Many of our drugs are taken orally. Rather than ending up in our stomach as usual, oral drugs can be brought to exactly where it is needed in the future. Hitting serious diseases at the source is getting easier and easier.
Developed by Dr Ka-hing Wong and Dr Yi Wang of the Department of Applied Biology and Chemical Technology at The Hong Kong Polytechnic University, a new plant-based capsule can take drugs directly to specific locations in the gastrointestinal (GI) tract. For instance, the new capsule can travel straight to the colon for local drug release, showing new promise for colonic diseases such as inflammatory bowel diseases, irritable bowel syndrome and colon cancer.
Thanks to the capsule’s only materials, pectin and zein, targeted drug delivery to specific locations of the GI tract can be achieved.
Pectin is a natural thickening agent obtained from most citrus fruits, commonly used in home cooking to make jams and jellies. As it is highly resistant to acids and alkalis, pectin can withstand the acidic environment of the stomach and leave there undigested. The drugs encapsulated are therefore well protected from degradation and loss of efficacy, allowing physicians to prescribe smaller doses of drugs. However, pectin swells when it comes in contact with water. To overcome this issue, zein - a type of water-insoluble corn protein and a natural food substance - is added to preserve the chemical integrity of pectin.
By varying the ratio of zein and pectin, the new capsules can be designed to target the stomach, the small intestine or the colon. Compared to conventional capsules, they are more suitable for the delivery of drugs that require controlled release of medication at targeted locations.
As drugs for the diseases of the small intestine or the colon encased in conventional capsules are usually released once they enter the stomach, they could be degraded or lost before reaching the sources of the problem, making it difficult to attain controlled release of medication. Bringing the drugs in the well-protected capsules straight to the source of the disease will boost their efficiency while sparing healthy tissues the drugs’ toxicity and harmful side effects.
The major ingredient of conventional capsules is gelatin obtained from the bones, tendons and skins of animals. Dr Wong said gelatin capsules posed a health risk. “The ingredients could be contaminated with diseases from infected livestock, for example, mad cow disease, if there was a lack of proper treatment in capsule manufacturing processes,” he explained. Man-made polymers are also frequently used in the production of capsules, but their health risks have yet to be examined.
The zein-pectin combination is a natural and animal-free alternative to gelatin and synthetic polymers. “In the future, natural plant-based capsules will be preferred because they leave zero concern for risks and safety in long term uses,” Dr Wong continued. For religious reasons, people such as Muslims also demand medicines not containing animal derivatives.
The novel method is inexpensive as fruit peel loaded with pectin usually goes to waste while zein is a kind of cheap byproducts in food production processes. For pharmaceutical companies, the capsules are easy to make. When only two types of ingredients are needed to make drug capsules targeting different parts of the GI tract, the Bill of Material is kept simple, which can streamline the logistics and planning of production processes.
The food-grade capsules also offer a simple, safe and natural solution to the nutrition market, enabling consumers to take a targeted approach to nourish their own body.
The widely-acclaimed breakthrough has won a Gold Medal as well as a Special Merit Award from the National Research Council of Thailand at the 42nd International Exhibition of Inventions of Geneva in Switzerland in April.
