Hot Melt Extrusion

Hot melt extrusion is a fast growing technology platform that is utilized to solve difficult formulation challenges, primarily in the area of solubilization.
n recent years Hot Melt Extrusion (HME) has been used extensively in solubility enhancement applications for polymer-based amorphous solid dispersions (provided the Drug Substance is thermally stable). In this respect, the technology competes directly with spray drying and may offer advantages in terms of cost and throughput.

How it works
Powders (drug substance, polymer and other excipients, if necessary) are fed into heated processing zones within the extruder. Modular twin co-rotating screws impart a high degree of shear and mixing into the molten mixture, creating a homogenous mass. After exiting the extruder, the molten extrudate is rapidly cooled and solidified. In most cases the solid extrudate is further processed into a powder and incorporated into a solid dosage form.

Applications


Solid dispersions
Amorphous solid solutions (drug molecularly dispersed in amorphous polymer system) are used to overcome solubility limitation of BCS class 2 and 4 drugs. In these applications, the polymer is capable of kinetically stabilizing the API in the solid state and after exposure to a dissolving media. Similarly, crystalline solid dispersions can be prepared which exhibit improved wetting and dissolution characteristics.

Controlled release
Controlled release extrudates can be obtained by adding water insoluble our high molecular weight water soluble polymers into the processing mixture.

Microencapsulated particles
Crystalline drug may be encapsulated with a polymer during processing. For example, enteric polymers can be used to protect drugs from the gastric conditions or for enhanced delivery to the site of maximum absorption. Similar approaches also can be used for the taste masking of drug substances.