Caffeine absorption

Diarrhea is a common problem that is usually self-limiting and of short duration. Increased accumulations of small intestinal and colonic contents are known to be responsible for producing diarrhea. The former may be caused by increased intestinal secretion which may be enterotoxin-induced, eg, cholera and E. col] or hormone and dmg-induced, eg, caffeine, prostaglandins, and laxatives decreased intestinal absorption because of decreased mucosal surface area, mucosal disease, eg, tropical spme, or osmotic deficiency, eg, disaccharidase or lactase deficiency and rapid transit of contents. An increased accumulation of colonic content may be linked to increased colonic secretion owing to hydroxy fatty acid or bile acids, and exudation, eg, inflammatory bowel disease or amebiasis decreased colonic absorption caused by decreased surface area, mucosal disease, and osmotic factors and rapid transit, eg, irritable bowel syndrome. 

This chapter describes use of solid-surface room temperature phosphorimetry (SSRTP) as a detection technique in the liquid chromatographic (LC) analysis of caffeine, theophylline, and theobromine. Measurements were made in a continuous mode, using a 2-nebulizer automatic system for SSRTP analysis (previously optimized for LC detection). Use of SSRTP and UV absorption detection was compared under identical experimental conditions.38... 

Caffeine and other methylxanthines easily cross biological membranes pH affects the rate of absorption. 

From the uv absorption spectra, a suitable wavelength is found for the simultaneous detection of aspirin, phenacetin and caffeine. Using phenacetin as internal standard, response factors are calculated for aspirin and caffeine and the results are used for the quantitative determination of aspirin and caffeine in an analgesic tablet. 

As noted above, disagreement has often been observed among different studies on the effects of fiber, phytic acid and protein source on mineral utilization. Some possible reasons include (a) estimates of absorption from single meals (with or without previous consumption of the same foods used in the test meal which may also affect results) may not always be equivalent to results from multi-day balance studies, (b) in balance studies, the failure to allow sufficient time (e.g., 1-2 weeks or more) for adaptation may alter the findings, (c) variations in the compositions of meals or diets, including mineral levels, between studies may influence the results obtained, and (d) the persons used as subjects vary and this may have an affect. In addition, in the fiber studies, the levels, types, and particle size of fiber fed have varied widely and levels of other possibly confounding components (e.g., caffeine, tanins, oxalates) may have differed. 

Figure 7.2 presents permeation across freshly isolated porcine buccal mucosa of caffeine and atenolol. Caffeine and atenolol are compounds with complete and poor human buccal absorption in vivo, respectively [10, 29],... 

Figure 7.3 Correlation analysis for Fapp values across freshiy isolated animal buccal mucosa and freshly isolated human buccal mucosa of Lucifer yellow, enalaprilat, atenolol, caffeine, sumatriptan, and fentanyl. Results from internal study by Absorption Systems Company.

Figure 7.5 Mucosal-to-submucosal (m-s), Tapp values across human buccal culture of midazolam (CYP3A4 substrate), bufuralol (CYP2D6 substrate), tolbutamide (CYP2C9 substrate), and the nonmetabolized, high-permeability control compound caffeine (average SEM, N = 1 — 3 replicates). (Asterisk) in the presence of CYP inhibitors (CYP3A4-ketoconazole CYP2D6-quinidine CYP2C9-suphaphenazole). In all treatments integrity of the culture was verified by permeation of Lucifer yellow (< 2.0 x 10-6 cm/s). Results from internal study by Absorption Systems Company.

Figure 7.6 Cumulative receiver concentrations of fentanyl, caffeine, and atenol vs time across cultured human buccal tissue (average SD, N = 3). Results from internal study by Absorption Systems Company.

Kamimori GH, Karyekar CS, Otterstetter R, Cox DS, Balldn TJ, Belenky GL, and Eddington ND (2002) The rate of absorption and relative bioavailability of caffeine administered in chewing gum versus capsules to normal healthy volunteers. Int. J. Pharm. 234 159-167. 

In the other method, PLS-1, the absorption spectra of caffeine solutions were recorded between 240-320 nm and the absorbance values recorded every 5 nm. 

The absorption spectra and first derivative spectra of 9 )ig mL solution of caffeine and energy drinks samples are given in Figs. 31.1 and 31.2. Upon examining the first spectra of two samples, it can be noticed that caffeine can be determined 287 and 260 nm. 

With the aim of improving the analysis of caffeine in energy drinks, the multivariate calibration method PLS-1 was tested. The method was evaluated by using the absorption spectra for the analysis. The absorption spectra of caffeine standards and samples were recorded in the 240-320 rrm range, digitized every 5 rrm. 

Anadin Extra contains paracetamol, aspirin and caffeine, the latter being a mild stimulant that increases the absorption and activity of the analgesics, paracetamol and aspirin. 

Walton et al. (2001a) examined data for compounds eliminated by the cytochrome P450 isoenzymes CYP1A2 in humans. Absorption, bioavailabihty, and route of excretion were generally similar between humans and the test species for each of the substances (caffeine, paraxanthine, theobromine, and theophylline). However, interspecies differences in the route of metabolism, and the enzymes involved in this process, were identified. The magnitude of difference in the internal dose, between species, showed that values for the mouse (10.6) and rat (5.4) exceeded the fourfold default factor for toxicokinetics, whereas the rabbit (2.6) and the dog (1.6) were below this value. 

Caffeine is often used in combination with ergotamine tartrate to improve digestive tract absorption. However caffeine has an antimigraine action itself. 

The ergot alkaloids are variably absorbed from the gastrointestinal tract. The oral dose of ergotamine is about 10 times larger than the intramuscular dose, but the speed of absorption and peak blood levels after oral administration can be improved by administration with caffeine (see below). The amine alkaloids are also absorbed from the rectum and the buccal cavity and after administration by aerosol inhaler. Absorption after intramuscular injection is slow but usually reliable. Bromocriptine and cabergoline are well absorbed from the gastrointestinal tract. 

Lysergic acid is a well known component especially as its amide derviative - lysergic acid diethyl amide (LSD) - to be considered in the next section on CNS drugs. Today ergotamine can be used in the treatment of chronic migraine headache although its side effects do not make it an appropriate prophylactic. It is usually compounded with caffeine and administered orally, by inhalation or suppository. The caffeine increases oral and rectal absorption of the ergotamine. Oral dose is 2 mg at onset and 2 mg at 30 minute intervals up to 6 mg with no more than 10 mg administered per week. 

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