Caffeine self-administration in humans: 1. Efficacy of cola vehicle.
Eight exclusive cola drinkers in Experiment 1 (mean caffeine intake = 157 +/- 74 mg/day) and 16 drinkers of both cola and coffee in Experiment 2 (mean caffeine intake = 579 +/- 201 mg/day) underwent 6 independent, double-blind weekly trials. Each trial began with a randomized cross-over sampling period of 1 day of access to noncaffeinated cola and 1 day of access to caffeinated (33 mg/8 oz) cola. During the subsequent 1- or 2-day test period, participants had unlimited concurrent access to the 2 colas. Reliable caffeine self-administration occurred in 2 of 8 participants in Experiment 1 and in 4 of 16 participants in Experiment 2. Self-reported drowsiness, fatigue, and headache were higher when participants received only placebo colas in Experiment 2, but not Experiment 1. Caffeine self-administration via cola occurs both among people whose primary source of caffeine is cola and among those whose primary source of caffeine is coffee.
Liguori
A
A
Department of Psychiatry, University of Vermont, Burlington 05401-1419, USA.
Hughes
J R
JR
Oliveto
A H
AH
D000328:Adult; D000339:Affect / Q000187:drug effects; D001519:Behavior / Q000187:drug effects; D001628:Beverages; D002110:Caffeine / Q000008:administration & dosage* / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage* / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000187:drug effects; D012054:Reinforcement, Psychology; D012646:Self Administration; D013649:Taste; D014202:Tremor / Q000139:chemically induced / Q000503:physiopathology
D000697:Central Nervous System Stimulants; D002110:Caffeine