Targeted Drug Delivery: A Review

Targeted drug delivery, also known as smart drug delivery, is a method of treatment that involves the increase in medicament in one or few body parts in comparison to others. Two strategies are widely used for drug targeting to the desired organ/tissue: passive targeting and active targeting. Drug delivery vehicles transport the drug either within or in the vicinity of target. An ideal drug delivery vehicle is supposed to cross even stubborn sites such as a blood brain barrier. Recently, nano medicine has emerged as the medical application of nanotechnology. Since nanoparticles are very small in size, nano drug delivery can allow for the delivery of drugs with poor solubility in water and also aid in avoiding the first pass metabolism of liver. Nanotechnology derived drug delivery can cause the drug to remain in blood circulation for a long time, thereby leading to lesser fluctuations in plasma levels and therefore, minimal side effects. These include polymer-drug conjugates and nano particulate systems such as liposomes, quantum dots, dendrimers, etc. There are several other approaches as well. These also include the strategies wherein the therapeutic agents are coupled with “targeting ligands” that possess the ability to recognize antigens associated with tumors.