Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Introduction: Caffeine, theophylline and theobromine are contained in coffee, chocolate (cocoa) and tea (black and green) as weakly basic natural alkaloids. The structures of the methylxanthine derivatives/xanthine derivatives including the above natural alkaloids together with synthetic ones are shown in Table 4.1 [1]. Theophylline, dyphylline (diprophylline) and proxyphylline are being used mainly as bronchodilators and/or heart stimulants. Caffeine mildly stimulates the central nervous system (CNS), awakens people, relieves them from general fatigue and activates mental activities. It has a relatively wide safe range of doses and its estimated oral lethal dose is said to be about 10 g. Therefore,. | 6 II.6.4 Methylxanthine derivatives by Osamu Suzuki Introduction Caffeine theophylline and theobromine are contained in coffee chocolate cocoa and tea black and green as weakly basic natural alkaloids. The structures of the methylxanthine derivatives xanthine derivatives including the above natural alkaloids together with synthetic ones are shown in Table 4.1 1 . Theophylline dyphylline diprophylline and proxyphyl-line are being used mainly as bronchodilators and or heart stimulants. Caffeine mildly stimulates the central nervous system CNS awakens people relieves them from general fatigue and activates mental activities. It has a relatively wide safe range of doses and its estimated oral lethal dose is said to be about 10 g. Therefore it is difficult to be poisoned by drinking coffee or tea. Caffeine becomes problematic when it is mixed in large amounts with an abused drug as an adulterant in such cases a large amount of caffeine can be ingested into a human body. As a fatal action of caffeine it acts on the heart provoking supra- O Table 4.1 Structures of methylxanthine derivatives R1 R2 R3 Misc. caffeine ch3 ch3 ch3 1 7-dimethylxanthine ch3 H ch3 OH dyphylline ch3 ch3 CH CHCH OH 3-isobutyl-1 -methylxanthine ch3 ch3cch3 ch3 H pentifylline QH13 ch3 ch3 pentoxyfylline CH3C CH2 4 0 ch3 ch3 OH proxyphylline ch3 ch3 CH2CHCH3 theobromine H ch3 ch3 theophylline ch3 ch3 H 1 3 9-trimethylxanthine ch3 ch3 8 9 single bond 7 8 double bond 9 CH3 Springer-Verlag Berlin Heidelberg 2005 492 Methylxanthine derivatives ventricular tachycardia or supraventricular arrythmia and finally cardiac collapse to death especially for children such poisoning can take place more easily 2 . Theophylline is mainly used for treatment of bronchial asthma. Its characteristic is a narrow safe range of its doses. Its blood therapeutic concentrations are said to be 8-20 pg mh but when the concentration exceeds 20 pg mh untoward effects appear 2 . Therefore care should be taken upon theophylline .
