Predicting caffeine plasma concentrations resulting from consumption of food or beverages: a simple method and its origin.

Multiple dosage regimens for therapeutic agents are commonly comprised of a constant dosing interval and a constant dose size. This is not true for the ingestion of a pharmacologically active agent that is a component in a dietary source. Caffeine is contained in foods and beverages that are regular components of the diet for many people. Because daily intake is unsystematic, a computer program was written to simulate caffeine plasma concentration-time courses following ingestion of variable amounts on irregular schedules. Literature values for caffeine pharmacokinetics, for the caffeine content in various foods and beverages, and for consumer habits were employed to simulate various caffeine plasma concentration-time courses. By searching for predictable traits in a wide variety of plasma concentration-time courses representing normal adults, a simple noncomputer method was developed to allow individuals to estimate caffeine plasma concentrations based on personal intake habits. Changes in the time courses due to smoking, oral contraceptive use, and liver disease, all of which alter caffeine pharmacokinetics, were also examined.