Targeted drug delivery (Site specific drug delivery)

Abstract

The conventional drugs used so far are small organic molecules meant to degrade the diseased protein, formed as a result of the interference of pathogens at cellular level. A high concentration of these drugs in the cells is necessary for desired therapeutic effect. This aggravates the problem of toxicity. Ever since the unraveling of human genome, attempts are being made to target the drugs selectively to the affected sites in order to increase their efficiency and simultaneously decrease their side effects. ‘Proteomics’ and ‘genomics’ have emerged as new disciplines. The ‘target identification’ for any ligand (drug) can now be achieved by identification of ‘right gene’, ‘right pathway’ and ‘right target,’ and the ‘right drug’ for ‘right patient’ can be developed. Genomics information decides the target validation, which is, in fact the association between particular target and disease process. Target validation can be achieved either at DNA level using gene knockout strategies and triplex formation, at RNA level using RNA interference (RNAi), at m-RNA level using antisense concept, at ribozyme level or at any other intermediate growth promoter site. Target validation is also possible via DNA- microarrays, stem cells or monoclonal antibodies. Recently, stem cells are being used for target identification and drug development. The application of aptamers, i.e., nucleic acids having well defined 3-<i>D</i> shape is gaining importance in target validation of drugs. The application of the knowledge of ‘Proteomics’, Transproteomics and ‘Genomics’ together with the array approach is likely to decide the future of drug development.