Abstract of a paper published in Biological Psychiatry
by Rick Strassman

Published in Biological Psychiatry Vol. 39:784-795, 1996

DIFFERENTIAL TOLERANCE TO
BIOLOGICAL AND SUBJECTIVE EFFECTS OF
FOUR CLOSELY-SPACED DOSES OF
N,N-DIMETHYLTRYPTAMINE IN HUMANS

Rick J. Strassman
Department of Psychiatry
School of Medicine

Clifford R. Qualls
Department of Mathematics and Biostatistics
School of Medicine

Laura M. Berg
Department of Psychiatry
School of Medicine

University of New Mexico
Albuquerque, New Mexico

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ABSTRACT

Tolerance to the behavioral effects of the short-acting, endogenous hallucinogen, N,N-dimethyltryptamine (DMT) is seen inconsistently in animals, and has not been produced in humans. The nature and time course of responses to repetitive, closely-spaced administrations of an hallucinogenic dose of DMT were characterized. Thirteen experienced hallucinogen users received intravenous 0.3 mg/kg DMT fumarate, or saline placebo, four times, at 30 minute intervals, on two separate days, in a randomized, double-blind, design. Tolerance to "psychedelic" subjective effects did not occur according to either clinical interview or Hallucinogen Rating Scale scores. ACTH, prolactin, cortisol and heart rate responses decreased with repeated DMT administration, while blood pressure did not. These data demonstrate the unique properties of DMT relative to other hallucinogens, underscore differential regulation of the multiple processes mediating the effects of DMT.