Methamphetamine self-administration by humans.
BACKGROUND
Methamphetamine abuse has become increasingly problematic. Yet, the reinforcing effects of methamphetamine in humans have not been systematically evaluated.


OBJECTIVE
To characterize methamphetamine's reinforcing effects in human research participants under controlled laboratory conditions.


METHODS
Eight healthy research volunteers (one female, seven males) completed this 20-day residential study. On days 1, 5, 9, 13 and 17, at 1000 hours, participants received the "sample" oral dose of methamphetamine (0, 5, 10 mg) that was available for the next 3 days and they also received an alternative reinforcer, a $1 voucher (redeemable for cash at study's end). Over a 3-day period, volunteers participated in an eight-trial choice procedure, during which they had the opportunity to self-administer the dose of methamphetamine they most recently sampled or to receive the $1 voucher.


RESULTS
Participants' choice to self-administer methamphetamine significantly increased when active methamphetamine (5 mg and 10 mg) was available compared to placebo. No difference of choice was noted between low-dose and high-dose methamphetamine. However, the sampled 10 mg methamphetamine dose significantly increased several "positive" subjective ratings including "High," "Good Drug Effect," and "Stimulated," whereas the sampled 5 mg methamphetamine dose did not. Both active methamphetamine doses caused significant reductions in daily total caloric intake, relative to the respective placebo conditions.


CONCLUSIONS
These data demonstrate that oral methamphetamine is a positive reinforcer in humans.
Hart
C L
CL
Division on Substance Abuse, New York State Psychiatric Institute and Department of Psychiatry, College of Physicians and Surgeons of Columbia University, 1051 Riverside Drive, Unit 120, New York, NY 10032, USA. clh42@columbia.edu
Ward
A S
AS
Haney
M
M
Foltin
R W
RW
Fischman
M W
MW
D000328:Adult; D004305:Dose-Response Relationship, Drug; D002149:Energy Intake; D005260:Female; D006801:Humans; D008297:Male; D008694:Methamphetamine / Q000008:administration & dosage*; D011597:Psychomotor Performance / Q000187:drug effects; D012054:Reinforcement, Psychology; D012646:Self Administration
D008694:Methamphetamine