Eudragit L30D-55 is an anionic polymer, which contains COOH as a functional group that dissolves at pH > 5.5. L30D-55 is known to be quite rigid with 20% elongation using 10% triethyl citrate as a plasticizer

[15]. Four representative formulations of coated pellets were prepared by varying the ratio of Eudragit L to Eudragit NE as shown in Table 2. The results of in vitro drug AG-014699 ic50 release Inhibitors,research,lifescience,medical studies (Figure 2) indicated that increasing the polymer coating level of Eudragit NE30D from 15% to 30% (w/w) caused a significant reduction in the drug release. The pellets coated with Eudragit NE30D at a coating level of 30% (w/w) showed negligible release during the 6h of dissolution test in HCl 0.1N and PBS (pH 7.4). Nevertheless, at the end of dissolution studies, the mean percent drug released was only 58%. Figure 2 Inhibitors,research,lifescience,medical Effect of coating level of Eudragit NE 30D on budesonide release. The effect of coating with Eudragit NE30D:

Eudragit L30D-55 blend on in vitro drug release for three different batches of weight gains of 30% (w/w) is shown in Figure 3. Batches F4, F5, and F6 released no drug in acidic medium, 12.8%, 18.5%, and 23.3%, at the end of 6hrs, while 57.4%, 70.5%, and 84.3% of drug was released at Inhibitors,research,lifescience,medical the end of 24hrs, respectively. In PBS (pH 7.4), the enteric polymer (Eudragit L30D-55) dissolved or leached out, thus increasing the permeability of the coating, offering less resistance for budesonide diffusion. Although drug release of formulation F6 in simulating intestinal fluid was not optimal, the 3: 7

ratio of Eudragit L30D-55 to Eudragit NE30D was selected for further studies in consideration of the near complete release at the end of dissolution Inhibitors,research,lifescience,medical run. Figure 3 Effect of the ratio of Eudragit L 30D 55 to Eudragit NE 30D on budesonide release. To achieve a desired release profile, a modification in the coating pattern was made. Xanthan gum as a release retardant polymer was chosen as the coating polymer for inner coating layer. Xanthan gum rapidly forms a gel layer Inhibitors,research,lifescience,medical that retards seeping of dissolution fluids into the core pellets and reduces the diffusion of drug from the core to negligible level and decreases the drug release from the formulation. Figure 4 shows the release of budesonide from pellets coated with various coating levels of xanthan gum Bay 11-7085 as inner coating. Coating with 2.5% (w/w) xanthan gum (F7) was not sufficient, and the drug release was the same as F6(P > 0.05). However, increasing the xanthan gum coating level to 12% (w/w) resulted in lower release in simulated intestinal fluid significantly (P < 0.05) with no effect on the total amount of drug released in 24hrs. Figure 4 Budesonide release profiles from pellets with an inner coat of xanthan gum and an outer coat of Eudragit L 30D 55: Eudragit NE 30D (3:7 ratio) showing the effect of coating level of xanthan gum on budesonide release profile.