Development of a multifunctional matrix drug delivery system surrounded by an impermeable cylinder.

A multifunctional drug delivery system based on hydroxypropyl methylcellulose (HPMC)-matrices (tablets) placed within an impermeable polymeric cylinder (open at both ends) was developed. Depending on the configuration of the device, extended release, floating or pulsatile drug delivery systems could be obtained. The release behaviour of the different devices was investigated as a function of HPMC viscosity grade, HPMC content, type of drug (chlorpheniramine maleate or ibuprofen), matrix weight, position of the matrix within the polymeric cylinder, addition of various fillers (lactose, dibasic calcium phosphate or microcrystalline cellulose) and agitation rate of the release medium. The drug release increased with a reduced HPMC viscosity grade, higher aqueous drug solubility, decreased HPMC content and increased surface area of the matrix. The release was fairly independent of the agitation rate, the position of the tablet within the polymeric cylinder and the length of the cylinder. With the pulsatile device, the lag time prior to the drug release could be controlled through the erosion rate of the matrix (matrix weight and composition).