Praziquantel (PZQ) is a drug largely used for the treatment of Schistosomiasis [1]. It is classified as a BCS class II drug
characterized by low water solubility and high permeability [2]. Several strategies have been studied to overcome the
problem of poor solubility of drugs, i.e. solid dispersion with hydrophilic carriers and inclusion complexation with
cyclodextrins [3-4]. These papers have shown that an increase of the drug solubility can be obtained changing the
physical state of the drug from crystalline to amorphous. In this work, PZQ has been comilled in a vibrational mill
with a mesoporous silica Syloid 244-FP to study the possible alteration of the solid state of PZQ versus an
amorphous state. Due to their nanoporous structures, high surface areas and large pore volumes, mesoporous silicas
have been recently used in the formulation of drugs with poor aqueous solubility [5]. Comilling process has been
carried out using different drug to silica weight ratios and two times of comilling.
The solid state of PZQ in physical mixtures and comilled binary systems has been characterized by DSC, X-ray
powder diffractometry, Scanning electron microscopy and FT-IR. Furthermore, a 5-months stability study was carried
out. Physical mixtures and coground systems were also tested to verify their in vitro activity against S. Mansoni
adult.An amorphous state of PZQ has been obtained by a simple solvent-free comilling process of only 15 minutes using
mesoporous silica as excipient. The 1:1 w/w amorphous system exhibited a prolonged physical stability and a high
bioactivity against Schistosoma Mansoni adult.
