Glycerol–Silicone Elastomers as Active Matrices with Controllable Release Profiles

Drug release regimes must be controlled for the optimal therapeutic effect. Although it is relatively straightforward to create first-order release matrices, it can be challenging to avoid an initial burst. Matrices with zero-order profiles are perceived to be beneficial in many cases but are even more difficult to formulate. We describe the straightforward synthesis of elastomeric composites prepared from silicone in which the active substance is dispersed in glycerol. The release of glycerol-soluble actives from the films of these materials was shown to be tunable with respect to the order of release (zero- or first-order) simply by changing the glycerol content. Importantly, release from the elastomers showed no burst effect. The discrete glycerol domains embedded within a silicone matrix act as reservoirs for active substances. Upon contact with aqueous media, the active substances are released from the matrices exhibiting zero-order, near zero-order, or first-order release kinetics. Various parameters that could influence the release process, including glycerol content, glycerol domain size, or membrane thickness, are thoroughly investigated, elucidating guidelines for creating matrices capable of delivering the active substances at desired rates. Additionally, the composites proved to absorb significant amounts of liquid water (up to 1850% of sample mass), a feature that can be tuned by the manipulation of the composite structure.