21 To study the release kinetics in-vitro release data was applied to kinetic models such as zero-order, first order, Higuchi and Korsmeyer–Peppas. 22 The formulated beads in optimized formulation were sealed in vials and kept for 90 days at 40 °C/75% RH. After 90 days of exposure

the beads were studied for drug content determination and in-vitro release. 17 Drug taken for the present study of formulation is zidovudine. When formulation F-4 is prepared Reverse Transcriptase inhibitor by taking drug along with HPMC, sodium alginate and KHCO3 all the peaks corresponding to the four constituents were found to be present in its higher spectra (Fig. 1) indicating that none of the functional groups of either drug or polymers have undergone any OSI-744 nmr chemical reaction. All functional groups are intact. Hence, it is a conformation that no chemical reactions have taken place amongst any of the four constituents in the formulation.

To study the thermal stability of the drug it is subjected for DSC studies (Fig. 2) in the range of 30 °C–250 °C. During the process of study it is observed that the drug starts melting with in the range of less than 1 °C. Same drug along with HPMC, sodium alginate and KHCO3 in formulation Formulation-4 when it is subjected for DSC studies, it give rise to wider degree of onset of melting process suggesting that the formulated batch is a mixture of drug and polymers but not pure reaction product. If it is in the purer form of the product it would have given sharp melting as the drug has done. The angle of repose values also ranged from 16 ± 0.39 to 21 ± 0.48 which indicates good flow properties of the granules (shown in Table 2). Four different formulations of zidovudine-loaded alginate beads were formulated by using sodium alginate and hydroxypropyl methylcellulose.

The mean entrapment efficiency L-NAME HCl and drug content was studied in triplicate and the results were found to be satisfactory (shown in Table 2). Each value represents mean ± SD of three determinations. Sodium alginate was used as a gelling polymer and along with it HPMC was used as a release retardant and rate controlling polymer. The combination of these two polymers was utilized for controlling the floating and release properties of zidovudine from the beads, over a desired duration of time. The percentage drug release at the end of 12 h from Formulations 1, 2, 3, and 4 were found to be 86.10, 95.64, 90.15, and 96.83, respectively. The release profiles of the drug are shown in Table 3 and graphical representation in Fig. 3. The kinetic data of all the formulations are shown in Table 4. When the data were plotted according to zero-order equation, the formulations showed correlation coefficient values between 0.9247 and 0.9652. But when the data were plotted according to the first order equation, the formulations showed significantly lower correlation coefficient vales than the zero-order plots i.e. from 0.