The use of polymer matrices to control the release of poorly soluble drugs is of growing interest in the pharmaceutical sector. Melt processes such as twin screw extrusion are used to mix polymer(s), drugs and other excipients where the drug is dispersed, typically in an amorphous form mixed at a molecular level. Choice of polymer or polymer blend can be used to control the rate and pH dependency of drug release. Here, the use of immiscible polymer blends has been investigated in order to control release rate of a poorly soluble drug. Two pharmaceutically acceptable polymers (ethyl cellulose and shellac) were selected to provide an immiscible blend, to which a poorly soluble drug could be added. The polymers and drug were melt compounded using twin screw extrusion at different drug loadings and mixing conditions. Physical properties of the samples were characterized by scanning electron microscopy, Raman imaging, differential and scanning calorimetry whilst drug release rate was measured by dissolution. Results indicated that the drug was dissolved primarily in only one of the polymeric phases and that the drug release rate was influenced by drug loading and mixing conditions.