Solid state transitions and CAP availability in surface solid dispersions of chloramphenicol stearate polymorphs

By grinding, chloramphenicol stearate Form III turns in Form I: then this form tends to become amorfous. So the grinding of both forms produces a "physically activated" form (FI*) with low crystallinity degree and high CAP availability.In the presence of microcrystalline cellulose, the transition from FIII to FI is accelerated, the amorphisation time does not change and the CAP availability increase.Therefore the results shown that CAP availability may be a function of the cristallinity degree and not of the polymorphic form of the ester.