Biodegradable polymers have been widely used in biomedical applications because of their known biocompatibility and biodegradability. Biodegradable polymers could be classified into synthetic and natural (biologically derived) polymers. Both synthetic and natural biodegradable polymers have been used for drug delivery, and some of them have been successfully developed for clinical applications. This entry focused on various biodegradable polymers that have been used in development of drug delivery systems. Advances in organic chemistry and nano/micro fabrication/manufacturing methods enable continuous progresses in better utilization of a wide range of novel biodegradable polymers in drug delivery
Polymers In Drug Delivery
Conventional forms of drug delivery generally rely on tablets, eye drops, ointments and intravenous solutions. Recently, a number of novel drug delivery technologies have developed. These newer technological development include drug modification by chemical means, career based drug delivery and drug entrapment in polymeric matrices or within pumps that are placed in desired bodily compartments. These technical development in drug delivery/targeting approaches improve the efficacy of drug therapy thereby improve human health. Still there are many infectious and other deadly diseases are uncured due to the problem encountered by formulation scientists in drug delivery approaches. There is a strong need to develop a proper delivery system to achieve the complete therapeutic effects of the existing drug molecules. Use of polymeric materials in novel drug delivery approaches has attracted the scientists. Polymer chemists and chemical engineers, pharmaceutical scientists are engaged in bringing out design predictable, controlled delivery of bio active agents. When the drug is delivered to the site of action by using polymer based drug delivery approaches the safety and bio compatibility is questionable. The characterization of biocompatible polymers is more focused in the field of formulation development and drug delivery approaches etc. the biodegradable polymers have properties of degrading in biological fluids with progressive release of dissolved or dispersed drug. There is various novel drug delivery approaches are developed in the pipeline of polymer based drug delivery approaches. The bio-safety and biocompatibility are the important characteristics needed for the use of polymers in the field of pharmaceutical formulation and in novel drug delivery approaches. The present paper review is focused in the advances of biodegradable polymers based drug delivery approaches.
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Biodegradable polymers have been widely studied for several drug delivery systems for human health purpose. During the last two decades, advances in biodegradable materials have been made significantly for the development in biomedical applications, and in this category there are industrial applications as well.
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.
The main advantages in using biodegradable polymers are there is no possibility of toxicity problems, their release rates can be customized and they degraded to form biocompatible or non-toxic products in biological fluids, which are removed from the body through normal metabolic pathways and physiological mechanisms. However, biodegradable polymers do produce ‘degradation by-products’ that must be tolerated with little or no adverse reactions within the biological environment.
For additional control and modulation of drug release using biodegradable polymers, Parenteral Depot Systems [PDS], Microspheres are also used.
Among the biodegradable polymers Poly-ε-caprolactone, Poly (lactide-co-glycolides) (PLGA) has been receiving increasing attention as matrix materials for controlled release drug formulations. Poly-ε-caprolactone and its derivatives, with a high permeability to many therapeutic drugs and lack of toxicity, are well suited for oral and controlled drug delivery.
In my power point presentation several biomaterials, mechanism of Biodegradation of Polymers, opportunities in controlled drug delivery in future e.t.c. in discussed in detail.
Polymers are indispensable in pharmaceutical technology for preparing drug delivery system where the therapeutic agent is released by diffusion or diffusion with gradual erosion of the polymeric matrix. Although it protects the drug from metabolism, dosage limitations, etc it has the disadvantage of sudden release of the therapeutic agent that may be hazardous especially with drugs having narrow therapeutic index. So to overcome this problem Molecular imprinted polymers have been developed and have become a focus of research due to their molecular recognition properties that binds and releases the therapeutic agent in a controlled manner when the equilibrium becomes critical. MIP-based DDS can be found for the three main approaches, developed to control the moment at which delivery should begin and/or the drug release rate, i.e. rate-programmed, activation-modulated, or feedback-regulated drug delivery. MIP’s have huge potential to bring about intelligent drug release. MIP’s have become a choice of drug delivery due to it properties like binding capacity, memory, etc. Based on the two approaches i.e. the pre-organized approach and the self-assembly approach molecular imprinted polymers are prepared by any of the polymerization techniques like bulk Polymerization, multi-step Swelling Polymerization, etc using monomers , crosslinkers ,initiators, porogenic solvents and the template molecule. They can be characterized by direct physical characterization methods like surface area, porosity measurements, etc. The molecular imprinted polymers have been used widely in chemical sensing, food analysis, separation of the enantiomeric compounds etc. By keeping the limitations of MIP’s like gelling effect to minimum it can become a target for research to prepare efficient drug delivery system practically through oral and transdermal routes.
NOVEL APPROACHES FOR COLON SPECIFIC DRUG DELIVERY The colon is advisable site where both local or systemic drug delivery can be achieved.
ENVIRONMENTALLY RESPONSIVE SYSTEMS
Nanoparticles hold tremendous potential as an effective drug delivery system.
The needle/syringe combination has become the drug delivery mainstay for drugs and vaccines deemed ineffective by other routes and has been optimized as a commodity scale product the world over. It is therefore not surprising that the needle architecture to which we are so accustomed is the focus of the first microdevice for drug delivery: “Microneedles.” Microneedles are designed to be painless whilst overcoming the natural barrier function of the skin. Microneedle therapy is a way to rejuvenate the skin without destroying the epidermis. Methods for manufacturing these microneedle devices include micromolding, microfabrication, microshaping, and combinations thereof. Micro needles have a number of potential benefits for patients, clinicians, and the pharmaceutical industry as compared with alternative delivery methods. Micro needles have a number of potential benefits for patients, clinicians, and the pharmaceutical industry as compared with alternative delivery methods. Many people, particularly children, are ‘needle-phobes’. In addition, there are several patients, such as diabetics who are dependant on multiple injections on a daily basis. Many other disease conditions also require the delivery of therapeutic agents to the skin, while the outbreak of a pandemic would necessitate mass vaccinations. A solution to the problems posed by needle-based injections is the development of microneedles. This technology will help realise the development of new and improved devices, which will be smaller, cheaper, pain-free and more convenient with a wide range of biomedical and other applications. The future of drug delivery is assured to be significantly influenced by microfabrication technologies. These microfabricated drug delivery devices can enable efficient drug delivery that was unattainable with conventional drug delivery techniques, resulting in the enhancement of the therapeutic activity of a drug.