Polymeric microspheres and nanoparticles can effectively be used in targeted drug delivery systems. These systems can be very beneficial in certain applications. Because of the large surface areas of the particles, they can easily be coated with targeting agents (ligands, peptides, proteins, etc.) that guide them to a particular location within the body. This allows for site-specific drug delivery, a method with several advantages. For example, chemotherapy drugs used to treat cancer have many negative side effects because they indiscriminately attack cells – healthy or tumorous. If targeted delivery is used in this instance, the chemo drugs are only exposed to tumorous cells, leaving healthy cells mostly unscathed. More specifically, there are certain traits unique to tumors that can easily be singled out. These traits can be used to attract nanoparticles modified using different targeting methods. One method involves coating nanoparticles with ligands for integrin, a receptor commonly expressed in tumors. When the coated nanoparticles reach the tumor, the interaction between the ligand and the integrin results in cellular uptake of the particles. Once inside of the cells, the drug can be released. Another method takes advantage of the lowered pH around tumors. The surfaces of nanoparticles are modified with cell-penetrating peptides before being quenched with a pH-sensitive masking peptide and a linking substrate. When the nanoparticles are exposed to the change in pH caused by the tumor, the charge of the pH-sensitive masking peptide is altered, leading to a cleavage of the substrate and the subsequent uptake of the nanoparticle by the tumor. These methods significantly reduce negative side effects while increasing efficacy of the drug.
Another area in which targeted drug delivery can be utilized is in treatment of renal diseases. Typically, drugs for renal diseases need to maintain a high concentration to ensure efficacy, but they interfere with non-steroidal anti-inflammatory drugs (NSAIDs). By using nanoparticles in the range of 50 – 100 nm in diameter, drugs can be targeted to proximal tubular cells within the kidney to treat the disease while reducing toxicity. Though macromolecules can also be used for this purpose, nanoparticles provide the distinct advantage of being so small as to prevent accumulation of drugs within the tubules.
Targeted drug delivery can also be used to treat other diseases in which specific cells or tissues are the direct cause, such as diabetes or some cardiovascular diseases. Overall, targeted drug delivery enhances the bioavailability and efficacy of the drug while allowing for lower dosages and substantially reducing toxicity.
Phosphorex has a team of scientists who can help in the microencapsulation of your specific API’s and coating or conjugating your selected ligands on drug loaded microspheres and nanoparticles to achieve targeted drug delivery. A representative from technical support would be happy to help you determine what is best for your individual application.