RESULTS AND DISCUSSION - FORMULATION AND EVALUATION OF SUSTAINED RELEASE MATRIX TABLETS OF STAVUDINE

 

RESULTS AND DISCUSSION

 

Construction of standard calibration curve for Stavudine

          Standard calibration curve was constructed by scanning the 10μg/ml solution of Stavudine in different buffer solutions used in the solubility study. This was described later in this chapter.

 

Determination of Stavudine solubility

          Stavudine has shown highest solubility in acetate buffer pH 4.5 (Table 5.1). The solubility of stavudine in 0.1N HCl, pH 6.8 phosphate buffer and water was 

In-vitro dissolution of capsule filled Sustained release mini tablets (FS-9)

          In vitro dissolution on the prepared Sustained release tablets was done with the same method employed previously. The drug release from Sustained release mini tablets was faster when compared with the formulation FS-2. However the drug release was Sustained up to 14 hrs (Table 5.17). Fig 5.15 shows the comparative dissolution profiles of the prepared Sustained release mini tablets (FS-9) with Sustained release tablets of formulation FS-2.

 

 

Preparation of Sustained release multiple mini tablets of stavudine

          Stavudine Sustained release multiple mini tablets were prepared with the use of 3 mm multi tip punches. The granules from formulation F-8 were selected for the preparation of release mini tablets. The granules from FS-2 was selected for the preparation of Sustained release matrix multiple mini tablets. The formulations were coded as FS-10 and FS-11 for the immediate and Sustained release multiple mini tablets respectively. Rapid disintegration was observed from the immediate release mini tablets. The hardness was 2-3 kg/cm2 for both formulations. For each capsule 4 Sustained release multiple mini tablets and 8 immediate release multiple mini tablets were filled in size „0‟ transparent hard HPMC capsules. Fig. 5.16 shows the photographs with yellow and white colors for immediate and Sustained release multiple mini tablets of stavudine respectively.

 

          The hardness of the immediate release and Sustained release multi tablets was found in the range of 2 kg/cm2. Thickness of the immediate release multi tablets was found to be 3 mm where as in Sustained release multi tablets, 2.33 mm of thickness was found. Very less friability was found in both the formulations. Rapid disintegration was observed in the immediate release multi tablets.

          The in vitro dissolution has shown that the drug release was Sustained up to 10 hr (Table 5.19). Faster drug release was observed in the tablets in the tablets of FS-11 when compared with FS-2 and FS-9 (Fig 5.17).

FTIR studies

          The FT-IR spectrum was taken for STAV powder. The spectra have shown characteristic peaks of the asymmetric and symmetric stretching of the methyl group at 2871.33 and 2961.33 cm−1, a band of peak at 1689.55 cm−1 owing to the stretching of aldehyde group, peaks at 1285.33 and 1165.12 cm−1 owing to asymmetrical and symmetrical stretching of the C-O-C system and a band peak at 3427.63 cm−1 owing to N-H stretching. Similar spectrum peaks were observed in the pure stavudine clearly indicates the stable nature of the drug in the formulation. Fig. 6.18 shows the FTIR spectrum of the prepared compression coated tablets of the stavudine.

Fig. 5.18 FTIR spectra of stavudine Sustained release tablets

Differential scanning calorimetry (DSC) study

          Differential scanning calorimetry (DSC) study of pure Stavudine showed a sharp endothermic peak at 172° C. The thermograms of stavudine matrix tablets showed similar endothermic peak at 171° C. This further confirms that there is no drug to polymer interaction. Fig. 5.19 shows the DSC endothermic melting process of the prepared compression coated tablets of the stavudine.

Fig. 5.19 DSC thermogram of stavudine Sustained release tablets