Effect of iontophoresis on skin permeation of defibrase / 药学学报

<p><b>AIM</b>To investigate the effect of iontophoresis on skin permeation of defibrase.</p><p><b>METHODS</b>Iontophoresis was carried out in side-by-side chambers, excised rat skin membrane (RSM) or human epidermis membrane (HEM). The effects of electrode polarity, permeation medium pH and ionic strength were evaluated.</p><p><b>RESULTS</b>Permeation of defibrase caused by anodal iontophoresis was more effective [the apparent permeability coefficient was (1.2 +/- 0.4) x 10(-4) cm x h(-1)] than that of cathodal iontophoresis [(4.3 +/- 1.4) x 10(-5) cm x h(-1)]. The amount of permeated defibrase caused by anodal iontophoresis in pH 7.4 medium was (25 +/- 5) x 10(-14) mol x cm(-2), which was higher than that of in pH 6. 4 permeation medium [(15 +/- 4) x 10(-14) mol x cm(-2)].</p><p><b>CONCLUSION</b>Iontophoresis could enhance skin permeation of defibrase. Electroosmotic flow effect played an important role.</p>

Diffusion behaviors of drugs in thermosensitive in situ gels / 药学学报

<p><b>AIM</b>To study the diffusion behaviors of drugs in thermosensitive in situ gels, and provide valuable information for designing such delivery systems.</p><p><b>METHODS</b>A free diffusion model was used to evaluate the effects of concentration, the property of drugs, as well as the gel compositions on the diffusivity of drugs.</p><p><b>RESULTS</b>Drug transport through the aqueous channels of the gel followed Fickian mechanism, and no significant influence on the diffusivity was observed when the drug concentration was lowered from 5% to 0.25%. The diffusion coefficients of propranolol, timolol maleate, and salbutamol sulfate were 0.91, 1.32, and 3.30 x 10(-6) cm2 x s(-1), respectively. The flux of hydrophilic drug was 3.6 fold faster than that of the lipophilic one implied the latter partitioned into the hydrophobic micellar core, and consequently the diffusion was retarded. The diffusivity was decreased with increased poloxamer and sodium hyaluronate concentration, due to the distorted aqueous channels and higher microviscosity.</p><p><b>CONCLUSION</b>The result suggested that sustained release could be achieved for the thermosensitive in situ gel by incorporating lipophilic drug or increasing polymer concentration.</p>

Cutaneous permeation kinetics and pharmacodynamics of topical lidocaine gel in rat / 药学学报

<p><b>AIM</b>To study the cutaneous permeation kinetics and pharmacodynamics of lidocaine gel.</p><p><b>METHODS</b>The concentration of lidocaine in dermis following topical application in rats was determined by the cutaneous microdialysis technique and related parameters were calculated; the pharmacodynamics of the gel was evaluated by electric stimulation method with EMLA (eutectic mixture of local anesthetics) cream as a control.</p><p><b>RESULTS</b>The peak of percutaneous absorption kinetic profile of lidocaine gel across rat skin occurred at 1.25 h; the onset time of local anesthetic action of lidociane gel was similar to that of EMLA, but both the duration and depth of anesthetic effect were superior to EMLA cream.</p><p><b>CONCLUSION</b>Lidocaine gel showed good anesthetic effect. The minimum effective concentration of lidocaine in dermis is 12 mg.L-1.</p>

Enhancement of gastrointestinal absorption of chitosan-coated insulin-loaded poly (lactic-co-glycolic acid) nanoparticles / 药学学报

<p><b>AIM</b>To study chitosan-coated poly (lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) on enhancing gastrointestinal absorption of insulin.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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)%.</p><p><b>CONCLUSION</b>Chitosan-coated PLGA-NPs could enhance gastrointestinal absorption of insulin.</p>

Effect of solution viscosity on polymer precorneal residence time evaluated by in vitro method / 药学学报

<p><b>AIM</b>To evaluate how solution viscosity affects the precorneal residence of five water-soluble polymers with different properties.</p><p><b>METHODS</b>Captive bubble technique was used, with the consecutive change of contact angle interpreted as an indication of desorption process, to study the residence of those polymers in vitro on freshly enucleated rabbit eyes under physiological conditions.</p><p><b>RESULTS</b>Carbopol and sodium hyaluronate (HA), which adsorbed to isolated ocular surface more than 15 min, showed the optimum precorneal retentive capabilities. When the solution viscosity increased from 12 mPa.s to 50 mPa.s, the residence time of carbopol and HA were prolonged 10 min and 7 min, respectively, but that of sodium carboxymethylcellulose was not affected.</p><p><b>CONCLUSION</b>The result suggested that higher viscosity is beneficial to improve the ocular residence time of bio-adhesive polymers.</p>

Study on preparation and oral efficacy of insulin-loaded poly(lactic-co-glycolic acid) nanoparticles / 药学学报

<p><b>AIM</b>To investigate the possibility of poly(lactic-co-glycolic acid) as a carrier for the delivery of macromolecular.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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)%.</p><p><b>CONCLUSION</b>PLGA-NPs might be used as a new oral carrier for protein drug delivery systems in the future.</p>

The enhancing effect of electroporation and iontophoresis on the permeation of insulin through human skin / 药学学报

<p><b>AIM</b>To study the enhancing effect of electroporation and iontophoresis on the permeation of insulin through human cadaver skin in vitro.</p><p><b>METHODS</b>Using side by side two-chamber diffusion cells, the flux of insulin achieved with iontophoresis and electrophoration were compared.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>Electroporation combined with iontophoresis can enhance the permeation of insulin significantly.</p>