Peptides are manufactured commercially by liquid- or solid-phase peptide synthesis, by hybrid synthesis using both solid- and solution-phase synthesis or by using recombinant DNA technologies. The technology applied to commercial manufacturing is determined by the size and nature of the peptide. Since the impurities in peptides tend to be generally similar to those in the product of interest, downstream processing steps such as purification and isolation are significant for producing highly purified active peptide pharmaceutical ingredients that meet the stringent regulatory requirements.