Upon exposure to air, it gradually loses ethylenediamine and absorbs carbon dioxide with the liberation of free theophylline. Its solutions are alkaline. 1 g dissolves in 25 mL of water to give a clear solution; 1 g dissolved in 5 mL of water crystallizes upon standing, but redissolves when a small amount of ethylenediamine is added. Insoluble in alcohol and in ether. Pharmacology
Like other methylated xanthine derivatives, aminophylline is both a

competitive nonselective phosphodiesterase inhibitor which raises intracellular cAMP, activates PKA, inhibits TNF-alpha and leukotriene synthesis, and reduces inflammation and innate immunity and
nonselective adenosine receptor antagonist.Aminophylline causes bronchodilation, diuresis†, central nervous system and cardiac stimulation, and gastric acid secretion by blocking phosphodiesterase which increases tissue concentrations of cyclic adenosine monophosphate (cAMP) which in turn promotes catecholamine stimulation of lipolysis, glycogenolysis, and gluconeogenesis, and induces release of epinephrine from adrenal medulla cells.†Note that diuresis is caused by an increase in cAMP which acts in the CNS to inhibit the release of antidiuretic hormone (arginine-vasopressin). Adenosine is an endogenous extracellular messenger that can regulate myocardial oxygen needs. It acts through cellular surface receptors which effect intracellular signalling pathways to increase coronary artery blood flow, slow heart rate, block atrioventricular node conduction, suppress cardiac automaticity, and decrease β-adrenergic effects on contractility. Adenosine also antagonizes chronotropic and ionotropic effects of circulating catecholamines. Overall, adenosine decreases the heart’s rate and force of contraction, which increases blood supply to the cardiac muscle. Given specific circumstances this mechanism (which is intended to protect the heart) may cause atropine-resistant refractory bradyasystole. Adenosines effects are concentration-dependent.
Adenosine’s receptors are competitively antagonized by methylxanthines such as aminophylline. Aminophylline competitively antagonizes the cardiac actions of adenosine at the cell surface receptors. Thus, it increases heart rate and contractility. Brand names
Euphyllin
Phyllocontin
Truphylline
Minomal R 175 mg tab
Minomal R 350 mg tab
Minomal SR 600 mg tab

References
External links
"Aminophylline". Drug Information Portal. U.S. National Library of Medicine.