A review on pH and temperature responsive gels and other less explored drug delivery systems

Abstract

Any imbalance in body's pH or temperature may alter immune response and lead to conditions such as autoimmune disorders, infectious diseases, cancer, and diabetes. Dual pH and thermo-responsive carriers are being considered as next-generation drug delivery systems, which are capable of releasing drugs intelligently in response to external or internal stimuli. These systems are characterized by minimal toxicity, improved therapeutic efficacy and reduced exposure to normal cells. Besides polymeric nanoparticles and polymeric micelles, which are most studied, there has been research being carried on other drug delivery systems which can respond to changes in pH and temperature for targeted drug release. Among those, gels have been studied mostly for their dual responsiveness. This review is prepared with an intention to provide an update on the progress of gel-based dual pH and temperature responsive drug delivery systems and other less-studied systems such as dendrimers, membranes, liposomes, microcapsules, microspheres, polymeric films, hollow spheres and protein nanoparticles for dual responsiveness. Various systems reported so far under these categories for targeted and controlled delivery of different classes of drugs such as antidiabetic and antibiotic drugs with special emphasis on anticancer drugs are discussed in this review.