D. Satya Sireesha

As an emerging drug carrier, hydrogels have been widely used for tumour drug delivery. A hydrogel drug carrier can cause less severe side effects than systemic chemotherapy and can achieve sustained delivery of a drug at tumour sites. In addition, hydrogels have excellent biocompatibility and biodegradability and lower toxicity than nanoparticle carriers. Smart hydrogels can respond to stimuli in the environment (e.g., heat, pH, light, and ultrasound), enabling in situ gelation and controlled drug release, which greatly enhance the convenience and efficiency of drug delivery. Here, we summarize the different sizes of hydrogels used for cancer treatment and their related delivery routes, discuss the design strategies for stimuli-responsive hydrogels, and review the research concerning smart hydrogels reported in the past few years

  Eye is the most exclusive organ of the body and various drug delivery systems are used to deliver drug into eye but there are various limitations like rapid precorneal drug loss of conventional systems. Ocular disposition and elimination of a therapeutic agent is dependent upon physicochemical, microbiological, pharmaceutical properties and ophthalmic irritancy properties of ocular dosage forms as well as the relevant ocular anatomy and physiology. To improve ocular drug contact time, bioavailability and residence time, and to reduce the  patient discomfort, frequency of dose, as well as to slow down the elimination of the drug  there are significant efforts concentrating towards newer drug delivery systems for ophthalmic administration. This review focuses on the various new drug delivery systems applied in eye like inserts, in-situ gel, the newly developed particulate and vesicular systems like liposomes, pharmacosomes and discomes, niosomes, nanoparticles, iontophorosis, corneal shields, drug embedded contact lenses, ocular wafers etc and the most recent advanced approaches of the ocular delivery systems like  the delivery of the genes and proteins to the internal structures which were used in treating the diseases  caused due to genetic mutation, along with safety evaluation of ocular drug delivery formulations with some case studies.   Key words: Ophthalmic disorders, advanced ocular therapy, control drug delivery systems, vesicular systems, safety evaluation.