ABSTRACT
Theophylline sustained release microspheres were prepared by applying the non-solvent addition method. The in-vitro release of the drug from the prepared microspheres of different size ranges [= 300, 300-600, 600-800, 800-1000 and 1000-1250 micro m] was studied. The effects of different ethylcellulose: theophylline ratios [1:2, 1:1 and 2:1] and different plasticizer [diethylphthalate] concentrations [10, 20 and 30% v/w] on theopylline release were also investigated. At different ethylcellulose: theophylline ratios [1:1, 2:1 and 1:2], the release of the drug decreased significantly when the polymer content was increased and the drug loading was decreased. Also, the release was significantly decreased [P<0.05] with increasing plasticizer concentration from 10 to 30%, with no significant difference between un-plasticized and 10% plasticizer