Carrier-Based Systems as Strategies for Oral Delivery of Therapeutic Peptides and Proteins: A Mini-Review

Peptides and proteins play an essential role in biological systems and the human body. Deficiency or dysfunction of peptides and proteins such as insulin can lead to various illnesses. The therapeutic use of peptides and proteins in some illnesses such as diabetes, cardiovascular disease, autoimmunity, and cancer, among others, is highly considered. Peptides and proteins have large molecular structures and are generally hydrophilic, and maintaining their spatial composition or tertiary configurations are necessary for their pharmacological activities. Maintaining the stability of the protein structure and composition is therefore very important and necessary to maintain functionality. There are different routes for peptides and proteins administration such as injection (subcutaneous, intravenous, and intramuscular), oral, nasal, pulmonary, rectal, and ocular routes. The oral administration route is better accepted by the patient due to safety and ease of use. However, oral administration often is unsuitable because of the physicochemical properties and macromolecular structure of proteins and the presence of gastrointestinal (GI) enzymes under an acidic environment within the stomach. Proteins and peptides undergo enzymatic degradation, tertiary structural alteration, and low absorption. This necessitates the need to use alternative oral drug delivery systems for peptides and proteins that maintain their overall structure and enhances their absorption and bioavailability. In this article, we review carrier-based oral drug delivery systems that were suitable for peptides and proteins.