- published: 06 Jun 2016
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Solid in which components are compatible and form a unique phase.
Note 1: The definition “crystal containing a second constituent which fits into and
is distributed in the lattice of the host crystal” given in refs., is not general
and, thus, is not recommended.
Note 2: The expression is to be used to describe a solid phase containing
more than one substance when, for convenience, one (or more) of the substances,
called the solvent, is treated differently from the other substances, called solutes.
Note 3: One or several of the components can be macromolecules. Some of
the other components can then act as plasticizers, i.e., as molecularly dispersed
substances that decrease the glass-transition temperature at which the amorphous
phase of a polymer is converted between glassy and rubbery states.
Note 4: In pharmaceutical preparations, the concept of solid solution is often
applied to the case of mixtures of drug and polymer.
Note 5: The number of drug molecules that do behave as solvent (plasticizer)
of polymers is small.