**5. Conclusions**

Cocrystallization led to altered crystallographic (supramolecular) features as compared to the parent components owing to the creation of a new multi-component crystal phase, which resulted to improved tabletability. This work assessed particle (crystal) and bulk level deformation behaviour of the molecular solids containing no active slip plane (i.e., MAL), a single active slip plane (i.e., RIV-MAL Co) and two slip planes of different surface topologies (RIV).

The BA in RIV was attributed to different surface topologies (flat and corrugated) of two active slip plane systems and higher elastic recovery of RIV crystals. The higher true density and the higher degree of intermolecular interactions due to the 3D interlocked structure offered reasonably good BS to MAL compacts. Concurrently, the strong intermolecular interactions resisted the densification under applied compaction pressure and hence resulted in a decrease in BA. The API and coformer displayed poor particle and bulk deformation; however, RIV-MAL compacts exhibited higher BA and greater BS. The cocrystal with highest BA and BS demonstrated significantly highest tabletability amongs<sup>t</sup> the three samples. The increasing BA was attributed to the presence of flat-layered slip plane and the higher inter-planar distance, while the higher BS was ascribed to the increased degree of intermolecular interactions. During tabletability evaluation of molecular organic solids, plasticity signifies the role of the only BA. The present work stresses the necessity of understanding the role of BS as well.

The particle level deformation parameter H/E was found to inversely correlate with bulk level deformation parameter σ0, which has been commonly used to indicate BS. We sugges<sup>t</sup> the utility of this correlation for estimation of bulk deformation behaviour based on the crystal deformation behaviour studied using nanoindentation experimentation. The predictability of this relationship needs to be further verified by studying more organic molecular solids.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/1999-4923/12/6/546/s1. Table S1. Slip plane identification by different methods. Figure S1. Heckel plot fitted for estimating Py value of for MAL. Figure S2. Heckel plot fitted for estimating Py value of RIV. Figure S3. Heckel plot fitted for estimating Py value of RIV-MAL Co.

**Author Contributions:** Conceptualization, and Methodology, D.P.K.; Formal Analysis, D.P.K. and V.P.; Investigation, D.P.K., V.P., A.K. and N.K.; Project administration and Supervision, A.K.B.; Writing—original draft, D.P.K. and A.K.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors acknowledge the technical support from Ram Naresh Yadav of IIT, Ropar (India) for nanoindentation experimentation and Jayprakash A. Yadav for CTC profiling. Kailas S. Khomane is deeply acknowledged for the insightful discussion. We are also thankful to MSN Laboratories, India, for providing gift sample of rivaroxaban API. Further, Dnyaneshwar acknowledges the Department of Pharmaceuticals, Ministry of Chemicals and Fertilizers, Government of India for Research Fellowship.

**Conflicts of Interest:** The authors declare no conflict of interest.
