Caffeine distribution

Pharmacokinetics The methylxanthines are well absorbed orally. Caffeine distributes throughout the body, including the brain. The drugs cross the placenta to the fetus and are secreted into the mother s milk. All the methylxanthines are metabolized in the liver, and the metabolites are then excreted in the urine. 

MDMA and MDE also produced locomotor patterns that differed significantly from other stimulants. Previous studies in rats have demonstrated that amphetamine-induced hyperactivity involves complex patterns of widely distributed locomotion with frequent directional changes (Geyer et al. 1986 Geyer et al. 1987). In contrast, similar levels of behavioral activation produced by scopolamine or apomorphine are associated with relatively smooth locomotor paths, in which the same movement patterns are frequently repeated. Other stimulants, such as caffeine or nicotine, increase the amount of locomotor activity without significantly altering its pattern (Geyer... 

Some effects of caffeine on the cardiovascular system may be related to modification of the Ca2+ content of the cells or its distribution within the cell. 

Figure 8.11 An OTC analgesic tablet (Excedrin) with three APIs. Spatial distribution of each API was obtained using PLS analysis. (A-C) PLS score images of acetaminophen, aspirin, and caffeine, respectively and (D-F) single-pixel microspectra (solid line) compared to pure component acetaminophen, aspirin, and caffeine spectra (dashed line), respectively.

Stir with a pencil or pen and discuss the change in color as a response to increased dose of food color in each glass. Discuss how some chemicals, caffeine being one, distribute throughout total body water. 

Beach, C. A., Mays, D. C., Sterman, B. M. and Gerber, N. 1985. Metabolism, distribution, seminal excretion and pharmacokinetics of caffeine in the rabbit. Journal of Pharmacology and Experimental Therapy, 233 18-23. 

Qualitatively, acetaminophen and aspirin appear to be more abundant than caffeine, which concurs with the label concentration values. Caffeine shows very distinctive areas of localized high concentration domains while aspirin is relatively evenly distributed on the spatial scale of the image. Acetaminophen appears to be somewhat in the middle, showing up as large domains that blend into one another. 

The purine derivatives caffeine, theobromine, and theophylline (Figure 6.135) are usually referred to as purine alkaloids. As alkaloids they have a limited distribution, but their origins are very closely linked with those of the purine bases adenine and guanine, fundamental components of nucleosides, nucleotides, and the nucleic acids. Caffeine, in the form of beverages such as tea, coffee, and cola is one of the most widely consumed and socially accepted natural stimulants. It is also used medicinally, but theophylline is... 

Drugs that show extensive tissue binding are said to have an apparent volume of distribution many times the total body size. For example, digoxin (see Chapter 35), which binds to plasma protein to the extent of 23%, has an apparent volume of distribution of 8 1/kg. The volume of distribution of drugs that do not bind to plasma or tissue proteins varies between the extracellular fluid volume (16 liters) and the total body water (42 liters). Insulin, sodium, and iodine are confined to the extracellular water, whereas caffeine and ethanol are distributed in the total body water. 

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