Time- and pH-dependent colon-specific drug delivery for orally administered diclofenac sodium and 5-aminosalicylic acid

Figure 1 Effect of different coating levels on the DS release from the coated tablets in distilled water. The tablets were coated at five levels of 3% (◇), 5% (○), 7% (△), 9% (□●), 11%(×) (w/w, total solid applied) (n = 6).

Figure 2 Effect of pH of the dissolution medium on DS release from the coated tablets. The tablets were coated at 7.5% (w/w, total solid applied) level (n = 6). pH1.0 (◇), pH2.0 (■), pH5.0 (▲), pH6.8 (○), pH7.6 (△) of the dissolution media.

Figure 3 DS dissolution profiles of test coated tablets (○) and the reference enteric coated tablets (◆) (n = 6).

Figure 4 5-ASA release profile of pellets coated at 25% level with various Eudragit^® L100-Eudragit^® S100 combination ra-tios of 1:0 (), 4:1 (□), 1:1 (△), 1:4 (○) and 0:1 (● ) (w/w), using the sequential pH change method (n = 6).

Figure 5 5-ASA release profile of pellets coated at 5 levels of uncoated (◆), 5% (□), 10% (△), 15% (○), 25% (●) (w/w, total solid applied) with Eudragit^® L100-Eudragit^® S100 combinations of 1:4 (w/w), using the sequential pH change method (n = 6).

Figure 6 Effect of pH of the dissolution medium on 5-ASA release of coated pellets coated at 25% level with Eudragit^® L100-Eudragit^® S100 combination ratios of 1:4 (w/w) (n = 6). PH1.2 (◆), pH6.0 (■), pH6.8 (▲), pH7.2 (○), pH7.5 (◇) of the dissolution media.

Figure 7 DS plasma concentration-time profiles after oral ad-ministration of coated formulation (△) and reference enteric formulation (●) in dogs at a dose of 100 mg/body. Each value represents mean ± SE (n = 6).

Figure 8 Comparison between the cumulative DS release per-centage in vitro f(t) and the absorption percentage in vivo F(t) of coated formulation (n = 6).