Abstract

The major drawback of orally administered drugs like theophylline in the treatment of asthma is its short duration of action, which leads to repeated administration and patient non-compliance. To overcome these drawbacks an attempt has been made to develop a sustained release dosage form of theophylline embedded in agar microbeads with hydrocolloid. The agar microbeads with hydrocolloid (guar gum) were prepared by extrusion method and dispersed phase congealing technique. The microbeads were characterized by particle size determination and drug release studies. The mechanism of drug release and the effect of guar gum in controlling the theophylline release from prepared beads were also investigated. The results indicated that the surface adhering drug was found to release immediately and a constant release was obtained up to 5 h from all the batches. The results also indicated that the rate of release of drug from agar microbeads was found to decrease as the concentration of the added hydrocolloid was increased. The drug release was found to be by diffusion mechanism without any swelling of the agar microbeads. From the results, it was also observed that the added hydrocolloid (guar gum) improved the gel strength of agar and the release rate was controlled significantly.