6) due to swelling of HPMC in contact with an aqueous medium and form a gel layer to whole tablet to control the drug release rate. The results obtained indicated that maximum release of RAM occurred in phosphate buffer pH 6.8 which was supported by Yuan et al.10 The tablets of batch (T3) showed uniform thickness (4.58 ± 0.37 to 4.5 ± 0.23 mm) and diameter (6.21 ± 0.13 to 6.35 ± 0.18 mm). The hardness was found to be

5.5 ± 0.6 kg/cm2. The friability and weight variation was within the official limits of <1% and ±5% respectively. The disintegration time taken by outer tablets was less than 15 min. In tab-in-tab formulations, RAM core tablets were not shown vertical and horizontal displacements in outer NIF tablet areas. This shows the center position of core tablet MK-8776 price in formulation. The NIF release was good and maximum BIBW2992 in vitro drug release in 2 h was seen (Fig. 7) due to its increase dissolution rate from gelatin microcapsules. It revealed that the compression of NIF-loaded gelatin microcapsules with excipients not playing major role in its release when compared with microcapsules.

The core tablet of RAM was CR and experienced 80% dissolution in 8 h under mild dissolution test conditions as shown in Fig. 8. RAM is unstable and can be easily degraded into different impurities. So in order to make RAM in stable dosage form, Eudragit was covered as an enteric coating polymer and lag time was observed at 2 h due to its resistance to SGF. Initially Eudragit delayed the disintegration time and later HPMC formed protective gel layer which controlled the penetration of additional water into the tablet. As the outer gel layer fully hydrated and dissolved, a new inner layer must replace it and be cohesive and continuous enough to retard the influx of water and control drug diffusion.13 Some small differences in evaluation parameters were observed in optimized tab-in-tab formulation as shown in Table 2. The dissolution study of the optimized batch at zero month and 3 months showed

some changes in drugs release profiles (Figs. 9 and 10). Both the dissolution studies showed the typical similar profiles but drugs PDK4 release was somewhat lower. NIF endures stability problem due to its photosensitive nature. Formulation of RAM dosage form leads to decrease in its assay due to mechanical stress, compression, manufacturing processes, excipients, storage conditions, heat, moisture, and alkaline pH (7–9). Tab-in-tab formulation was developed to overcome such problems and to improve the stability of drugs.4 The release NIF from formulation (T3) was completed in about 2 h and appeared to be rapidly and readily absorbed through GI tract as shown in Fig. 11. The results suggested that the higher initial plasma concentration of NIF were due to the increase in dissolution rate and due to the crystallinity change to amorphous form in the gelatin microcapsule at stomach. NIF absorption was less influenced and no potential interaction with RAM could readily be detected.