Effect of Tween-80 on the permeability of rhodamine 123, a P-gp substrate across rat intestinal membranes in vitro / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the effect of Tween-80 in modulating rhodamine123 (R123) permeability across the intestinal membranes.</p><p><b>METHODS</b>The permeability of R123 or fluorescein sodium (CF) across isolated rat intestinal membranes at the concentration of 5 microg/ml was evaluated using an in vitro diffusion chamber system, in the presence or absence of Tween-80 at different low concentrations. The concentration of R123 or CF in the receptor chamber was determined using fluorospectrophotometry.</p><p><b>RESULTS</b>The intestinal membrane permeability of R123 gradually decreased from the jejunum to the ileum and then to the colon. The serosal-to-mucosal transport of R123 was much greater than its mucosal-to-serosal transport. In the presence of low concentrations of Tween-80, the absorptive transport of R123 was significantly increased while its secretory transport decreased depending on the concentration of Tween-80. However, Tween-80 at the experimental concentrations was found to obviously affect the CF transport across the intestinal membranes.</p><p><b>CONCLUSION</b>Low concentrations of Tween-80 may promote the absorption of P-gp-mediated drugs and therefore improve the oral bioavailability of these drugs.</p>

Qualitative fingerprint and quantitative determination of caffeic acid in compound dandelion enema / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a qualitative and quantitative reversed-phase high-performance liquid chromatography (RP-HPLC) with fingerprinting technique for quality control of compound dandelion enema.</p><p><b>METHODS</b>HPLC was utilized for quality assessment of 10 batches of samples. RP-HPLC analysis was performed on a Hypersil BDS C18 column (4.6 mm x 250 mm, 5 microm) with the mixture of acetonitrile (A) and potassium phosphate solution (B) (pH3.2) as the mobile phase in gradient mode. The concentrations of solvent A were 10%, 80% and 80% at 0, 38 and 40 min, respectively. The column temperature was set at 35 degrees C, the flow rate at 0.7 ml/min and the detection wavelength at 254 nm.</p><p><b>RESULTS</b>HPLC fingerprinting was established from the 10 batches, and the data showed 23 characteristic peaks in the compound dandelion enema for use as index peaks for qualitative identification. Comparison of the retention time and the on-line UV spectra of the samples with the chemical standards identified peaks 3, 4 and 8 as protocatechualdehyde, caffeic acid and ferulic acid, respectively. The contents of caffeic acid in the compound dandelion enema ranged between 63.7 and 136.8 microg/ml.</p><p><b>CONCLUSION</b>High specific chromatographic fingerprinting and quantitative measurement of caffeic acid allows rigorous quality control of compound dandelion enema.</p>