Biomedical subjects

Yan Pan

Publications and source records attributed to Yan Pan.

23 records · Page 2Linked to original sources

PubMed2003

[Enhancement of gastrointestinal absorption of chitosan-coated insulin-loaded poly (lactic-co-glycolic acid) nanoparticles].

AIM: To study chitosan-coated poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) on enhancing gastrointestinal absorption of insulin. METHODS: Insulin-loaded PLGA multiple emulsions were prepared by a double-emulsion method. Using chitosan as a stabilizer, chitosan-coated PLGA-NPs was prepared. The changes of the morphology, size distribution and Zeta potential of the NPs were examined. The encapsulation efficiency was determined by HPLC. The release behaviors in vitro were assessed, and the hypoglycemic effects were evaluated by monitoring the glucose levels in diabetic rats. RESULTS: Chitosan-coated PLGA-NPs showed a narrow size of distribution and regular surface with layer structure and their Zeta potential can be changed by chitosan. Chitosan-coating increased the encapsulation efficiency of insulin, reduced the initial burst and improved the release behavior of the NPs. About 14-16 h after intragastric administration of chitosan-coated INS-PLGA-NPs, the plasma glucose level decreased significantly compared with intragastric administration of same dose of non-coated NPs (P < or = 0.05), and the relative pharmacological availability was increased up to (15.4 +/- 1.2)%. CONCLUSION: Chitosan-coated PLGA-NPs could enhance gastrointestinal absorption of insulin.

Animals↗

PubMed2002

Bioadhesive polysaccharide in protein delivery system: chitosan nanoparticles improve the intestinal absorption of insulin in vivo.

There are many ongoing investigations to improve the oral bioavailability of peptide and protein formulations. Bioadhesive polysaccharide chitosan nanoparticles (CS-NPs) would seem to further enhance intestinal absorption of them. In this study, Insulin-loaded CS-NPs were prepared by ionotropic gelation of CS with tripolyphosphate anions. Its particle size distribution and zeta potential were determined by photon correction spectroscopy and laser Dopper anemometry. The ability of CS-NPs to enhance intestinal absorption of insulin and increase the relative pharmacological bioavailability of insulin was investigated by monitoring the plasma glucose level of alloxan-induced diabetic rats after oral administration of various doses of insulin-loaded CS-NPs. CS-NPs had a particle size in the range of 250-400 nm and its polydispersity index was smaller than 0.1, positively charged, stable. Insulin association was found up to 80% and its in vitro release showed a great initial burst with a pH-sensitivity property. CS-NPs enhanced the intestinal absorption of insulin to a greater extent than the aqueous solution of CS in vivo. Above all, after administration of 21 I.U./kg insulin in the CS-NPs, the hypoglycemia was prolonged over 15 h and the average pharmacological bioavailability relative to SC injection of insulin solution was up to 14.9%.

Adhesives↗

PubMed2002

Relationship between drug effects and particle size of insulin-loaded bioadhesive microspheres.

AIM: To formulate and characterize insulin-loaded adhesive microspheres (MP) and evaluate drug effects of MP with various sizes, 120, 350, and 1000 nm in diameter, in the alloxan-induced diabetic rats. METHODS: Insulin-loaded MP were formulated by an ionotropic gelation procedure. Particle size distributions were determined by photon correlation spectroscopy and optical microscopy. The factors that influenced the particle sizes and loading capacity were investigated, and the release properties were assessed in vitro. The hypoglycemic effect was investigated by monitoring the plasma glucose level of the alloxan-induced diabetic rats after oral administration. RESULTS: All the MPs with three sizes formulated were in the desired size range, and the loading capacity was 15.3 %+/-1.7 % (120 nm), 32.4 %+/-2.4 % (350 nm), and 53.3 %+/-2.7 % (1000 nm) respectively. The particle size also had an influence on the release property of the MPs. Half an hour later, 25 %+/-4 % (120 nm), 18.3 %+/-2.4 % (350 nm), and 8.6 %+/-1.3 % (1000 nm) of insulin were released. MP with different sizes had various degree of hypoglycemic effects after 10 h (P<0.05 vs control insulin solution). The plasma glucose level of 350 nm size particles remarkably decreased 15 h later (P<0.05 vs 120 nm) or 35 h later (P<0.01 vs others). The relative pharmacological availability was 10.2 %+/-0.5 % (120 nm), 14.9 %+/-1.3 % (350 nm), and 7.3 %+/-0.8 % (1000 nm) respectively. Particles of 350 nm showed a comparatively higher availability (P<0.05). CONCLUSION: Adhesive CS-MP were helpful in increasing the relative pharmacological bioavailability of insulin, and a distinct advantage of proper particle size helped to increase the drug effects.

Animals↗

PubMed2002

[The enhancing effect of electroporation and iontophoresis on the permeation of insulin through human skin].

AIM: To study the enhancing effect of electroporation and iontophoresis on the permeation of insulin through human cadaver skin in vitro. METHODS: Using side by side two-chamber diffusion cells, the flux of insulin achieved with iontophoresis and electrophoration were compared. RESULTS: The application of high-voltage pulse combined with iontophoresis resulted in higher flux transdermal permeation of insulin than either one technique alone (P < 0.05). Pulsing at a higher voltage increased the flux of insulin more dramatically than pulsing at a lower voltage (P < 0.01). The transdermal transport of insulin by 90 pulse of 500 V (exponential pulse generater, pulse time: 20-24 ms, pulse frequency: 3 pulse.min-1) followed by iontophoresis led to a quick input and a high steady flux. CONCLUSION: Electroporation combined with iontophoresis can enhance the permeation of insulin significantly.

Electroporation↗

PubMed2002

[Study on preparation and oral efficacy of insulin-loaded poly(lactic-co-glycolic acid) nanoparticles].

AIM: To investigate the possibility of poly(lactic-co-glycolic acid) as a carrier for the delivery of macromolecular. METHODS: Insulin-loaded poly (lactic-co-glycolic acid) nanoparticles (INS-PLGA-NPs) was prepared by a double-emulsion solvent evaporation method. The size distribution was examined by photo-correlation spectrometry. The entrapment efficiency was determined by HPLC and important factors that affected the entrapment efficiency were investigated. The loading mechanism of different size nanoparticles was assayed by radioimmunoassay (RIA). INS-PLGA-NPs release behavior in vitro was carried out under sink condition. After oral administration of the nanoparticles to alloxan-induced diabetic rats, its glucose level was determined by glucose oxidize method and the oral pharmacological bioavailability in contrast to s.c. of insulin solution was calculated according to the area over the curve. RESULTS: The INS-PLGA-NPs was prepared with poloxamer 188 as a emulsifier, the mean diameter was 149.6 nm and the polydispersity index was decreased to 0.09. While the entrapment efficiency was increased to 42.8%. Most of the insulin loaded was adsorbed on the surface of the nanoparticles. The release behavior in vitro showed an initial burst effect followed by a slower rate stage. After oral administration of 10 u.kg-1 INS-PLGA-NPs, the plasma glucose level decreased significantly after 4 h (P < 0.05), 10 h later the glucose level decreased to the lowest (52.4% +/- 10.2%, P < 0.01) and the relative pharmacological bioavailability is (10.3 +/- 0.8)%. CONCLUSION: PLGA-NPs might be used as a new oral carrier for protein drug delivery systems in the future.

Administration, Oral↗