All-natural polymer additive for medications

ALL too often, when a person takes a pill full of a potent and effective drug, the drug passes straight through the body, not reaching the organ where it is needed — a waste of money and inconvenient if it is a cold medicine, but potentially dire if it is a treatment for a serious illness.

Polymer chemists at Virginia Tech and pharmaceutical scientists at Purdue University have teamed up to design a solution.

Their research to identify, understand, and create new polymer additives that enhance the ability of orally administered drugs to reach the bloodstream has been published in a series of journals.

In a special edition of Carbohydrate Polymers, they introduced an all-natural polymer that can be used with a range of medicines to prevent crystallization during transport and storage; it then traverses the digestive tract until the still fully potent medicine is released from the polymer in the small intestine, where it is best absorbed into the bloodstream.

Kevin Edgar, a professor of biomaterials and bioprocessing in the College of Natural Resources and Environment at Virginia Tech and an expert in polymer synthesis, approached Lynne Taylor, a professor of industrial and physical pharmacy at Purdue University, about collaboration.

“Dr. Taylor is one of the leading pharmaceutical scientists in the world,” said Edgar. “We decided that by combining her ability to understand how drugs, polymers, and the human body interact, with our ability to make new polymers based on natural, renewable polysaccharides, we could address the challenge of making some very important drugs more bioavailable through the creation of polymers tailor-made for this purpose.”

Many important drugs are like table salt; they crystallize easily. When they do, the crystals are stubbornly difficult to dissolve. They crystallize instead of remaining dispersed, whether in the pill or after release in the digestive tract. Many medicines locked into crystals don’t dissolve fast enough to work properly. If that happens, they can’t reach their target.

Polymers are introduced to interfere with crystallization. “But the polymers that are presently FDA approved are not effective in meeting all the challenges,” said 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.”

Imagine sugar dissolved in water. If a bit of dust is introduced, it can lead to nucleation — the sugar sticks to the dust — and then crystal growth. In this example, the polymer would cover the dust mote and repel the sugar molecules, preventing nucleation.

“Stopping nucleation is relatively easy, like stopping a skier before he starts down the hill,” said Edgar. “Stopping growth is harder, like trying to stop the skier once he is speeding down the slope. But our polymers can do both — stop nucleation and growth.”

Edgar and Taylor are working with natural cellulose to create derivatives known as cellulose esters. “They are the polymers used to create LCD screens, automotive paint, and cellophane tape,” said Edgar. “Cellulose is an abundant, renewable, completely natural polymer used by nature as the ‘steel reinforcing rod’ ofNike Air Max 90