Paper Title
Preparation And Physicochemical Evaluation of Tocopheryl Polyethylene Glycol Succinct 1000, 5000 (Tpgs 1k, 5k) Micelles For Delivery Of Paclitaxel

Abstract
The objective of the present study was to evaluate the potential of paclitaxel (PTX) loaded mixed micelles fabricated from tocopheryl polyethylene glycol succinate 1000, 5000 (TPGS 1K, 5K) as a sustained release system. Here, we developed a micellar system with a newly synthesized TPGS5k polymer, which showed lower CMC of 0.078 mg/ml compared with traditional micelles prepared with TPGS1k to achieve sustained and controlled drug delivery. The blank and drug loaded micelles were prepared in different weight ratios of TPGS1K/TPGS5K by solvent evaporation technique. Physicochemical properties of the micelles such as critical micelle concentration, micelle size, entrapment efficiency, and release properties were investigated in detail. The results showed that mixed micelles made of TPGS 1K and TPGS 5K (weight ratio 3:7) had lowest CMC value, indicating that they were most stable towards dilution among micelles. Particle sizes and zeta potentials of the micelles were in the range of 50.3�102 nm and 18.5�28.3 mV, respectively. The drug entrapment efficiencies of the micelles were within 63.6�92.5% (w/w). The results revealed that adding TPGS 5K could increase the drug loading. The drug loaded micelles exhibited a sustained release behavior in dissolution medium. From the micellar formulation, approximately 30% of PTX was released within 10 h at 37◦C, afterwards, the release rate slowed down and was almost complete after 5 days. In comparisons, 50% of PTX was released rapidly from Anzatax� (PTX in Cremophor El) within 5 h and it was released completely after 30 h. Index Terms- Paclitaxel, α-tocopheryl polyethylene glycol succinate, Micelles