Preparation and characterization of propranolol hydrochloride nanoparticles: a comparative study.

The water-in-oil-in-water (w/o/w) emulsification process is the method of choice for the encapsulation inside polymeric particles of hydrophilic drugs such as proteins and peptides which are high molecular weight macromolecules. Our objective was to apply this technique in order to formulate nanoparticles loaded with both a hydrophilic and a low molecular weight drug such as propranolol-HCl. Nanoparticles were prepared using a pressure homogenization device with various polymers (poly--caprolactone, poly(lactide-co-glycolide), ethylcellulose) and different amounts of drug and were compared in terms of particle size, encapsulation efficiency and drug release. Higher encapsulation efficiencies were obtained with both PCL (77.3%) and PLGA (83.3%) compared to ethylcellulose (66.8%). The in vitro drug release was characterized by an initial burst and an incomplete dissolution of the drug. When decreasing the polymer/drug ratio, the release appeared more controlled and prolonged up to 8 h. It can be concluded that nanoparticles prepared by w/o/w emulsification followed by solvent evaporation might be potential drug carriers for low molecular weight and hydrophilic drugs. Copyright 2004 Elsevier B.V.