Poly(propylene glycol) vs Sugar Alcohol-Based Aqueous Biphasic System to Extract Drugs and Subsequent Recovery of the Polymer

Abstract

A carbohydrate-based aqueous biphasic system (ABS) has been designed by adding an aqueous solution of sugar alcohols (d-mannitol and glycerol) to poly(propylene glycol) (PPG#400). The phase diagrams of the ABSs have been constructed using the turbidometric titration method at 309 K. The tie-line lengths and the slope of tie lines of the system have been obtained using the gravimetric method. The use of sugar alcohol to replace the salt-rich phase for phase separation makes the ABS apt for extracting different molecules of biological relevance. Using one of these newly constructed eco-friendly ABSs, d-mannitol vs PPG#400, the extraction behaviors of Ivermectin and Doxycycline (which have been extensively used to treat COVID-19 patients) were studied at different pH values. About 90% of Ivermectin and 70% of Doxycycline has been extracted to the polymer-rich phase of ABS at pH 7 in single extraction. The extraction patterns of these two drugs remain almost the same even in the presence of l-ascorbic acid and zinc acetate, which are also administered as combination drugs in the treatment of COVID-19. We have also studied the extraction behavior of Prednisolone, a corticosteroid, which also is widely recommended to particularly treat the severity of the cytokine storm that arises in many patients at the third phase of COVID-19. Complete extraction of Prednisolone has been achieved at pHs 3 and 5, and ∼97% of extraction has been achieved at pH 7. The objective of such extraction is to design cleaner methods of remediation of these drugs to minimize their exposure to the environment that may lead to drug resistance in the environment. We have also recovered the polymer using thermoseparation and adsorption techniques after extraction experiments to make the method environmentally as well as economically viable. ©