Preparation and property of mPEG-PLA/pluronic mixed micelles and their role in solubilization of propofol

Novel mixed polymeric micelles formed by biocompatible polymers,mPEG-PLA and Pluronic P105,were fabricated and used as a nanocarrier to solubilize the poorly soluble anesthetic drug propofol.Propofol was added directly to an aqueous solution of mPEG-PLA/Pluronic P105 mixed micelles and stirred into a micellar solution.The average particle size and size distribution of micelles were evaluated by the dynamic light scattering technology.Drug loading content,encapsulation efficiency and free drug concentration were determined by using ultracentrifugation and lyophilization.In vitro release characteristic of propofol formulation was investigated by dialysis method.The physical stability of mixed micelles was also assessed under storage condition（4 oC） after six months.Sleep-recovery studies in male Sprague-Dawley rats,at a dose of 10 mg/kg were performed to compare the pharmacodynamic profiles of propofol in mixed micelles with that of commercial lipid emulsion（CLE）.The results indicated that solubilization of propofol in the mixed micelles was more efficient than that in mPEG-PLA alone.Micelles with the optimized composition of mPEG-PLA/Pluronic P105/Propofol（10：4：5,w/w/w） had particle size of about 90 nm with narrow distribution（polydispersity index of about 0.2）.The content of free propofol in the aqueous phase of mixed micelles was significantly lower than that in CLE（P〈0.05）.There was no remarkable differences for particle size,polydispersity index,and free drug concentration when the mix micelles were stored at 4 oC for six months,suggesting that the propofol-loaded mixed micelles were stable for at least six months.The accumulative release of mixed micelles was significantly higher than that of CLE at the corresponding time points,suggesting that quick release rate for mixed micelles might produce favorable pharmacological effect.No significant differences in the unconsciousness time and recovery time of righting reflex were observed between the mixed micelles and CLE（P〉0.05）.In conclusion,the mixed micelle of mPEG-PLA and pluronic copolymer may be a promising candidate for intravenous delivery of propofol in clinic.

Preparation and characterization of nanosized ethosomes loaded with tetrandrine and their in vivo efficacy in arthritis treatment

The purpose of this work was to explore the feasibility of ethosomes for improving the anti-arthritic efficacy of topically administered tetrandrine, a bisbenzylisoquinoline alkaloid. Ethosomes were prepared by using the transmembrane pH-gradient loading method and characterized by mean diameter, morphology and entrapment efficiency. The prepared tetrandrine-loaded ethosomes exhibited spherical shape with about 78 nm of average diameter and entrapment efficiency of （52.87±3.81）%, whereas the liposomes had bigger size （99 nm） and higher entrapment efficiency （98.80±0.01）%. In addition, ethosomes exhibited favorable and enhanced penetration behavior as compared with liposomes. More importantly, tetrandrine-loaded ethosomes had a significantly better anti-adjuvant arthritis efficacy in rats compared to liposomes formulation, but no significant difference in the anti-arthritic efficacy between tetrandrine-loaded ethosomes and commercial dexamethasone ointment was observed. These results suggest that ethosomes would be a promising nanocarrier for topical delivery of tetrandrine across skin.