Polymeric nanocarriers in targeted drug delivery systems: A review

Today's medicine mainly relies on conventional means of therapeutics delivery to the human body, such as tablets, capsules, syrups, and injectable drugs. Utilizing such techniques are associated with a number of drawbacks including the need of high drug dosage, causing transient drug concentration changes in the patient's body, poor solubility, poor bioavailability, drug degradation, and interaction with the biological environment (enzymes and proteins). To address these issues, nanotechnology-based novel drug delivery methods are proposed. Among the plethora of novel drug delivery techniques, the use of polymeric nanocarriers is shown to be promising. In fact, they focus on three main questions: first, where should a drug be released? Second, when should the drug be released? And finally, how should the drug be released? In this review, we are confined to explaining some concepts regarding to polymeric nanocarriers. First, different kinds of polymeric nanocarriers have been explained, in terms of their structures and properties. Second, different fabrication methods, for each one, have been elaborated. Finally, a handful of works carried out have been reviewed for their special structure, their kind of polymers which is used, and the drug which is encapsulated.