Comparison of a sustained-release preparation (Theo-Dur) with a conventional preparation (Nuelin) in the treatment of chronic asthma.

In a double-blind, cross-over trial comprising 19 adult asthmatic patients a sustained-release preparation of theophylline (Theo-Dur), given twice daily, was compared with a conventional fast-release preparation (Nuelin), given three times daily. The theophylline doses were individually titrated to give plasma concentrations in the lower region of the therapeutic interval. The sustained-release preparation gave higher morning theophylline concentrations than the fast-release preparation (9.2 vs 5.9 mg/l). This resulted in somewhat higher morning peak flow values during Theo-Dur treatment. However, the difference in asthma symptoms was not significant and the patients showed no preference for either preparation. We conclude that the advantage of a sustained-release preparation over a conventional fast-release theophylline preparation is the lower dosing frequency rather than the better clinical effect in patients who suffer from chronic asthma, but whose disease is in a relatively stable phase.