ABSORPTION AND SUBJECTIVE EFFECTS OF CAFFEINE FROM COFFEE, COLA AND CAPSULES

Coffee is often perceived as producing greater pharmacological effects than cola. The present study compared the magnitude and rapidity of p eak caffeine levels and subjective effects between coffee and cola. Th irteen users of both coffee and cola (mean daily caffeine consumption = 456 mg) ingested 400 mg caffeine via 12 oz unsweetened coffee, 24 oz sugar-free cola or 2 capsules in a random, double-blind, placebo-cont rolled, within-subjects design. Subjects provided a saliva sample and completed subjective effect scales 15 min before and 30, 60, 90, 120, 180 and 240 min after ingestion. Mean peak saliva caffeine levels did not differ between coffee (9.7 +/- 1.2 mu g/ml) and cola (9.8 +/- 0.9 mu g/ml) and appeared to be greater with these beverages than with the capsule (7.8 +/- 0.6 mu g/ml; p = NS). Saliva caffeine levels peaked at similar times for coffee (42 +/- 5 min) and cola (39 +/- 5 min) but later for capsule (67 +/- 7 min; p = 0.004). There was no main effect of vehicle or interaction of vehicle and drug on magnitude of peak ef fect or time to peak increase on self-report scale's. In summary, peak caffeine absorption, time to peak absorption, and subjective effects do not appear to be influenced by cola vs. coffee vehicle. Perceived d ifferences in the effects of coffee vs. cola may be due to differences in dose, time of day, added sweetener, environmental setting or conti ngencies. (C) 1997 Elsevier Science Inc.