Recent advancement in drug delivery system.

Ease of drug administration, safety, affordability and efficacy are the major concerns in pharmacotherapy leading to exploration of better drug delivery systems. Liposomes are lyotropic liquid crystals composed mainly of amphiphilic bilayers and these are more frequently used as drug carriers. Liposomes help reduce the toxicity and deliver the drug to the target tissue. So far, liposomes have been the most intensively studied lipid-based delivery system. In liposomes, a hydrophilic drug can be trapped in aqueous interior or channels between successive phospholipids bilayers whereas a hydrophobic drug can reside with the bilayer itself. The non-toxic and nonimmunogenic bilayers dissipate allowing the diffusion of the drug into the tissues. Attachment of polyethyl glycol to the surface of liposome (known as stealth liposome) aids in the better targeting of the drug to the tissues. Pegylated proteins and polymers of lactic and glycolic acids have been well studied as drug carriers and found to be resistant to phagocytosis and complement activation. Newer DNA based strategies including DNA vaccination and antisense oligonucleotides and immunomodulation show good results for new therapeutic systems. Though the DNA based therapeutic systems have high selectivity and specificity with few adverse effects, these systems are so far restricted to animal models and clinical trials.