The proposed compositions and methods for preparation thereof relate to pharmacology, medicine, veterinary science and pharmaceutical industry. The compositions can be used for preparing infusion solutions of antimicrobial (antibacterial and antifungal) preparations increasing therapeutic efficiency thereof. The compositions include nanostructured colloidal silica and are efficient when treating overwhelming sepsis of tested animals. The pharmaceutical compositions have a proven and significant clinically important potentiating impact on therapeutic efficiency of the infusion solution, when treating inflammatory diseases, in comparison with traditional solvents.