Adenosine Theophylline

Contant G., Gouault-Heilmann M., Martinoli J. L. Heparin inactivation during blood storage Its prevention by blood collection in citric acid, theophylline, adenosine, dipyridamole—CTAD mixture. Thromb Res 1983 31,365-74. 

Kuhne T., Homstein A., Semple J., et al. Flow cytometric evaluation of platelet activation in blood collected into EDTA vs. Diatube-H, a sodium citrate solution supplemented with theophylline, adenosine and dipyridamole. Am J Hematol 1995 50,40-5. 

THEOPHYLLINE ADENOSINE 1 efficacy of adenosine Theophylline and other xanthines are adenosine receptor antagonists Watch for poor response to adenosine higher doses may be required... 

Kinoshita, Imoto etal.11 14) synthesized other anionic models, 5 (APVP), CPVP, UPVP, TPVA, HPVA, THPVA, and 6 (AMPPVA), by the polymer reaction of N-eoupled(2-dihydrogenphosphate)-ethylderivatives of nucleic acid bases (or adenosine-5 -phosphate, AMP) with polyvinylaleohol. A, C, U, T, H, and TH denote adenine, cytosine, uracil, thymin, hypoxanthine, and theophylline, respectively. The authors reported the apparent hypochromities of 3 to 16% for many kinds of mixtures of the models and DNA or RNA, as compiled in Table 1. However, for the mixtures APVA + RNA, HPVA + RNA HPVA + DNA, THPVA + RNA, CPVA + DNA and CPVA + RNA, no hypochromicity was detected. 

Beyond Viagra, there are a number of other PDE inhibitors that are used clinically. In fact, the classic drugs papaverine and dipyridamole were used clinically before their effects on PDEs were known. Caffeine and theophylline (a compound found in tea) are also PDE inhibitors. However, all of these drugs most likely have multiple targets, making conclusions regarding the roles of PDEs in processes that are sensitive to these agents difficult to interpret. Certainly, some of their effects are due to their actions on adenosine receptors. 

A number of studies have shown that adenosine inhibits neuronal firing both in vitro and in vivo and is itself released during intense neuronal activity. It can protect against PTZ seizures in rodents while the antagonist theophylline is proconvulsant. No clear picture of its role in human epilepsy has emerged. 

It is perhaps not surprising that, sinee adenosine has been presented as an endogenous inhibitor of neuronal funetion with its antagonists, like theophylline, being stimulants (see Chapter 13), it should have been implieated in sleep induetion. 

Adenosine Direct AV nodal inhibition 6 mg IV rapid bolus If no response in 1-2 minutes, 12 mg IV rapid bolus If no response in 1-2 minutes, 12 mg IV rapid bolus Theophylline inhibits response to adenosine Dipyridamole accentuates response to adenosine... 

Theophylline is also considered an alternative to inhaled corticosteroids for the treatment of mild persistent asthma however, limited efficacy compared to inhaled corticosteroids, a narrow therapeutic index with life-threatening toxicity, and multiple clinically important drug interactions have severely limited its use. Theophylline causes bronchodilation through inhibition of phosphodiesterase and antagonism of adenosine and appears to have anti-inflammatory and immunomodulatory properties as well.36... 

Caffeine and theophylline affect cerebral circulation, most likely through their effect as adenosine antagonists. 

Theophylline and aminophylline may produce bronchodilation by inhibition of phosphodiesterase (thereby increasing cyclic adenosine monophosphate levels), inhibition of calcium ion influx into smooth muscle, prostaglandin antagonism, stimulation of endogenous catecholamines, adenosine receptor antagonism, and inhibition of release of mediators from mast cells and leukocytes. 

Vinyl alcohol copolymer gel is hydrophilic and has been developed for aqueous-phase size-exclusion liquid chromatography however, it is less polar than the polysaccharides. Its specificity permits the direct injection of a biological sample without deproteinization. For example, blood serum from a patient suffering from chronic nephritis has been injected directly as a measure of the degree of dialysis (Figure 3.17). Adenosine triphosphate, adenosine diphosphate, and adenosine monophosphate in red blood cells have also been separated directly (Figure 3.18). Theophylline in blood serum has been... 

The mechanism of action of theophylline as a broncholytic is unknown. However, some hypotheses are based on its structural similarity to adenosine and 3X5i-cyclic adenosinemonophosphate. 

It is believed that theophylline can inhibit phosphodiesterase, which in turn can lead to elevated levels of cellular cyclic adenosine monophosphate, and subsequently, to the weakening of smooth musculature of the respiratory tract. However, theophylline is not a powerful phosphodiesterase inhibitor, and the necessary concentrations for this cannot be achieved in vivo. 

On the other hand, theophylline inhibits reverse uptake catecholamine uptake, which can elevate the level of cychc adenosine monophosphate, thus causing a broncholytic effect. Finally, theophylline is an adenosine receptor blocker, and this may be responsible for its broncholytic effect. 

Despite the fact that the last mechanism may be basic for theophylline, a few xanthines, which in general lack the ability to bind with adenosine receptors, express the same, if not more broncholytic activity than theophylline. 

Action on the CNS depends directly on the dose of administered drug, and can be manifested as fatigue, anxiety, tremors, and even convulsions in relatively high doses. Theophylline acts on the cardiovascular system by displaying positive ionotropic and chronotropic effects on the heart, which, can likely be linked to the elevated influx of calcium ions by modulated cyclic adenosine monophosphate and its action on specific cardiac phosphodiesterases. In the gastrointestinal system, methylxanthines simultaneously stimulate secretion of both gastric juice and digestive enzymes. 

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