As a CNS stimulant caffeine is more active than theophylline.
{"Image DocumentName": "As a CNS stimulant caffeine is more active than theophylline.", "Image ImageDescription": "In higher doses caffeine causes nervousness, restlessness, panic, insomnia, and excitement. Still higher doses produces. tremor, arrhythmia, delirium, and convulsions. Methylxanthines, especially caffeine, also stimulate medullary. vagal, respiratory and vasomotor centres (analeptic effect). Vomiting in higher doses is due to both to gastric irritation and. stimulation of chemoreceptor trigger zone (CTZ). Methylxanthines directly stimulate the heart and increase force. of myocardial contraction. They tend to increase heart rate by. direct action, but also decrease it by vagal stimulation. Net effect. is variable. Tachycardia is more common with theophylline.", "Image XResolution": "37", "Image YResolution": "37", "Image ResolutionUnit": "Pixels/Centimeter", "Image Software": "SlidePlayer", "Image YCbCrPositioning": "Centered"}