THE EFFECTS OF 600 MG OF SLOW-RELEASE CAFFEINE ON MOOD AND ALERTNESS

Background Caffeine is the most widely used psychostimulant. purpose: This study evaluated the pharmacokinetics and effects on mood and aler tness of a single oral administration of 600 mg of a slow release caff eine (SRC) on a large group of healthy subjects. Method: In this doubl e-blind, parallel-group study, 120 young adult males were randomly ass igned to either a caffeine group (CG, n = 100) or a placebo group (PG, n = 20). After a normal sleep, each subject took 600 mg of a SRC or a placebo. Circulating caffeine was determined by salivary caffeine ass ays after acetylation phenotype categorization. Mood, alertness and no cturnal sleep were evaluated by visual analog scales (VAS). Results: T his SRC was well tolerated probably due to its relative low plasmatic Cmax (10.37 mu g . ml(-1)). Between CG and PC, there were no differenc es for alertness, contentedness and sleep quality of the night after t reatment (N2) compared to the previous night (N1). VAS scores showed a decrease in calmness in the CC (p < 0.01). Sleep latency in N2 was si gnificantly increased with caffeine (p < 0.01). Calmness, sleep onset latency, quality of sleep onset and overall rating of N2 compared to N 1 were correlated with caffeine levels, which were only influenced by tobacco consumption. Conclusions: Although a single oral dose of 600 m g of a SRC is well tolerated, further evaluation must be done on alert ness and pharmacokinetics with fatigued subjects and with females usin g oral contraceptives.