Sustained-release theophylline, which is generally prescribed as a twice-daily equal-dose regimen, is one of the more common asthma treatments. the development of a sustained-release drug delivery technology that enables improved control of the theophylline blood levels represents a significant advancement in both the efficacy and safety of dosing.

A crossover study was conducted with 25 adult chronic asthmatic patients requiring daily bronchodilator therapy. The study group included thirteen males and twelve females with ages ranging from 19 to 71 years. The overall approach was to place the patients first on the twice-daily preparation(Etheophyl®) for 28 days at 8 AM and 8 PM, and measure the pulmonary function and theophylline level on the 28th day. the patients were subsequently switched to the once-daily preparation(Uniphyl®) in the same daily dose at 8 PM on the 29th day and the same parameters were measured on the 56th day.

the mean serum levels of theophylline were 8.18±1.66µg/ml in the Etheophyl®-treated period and 8.00±1.75µg/ml in the Uniphyl®-treated period. In addition, the FEV1 showed 71.40±7.48 percent in the Etheophyl®-treated and 69.18±9.00 percent in the Uniphyl®-treated period. Thus there were no significant differences between the once-daily and twice-daily preparation.

The results indicated little clinical differences between the two medication. The two drugs are equally effective in controlling asthma over the four weeks of treatment.