Two methods for the simultaneous determination of Emtricitabine and Tenofovir by spectroscopy have been developed. These two simple, accurate and precise methods include Area Under the Curve (AUC) method and Dual Wavelength Method. From a solvent effect studies and the spectral behaviours of Emtricitabine and Tenofovir, methanol was selected as solvent. Emtricitabine shows maximum absorbance at 281 nm and Tenofovir shows maximum absorbance at 259 nm. For the AUC method, the wavelength ranges between 242-248 nm and 269-275 nm were selected with reference to the absorbance curves plotted between the wavelengths of 200-400 nm. In the second method i.e. Dual method in which two wavelengths were selected for each drug in a way so that the difference in absorbance is zero for another drug. Emtricitabine shows equal absorbance at 230.696 nm and 250 nm, where the differences in absorbance were measured for the determination of Tenofovir. Similarly, differences in absorbances at 250 nm and 268.670 nm were measured for determination of Emtricitabine. These methods allows rapid analysis of two drug combination. The results of analysis were validated statistically and by recovery studies. This tablet containing both drugs was assayed using the methods developed, showing a good accuracy and precision.

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.