Targeted Drug Delivery

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Targeted drug delivery is the most important goal of pharmaceutical research and development. Drug delivery is the method or process of administering a pharmaceutical compound to achieve a therapeutic effect in humans or animals. Drug delivery is the method or process of administering a pharmaceutical compound to achieve a therapeutic effect in humans or animals. Drug Delivery technologies are patent protected formulation technologies that modifies drug release profile, absorption, distribution and elimination for the benefit of improving product efficacy & safety and patient convenience & compliance. Most common methods of delivery include the preferred non-invasive peroral (through the mouth), topical (skin), transmucosal (nasal, buccal/sublingual, vaginal, ocular and rectal) and inhalation routes. Many medications such as peptide and protein, antibody, vaccine and gene based drugs, in general may not be delivered using these routes because they might be susceptible to enzymatic degradation or can not be absorbed into the systemic circulation efficiently due to molecular size and charge issues to be therapeutically effective. For this reason many protein and peptide drugs have to be delivered by injection. For example, many immunizations are based on the delivery of protein drugs and are often done by injection.

Current efforts in the area of drug delivery include the development of targeted delivery in which the drug is only active in the target area of the body (for example, in cancerous tissues) and sustained release formulations in which the drug is released over a period of time in a controlled manner from a formulation.

In principle, drug targeting can be achieved by physical, biological, or molecular systems that result in high concentrations of the pharmacologically active agent at the pathophysiologically relevant site. If successful, the result of the targeting would be a significant reduction in drug toxicity, reduction of the drug dose, and increased treatment efficacy. All in all, it is evident that with a biologically active agent of reasonable activity at hand, targeting to the site of action should be superior to molecular manipulations aimed at refining the receptor substrate interactions.

Mechanism-based classification of drug targeting:

1. Physical

2. Biological

3. Chemical (site specific or targeting systems)

Targeted drug Delivery for Cancer

In Cancer the drug delivery process is not simply wrapping a drug in a formulation for different routes of delivery. The current focus in development of cancer therapies is on targeted drug delivery to provide therapeutic concentrations of anticancer agents at the site of action and spare the normal tissues.

Table I: Strategies for drug delivery in cancer
Direct introduction of anticancer drugs into tumor
Injecting directly into the tumor
Tumor necrosis therapy
Injection into the arterial blood supply of cancer
Local delivery by anticancer drugs by electroporation (electrochemotherapy)
Routes of drug delivery
Intraperitoneal
Intrathecal
Nasal
Oral
Pulmonary inhalation
Transdermal drug delivery
Vascular route: intravenous, intra-arterial