2.1.4. Powder X-ray Diffractometry

The diffraction profiles of RSP, RM-β-CD, and their RSP/RM-β-CD PM and KP are depicted in Figure 5.

**Figure 5.** Powder X-ray diffractometry (PXRD) pattern of RSP, RM-β-CD, and RSP/RM-β-CD binary products physical mixture (PM) and kneaded product (KP).

The RSP crystalline nature is emphasized by the two crystalline reflections of high intensity at 14.19 and 21.27 2*θ* in addition to other characteristic reflections at 14.79; 16.42; 18.44; 18.93; 19.74; 23.15; and 29.00 2*θ* [22]. The diffraction pattern of RM-β-CD reveals two broad peaks and many undefined, diffused peaks of low intensities, reflecting its amorphous nature [19,50]. The PXRD pattern of both RSP/RM-β-CD PM and KP present a marked diminution of RSP characteristic diffraction peaks along with the disappearance of several RSP characteristic reflections in the diffractogram of both PM (at 16.42; 18.44; 18.93 2*θ*) and KP (at 14.79; 16.42; 18.44; 18.93; 23.15 and 29.00 2*θ*), which indicate a reduction in drug crystallinity in the binary products. Furthermore, new peaks are observed in the diffraction patterns of the RSP/RM-β-CD binary systems both PM (at 9.42; 11.43; 17.40 2*θ*) and KP (at 9.42; 11.42; 17.44 2*θ*). These data suggest that interaction occurs between the drug substance and the CD and demonstrate the inclusion complex formation in solid state, confirming the results obtained using thermal methods.
