[Studies on solubility enhancement of curcumin by Polyvinylpyrrolidione K30].

OBJECTIVE: To study solubility enhancement of curcumin by Polyvinylpyrrolidione K30 (PVP K30). METHODS: Solid dispersion systems (SDS) of curcumin in PVP K30 were prepared at various weight ratios by co-evaporation of curcumin and PVP K30 ethanol solution. The differential scanning calorimetry (DSC) and powder X-ray diffractometer method were used to describe the status of curcumin in carriers, the UV spectrometry method for determination of curcumin in mediums was established. RESULTS: The curcumin SDS was successfully prepared, the UV spectrometry method was accurate and reliable, and no interference occurred from carrier. The solubility rate in vitro of curcumin was significantly raised. Compared to curcumin, the solubility of curcumin in SDS increased at least 880 folds. CONCLUSION: PVP K30 improves the solubility of curcumin well.

[Preparation and evaluation in vivo and in vitro of glimepiride gel-matrix controlled-release patch].

AIM: To study the pharmaceutical characterization, the pharmacokinetics and relative bioavailability of glimepiride gel-matrix controlled-release patch in rats. METHODS: An HPLC method was established for the determination of glimepiride in the permeation receptor and patch. The permeation rate and penetration mechanism of glimepiride-TDDS through rabbit skin in vitro was examined. The determination of drug content and the examination of weight difference and stability of the glimepiride-TDDS were carried out. Another HPLC method after pre-column derivatization was developed to determine the glimepiride serum concentration and then employed to study the pharmacokinetics and relative bioavailability of glimepiride after a single dose of oral or patch administration in rats. RESULTS: The permeation tests through excised rabbit skin demonstrated that the optimized glimepiride controlled-release patch exhibited zero-order kinetic characteristics that satisfied the demands of original design. The determination of glimepiride content and the quality control of weight difference of the patch accorded with Pharmacopoeia of the People's Republic of China of 2000 edition and the pharmaceutical characterization showed good stability. The HPLC method for the determination of serum glimepiride was shown to be a sensitive and simple one. The pharmacokinetic results showed that TDDS could decrease the maximum serum concentration, prolong the peak time, extend the MRT by 5.5 times compared with oral administration and maintain the serum concentration of glimepiride at a higher level even after 120 h of administration. The relative bioavailability of glimepiride-TDDS was 20.3% versus oral administration. CONCLUSION: The glimepiride-TDDS showed a slower, longer and smoother serum concentration-time profile, as compared with conventional oral administration in both absorption and elimination phase. As a result, it was evident that the patch exhibited good controlled-release properties.