Abstract:

Biodegradable polymer poly(lactic-co-glycolic acid)(PLGA) was used to encapsulate the pharmacological activity metabolite of tolterodine by means of O/W emulsion solvent evaporation method via homogenization in the emulsification process. The influences of preparation parameters were investigated. The results indicate that increa- sing PLGA concentration from 15% to 40% made the encapsulation efficiency of 5-hydroxymethyl derivative of tolterodine(5-HMT) increased from 55.39% to 76.32%, and the particle size increased from 34.33 μm to 70.78 μm. In addition, when homogenization speed increased from 850 r/min to 2300 r/min, both particle size and encapsulation efficiency of microspheres decreased. An increase in the volume of aqueous phase led to higher encapsulation efficiency and bigger particle size. Increasing temperature made encapsulation efficiency and particle size change significantly. While reaction temperature increased from 20 ℃ to 50 ℃, the encapsulation efficiency decreased from 70.44% to 24.07%, and particle size increased from 38.66 μm to 69.38 μm. High reaction temperature(over 40 ℃) may lead to porous surface of microspheres. Porous surface, encapsulation efficiency and particle size influenced on the in vitro release of 5-HMT together.

Key words: Poly(lactic-co-glycolic acid); Microsphere; Tolterodine; Tolterodine metabolite