Effect on viscosity of cellulose derivatives against pseudo-polymorphism conversion of amorphous theophylline using a terahertz spectroscopy

Effect on viscosity of cellulose derivatives against pseudo-polymorphism conversion from an amorphous theophylline to theophylline anhydride form during a pharmaceutical manufacturing process was investigated using a terahertz spectroscopy. In order to investigate an effect on viscosity of binders against pseudo-polymorphism conversion of an amorphous theophylline, cellulose derivatives were used as a binder to prepare granules for a tableting. The start times of conversion to anhydride were almost same except the cellulose derivative which has the lowest viscosity. This tendency was similar between two drying temperatures. Pseudo-polymorphism conversion of amorphous theophylline to an anhydride with a binder had tendency progressing faster at a higher drying temperature. The time-course changes of terahertz absorptions suggest that a rate of pseudo-polymorphism conversion was affected by viscosity of cellulose derivatives.