Crosslinked chitosan and chitosan/poly(ethylene oxide) (PEO) blend membranes were prepared using the solution casting technique for eleutherococcus sentisocus (ES) and vitamin B-12 release. A naturally occurring and nontoxic crosslinking agent, genipin, was used to form the chitosan and chitosan/PEO blend networks. The permeability of vitamin B-12 through the membranes was investigated. The effect of crosslink density of the membrane on the drug release behavior was assessed. The drug release rate decreased with increasing crosslink density, and was very sensitive to crosslink density at low crosslink densities. PEO was introduced into the membrane to adjust the mesh size of the membrane and to control the drug release rate by PEO molecular weight and amount used. The drug release rate was sensitive to medium pH. For ES release from crosslinked chitosan carriers, the release rate was controlled by both the mesh size of the membrane and the molecular interactions between chitosan and ES. (c) 2006 Wiley Periodicals, Inc.