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Caffeine's biological half-life – the time required for the body to eliminate one-half of a dose – varies widely among individuals according to factors such as pregnancy, other drugs, liver enzyme function level (needed for caffeine metabolism) and age. In healthy adults, caffeine's half-life is between 3 and 7 hours. [5]
Caesium in the body has a biological half-life of about one to four months. Mercury (as methylmercury) in the body has a half-life of about 65 days. Lead in the blood has a half life of 28–36 days. [29] [30] Lead in bone has a biological half-life of about ten years. Cadmium in bone has a biological half-life of about 30 years.
In this situation it is generally uncommon to talk about half-life in the first place, but sometimes people will describe the decay in terms of its "first half-life", "second half-life", etc., where the first half-life is defined as the time required for decay from the initial value to 50%, the second half-life is from 50% to 25%, and so on.
Of course, caffeine shows up in some foods, too. Dark chocolate (70% to 85%), for example, contains more than 22 milligrams of caffeine per ounce, according to the U.S. Department of Agriculture ...
Caffeine does not give you energy, just delays fatigue for a little while longer.” In other words, that 2 p.m. cup of coffee is just delaying the inevitable. At first, caffeine might appear to ...
Paraxanthine, also known as 1,7-dimethylxanthine, is an isomer of theophylline and theobromine, two well-known stimulants found in coffee, tea, and chocolate mainly in the form of caffeine. It is a member of the xanthine family of alkaloids , which includes theophylline, theobromine and caffeine .
Caffeine Properties Chemical formula. C 8 H 10 N 4 O 2: Molar mass: 194.194 g·mol −1 Appearance Odorless, white needles or powder Density: 1.23 g/cm 3, solid [1 ...
The kinetic isotopic effect of substitution of deuterium for hydrogen within the caffeine molecule and its potential role in altering caffeine’s pharmacokinetics was first described by Horning et al., [7] which demonstrated d9-caffeine to have a prolonged half-life in rodents relative to regular caffeine. Subsequent in vitro experiments with ...