APIs (active pharmaceutical ingredients) are the substances in drugs that are pharmaceutically active, such as oxytocin acetate, enfuvirtide acetate, and so on. Catalog peptides are commercially available sequences. They are usually produced in bulk at high levels of purity. These peptides are usually customized to customers' specific requests. For example, specific sequences, modifications, purity levels, or lengths may be required by the customer. The turnaround time for most API peptides is 2-3 weeks.