Liquisolid compacts: The effect of cosolvent and HPMC on theophylline release

Liquisolid technique as an approach was developed to sustain the drug release from matrix compacts. Liquisolid tablets were prepared by mixing liquid medication with silica–Eudragit RL or RS followed by the compaction of the mixture. For comparison purposes physical mixtures of all ingredients were prepared. The effect of the type of liquid medication and HPMC concentration on drug release was investigated. The interaction between excipients and theophylline was investigated by differential scanning calorimetry. Comparison study of physicomechnanical properties of liquisolid tablets with conventional tablets showed that most of liquisolid formulations had superior flowability and compactibility in comparison with physical mixtures. The results suggested that the presence of non-volatile cosolvent is vital to produce slow release pattern for some of liquisolid compacts. The type of cosolvent had significant effect on drug release and it was revealed that by changing the type of cosolvent the desirable release profile is achievable. The sustained release action of HPMC was enhanced in liquisolid compacts in comparison to simple sustained release matrix tablets. It was shown that liquisolid compacts has a potential to produce zero-order release kinetics for less water soluble drugs such as theophylline.