Impact of Polymeric Excipient Selection and Process Variables on Hot Melt Extrusion

The Pharmaceutical industry is just now beginning to adopt extrusion processing to produce solid dosage forms.  Both non-molten (e.g. extrusion spheronization) and molten (e.g. Hot Melt Extrusion) extrusion is being practiced.   There are many published examples of these techniques being used to produce pharmaceutical dosage forms. This presentation will be limited to Hot Melt Extrusion (HME).

HME is now being used by formulators to extrude combinations of APIs, polymers, and plasticizers into various dosage forms. A significant number of benefits have been proposed for using HME over traditional processing techniques. These include improved bioavailability of poorly soluble APIs, fewer unit operations, improved content uniformity, an anhydrous process, a low energy alternative to high shear granulation, and reduced cost to manufacture compared to conventional processing.

The selection of the polymeric excipient to be used in HME is a very important consideration. Excipients must be chosen such that the formulation can be processed at conditions where the components are not degraded. Further, excipient choice is expected to have a direct impact on the dissolution profile and API morphology obtained.    Processing variables (e.g. extrusion temperature, equipment configuration, etc.) can also have a significant impact on the characteristics of the extruded material. The formulations used for this study included various grades of ethylcellulose, hypromellose, and polyethylene oxide with model drugs. The focus of this presentation will be on the impact excipient selection and processing variables have on dissolution profiles, API morphology, and formulation stability. Data will be presented that demonstrates varied dissolution profiles, as well as the successful generation of solid dispersions that survive 6 month accelerated stability testing.

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