Uses and abuses of theophylline.

Theophylline remains a useful drug for obstructive lung disease. As time goes by, our concepts about why it is effective are changing. Its actions on respiratory muscle, myocardium, and pulmonary vasculature may some day overshadow its bronchodilating effect. In the meantime, it is a good bronchodilator but has so narrow a therapeutic window that great caution is needed in establishing a safe dose.