EFFECT OF CELLULOSE DERIVATIVES ON ALGINATE MICROSPHERES PREPARED BY EMULSIFICATION

Generally discrete and spherical calcium alginate microspheres with a high drug encapsulation efficiency were readily prepared by an emulsif ication process. They were found to release drug rapidly. In the prese nt study, co-polymer in the form of cellulose derivatives was added to sodium alginate in an attempt to modify the drug release profiles of the microspheres. The effects of cellulose derivatives on the morpholo gy and drug encapsulation efficiency of the microspheres were also eva luated. The cellulose derivatives increased the degree of agglomeratio n of the microspheres. Small and spherical microspheres were produced from cellulose derivatives of low viscosity while larger microspheres which tended to be elongated were produced from cellulose derivatives of high viscosity. The drug encapsulation efficiency and the drug rele ase profiles were influenced by the chemical nature of the cellulose d erivative as well as its viscosity. The efficiency of drug encapsulati on generally increased while the rate of drug release decreased with i ncreasing viscosity of the cellulose derivatives. Less hydrophilic cel lulose derivatives such as methyl cellulose and hydroxypropylmethyl ce llulose were found to increase the efficiency of encapsulating sulphag uanidine, while more hydrophilic cellulose derivatives such as hydroxy propyl cellulose and carboxymethyl cellulose had the opposite effect. Among the cellulose derivatives used, only hydroxypropyl cellulose ret arded the drug release of the microspheres.