Oral Delivery of Macromolecular Drugs
Small-molecule drugs in oral solid-dosage forms are considered the first line of defense in treating diseases of the gastrointestinal (GI) tract, which affect millions of patients around the world each year. A number of patients, however, either do not respond to these drugs or experience side effects from these drugs.
Macromolecular drugs, such as peptides, proteins, and antibodies, offer a newer class of drugs that can treat diseases of the GI tract, such as inflammatory bowel disease (IBD). These drugs have demonstrated improved efficacy and represent a new paradigm of treatments for IBD.
Macromolecular drugs are usually injected subcutaneously or intravenously, and only a fraction of the administered dose reaches the disease sites in the GI tract. There has been tremendous amount of research to capitalize on the potential benefits of oral delivery macromolecular drugs, which include:
- Better patient acceptance and adherence
- More convenient dosing, including patient self-dosing
- An improved therapeutic profile.
This article reviews current treatment options, analyzes the knowledge and technology gaps that have prevented development of more oral macromolecule dosage forms so far, and discusses some approaches that are being tried and could be used in the future to overcome these gaps.
Inflammatory bowel disease (IBD) is a chronic inflammation of the gastrointestinal (GI) tract that is mediated by the host immune system and is prevalent in Western countries (1, 2). In Europe alone, approximately three million individuals are estimated to have IBD (3).
IBD can be subdivided into two types: Crohn’s disease and ulcerative colitis. Inflammation seen in Crohn’s disease spreads deep into tissues and involves the small intestine, large intestine, or both. Patients with Crohn’s disease may have multiple, non-continuous areas of inflammation. Therefore, the drugs must be available at different points in the GI tract.
Ulcerative colitis causes inflammation in the innermost lining of the large intestine and rectum. Treating patients with ulcerative colitis requires drugs that are protected and released in the distal portion of the GI track. IBD patients suffer from mild to severe symptoms comprising diarrhea, abdominal pain, malnutrition, and an increased risk of colorectal cancer development