Related Pharmacokinetics of Coffee

Deaths from ocular caffeine are rare. The lethal dose of caffeine taken by adults for a short time is about 5-10g, and adverse reactions can occur after taking 1 g, which are mostly seen in central nervous system and circulatory system symptoms. Early symptoms such as insomnia, restlessness and agitation progress to mild coma, vomiting, convulsions, muscle tension and tremors. Tachycardia and extrasystoles are also common. In addition, breathing is accelerated.

Methylxanthines are readily absorbed when administered orally, rectally or by injection. These compounds are widely distributed throughout the body,

It can pass through the placenta barrier and can also be secreted by milk.

The apparent volume of distribution of caffeine and theophylline is similar, usually 0.4- 0.6 L/kg. The binding ratio of theophylline to plasma protein was higher than caffeine, and decreased with the increase of concentration. These compounds are mainly metabolized in the liver. Only 15% theophylline and 5% caffeine are excreted unchanged in urine. Caffeine has a plasma half-life of 3-7 hours, twice as long in women who use sterols late in pregnancy or for prolonged periods. Premature infants eliminate methylxanthines very slowly, with an average half-life of more than 50 hours for caffeine. Caffeine is mainly metabolized by demethylation and oxidation at position 8. The main metabolites in urine are L-methylxanthine, 1-methyluric acid, etc., and a small amount can also form other xanthine compounds such as theophylline and theobromine.