Site-specific drug delivery cell targeting

PU-based drug delivery systems can be manipulated to have site-specific release (via cell targeting designs) and controllable drug release kinetics [128]. 

Polymeric microparticles have been studied and developed for several years. Their contribution in the pharmacy field is of utmost importance in order to improve the efficiency of oral delivery of drugs. As drug carriers, polymer-based microparticles may avoid the early degradation of active molecules in undesirable sites of the gastrointestinal tract, mask unpleasant taste of drugs, reduce doses and side effects and improve bioavailability. Also, they allow the production of site-specific drug targeting, which consists of a suitable approach for the delivery of active molecules into desired tissues or cells in order to increase their efficiency. 

The success of treating tumours, especially solid tumours, by systemic therapy depends on various characteristics of the tumour. Besides the importance of intrinsic drug activity and the potential targets within the tumour cells, drug pharmacokinetics and whole body distribution, site of delivery and the ability of site-specific targeting (affinity) are important features. 

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