The influence of diluent on the release of theophylline from hydrophilic matrix tablets.

The role of beta-cyclodextrin (beta-CD) on the apparent solubility of theophylline was investigated by the solubility method. Binary systems of theophylline and beta-CD were prepared using the dry co-grinding method. Their characterization was performed by differential scanning calorimetry (DSC). The dissolution rate of theophylline and theophylline/beta-CD and dissolution studies of matrix tablets prepared from mixtures containing theophylline and ground theophylline were carried out. It can be concluded that beta-CD is related to an increase in the apparent solubility and dissolution rate of the drug, promoting improvement on the release of theophylline from matrices manufactured with hydroxypropylmethylcellulose (HPMC). This can be attributed to the amorphous state and the increased wettability of the drug.