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New gel pill could mean an end to injections

September 16, 2004

Scientists in India have developed a new gel that is taken orally and is capable of delivering drugs to manage diseases often requiring an injection. The research, published in the journal Polymer International, suggests the gel could offer a painless way of treating diabetes, ulcerative colitis, Crohn's disease, bowel cancer, constipation and some infections, all of which require local drug delivery.

In these conditions, oral administration of medication cannot be achieved easily because highly acidic gastric fluid in the stomach contain enzymes that can break down the active drug before it reaches the target site. But Dr Sunil Bajpai and Ms Seema Dubey from the Polymer Research Laboratory at Government Model Science College in Jabalpur, India, produced a polymer gel into which a drug may be simply loaded.

'Intelligent materials'
The hydrogel system has been designed so that when swallowed by the patient, it passes through the stomach retaining the majority of the drug by protecting it from the stomach acids. 56 % of the drug is released where it is needed - further down the gastrointestinal tract in the colon. It is deposited when the gel swells in response to the colon's (high) alkaline pH.

"The terpolymeric hydrogel system studied by our team provides an alternative to the parenteral medication of insulin. It is now necessary to carry out in vivo studies of this hydrogel system so that it could be further modified to produce oral delivery pills," says Bajpai.

In the body
To test the gel, the scientists put vitamin B2 in the hydrogel in place of a drug and studied its releasing capacity in conditions simulating a human body, namely gastric (pH 1.0) and intestinal (pH 7.4) fluids at a body temperature of 37oC, under various experimental conditions. This helped to predict the behaviour of the vitamin-loaded gel in body conditions.

Problems caused by other medication, such as sudden increase and subsequent rapid decrease of blood serum concentration, which sometimes reaches a toxic and ineffective level, can be prevented using the new gel, which gives targeted, controlled release of the drug.

"This is important in a number of diseases and medical conditions. The new material developed in this research is simple, elegant, versatile, and performs well," says Dr Malcolm Purbrick, Industrial Polymer Science Editor of Polymer International.


Society of Chemical Industry