[Filler-controlled release from suspension matrices (laminates)]

The release from a matrix (polyethylenmineral oilgel, Plastibase) with drug (bupranolol) in suspension can be controlled by a controlling layer of the same material which is saturated with the drug. Thus, after a burst period zero order release is reached from the laminate, before square root t-kinetics predominate. The duration of constant release may be extended with fillers in the controlling layer (glass beads, d less than 20 microns). Increasing the thickness of the controlling layer increases both duration of constant release and time to reach it, the latter to a lower extent.