Divergent Effects of Turmeric Crude Extract on
P-Glycoprotein Activity in Healthy Male Subjects:
A Randomized Crossover Study
Nut Koonrungsesomboon MD, PhD1,2, Nutthiya Hanprasertpong MD, PhD1, Saranyapin Potikanond MD, PhD1,
Juntra Karbwang MD, PhD2, Supanimit Teekachunhatean MD, PhD1,3
Affiliation :
1 Department of Pharmacology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
2 Department of Clinical Product Development, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
3 Center of Thai Traditional and Complementary Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
Background : Curcuminoids, major ingredients of turmeric crude extract, have shown P-glycoprotein [P-gp] inhibitory properties in both
in vitro and in vivo studies. However, their potential interaction with drugs known as P-gp substrates in humans is not characterized.
Objective : To investigate the effect of turmeric crude extract on P-gp activity in healthy subjects.
Materials and Methods : This preliminary, open-label, randomized, two-period, crossover study was conducted in 12 healthy male
volunteers. Pharmacokinetic [PK] parameters of digoxin, a P-gp probe, were measured following a single oral dose of 0.5 mg digoxin
administered without and with concurrent use of turmeric extract (equivalent to 500 mg of curcuminoids, given twice daily for
four days prior and three days after a single dose of digoxin).
Results : Considering ±25% change of maximum plasma concentration [Cmax] of digoxin in each individual subject to be of clinical
relevance, three categories of interaction between turmeric extract and digoxin were observed. With concurrent use of turmeric
extract, Cmax of digoxin increased, remained unchanged, and decreased in six, four, and two subjects, respectively.
Conclusion : These (cid:976)indings suggest that medical professionals should be aware of possible divergent interactions between turmeric
crude extract and P-gp substrates for the proper monitoring of their individual patients.
Keywords : Turmeric extract, Digoxin, Pharmacokinetics, Drug interactions, P-glycoprotein, Healthy volunteers
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