Effects of sphere size, polymer to drug ratio and plasticizer concentration on the release of theophylline from ethylcellulose microspheres

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 [theophylline ratios [12, 11 and 21] and different plasticizer [diethylphthalate] concentrations [10, 20 and 30% v/w] on theopylline release were also investigated. At different ethylcellulose theophylline ratios [11, 21 and 12], 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