Molecular Dynamics in Amorphous Atropine and Tolnaftate

During the development of new pharmaceutical products in amorphous form, the molecular mobility of amorphous active ingredients has to be characterized in detail. Here, using broadband dielectric spectroscopy, the molecular mobility in supercooled liquid a nd glassy states of two pharmaceuticals namely atropine and tolnaftate have been studied. The dielectric permittivity and loss spectra of glassy and ultraviscous states of the above two pharmaceuticals have been measured for some test frequencies over a wi de temperature range. structural �- relaxation peak was observed which shifts towards lower frequencies as the temperature decreases and kinetically freezes at T g. The secondary relaxations per intramolecular modes and are usually designated as in tolnaftate no secondary relaxation processes is observed in the loss frequency tail of the �-peak, called excess wing is observed. samples. The dielectric relaxation time increases on cooling according to the Vogel secondary relaxation process shows Arrhenius behavior.