Preparation and in vitro release behavior of urapidil hydrochloride loading into microspheres based on poly(L-lactide)

Microencapsulation of the antihypertensive drug urapidil hydrochloride was investigated as a means of controlling drug release and minimizing or eliminating local side effects. Poly(L-lactide) (PLLA) microspheres were prepared using an alternative oil-in-water (O/W) solvent-evaporation method such as the O/W cosolvent solvent-evaporation method and O/W with various electrolytes added to the aqueous phase method. The surface morphology and the size of the microspheres were observed by scanning electron microscope. Meanwhile, the drug loading efficiency of microspheres and the in vitro release of urapidil hydrochloride from microspheres were performed. The release study indicated that the urapidil hydrochloride-PLLA microspheres exhibited better sustained release capacity, and the kinetics of urapidil hydrochloride-PLLA microspheres in vitro release could be described by the Higuchi equation.