Formulation and in-vitro Evaluation of Theophylline Floating Tablets

As technology continues to gain strong footing in the medical sciences, the application of its principles to overcome drug formulation challenges and the presentation of selected potently useful drugs have been encouraged. In the study presented in this chapter, our team undertook to formulate a floating drug delivery system of theophylline hydrochloride using a synthetic polymer and then investigate the effect of polymer concentration on tablet buoyancy and drug release properties. Hydroxypropyl methylcellulose (HPMC) is the polymer used at different concentration of 15% (F1), 20% (F2) and 30% (F3) for three formulation batches of floating tablets. The method employed was wet granulation and sodium bicarbonate along with citric acid as the gas generating agent. The physical properties of the granules and the floating tablets were evaluated. Also, the physicomechanical properties, buoyancy and swelling characteristic of the tablet were determined. The drug release study was done as outlined in the USP I (basket method) for 8h in 900 ml 0.1N HCl at 50 rpm. Samples were withdrawn at a predetermined time and analysed using a UV spectrophotometer at of 271 nm wavelength. All obtained data were statistically analyzed by one-way analysis of variance (ANOVA). The differences between means were considered significant at P<0.05. The result showed that polymer (HPMC) concentration significantly (p<0.05) increased swelling index and improved floating lag time, it had no significant effect on the total floating time. Percentage drug release at the end of 8 h was 100%, 98.2% and 96.13% for formulation F1, F2 and F3, respectively. All three formulations followed the Higuchi kinetics model of drug release while the mechanism of drug release was the non Fickian diffusion with exponents of 0.46, 0.51 and 0.56 for the respective batch. Batch F3 showed a better drug control and floating properties than batches F1 and F2. Polymer concentration influenced the onset of floating and controlled the release of theophylline.