Dual drug release electrospun core-shell nanofibers with tunable dose in the second phase

This study reports a new type of drug-loaded core-shell nanofibers capable of providing dual controlled release with tunable dose in the second phase. The core-shell nanofibers were fabricated through a modified coaxial electrospinning using a Teflon-coated concentric spinneret. Poly(vinyl pyrrolidone) and ethyl cellulose were used as the shell and core polymer matrices respectively, and the content of active ingredient acetaminophen (APAP) in the core was programmed. The Teflon-coated concentric spinneret may facilitate the efficacious and stable preparation of core-shell nanofibers through the modified coaxial electrospinning, where the core fluids were electrospinnable and the shell fluid had no electrospinnability. The resultant nanofibers had linear morphologies and clear core-shell structures, as observed by the scanning and transmission electron microscopic images. APAP was amorphously distributed in the shell and core polymer matrices due to the favorite second-order interactions, as indicated by the X-ray diffraction and FTIR spectroscopic tests. The results from the in vitro dissolution tests demonstrated that the core-shell nanofibers were able to furnish the desired dual drug controlled-release profiles with a tunable drug release amount in the second phase. The modified coaxial electrospinning is a useful tool to generate nanostructures with a tailored components and compositions in their different parts, and thus to realize the desired functional performances.

[Therapeutic effect of methyl 5-aminosalicylate on experimental ulcerative colitis in rabbits]

Using the improved Kirsner model of ulcerative colitis in rabbits, we found that the therapeutic effect of methyl 5-amino salicylate hydrochloride (M-5-AS) was similar to that of sulfasalazine (salicylazosulfapyridine, SZ). The length of pathological damage and the range of diffuse ulcers were decreased in comparison with the control group (P less than 0.01, 0.05). Microscopically, tissue repairing at the regions of ulcers and proliferation in serolemma were noted, and the edema in muscular mesenchyme was less evident in the treated rabbits. M-5-AS completely inhibited the spontaneous contraction of rat stomach fundus strips and colon. The IC50 of the resting tone of the 2 tissues were 1.30 +/- 0.39 and 0.72 +/- 0.25 mmol/L, respectively. In addition, M-5-AS antagonized the contraction induced by human fresh semen. The results suggest that the therapeutic mechanism is related to the antagonism of prostaglandins in the inflammatory regions.