4. The Fig. 4 (A) shows the large crystals of pure MK 2206 IBS. Fig. 4 (B), (C), (D), (E) and (F) of SSDs are shown to be irregular matrices due to the porous nature of the carrier with the fine particles of the drug embedded in it. Therefore it is possible that the reduced particle size, increased surface area and the close contact between
the hydrophilic carrier and the drug may be the reason for the enhanced drug solubility of the SDs. Mean dissolution time (MDT) value is used to characterize drug release rate from a dosage form, which indicates the drug release retarding efficiency of polymer. These values are shown in Table 1. SSD of IBS prepared with CP (1:10) showed lower MDT value (2.316 ± 0.5 min) in comparison to SSD prepared with SSG, MC, CC and PS which show 4.146 ± 0.7, 4.791 ± 0.1, 4.887 ± 0.2 and4.987 ± 0.05 min, respectively. This finding can be attributed to the immediate release by SSD of IBS with CP. The observed order of MDT releasing profile is as follows: crospovidone > sodium starch glycolate > microcrystalline cellulose > croscarmellose > potato starch. SSD of IBS showed good dissolution efficiency (DE = 76.36%) with
CP. The SSD of IBS with SSG, MC, CC and PS shows dissolution efficiency of 71.92%, 71.10%, 70.31% and 69.89% respectively. The dissolution efficiencies of commercial formulations and the pure forms are 69.45% and 58.31% respectively, which are shown in Table 1. The order of % DE releasing profile
is as follows. crospovidone > sodium starch glycolate > microcrystalline cellulose > croscarmellose > potato High Content Screening starch > marketed formulation > plain drug. The dissolution profiles of the SSD and physical mixtures of CP, CC, MC, PS, SSG, marketed product and plain drug were plotted as shown in Fig. 5. The dissolution rate of IBS in physical mixtures as well as in SSD was higher for all SDs as compared with plain IBS. Plain IBS showed a poor dissolution rate whereas physical mixtures showed slight enhancement due to the presence of SD in the respective mixtures. Dissolution profiles of all for the SSD for all SD showed a trend of increase in dissolution rate with increase in SD. The Drug: SD was taken in the proportions of 1:1, 1:5, and 1:10. SSD with 1:10 proportion showed maximum drug release. The SSD drug release for various formulations is found to be CP – 98.18% (10 min), SSG – 94.29% (13 min), MC – 93.13% (12 min), CC – 93.68% (14 min), PS-93.07% (14 min), whereas for marketed formulation – 95.53% (25 min) and pure IBS – 25.21% (30 min). This shows that SSD with CP showed better dissolution profile than SSG, MC, CC and PS. The improved dissolution could be attributed to a reduction in particle size of the drug, its deposition on the surface of the SD and improved wettability. CP has very fine particle sizes and hence has large surface areas.