Dosing Psychedelics and MDMA.

Classic psychedelics, including psilocybin, lysergic acid diethylamide (LSD), dimethyltryptamine, and mescaline, and entactogens/empathogens, especially 3,4-methylenedioxymethamphetamine, have received renewed attention in psychiatric research and may be developed into medications for such indications as anxiety, depression, cluster headache, and posttraumatic stress disorder, among others. However, identifying proper doses is crucial. Controlled study data on dosing using well-characterized pharmaceutical formulations of the substances are scarce. The dose equivalence of different substances, dose-response effects, and subjective effects of different doses are of great interest and practically important for their clinical use in psychotherapy. Furthermore, the so-called microdosing of psychedelics has recently gained popularity, and the first placebo-controlled studies of LSD have been published. This chapter discusses different aspects of psychedelic dosing, including pharmaceutical aspects, definitions and characteristics of different doses, including microdoses, aspects of personalized dosing, and non-pharmacological factors, that can influence the response to psychedelics.