**Combining Mechanochemistry and Spray Congealing for New Praziquantel Pediatric Formulations in Schistosomiasis Treatment**

**Beatrice Albertini 1,\*, Beatrice Perissutti 2, Serena Bertoni 1, Debora Zanolla 2, Erica Franceschinis 3, Dario Voinovich 2, Flavio Lombardo 4,5, Jennifer Keiser 4,5 and Nadia Passerini 1,\***



**\*** Correspondence: beatrice.albertini@unibo.it (B.A.); nadia.passerini@unibo.it (N.P.)

Received: 18 February 2019; Accepted: 8 March 2019; Published: 12 March 2019

**Abstract:** Praziquantel (PZQ) is the first line drug for the treatment of schistosome infections and is included in the WHO Model List of Essential Medicines for Children. In this study, the association of mechanochemical activation (MA) and the spray congealing (SC) technology was evaluated for developing a child-friendly PZQ dosage form, with better product handling and biopharmaceutical properties, compared to MA materials. A 1:1 by wt PZQ—Povidone coground—was prepared in a vibrational mill under cryogenic conditions, for favoring amorphization. PZQ was neat ground to obtain its polymorphic form (Form B), which has an improved solubility and bioactivity. Then, activated PZQ powders were loaded into microparticles (MPs) by the SC technology, using the self-emulsifying agen<sup>t</sup> Gelucire® 50/13 as a carrier. Both, the activated powders and the corresponding loaded MPs were characterized for morphology, wettability, solubility, dissolution behavior, drug content, and drug solid state (Hot Stage Microscopy (HSM), Differential Scanning Calorimetry (DSC), X-Ray Powder Diffraction Studies (PXRD), and FT-IR). Samples were also in vitro tested for a comparison with PZQ against *Schistosoma mansoni* newly transformed schistosomula (NTS) and adults. MPs containing both MA systems showed a further increase of biopharmaceutical properties, compared to the milled powders, while maintaining PZQ bioactivity. MPs containing PZQ Form B represented the most promising product for designing a new PZQ formulation.

**Keywords:** poorly water soluble drug; solubility enhancement; grinding; spray congealing; neglected tropical diseases; polymorph
