Novel functionalization strategies to improve drug delivery from polymers

ABSTRACT

Introduction: The utility of controlled and sustained release of drugs from polymeric systems, both bulk (hydrogels) and colloids (nanoparticles), is a key point that should be addressed. Unfortunately, classic delivery systems are essentially driven by diffusion, which is very quick due to the high concentration gradient present in the body.

Area covered: This review provides an overview of functionalization strategies which have been used to reduce release rates by taking advantage of post-polymerization functionalization of polymers. This paradigm is extremely useful in the pharmacological treatment of several diseases, particularly multifactorial diseases, which may require a variety of release kinetics for different drugs from a single device.

Expert opinion: Polymer chains can be functionalized with several post-polymerization strategies in order to link, with a cleavable bond, drug molecules to reactive points of the polymeric network. Following this strategy, the main mechanism related to drug release is the breakage of the link that could be opportunely chosen depending on the medical needs: the weaker the bond, the higher the release rate.

KEYWORDS:

• Diffusion
• hydrogels
• nanoparticles
• post-polymerization
• transport phenomena

Article highlights

• Delivery of drugs is essentially driven by diffusion

• Diffusion mechanism though polymers is very quick due to the high clearance

• Polymer chains could be functionalized with drug molecules to reduce and control the release rates

• The breakage of the link between drugs and polymers regulates the release: weaker the bond, higher the release rate.

This box summarizes key points contained in the article.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Additional information

Funding

This paper was not funded.