Thymosin-loaded enteric microspheres for oral administration: preparation and in vitro release studies.
Thymosin, a water-soluble polypeptide compound, was encapsulated within enteric microspheres of acrylic acid resin II by modified oil in oil (o/o) emulsion solvent evaporation method. The mixture emulsifier composed of lecithin and Span 80 was critical to the formation of sphere-shaped thymosin microparticles. Optimizing process parameters, such as the volume ratio of organic solvent to water, initial drug feed and polymer concentration, resulted in high drug encapsulation efficiency of 89.7% (6% polymer concentration and 0.5% initial drug feed). In vitro release studies suggested that thymosin release from microspheres exhibited pH dependent profiles. For formulation with 6% polymer concentration and 0.5% initial drug feed, 68.7% thymosin was released within 4h in pH 6.8 PBS buffer, while only 6.5% was observed in acid medium.
Yang
Ju Fei
JF
College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310031, PR China.
Qiu
Li Yan
LY
Jin
Yi
Y
Zhang
Jian Xiang
JX
D000179:Acrylates; D000284:Administration, Oral; D004339:Drug Compounding; D004655:Emulsions; D005079:Excipients; D006601:Hexoses; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D010713:Phosphatidylcholines; D012995:Solubility; D012997:Solvents; D013947:Thymosin / Q000008:administration & dosage* / Q000737:chemistry
D000179:Acrylates; D004655:Emulsions; D005079:Excipients; D006601:Hexoses; D010713:Phosphatidylcholines; D012997:Solvents; C018665:sorbitan monooleate; D013947:Thymosin