A comparison of steady state plasma theophylline concentrations with conventional and sustained release formulations.

The absorption of theophylline from a sustained release formation (Phyllocontin) in relation to drug absorption from a conventional formulation was assessed at steady state in a multiple-dose study. Seven healthy adult subjects were studied using a two 5-day period crossover design. The data from this study indicate that the sustained release tablet has acceptable sustained release characteristics and should provide both reliable and complete drug absorption, giving it advantage over conventional formulations during chronic therapy of patients with reversible airways obstruction.