The objective of the present work was to develop a floating-pulsatile oral drug delivery system of atenolol with addition of hydroxylpropyl methylcellulose (HPMC) K100 M, HPMC K4 M, and HPMC E15 LV in different ratios with citric acid and sodium bicarbonate as gas-forming agents. The system consist of three different parts: a core tablet, containing the active ingredient; a bottom layer that erodes; and a top cover floating layer. Atenolol, a β-blocker, is prescribed widely in diverse cardiovascular diseases, for example, hypertension, angina pectoris, arrhythmias, and myocardial infarction. Developed formulations were evaluated for their physical properties and vitro release as well as in vivo behavior. The results showed that K3 (180 mg HPMC K4 M) and K6 (290 mg of HPMC E15 LV) with a buoyant layer were the best formulations with the lag times of 5.2 ± 0.1 h and 4.1 ± 0.2 h, respectively, and were found to be the best choice for manufacturing tablets.

Two methods for simultaneous determination of Emtricitabine and Tenofovir Disoproxil Fumarate by spectroscopy have been developed. First method is Simultaneous equation method and second method is Absorbance ratio Method. From a solvent effect studies and the spectral behaviours of Emtricitabine and Tenofovir Disoproxil Fumarate, methanol was selected as solvent. Emtricitabine shows maximum absorbance at 281 nm and Tenofovir Disoproxil Fumarate shows maximum absorbance at 259 nm. Linearity in concentration range of 6-48 µg/mL and 4-32 µg/ mL was shown for Tenofovir Disoproxil Fumarate and Emtricitabine, respectively. In the first method, the concentration of the drugs were determined by using simultaneous equation and in second method the concentration of drugs were determined by using ratio of absorbances at isoabsorptive point and at the ëmax of one of the drug. The results of analysis were validated statistically and by recovery studies. Tablet containing both drugs was assayed using the methods developed, showing a good accuracy and precision.