Stimuli-responsive drug delivery systems

Many drugs that are delivered orally or parenterally do not include mechanisms for sustained release, and as a result they require higher and more frequent dosing to achieve any therapeutic effect for the patient.

[1] As a result, the field of drug delivery systems developed into a large focus area for pharmaceutical research to address these limitations and improve quality of care for patients.

These drug delivery systems can be applied both as diagnostic and treatment tools for diseases like cancer to achieve long-term action and maximize the therapeutic effect.

[1] Much work is still being done to continue the development of this field in hopes of one day making stimuli-responsive drug delivery systems commonplace in medical practice.

[2] These hydrophilic and hydrophobic interactions can cause the destabilization of these systems, which lead to conformational changes that cause the drug carrier to breakdown or degrade.

[3] Redox responsive drug delivery systems rely on the natural reduction-oxidation reactions that occur in the body and the availability of reducing or oxidative-agents in the extracellular and intracellular space.

The increased level of GSH in tumor cells combined with its ability to cleave disulfide bonds has led to the development of drug delivery systems, such as polymeric micelles, synthesized with disulfide bonds that are subsequently cleaved by intracellular GSH, which cause the breakdown of the micelle and the intracellular release of the encapsulated therapeutic.

Deviations from physiological pH occur in numerous disease states including infection, inflammation, and cancer, which makes this stimulus one of the most widely researched in the field of endogenous chemically responsive drug delivery systems.

[3] pH-responsive polymers can be selected for certain applications based on characteristics like the drug concentration, number of ionizable groups, and the type of carrier being used.

There are many limitations that exist within the field of endogenous chemically responsive drug delivery systems that prevent many of these products from approved to be used in a clinical setting.

One of the primary challenges of endogenous chemically responsive drug delivery is the inability to address or overcome patient heterogeneity.