Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Novel polymer helps oral medications reach the bloodstream

28.08.2013
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 issue of the Elsevier journal 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, professor of biomaterials and bioprocessing in the College of Natural Resources and Environment at Virginia Tech, an expert in polymer synthesis, approached Lynne Taylor, 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’ of trees and a major component of all plants.”

The Virginia Tech and Purdue groups have discovered that the effective design for pharmaceutical applications is cellulose omega-carboxyesters, which are cellulose esters that the researchers have enhanced with acids that already occur in the human body.

“For example, adipic acid, a natural acid present in sugar cane, can be attached to cellulose acetate to make an adipate ester,” said Edgar. “Cellulose acetate is already used in many medicines that people take today; it controls the rate of release of the drug.”

The researchers figured out how to make omega-carboxyesters that keep different kinds of medicines dispersed and prevent them from crystallizing — in other words, creating pills with higher bioavailability.

“No polymers work in every drug formulation, but these are some of the most broadly effective bioavailability enhancement polymers we’ve seen.” said 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.”

The final neat trick, after creating a polymer that binds the medicines so they cannot crystallize, is to make sure that polymer also knows when to let go.

“The small intestine is where many medicines have the best chance to enter the bloodstream,” said 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.”

Cellulose adipate esters and their cousin omega-carboxyester, cellulose acetate suberate, are no more complicated to make than those in adhesive tape and other inexpensive products, except that they are made with a different set of natural acids.

“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,” said Edgar.

“We are excited by these compounds, and there are companies interested in making the investments to get them approved,” Edgar added.

The article in Carbohydrate Polymers, “Synthesis and structure-property evaluation of cellulose omega-carboxyesters for amorphous solid dispersions,” describes the successful use of the novel polymers with the anti-HIV drug ritonavir. The article is by Haoyu Liu of Shanghai, China, a doctoral student studying macromolecular science and engineering in Virginia Tech’s College of Natural Resources and Environment; Grace A. Ilevbare, who recently received her doctorate from the College of Pharmacy at Purdue University; Benjamin P. Cherniawski of Afton, Va., a senior majoring in chemistry in Virginia Tech’s College of Science at the time of the research; Earl T. Ritchie, an undergraduate chemistry major at Clemson University who conducted summer research with the Macromolecules and Interfaces Institute at Virginia Tech; Taylor; and Edgar.

An article in the April 18, 2013, American Chemical Society journal Molecular Pharmaceutics described how a group of chemically diverse polymers worked to stabilize three structurally different medicines: ritonavir and efavirenz, both used for treating HIV, and celecoxib, used for treatment of arthritis and other painful inflammations. The article “Impact of polymers of crystal growth rate of structurally diverse compounds from aqueous solution” was authored by Ilevbare, Liu, Edgar, and Taylor.

The group had previously published research examining a range of commercially available and novel polymers used with ritonavir; resveratrol, which is the beneficial compound in chocolate and red wine; and ellagic acid, the flavonoid in walnuts and many kinds of berries that acts against oxidation-related chronic diseases, such as cancer and cardiovascular disease. Their work continues with other drugs, including important antibacterial drugs such as those used against tuberculosis.

“Improved bioavailability means a scarce and expensive drug can be used to treat more patients and with fewer side effects,” said Taylor. “Fewer doses will be required, overall making it easier for patients to take their drugs on time every day — nothing is more important for vanquishing disease and for preventing the development of resistant organisms.”

The College of Natural Resources and Environment at Virginia Tech, which consistently ranks among the top three programs of its kind in the nation, advances the science of sustainability. Programs prepare the future generation of leaders to address the complex natural resources issues facing the planet. World-class faculty lead transformational research that complements the student learning experience and impacts citizens and communities across the globe on sustainability issues, especially as they pertain to water, climate, fisheries, wildlife, forestry, sustainable biomaterials, ecosystems, and geography. Virginia Tech, the most comprehensive university in Virginia, is dedicated to quality, innovation, and results to the commonwealth, the nation, and the world.

Lynn Davis

540-231-6157
davisl@vt.edu

Lynn Davis | EurekAlert!
Further information:
http://www.vt.edu

More articles from Life Sciences:

nachricht What the world's tiniest 'monster truck' reveals
23.08.2017 | American Chemical Society

nachricht Treating arthritis with algae
23.08.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

What the world's tiniest 'monster truck' reveals

23.08.2017 | Life Sciences

Treating arthritis with algae

23.08.2017 | Life Sciences

Witnessing turbulent motion in the atmosphere of a distant star

23.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>