Caffeine elimination

Balogh, A., Harder, S., Vollandt, R. and Staib, A.H. (1992) Intra-individual variability of caffeine elimination in healthy subjects. International Journal of Clinical Pharmacology, Therapy, and Toxicology, 30 (10), 383—387. 

Lane JD, Steege JF, Rupp SL, Kuhn CM. (1992). Menstrual cycle effects on caffeine elimination in the human female. EurJ Clin Pharmacol. 43(5) 543-46. 

Van Dongen HPA, Price NJ, Mullington JM, Szuba MP, Kapoor SC, Dinges DF. Caffeine eliminates psychomotor vigilance deficits from sleep inertia. Sleep 2001 24 813-819. 

Selection criteria for liver tests 92 9.5 Caffeine elimination test (CET) 109... 

Wang, T., Kleber, G., Stellaard, F., Baumgartner, G. Caffeine elimination a test of liver function. Klin. Wschr. 1985 63 1124-1128... 

D. Enhanced elimination. Repeat-dose activated charcoal (see p 57) may enhance caffeine elimination. Seriously intoxicated patients (with multiple seizures, significant tachyarrhythmias, or intractable hypotension) may require hemodialysis or charcoal hemoperfusion (see p 55). 

Joeres R, Klinker H, Heusler H, Epping J, Richter E Influence of mexiletine on caffeine elimination Pharmacol Ther( 9Z7) 33,163-9... 

Joeres R, Richter E Mexiletine and caffeine elimination NEnglJMcd 9Zl) 317,117... 

Balogh A, Klinger G, Henschel L, Bomer A, VoUantii R, Kuhnz W. Influence of etiiinylestra-diol-containing combination oral contraceptives witii gestodene or levonorgestrel on caffeine elimination. EurJ Clin Pharmacol (1995) 48,161-6. 

Established interactions. Based on the results of two studies, on a scale of 100 to 0, the relative potencies of these quinolones as inhibitors of caffeine elimination have been determined as follows enoxacin 100, pipemidic acid 29, ciprofloxacin 11, norfloxacin 9 and ofloxacin 0. From further studies, clinafloxacin appears to be similar to enoxacin (profound effect), pefloxacin to norfloxacin (to which it is metabolised modest effect), and fleroxacin, lomefloxacin, rufloxacin, and trovafloxacin appear to behave like ofloxacin (no effect). Patients taking enoxacin might be expected to experience an increase in the effects of caffeine (such as headache, jitteriness, restlessness, insomnia) if, for example, they continue to drink their usual amounts of caffeine-containing drinks (tea, coffee, cola drinks, etc.). They should be warned to cut out or reduce their intake of caffeine if this occurs. The authors of one report suggest that patients with hepatic disorders, cardiac arrhythmias or latent epilepsy should avoid caffeine if they take enoxacin for one week or more. The effects of pipemidic acid arc less, and those of ciprofloxacin, norfloxacin and pefloxacin arc probably of little or no clinical importance. Fleroxacin, lomefloxacin, ofloxacin, rufloxacin, and trovafloxacin do not interact. 

Stille W, Harder S, Mieke S, Beer C, Shah PM, Freeh K, Staib AH. Decrease of caffeine elimination in man during co-adm inistration of 4-quinol ies. JAntimicrob Chemoffter (1987) 20, 729-34. 

Nawoot S, Woi D, Mays DC, Gerber N. Inhibition of caffeine elimination by verapamil Clin PharmacolTher 9ZZ)Ai, 148. 

Gender, exercise, and thermal stress have no effect on caffeine pharmacokinetics in men and women. Cigarette smoking increases the elimination of caffeine, whereas decreases have been observed during late pregnancy or with the use of oral contraceptives and in patients with liver diseases. Drug interactions leading to impaired caffeine elimination are frequently reported. 

Potential consumer benefits from biotechnology (56) are cost and quaUty. The use of biotech means to increase the level of various sulfur-containing amino acids in coffee proteins, and to enhance sucrose and oil levels, could have an impact on the flavor and aroma of the finished ground coffee product. Also, caffeine level modification/elimination through genetic manipulations of the coffee plant could yield low caffeine coffee without additional processing by the manufacturer. 

Similar methods with modifications such as the one by Schutz et al.8 have been in use for over 20 years. In 1968, Ferren and Shane9 published a paper on the differential spectrometric determination of caffeine in soluble coffee and drug combinations. It had the advantage of eliminating a preliminary separation that was required by the earlier method. While the method was successful for coffee, it was not as successful in the determination of caffeine in acetaminophen/phenacetin/caffeine tablets. They proposed that phenacetin was a limiting factor. The official AOAC methods for these methylxanthines in coffee and tea still involve similar methods.10... 

The desirability of partial shade on tea estates has been a controversial subject. Desirable effects include temperature moderation at the leaf surface, which decreases low-humidity stress, and an increased yield of chlorophyll, amino acid, and caffeine production. The undesirable effects include decreased photosynthetic activity and competition for water and solid nutrients by the shade tree employed. In general, the trend has been toward the elimination of shade in most black-tea growing areas. Green tea products benefit from the additional chlorophyll and amino acid pro-... 

Burdyga That s my feeling. I can clearly see that when I apply caffeine it induces Ca2+ sparks and Ca2+ waves. If I stimulate the cells using high-K+ solution to initiate action potential I can see that Ca2+ transient rises instantly in all parts of the cell. In most cases the amplitude of Ca2+ signal is smaller and the kinetics of the Ca2+ rise is slower in the area of the major initiating site, and CPA eliminates the difference, so it must be acting as a buffer. 

Caffeine pharmacokinetics are nonlinear. For example, when comparing a 500 mg dose to a 250 mg dose, the clearance is reduced and elimination half-life is prolonged with the higher dose (Kaplan et al. 1997). Thus, larger doses prolong the action of the drug. Active metabolites of caffeine are paraxanthine, and to a lesser degree, theobromine, and theophylline. Urinary metabolites are I-methylxanthine, l-methyluric acid, and an acetylated uracil derivative. 

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. 

Not all agents can be readily metabolized. The toxic metals lead and mercury are elements that cannot be degraded but must still be removed from the body. Another important mechanism of detoxification is the attachment or binding of another compound to a toxic chemical to make it easier for the kidney to filter the compound out of the blood and excrete it in the urine. A primary purpose of the kidney is to screen the blood for waste products and concentrate them in the urine for excretion, as occurs, for example, with mercury. Caffeine is excreted in the urine at approximately the same concentration as the blood because the kidney cannot concentrate caffeine. Vitamins, however, are readily concentrated and excess quickly eliminated in the urine. 

This FDA document provided information on caffeine during pregnancy and advises pregnant women to eliminate caffeine from their diets . 

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