A Facile Way to Enhance the Therapeutic Efficacy of Hydrophobic Drugs via Amorphous Solid Dispersions.

Abstract

Approximately 40% of marketed drugs and 75% of invested drugs in the pharmaceutical field are poorly soluble hydrophobic drugs with minimal solubility in water which make them difficult to be absorbed by the body and significantly limiting their applications. Among chemotherapeutic agents, numerous antitumor drugs such as platinum compounds, camptothecin, paclitaxel and others are also restricted in processing and preparation due to solubility issues. Therefore, improving the solubility and enhancing the therapeutic efficacy of drugs have always been significant research topics in current pharmaceutics. Herein, we propose an amorphous solid dispersion system PRTA-DOX, involving the protein drug protamine sulphate and hydrophobic doxorubicin as the model hydrophobic drug. In previous studies, ASD (Amorphous Solid Dispersion) has been demonstrated to enhance the solubility of hydrophobic drugs and result in a storage-stable system. Protamine sulphate as a marketed drug is reliable in safety and conveniently obtained. Doxorubicin, an antitumor drug with a broad antitumor spectrum, is commonly used in the treatment of breast cancer. Typically, doxorubicin is prepared in the form of a hydrochloride salt to increase its solubility. However, the utilization of doxorubicin hydrochloride is reduced due to drug resistance issues in biological cells and it exhibits higher toxicity to the body. In this system, protamine sulphate which is rich in arginine guanidino hydrophobic planes physically mixes with doxorubicin which is a hydrophobic molecule with aromatic rings and they are connected through weak interactions: π-π conjugation. They constitute an amorphous solid dispersion system which increases the solubility of hydrophobic doxorubicin, enhances cellular uptake, mitigate some cellular drug resistance and thereby achieves the purpose of improving therapeutic efficacy.