Caffeine typical effects

Chemical stimulants caffeine and others. Stimulants of the central nervous system - such as caffeine, taurine, and amphetamines - are often used to counteract the effects of fatigue. As noted in many surveys of driver coping behaviors, one of the more common approaches to counteract fatigue is to ingest a stimulant, especially caffeine typically in the form of coffee (Lucidi et al., 2006 Nguyen et aL, 1998). 

The plasma concentrations of caffeine in the rats exposed to the 0.25 and 1.0 mg ml solutions were within the range of those fonnd in typical users of caffeinated beverages. Caffeine may weakly stimnlate dopamine mechanisms via its antagonist action at adenosine receptors (Herrera-Marschitz et al. 1988 Casas et al. 1989 Ferre et al. 1992 Fredholm et al. 1999), and in small doses it may have enhanced the dopaminergic component in the nicotine discriminative stimulns through an effect... 

Extracts of coffee bean and cocoa bean have been produced experimentally that contained about 3% of caffeine and 3% theobromine respectively without the disadvantage of flavour concentration typically associated with those raw materials. These are potentially alternative natural sources of effective stimulants to guarana and kola. Other supplementary herbs that have a place in energy... 

Ephedra supplements typically contain caffeine, and users may consume caffeine in carbonated beverages, coffee, or tea. Researchers suspect that caffeine may enhance ephedra s stimulant effects on cardiovascular and/or central nervous system responses. This may account for the types of adverse events that have been reported by ephedra users. 

A number of issues, however, prove to be problematic with the use of caffeine. First, tolerance appears to rapidly develop with repeated doses (50). Second, there is substantial interindividual variability in the rate of metabolism and in the frequency of undesired effects such as tremor, jitteriness, and insomnia. Interestingly, despite the widespread use of caffeine, and the strong reluctance of many users to forgo consumption and their inclination to typically escalate dose (i.e., number of servings of coffee or cola), routine caffeine consumption is usually not viewed as drug use, much less drug abuse. 

Mosbach and co-workers developed a method to prepare molecularly imprinted polymers by precipitation polymerization [24]. They started from a dilute, homogenous solution of the monomer methacrylic acid (MAA) and the crosslinker trimethylolpropane trimethacrylate (TRIM) or ethylene glycol dimethacrylate (EGDMA). The polymer formed in the presence of the template molecule 17/1-estradiol, theophylline, or caffeine contained a high proportion of discrete spheres of diameter less than a micron. Because the effect of coalescence becomes predominant with higher solid content of the reaction mixture, this approach is limited to solid contents of typically <2 wt%. 

Theobromine (3,7-dimethylxanthine, 3,7-dihydro-3,7-dimethyl-lW-purine-2,6-dione). C7H,N402, Mr 180.17 formula, see under theophylline. Monoclinic, bitter tasting needles, mp. 357 °C, sublimes at 290-295 °C, soluble in hot water, alkali hydroxides, concentrated acids, moderately soluble in ammonia, poorly soluble in cold water and alcohol. With acids T. forms salts which decompose in water detection by the murexid reaction. T. is the main alkaloid of cocoa (Theobroma cacao, 1.5-3 wt.-%), from which it is obtained - especially from the husks in which it accumulates during fermentation. The typical bitter taste of cocoa is the result of interactions between T. and the pip-erazinediones formed in the roasting process. T. has diuretic, vasodilatory, and stimulating effects on cardiac muscle. The activities are weaker than those of the structurally related caffeine (a methylation product of T.) with which it co-occurs in cola nuts. For further pharmacological properties, see table under theophylline. 

Although green tea usually contains less caffeine than black tea, it is by no means caffeine-free. A cup of black tea may contain as much as an espresso (about 100 mg). A cup of green tea typically contains about one third of this amount. High tatmin content in green tea slows down the take-up of caffeine and moderates the stimulating effect. Recent research shows that the presence of an amino acid named L-theanine is also significant (Fig. 3.25). 

A discussion of the detailed results of Hindmarch et a/. s (1991) study is beyond the scope of this book, but three general conclusions that can be drawn from their findings are worth noting here. First, some drugs can have a positive effect on performance - at least in tiie short run. Exan les are nicotine and caffeine that typically improve performance relative to placebo. This is particularly importmt because in most experimental drug and alcohol studies subjects are instructed not to smoke or drink coffee for several hours before the experiment. In contrast, in real-life people often smoke and drink coffee which can - at least to some extent -counteract the effects of a depressant. The consistently positive effects of caffeine on fatigue... 

Fenetylline is an interesting example where the molecule consists of a combination of sympathomimetic-like entities. In this compound the caffeine derivative theophylline is fused to amfetamine and it has been used for the treatment of ADHD and narcolepsy. It has been claimed that fenetylline showed fewer amfetamine-type side effects such as elevated blood pressure, tremor and fine motor activity, but became ill al due to increased numbers of abusers. A typical adult dose of fenetylline hydrochloride is 25-50 mg once or twice a day. Fenetylline abuse has been reported to be particularly prominent in the Middle East and a large number of counterfeit products are circulating. 

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