Chemistry Reference
In-Depth Information
10
HOT MELT EXTRUSION OF
AMORPHOUS SOLID
DISPERSIONS
Kieran Crowley
1
and Andreas Gryczke
2
1
Quotient Clinical Ltd., Nottingham, U.K.
2
Global Development and Technical Marketing Solubilisation, BASF SE,
Ludwigshafen, Germany
10.1 INTRODUCTION
The term extrusion describes a process of force feeding a material through an opening of
well-de
ed physical and possibly
chemical properties. Hot melt extrusion (HME) is a process that uses rotating screws
to mix and feed materials at elevated temperatures through a die opening(s) followed by
downstream cooling to produce solidi
ned dimension to form an extrudate with modi
ed phase. The typical requirement for HME is that
at least one component, usually polymer, is heated to signi
cantly above its thermo-
dynamic glass transition temperature so that the necessary softening of materials for
extrusion takes place. The opportunity to form drug in polymer solid dispersions with
HME is obvious, as much theory de
ning pharmaceutical solid dispersions centers on
physical and chemical properties above and below the glass transition temperature [1,2].
During the hot melt extrusion process, a series of well-controlled events must occur
to ensure that solid dispersion phase is generated with consistent phase structure and
high chemical purity. These process events include some or all of the following:
