Interest in hot-melt extrusion techniques for pharmaceutical applications is growing rapidly with well over 100 papers published in the pharmaceutical scientific literature in the last 12 years. Hot-melt extrusion (HME) has been a widely applied technique in the plastics industry and has been demonstrated recently to be a viable method to prepare several types of dosage forms and drug delivery systems. Hot-melt extruded dosage forms are complex mixtures of active medicaments, functional excipients, and processing aids. HME also offers several advantages over traditional pharmaceutical processing techniques including the absence of solvents, few processing steps, continuous operation, and the possibility of the formation of solid dispersions and improved bioavailability. This article, Part I, reviews the pharmaceutical applications of hot-melt extrusion, including equipment, principles of operation, and process technology. The raw materials processed using this technique are also detailed and the physicochemical properties of the resultant dosage forms are described. Part II of this review will focus on various applications of HME in drug delivery such as granules, pellets, immediate and modified release tablets, transmucosal and transdermal systems, and implants.

Pharmaceutical Applications of Hot-Melt Extrusion: Part I

Direct compression is the preferred method for the preparation of tablets. The present review outlines the importance of the functionality of the directly compressible adjuvants in the formulation of tablets. The co-processing is the most widely explored method for the preparation of directly compressible adjuvants because it is cost effective and can be prepared in-house based on the functionality required. Hence, the present review focuses on the properties of the co-processed directly compressible adjuvants available in the market.

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A review of co-processed directly compressible excipients.

In today's pharmaceutical arena, it is estimated that more than 40% of new chemical entities produced during drug discovery efforts exhibit poor solubility characteristics. However, over the last decade hot-melt extrusion (HME) has emerged as a powerful processing technology for drug delivery and has opened the door to a host of molecules previously considered unviable as drugs. HME is considered to be an efficient technique in developing solid molecular dispersions and has been demonstrated to provide sustained, modified and targeted drug delivery resulting in improved bioavailability. This article reviews the range of HME applications for pharmaceutical dosage forms, such as tablets, capsules, films and implants for drug delivery through oral, transdermal, transmucosal, transungual, as well as other routes of administration. Interest in HME as a pharmaceutical process continues to grow and the potential of automation and reduction of capital investment and labor costs have made this technique worthy of consideration as a drug delivery solution.

Applications of hot-melt extrusion for drug delivery.

Ethylene vinyl acetate as matrix for oral sustained release dosage forms produced via hot-melt extrusion.

Introduction: Niche applicability and industrial adaptability have led hot melt extrusion (HME) techniques to gain wide acceptance and have, therefore, solidified their place in the array of pharmaceutical research and manufacturing operations. Melt extrusion's momentum has resulted in extensive research publications, reviews and patents on the subject for over a decade. Currently, > 50% of the new drug candidates are speculated to be highly lipophilic and thus poorly bioavailable. HME is a key technology for these and other formulation and processing issues. Areas covered: Various approaches have been addressed using HME in developing solid molecular dispersions and have demonstrated viability to provide sustained, modified and targeted drug delivery resulting in improved bioavailability. This review provides a holistic perspective on HME from equipment, processing and materials to its varied applications in oral delivery (immediate release, sustained release, taste masking, enteric and targeted release,...

Britta Schroeder

Papers

Physicochemical properties and mechanism of drug release from ethyl cellulose matrix tablets prepared by direct compression and hot-melt extrusion.

The influence of guaifenesin and ketoprofen on the properties of hot-melt extruded polyethylene oxide films.