Theophylline: short term treatment.

In this review article on short term-effects of theophylline, results of studies with single administration of theophylline are compiled, supplemented by several studies with a therapeutic administration up to 4 Days. Data at hand show limited to moderate bronchodilatator effect of theophylline, which is comparable to beta 2-adrenergic drugs only in some studies using high dose regimen with theophylline levels of about 20 mg/l, i.e. with a considerable risk of unwanted side effects. In normal subjects no bronchodilatator effect is present at all, thus differing from beta 2-adrenergic drugs. In contrast, protection against allergic and non-allergic (exercise) stimuli is provided by theophylline already at serum levels about 3-4 mg/l, and with a dose-dependent increase of protection. These data are in accordance with in vitro-studies, demonstrating protection against leukocyte histamine release, rat passive cutaneous anaphylaxis, and mast cell degranulation. In man, there is a transient increase of alveolar ventilation via an increase of total ventilation VE, tidal column Vt, and respiratory frequency f. This phenomenon may, at least in part, be due to an increase of contractility of the respiratory muscles, as suggested by a recent study, demonstrating an inhibition of diaphragmatic fatigue by theophylline. In conclusion, theophylline seems to act via several mechanisms: bronchodilation, protection against various stimuli, increase of ventilation and muscular contractility, which might explain its clinical benefit, although less potent than other drugs as a bronchodilatator of prophylactic agent.