial, nine experienced psychedelic drug users received PO the two following treatment combinations at least 1 week apart: (a) a lactose placebo and then, 4 h later, an ayahuasca dose; and (b) two ayahuasca doses 4 h apart. All ayahuasca doses were freeze-dried Amazonian-sourced tea encapsulated to a standardized 0.75 mg DMT/kg bodyweight. Subjective, neurophysiological, cardiovascular, autonomic, neuroendocrine, and cell immunity measures were obtained before and at regular time intervals until 12 h after first dose administration.

Results

DMT plasma concentrations, scores in subjective and neurophysiological variables, and serum prolactin and cortisol were significantly higher after two consecutive doses. When effects were standardized by plasma DMT concentrations, no differences were observed for subjective, neurophysiological, autonomic, or immunological effects. However, we observed a trend to reduced systolic blood pressure and heart rate, and a significant decrease for growth hormone (GH) after the second ayahuasca dose.

Conclusions

Whereas there was no clear-cut tolerance or sensitization in the psychological sphere or most physiological variables, a trend to lower cardiovascular activation was observed, together with significant tolerance to GH secretion.

Keywords

Ayahuasca Psychedelics Repeated dose administration Tolerance 

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Copyright information

© Springer-Verlag 2011

Authors and Affiliations

  • Rafael G. dos Santos
    • 1
    • 2
    • 3
  • Eva Grasa
    • 4
  • Marta Valle
    • 3
    • 4
    • 5
  • Maria Rosa Ballester
    • 2
    • 3
    • 4
  • José Carlos Bouso
    • 1
    • 2
  • Josep F. Nomdedéu
    • 6
  • Rosa Homs
    • 7
  • Manel J. Barbanoj
    • 2
    • 3
    • 4
  • Jordi Riba
    • 1
    • 2
    • 3
    • 4
    • 8
  1. 1.Human Experimental NeuropsychopharmacologyIIB Sant PauBarcelonaSpain
  2. 2.Centre d’Investigació de MedicamentsHospital de la Santa Creu i Sant PauBarcelonaSpain
  3. 3.Departament de Farmacologia i TerapèuticaUniversitat Autònoma de BarcelonaBarcelonaSpain
  4. 4.Centro de Investigación Biomédica en Red de Salud Mental, CIBERSAMBarcelonaSpain
  5. 5.Pharmacokinetic and Pharmacodynamic Modelling and SimulationIIB Sant PauBarcelonaSpain
  6. 6.Servei Laboratori d’HematologiaHospital de la Santa Creu i Sant PauBarcelonaSpain
  7. 7.Servei de Bioquímica ClínicaHospital de la Santa Creu i Sant PauBarcelonaSpain
  8. 8.Human Experimental Neuropsychopharmacology, Institut de RecercaHospital de la Santa Creu i Sant PauBarcelonaSpain

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