The aim of the study was to enhance the solubility and bioavailability of praziquantel (PZQ) through mechanochemical preparation of its solid compositions with the disodium salt of glycyrrhizic acid (Na2GA). The compositions were studied in the solid phase by means of scanning electron microscopy, powder X-ray diffraction and thermal analysis, and in solutions by means of HPLC, gel permeation chromatography, phase solubility assay and 1H NMR spectroscopy. PZQ permeability was studied by means of parallel artificial membrane permeability assay and with a monolayer of Caco-2 cells. The pharmacokinetic characteristics and acute toxicity of PZQ and its compositions were studied on mice. Solubility of PZQ in the compositions increases up to 3.5 times. The micelles in Na2GA solutions possess a molecular mass of ∼60 kDa. An increase in PZQ solubility may be due to its inclusion into micelles of glycyrrhizic acid. The permeability of PZQ was found to be much higher from its composition with Na2GA in comparison with initial PZQ. An increase in PZQ bioavailability by a factor of 3 in laboratory mice and changes of pharmacokinetic curve shape were demonstrated for the oral administration of its composition with Na2GA. The solid compositions show high chemical stability under rapid storage test. The obtained PZQ compositions may be a promising basis for the development of anthelmintic preparations with increased efficiency.