Targeted mucosal delivery of drugs and vaccines

Abstract

Targeted and more efficient delivery of molecules for therapeutic and prophylactic applications is a priority for the pharmaceutical industry. Effective strategies should reduce the required dose, increase safety and improve efficacy by focusing molecules at the desired site of action. Mucosal routes of drug and vaccine delivery offer a number of logistical and biological advantages compared with injection. Oral delivery is particularly attractive as a result of the ease of administration. However, gastrointestinal degradation and low levels of absorption generally render this route of peptide and protein drug delivery ineffective. Alternative mucosal routes such as the nasal, rectal, pulmonary and ocular routes are also being investigated. Mucosal delivery of protein and peptide vaccine antigens generally stimulates poor immune responses and may induce immunological tolerance. A range of delivery systems is being developed to enhance the efficacy of mucosally administered drugs and vaccines. One strategy is bioadhesion, which may increase the duration or intensity of contact between molecules and the epithelium. Bioadhesion strategies may be non-specific, achieving adhesion via physical interactions with mucus and/or epithelia or specific systems that recognise receptors on the epithelial cells. Lectins are proteins or glycoproteins of non-immune origin capable of binding to one or more specific sugar residues. Plant lectins have many suitable properties as specific targeting agents. Some of these molecules can withstand the proteolytic conditions in the gut, bind specifically to epithelial cells and be transported across the epithelium. In addition, there is active research into bacterial lectins and toxins for drug and vaccine delivery. This review examines the potential for targeted mucosal drug and vaccine delivery.

• bioadhesion
• drug delivery
• epithelia
• lectin
• mucosal
• nasal
• oral
• targeting
• vaccine