ABSTRACT
More effective and tailored drug delivery systems (DDS) are continuously investigated, tested, and, eventually, marketed. In the last 30 yr, the pharmaceutical industry has made substantial steps in this direction. Drug products containing proteins and peptides, as therapeutic agents, are a perfect example of these two intimately correlated aspects: route of administration and quality of life. In the past 60 yr, hormones, serum proteins, and enzymes have been extensively used in therapy as active ingredients.[1,2] But recently, molecular biology and, especially, recombinant deoxyribonucleic acid (DNA) technology have made tremendous progress resulting in the availability of a wide variety of peptide-and protein-based therapeutics for poorly controlled diseases. For this class of drugs, however, the parenteral route represents today the predominant route of administration, as the bioavailability of alternative routes is extremely low and variable.
