In case you missed Part 1: Mary Paine is a pharmaceutical sciences researcher and associate professor at the Washington State University College of Pharmacy. She leads the Center of Excellence for Natural Product-Drug Interaction Research (NaPDI Center) in Spokane.

“Patients often seek herbal and other natural products as a ‘natural,’ and therefore perceived as ‘safe,’ means to alleviate illnesses or supplement prescribed therapeutic regimens,” Paine said. “Co-consuming natural products with conventional medications—either prescription or over-the-counter—can lead to adverse interactions.”

Funded by the National Institutes of Health National Center for Complimentary and Integrative Health, the mission of the NaPDI Center is to contribute to the scientific knowledge available to researchers, and ultimately to health care providers and patients, about the potential risks of mixing herbs (or other natural products) with drugs.

Read all of Part 1 here: PART 1 – expanding scientific knowledge

The NaPDI Center

Part 2 (of 3)

The challenges of studying natural products are diverse. Inconsistencies within the natural products themselves, including seasonal changes leading to variable ingredient composition, inconsistency in manufacturing, and the complexities of multiple bioactive ingredients in a single natural product, are just the beginning of the potential variables. On the scientific side, there is not a harmonized method on how to properly assess these complex interactions. For those interested in conducting this kind of research, there’s is a lack of information on even where to start. That’s why the NaPDI Center started as a think tank.

Once the NaPDI Center was established, the group tackled identifying a list of natural products as potential “precipitants” of clinically significant interactions with commonly used drugs. This list needed to be narrowed and prioritized to identify the first few natural products to study. For each of the candidate natural products, the center identified existing gaps in the scientific literature with respect to interaction targets, which include drug metabolizing enzymes, transporters, and receptors within cells; and human subject studies assessing how natural products alter the absorption, distribution, metabolism and/or excretion of drugs. You can predict these interactions through in vitro studies and mathematical models, or observe them through clinical studies.

The final list of natural products to study includes green tea, goldenseal, cannabis, and licorice.

The center’s researchers want to establish a way to create consistency and reliability in the quality of information that the scientific community will be producing in this area. The end goal is developing a set of recommended approaches to determine whether the interactions between natural products and drugs within the body have real, measurable effects and documenting what they are.

The center is organized into four research cores: administrative, analytical, informatics, and pharmacology. The center also includes an internal steering committee and executive committee, and an external advisory panel.

  • The administrative core manages center operations, internal and external communications, regulatory compliance, and finance.
  • The pharmacology core conducts research, collecting data through human in vitro studies, mathematical modeling and simulation, and clinical studies.
  • The analytical core sources and characterizes each natural product for both in vitro and clinical studies. Activities include profiling the chemistry of various commercial preparations of each natural product and mapping out optimal processes such as how to identify the best commercial products for study.
  • The informatics core is developing an online data repository and website where researchers can access scientific data generated by the analytical and pharmacology cores and recommended approaches.

The center is developing a set of recommended approaches for researchers to follow, which is important for the quality and consistency of future studies done in the area of natural products. The NaPDI Center has published results in the Journal of Pharmaceutical and Biomedical Analysis and the Journal of Natural Products, and now in the journal Drug Metabolism and Disposition on work completed so far, with several more articles currently in progress.

Collaborating partners that make up the NaPDI center include:

Washington State University

Mary PaineDr. Mary Paine, College of Pharmacy and Pharmaceutical Sciences
Paine serves as principal investigator and leads the administrative and pharmacology cores. In addition, she serves on the center steering committee, executive committee and analytical core.

John ClarkeDr. John Clarke, College of Pharmacy and Pharmaceutical Sciences
Clarke serves on the pharmacology core.


Michael GibsonDr. K. Michael Gibson, College of Pharmacy and Pharmaceutical Sciences
Gibson serves on the executive committee and administrative core.


Bruce PinkletonDr. Bruce Pinkleton, Edward R. Murrow College of Communication
Pinkleton serves on the informatics core.


Rebecca CooneyRebecca Cooney, Edward R. Murrow College of Communication
Cooney serves on the informatics core.


Deena HadiDeena Hadi, College of Pharmacy and Pharmaceutical Sciences
Hadi serves as the program manager of the center and on the administrative core.


University of Washington

Danny ShenDr. Danny Shen, School of Pharmacy
Shen serves on the administrative core.


Ken ThummelDr. Ken Thummel, School of Pharmacy
Thummel serves on the center steering committee, executive committee and analytical core.

Allan RettieDr. Allan Rettie, School of Pharmacy
Rettie serves on the pharmacology core.


Jashvant UnadkatDr. Jashvant Unadkat, School of Pharmacy
Unadkat serves on the pharmacology core.


University of North Carolina Greensboro

Nicholas OberliesDr. Nicholas Oberlies, Department of Chemistry and Biochemistry
Oberlies serves on the center steering committee and leads the analytical core.


Nadja CechDr. Nadja Cech, Department of Chemistry and Biochemistry
Cech serves on the center steering committee and analytical core.


University of Pittsburgh

Richard BoyceDr. Richard Boyce, School of Medicine, Department of Biomedical Informatics
Boyce serves on the center steering committee and leads the informatics core.


City of Hope

City of Hope is one of 49 comprehensive cancer care centers designated by the National Cancer Institute located in Duarte, California.

Jeannine McCuneDr. Jeannine McCune, Department of Population Sciences
McCune serves on the center steering committee, executive committee, and administrative core.

National Center for Complementary and Integrative Health

This center is the National Institutes of Health lead center for scientific research on the diverse medical and health care systems, practices, and products that are not generally considered part of conventional medicine.

D. Craig HoppDr. D. Craig Hopp, Division of Extramural Research
Hopp serves as the center’s program officer and on the center steering committee.


External advisory panel

Russ Altman, MD, PhD, Stanford University
Shiew-Mei Huang, PhD, U.S. Food & Drug Administration
Ah-Ng Tony Kong, PhD, Rutgers University
Amy Roe, PhD, DABT, Procter & Gamble

By providing resources that will allow scientific work surrounding natural product-drug interactions to be consistent and replicable, the NaPDI Center is starting to expand our knowledge in this area. According to Paine, this could ultimately increase the safety of natural products, which is important for people across the nation who are just trying to do what they can to live their best, healthy life.

Part 3: The future of the NaPDI Center: public health impact