Asthma methyl xanthines

Effects relaxation of bronchi, increase in respiration, stimulation of cardiac muscle, diures(f> Methyl xanthines are used in the treatment of asthma. 

Methylxanthine is the major purine constituent of human urine (3.1 g in 10001) (1898ZPC(24)364). 3- and 7-Methylpurines are also minor constituents of urine, especially following large doses of caffeine or other methylated xanthines. 1,3-Dimethylxanthine (theophylline) occurs with caffeine in tea leaves and is a powerful diuretic and has been used clinically for this purpose (generally as an adduct with salts of organic acids) and also in the treatment of asthma. 1,7-Dimethylxanthine (paraxanthine) is also an efficient diuretic and, in addition, possesses antithyroid properties (45JCS751). The main purine constituent... 

Theophylline is a methylated xanthine which exemplifies a clinically useful drug with a narrow margin of safety. Theophylline is used to treat bronchial asthma as well as apnea and bradycardia in premature infants. Serum concentrations must be maintained between 10 and 20 lg/ ml because it is ineffective at lower concentrations and it produces undesirable effects at higher concentrations. 

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