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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.
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 ...
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.
Paraxanthine is believed to exhibit a lower toxicity than caffeine and the caffeine metabolite, theophylline. [ 22 ] [ 23 ] In a mouse model, intraperitoneal paraxanthine doses of 175 mg/kg/day did not result in animal death or overt signs of stress; [ 24 ] by comparison, the intraperitoneal LD50 for caffeine in mice is reported at 168 mg/kg ...
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 ...
Alternatively, since the radioactive decay contributes to the "physical (i.e. radioactive)" half-life, while the metabolic elimination processes determines the "biological" half-life of the radionuclide, the two act as parallel paths for elimination of the radioactivity, the effective half-life could also be represented by the formula: [1] [2]
Methylliberine has a short half-life of only 1.5 hours compared to the 5-7 hour half life of caffeine. [5] An interaction study showed concomitant administration of both caffeine and methylliberine increases the half-life of caffeine by about 2 fold. [5] This is likely due to inhibition of the CYP1A2 enzyme. [5]