Design of a core-shelled polymer cylinder for potential programmable drug delivery

A cylindrical dosage form comprising a laminated composite polymer core and a hydrophobic polycarbonate coating was proposed for programmable drug del ivery. In the core, poly[(ethyl glycinate) (benzyl amino acethydroxamate) p hosphazene] was synthesized as drug-loaded layers for its strong pH-sensiti ve degradation (eroded after 1.5 days at pH 7.4 and more than 20 days at pH 5.0 and 6.0). Poly(sebacic anhydride)-b-polyethylene glycol or poly(sebaci c anhydride-co-trimellitylimidoglycine)-b-poly(ethylene glycol) was selecte d as isolating layers for their good processing properties at room temperat ure and suitable erosion duration. The in vitro drug release studies of the se devices were conducted under physiological conditions (pH 7.4). The resu lts revealed that the model drugs (brilliant blue, FITC-dextran, myoglobin) could be released in typical pulsatile manner. Moreover, the duration time of drug release (24-40 h) and the lag time (18-118 h) could be separately regulated by the mass of polyphosphazene and the type or mass of polyanhydr ide. In this experiment, the cooperative effect of polyanhydrides and pH-se nsitive degradable polyphosphazene was specially demonstrated, which offers a new idea to develop a programmable drug delivery system for single dose vaccine and other related applications. (C) 2001 Published by Elsevier Scie nce B.V.