A New Theophylline Ointment with Rapid and High Transdermal Delivery

A transdermal therapeutic system (TTS) for the delivery of theophylline would be useful for treating bronchial asthma, especially in the case of asthma attacks in outpatients. We prepared several new types of theophylline and aminophylline ointments using transdermal absorption enhancers and measured the in vivo transdermal absorption efficiency of theophylline in rats. Among the ointments tested, a washable ointment of theophylline with N-methyl-2-pyrrolidone as a solvent and isopropyl myristate as an absorption enhancer showed the best results. The highest absorption was obtained with a concentration of 2% theophylline and 57% isopropyl myristate. The ointment was quite stable for at least 56 days at room temperature. An aminophylline ointment prepared in the same way showed less absorption and the change in appearance started after 1 week at room temperature. The serum levels of theophylline in the rats applied with the new theophylline ointment reached 10μg/mL after 2 h and a maximum level of 20μg/mL after 6 h. There was no apparent time lag in the absorption. These results suggest that a transdermal therapeutic system for the delivery of theophylline can be useful, even in the case of asthma attack.