In recent years there is significant interest in using biodegradable polymeric microspheres for drug delivery. Delivering drugs through biodegradable microspheres has numerous advantages compared to conventional delivery systems. While in conventional systems the drug is usually released shortly after delivery and stops working after a brief period of time, biodegradable polymer offers a way to provide sustained release over a longer time, thus eliminating the need for multiple doses and ensuring sustained and controlled drug delivery over weeks or months.
“Controlled and sustained drug delivery take place when a polymer (natural or synthetic) will prudently combined with a drug or other active substance in such a way that the active substance is released from the material in a tailored manner. The release of the active substance may be stable over a long period, it may be repeated over a long period, or it may be activated by the environment or other external actions. In any situation, the purpose behind controlling the drug delivery is to achieve more effective therapies while eliminating the adverse effects of both under- and overdosing,” according to Controlled Drug Delivery by Biodegradable Polymer by Raghanaveen.
Use of biodegradable polymers minimizes the possibility of toxicity problems, but does produce by-products that must be tolerated without adverse reactions.
According to the Polymeric Drug Delivery – A Brief Review, the three key advantages that polymeric drug delivery products can offer are:
- Localized delivery of drug: The product can be implanted directly at the site where drug action is needed and hence systemic exposure of the drug can be reduced. This becomes especially important for toxic drugs which are related to various systemic side effects (such as the chemotherapeutic drugs).
- Sustained delivery of drugs: The drug encapsulated is released over extended periods and hence eliminates the need for multiple injections. This feature can improve patient compliance especially for drugs for chronic indications, requiring frequent injections (such as for deficiency of certain proteins).
- Stabilization of the drug: The polymer can protect the drug from the physiological environment and hence improve its stability in-vivo. This particular feature makes this technology attractive for the delivery of labile drugs such as proteins.
Polymer microspheres delivery systems offer a lot of advantages in chemotherapy where they provided localized sustained release and reduced toxicity at the same time, since the drug can be localized by direct injection of drug-loaded-microspheres into tumor tissue, thus minimizing negative effect to the healthy tissues.