More rapid absorption can be achieved by chewing caffeine-containing gum or other preparations that allow absorption through the oral mucosa. When it is consumed in beverages (most commonly coffee, tea, or soft drinks) caffeine is absorbed rapidly from the gastrointestinal tract and distributed throughout body water. These effects include mild CNS stimulation and wakefulness, ability to sustain intellectual activity, and decreased reaction times.Ĭaffeine is rapidly and completely absorbed in humans, with 99 percent being absorbed within 45 minutes of ingestion (Bonati et al., 1982 Liguori et al., 1997). The pharmacological effects of caffeine are similar to those of other methylxanthines (including those found in various teas and chocolates). This wide range in the plasma mean half-life of caffeine is due to both innate individual variation, and a variety of physiological and environmental characteristics that influence caffeine metabolism (e.g., pregnancy, obesity, use of oral contraceptives, smoking, altitude). However, caffeine's elimination half-life may range between 1.5 and 9.5 hours, while the total plasma clearance rate for caffeine is estimated to be 0.078 L/h/kg (Brachtel and Richter, 1992 Busto et al., 1989). The mean half-life of caffeine in plasma of healthy individuals is about 5 hours. Structurally, caffeine (and the other methylxanthines) resembles the purines.
In pure form, it is a bitter white powder. This chapter provides a brief summary of the metabolism and physiological effects of caffeineĬaffeine (1,3,7-trimethylxanthine) is a plant alkaloid with a chemical structure of C 8H 10N 4O 2 (see Figure 2–1) and a molecular weight of 194.19. It has numerous pharmacological and physiological effects, including cardiovascular, respiratory, renal, and smooth muscle effects, as well as effects on mood, memory, alertness, and physical and cognitive performance. As stated in Chapter 1, caffeine is the most widely used central nervous system (CNS) stimulant in the world.
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