Contribution to the study of new graft copolymer matrices for drug delivery systems. Technological study

Cellulose and starch derivatives have long been used for their ability to sustain the release of drugs. The use of polymer mixtures represents a potential way of achieving the required release properties. It is known that the release of a drug from a matrix system is produced by diffusion through the gel formed. The aim of this work is focused on the study of viscosity, flowability and compactibility values of polymers for drug delivery matrices. Previously synthesized graft copolymers were used: hydroxypropyl starch-methyl methacrylate (HS-MMA), carboxymethyl starch-MMA (CS-MMA) and hydroxypropyl cellulose-MMA (HC-MMA). It is known that polymers with the highest swelling capacity give highest viscosity value. HC-MMA and CS-MMA graft copolymers can be considered pseudogels because through mechanical-dynamical analysis, an intersection point between the storage modulus and the loss modulus can be seen. All the polymers fulfilled in general the requirements for good flow which will predict a good die filling during the tableting. However, L-products have the higher values for the compactibility and lubrication coefficient and the lower values for ejection and maximum upper force. Also, from the study of gel formation done with these products, we can state that L-products will probably lead to more interesting excipients to the obtaining of control release matrices. (C) 1997 Elsevier Science B.V.