Preparation of silybin-phospholipid complex and its bioavailability in rats / 药学学报

<p><b>AIM</b>To prepare silybin-phospholipid complex and study its physicochemical properties. To compare the pharmacokinetic characteristics and bioavailability after oral administration of silybinphospholipid complex and silybin material in rats.</p><p><b>METHODS</b>Using acetone as a reaction medium, silybin and phospholipid were resolved into the medium, when the organic solvent was clear, then removed under vacuum evaporation, silybin-phospholipid complex was obtained. The new complex' s physicochemical properties including DSC, UV, IR were determined. The concentrations of non-conjugated and total silybin after oral administration of silybin-phospholipid complex and silybin material at different time in rats were determined by RP-HPLC. The pharmacokinetic parameters were computed by software program 3P97.</p><p><b>RESULTS</b>Experiment results showed that silybin and phospholipid in the silybin-phospholipid complex were combined by non-covalent-bond, not forming a new compound and the solubility of silybin-phospholipid complex in water and n-octanol was effectively enhanced. It was found that mean plasma concentration-time curve of silybin after oral administration of silybin-phospholipid complex in rats was in accordance with one-compartment model with first-order absorption. Pharmacokinetic parameters of non-conjugated and total silybin in rats were respectively T(max) 10 min and 2 h; C(max) 0.11 and 1.08 microg x mL(-1); T1/2 2.18 and 3.84 h; AUC(0-infinity) 1.71 and 12.94 microg x mL(-1) x h. However, after oral administration of silybin material, plasma levels of both non-conjugated and total silybin were within the analytical detection limit.</p><p><b>CONCLUSION</b>It was concluded that after oral administration of silybin-phospholipid complex in rats the bioavailability of silybin increased greatly. This was mainly due to an obvious improvement of the lipophilic property of silybin-phospholipid complex compared with silybin material and an increase in gastrointestinal absorption.</p>

Preparation of silymarin proliposomes and its pharmacokinetics in rats / 药学学报

<p><b>AIM</b>To study the preparation of silymarin proliposomes. To study its physicochemic properties, its pharmacokinetical characteristics and bioavailability in rats after oral administration.</p><p><b>METHODS</b>Silymarin proliposomes were prepared by film-deposition on carriers. When the proliposomes were contacted with water to form liposome suspensions, the tests of physicochemical properties including encapsulation efficiency, particle size and stability of the formed liposome suspensions were determined by HPLC, laser-particle-sizer and etc. The concentrations of non-conjugated and overall silymarin in plasma of rats and their pharmacokinetic behaviors after oral administration were studied by RP-HPLC. The pharmacokinetic parameters were computed by software program 3P97.</p><p><b>RESULTS</b>The encapsulation efficiency of silymarin liposomes could be more than 90%, with an average particle size of about 238.8 nm and a very good stability. The high bioavailability of silymarin proliposomes could be gotten by oral administration.</p><p><b>CONCLUSION</b>Compared with silymarin, silymarin proliposome is a stable and easily industrialized preparation and did enchance the gastrointestinal absorption of silymarin.</p>

Studies on the insulin-liposomes double-coated by chitosan and chitosan-EDTA conjugates / 药学学报

<p><b>AIM</b>To evaluate the characteristics, the hypoglycemic efficacy and the pharmacokinetics of the insulin-liposomes double-coated by chitosan (CH) and chitosan-EDTA conjugates (CEC).</p><p><b>METHODS</b>Insulin-liposomes were prepared by reversed-phase evaporation. The protection of insulin against peptic and tryptic digestion was studied with HPLC. The hypoglycemic effects of insulin-liposomes were investigated using the glucose oxidase method after oral administration to rats. Serum insulin concentration in rats were determined by radio-immunoassay, and were assessed by Pkanalyst computer program.</p><p><b>RESULTS</b>The insulin-liposomes double-coated by CH and CEC was shown to protect insulin against digestion of pepsin, trypsin and gastrointestinal contents. In glucose tolerance test in normal rats, as compared with phosphate buffer solution control group, the insulin-liposomes coated by CH and CEC could reduce the glucose-induced peak of hyperglycemia. The reduction of the insulin-liposomes double-coated by CH and CEC was superior to that of other insulin-liposomes. When administered intragastrically to normal rats, the insulin-liposomes coated by CH and CEC could reduce glycemia measured after an overnight fast. The hypoglycemic effect the insulin-liposomes double-coated by CH and CEC was superior to that of other insulin-liposomes, and the dosage of 50 mu x kg(-1) decreased by 45.98% of initial blood glucose level at 1 h. As compared with subcutaneous injection, the relative pharmacological bioavailability was 17.02% calculated by area under the curve of glucose level versus time profile after oral administration of the insulin-liposomes double-coated by CH and CEC to rats. The serum insulin concentration-time curves were found to best fit the one-compartment open model. As compared with subcutaneous injection, the relative bioavailability was 8.91% calculated by the area under the curve of serum insulin concentration versus time profile after oral administration of the insulin-liposomes double-coated by CH and CEC to rats.</p><p><b>CONCLUSION</b>The stability and absorption of insulin-liposomes double-coated by CH and CEC was superior to that of the insulin-liposomes coated either by CH, or by CEC respectively.</p>