Solid state characteriza on XRPD of crystalline RTV star ng material was consistent with the stable orthorhombic form II of RTV (Cambridge Structural Database (CSD) RefCODE YIGPIO01, space group P212121). None of the films exhibited diffrac on peaks indica ve of crystallinity (Figure ). Also, according to PLM analyses, the films prepared at all ra os were amorphous, homogeneous single-phase dispersions, and free of trace crystallinity (data not shown). DSC thermograms also suggested the ASDs were single phase systems, with each exhibi ng a single glass transi on temperature (Tg) progressively decreasing from 89.9 °C (midpoint) for 0% drug loading (100% PVPVA)) to 42.9 °C (midpoint) for 100% drug loading (Figure ). These Tgs are slightly lower than the values reported by Krummnow et al 10 (at 325.99 K and 380.74 K for amorphous RTV and PVPVA respec vely), probably due to different sample prepara on condi ons and/or measurement parameters.