A Controlled Release Theophylline Delivery System Based on a Bilayer Floating System

Bilayer floating drug delivery is an approach that helps to overcome the shortcomings of single-layered tablets. There is little or no fluctuation of the drug in the blood stream or tissue, while control is enabled over the time and site of drug release. In the current study, bilayer theophylline matrix tablets were formulated by double compression and evaluated using granules produced by polymeric granulation and simple coacervation techniques.

Bilayer floating theophylline tablets containing an immediate release layer (IRL) and a sustained release layer (SRL) were prepared. Granules for the IRL section were produced by wet granulation, while those for the SRL section were produced by polymeric granulation and simple coacervation techniques using Eudragit RL100 and carboxymethyl cellulose (CMC) as binder. The resulting granules were characterized for flowability and packing properties. Granules with adequate flow were compressed into flat-faced tablets 12 mm in diameter using a single punch tableting machine at an arbitrary load of 28 kgF on a load scale. The tablets were evaluated for hardness, weight variability, disintegration, friability, swelling index, floating time, and in vitro drug release.

The angle of repose and Hausner ratio were 29.07±0.330 to 40.08±0.660 and 1.07±0.01 to 1.28±0.01, respectively. Tablets hardness values ranged from 4.74±0.36 to 9.84±0.49 kgF, while percentage friability ranged from 0.5% to 1.51%. Floating lag time was between 1±0.41 and 9±0.71 min, while the total floating time was between 1 min and 9 h. Over 50% of the drug was released within 7 h.

Drug release from the tablets showed a prompt release phase and an extended release phase. Therefore, appropriate combination of Eudragit and CMC and the right reagent can produce well retarded bilayer floating tablets.