*Article* **Towards the Development of Novel Diclofenac Multicomponent Pharmaceutical Solids**

**Francisco Javier Acebedo-Martínez 1, Carolina Alarcón-Payer 2, Helena María Barrales-Ruiz 1,3, Juan Niclós-Gutiérrez 3, Alicia Domínguez-Martín <sup>3</sup> and Duane Choquesillo-Lazarte 1,\***


**Abstract:** Multicomponent pharmaceutical materials offer new opportunities to address drug physicochemical issues and to obtain improved drug formulation, especially on oral administration drugs. This work reports three new multicomponent pharmaceutical crystals of the non-steroidal antiinflammatory drug diclofenac and the nucleobases adenine, cytosine, and isocytosine. They have been synthesized by mechanochemical methods and been characterized in-depth in solid-state by powder and single crystal X-ray diffraction, as well as other techniques such as thermal analyses and infrared spectroscopy. Stability and solubility tests were also performed on these materials. This work aimed to evaluate the physicochemical properties of these solid forms, which revealed thermal stability improvement. Dissociation of the new phases was observed in water, though. This fact is consistent with the reported observed layered structures and BFDH morphology calculations.

**Keywords:** diclofenac; nucleobases; mechanochemical synthesis; multicomponent materials; pharmaceutical solid forms
