Polymer Helps Medicine Get to Its Target

The medicine in pills sometimes doesn’t reach its intended target when the body does not absorb it. But thanks to some polymer research by scientists at medicinetwo American universities, that all may change.

Kevin Edgar, a polymer chemist at Virginia Tech, and Lynne Taylor, a pharmaceutical scientist at Purdue University, have designed an all-natural polymer that covers oral medication to help it pass more efficiently through a patient’s digestive system. The polymer is designed to release the medication once the pill reaches the small intestine, where it can best be absorbed into the bloodstream, reports Laboratory Equipment.

A disadvantage with oral drugs is that they can crystallize like table salt. When they do, they do not dissolve well. If they don’t dissolve, or dissolve slowly, then the medicine won’t be absorbed in the digestive tract where it can treat a problem.

But the scientists came up with a solution that resolves that problem. Laboratory Equipment explains further:

Polymers are introduced to interfere with crystallization. ‘But the polymers that are presently FDA approved are not effective in meeting all the challenges,’ says Edgar. ‘They may prevent a process called nucleation but not stop growth of the crystal if it gets started. Or they may not continue to work after a period of time or if conditions are too hot or too damp. We needed to design a better polymer.’

The scientists have chosen the natural polymer, cellulose, to work their magic. From that, they create derivatives known as cellulose esters.

“They are the polymers used to create LCD screens, automotive paint, and cellophane tape,” says Edgar. “Cellulose is an abundant, renewable, completely natural polymer used by nature as the ‘steel reinforcing rod’ of trees and a major component of all plants.”

The most effective form of the cellulose esters is omega-carboxyesters that keep a wide range of medicines from crystallizing. “No polymers work in every drug formulation, but these are some of the most broadly effective bioavailability enhancement polymers we’ve seen,” says Edgar. “We have already found that they enhance the stability and solubility of three HIV drugs, a pain reliever, two antibiotics and five flavonoids, which are potent drug-like molecules that occur naturally in nuts, fruits and vegetables.”

Not only does the polymer need to prevent crystallization by binding to the medicine properly, but it must also allow its release. “The small intestine is where many medicines have the best chance to enter the bloodstream,” says Taylor, “so often the ideal polymer will hang onto the drug through the acidic environment of the stomach, and then release the medicine in the benign environment of the small intestine.”

Introducing cellulose omega-carboxyester into the body should not be a problem, Edgar says. “Most of the cellulose omega-carboxyester just passes through the body unchanged and unabsorbed. If any of it breaks down in the gastrointestinal tract, it breaks down into things that are part of our diet anyway,” he says. “We are excited by these compounds, and there are companies interested in making the investments to get them approved.”

Source: “Polymer Helps Oral Meds Reach Bloodstream,” Laboratory Equipment, 8/29/13
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