Continuous advance in biotechnology are impacting on drug delivery. The challenges facing drug delivery of proteins and peptides are numerous. These novel complex drugs are efficacious, in large part, because of their tertiary structure. This funcfional dependence on tertiary structure also dooms these molecules to inherent instability. Short half-lives secondry to protease and "first pass" liver metabolism result in rapid clearance of proteins from the biological systerm. The very size of these amino acid polymers block their transport across biological membranes. Indeed absorption does not correlate with bioavailability because, in the very act of absorption, the protein may provoke denaturation or degradaton. Liposomal drug delivery system has been investigated for increasing the half-life of protein and peptide drugs in biological system, and it will been one of most effective DDS for oral route of protein peptide drug delivery.
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