How Does Proprietary Hot-Melt Extrusion Work

How Does Proprietary Hot-Melt Extrusion Work

Hot-melt extrusion is the dispensation of polymeric materials above their glass transition temperature. This is done in order to effect molecular level mixing of polymers and/or thermoplastic binders of active compounds.

This blog focuses on how Hot-melt extrusion works. Continue reading to learn more.

At Abbvie, our service package provides terminal sterilization. This includes a hundred percent vial visual inspection with the use of labeling and packaging, polarized light, and batch certification. 

How it Works

The process of proprietary hot-melt extrusion combines kneading, blending, degassing, melting, and conveying into a continuous process. The various substances involved are constantly added into the processing barrel or section of the extruder in an accurately controlled way. Co-screw shafts are responsible for regulating material mixing and transportation. It also determines the residence time in the different zones.

Temperatures Involved

Diverse temperature profiles can be put in each zone to meet the processing needs of the active pharmaceutical ingredient and that of the polymer. On the other hand, gasses and air are removed from the molten mass. This is achieved by using a vacuum unit to assure a bubble-free discharge of molten extrudate via a nozzle at the end of the processing section. Upon cooling of the molten extrudate, a solid product is formed.  

Twin-Screw Extruders

Twin-screw extruders can be configured in many ways to meet various blending, kneading, and conveying requirements. The essential parameters of the screw elements are the number of flights, the element pitch, and the inner and outer diameter of the screws.

Compensation and mixing of the concentration differences are attained by mixing elements of the equipment. The use of reverse-conveying screw elements increases intermixing. This means that the ability to arrange the screw element of the extruder in nearly any combination allows the extruder to be adapted for almost all extrusion tasks.

Essential Parameters

For the extruder of active pharmaceutical ingredients, feed rate and screw speed are the most essential process parameters. Low screw speeds lead to long residence time of the material possessed by the extruder. And this leads to an increase in impurities and degradation. On the other hand, high screws high screw rotation speeds may lead to physical instability and incomplete mixing, which results in recrystallization of an amorphous active pharmaceutical ingredient.

Shaping of the Molten Mass

Shaping of the molten mass takes place when passing under pressure via a die having a tiny cross-section. The die flow channel must be aerodynamically modeled. This is to enable appropriate melt flow to be attained. In addition to this, the elasticity of the cooling rate of the polymer melt and the polymer melt itself after passing through the die is essential. At this point, the temperature and pressure must be constant to attain a uniform product.

Active pharmaceutical ingredients, excipients, and solid carriers are either combined or dosed individually in a specifically controlled mixture for dosing. This is done with gravimetric dosing systems that are selected over volumetric systems of dosing in pharmaceutical applications. Gaseous or liquid components may be introduced directly into the melt via side feeding devices. 

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