Open Access Research article

Evaluation of the transporter-mediated herb-drug interaction potential of DA-9801, a standardized dioscorea extract for diabetic neuropathy, in human in vitro and rat in vivo

Im-Sook Song1, Tae Yeon Kong2, Hyeon-Uk Jeong2, Eun Nam Kim2, Soon-Sang Kwon2, Hee Eun Kang2, Sang-Zin Choi3, Miwon Son3 and Hye Suk Lee2*

Author Affiliations

1 College of Pharmacy and Research Institute of Pharmaceutical Sciences, Kyungpook National University, Daegu 702-701, Korea

2 College of Pharmacy, The Catholic University of Korea, Bucheon 420-743, Korea

3 Research Center, Dong-A ST Co., Ltd., Yongin 446-905, Korea

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BMC Complementary and Alternative Medicine 2014, 14:251  doi:10.1186/1472-6882-14-251

Published: 17 July 2014

Abstract

Background

Drug transporters play important roles in the absorption, distribution, and elimination of drugs and thereby, modulate drug efficacy and toxicity. With a growing use of poly pharmacy, concurrent administration of herbal extracts that modulate transporter activities with drugs can cause serious adverse reactions. Therefore, prediction and evaluation of drug-drug interaction potential is important in the clinic and in the drug development process. DA-9801, comprising a mixed extract of Dioscoreae rhizoma and Dioscorea nipponica Makino, is a new standardized extract currently being evaluated for diabetic peripheral neuropathy in a phase II clinical study.

Method

The inhibitory effects of DA-9801 on the transport functions of organic cation transporter (OCT)1, OCT2, organic anion transporter (OAT)1, OAT3, organic anion transporting polypeptide (OATP)1B1, OATP1B3, P-glycoprotein (P-gp), and breast cancer resistance protein (BCRP) were investigated in HEK293 or LLC-PK1 cells. The effects of DA-9801 on the pharmacokinetics of relevant substrate drugs of these transporters were also examined in vivo in rats.

Results

DA-9801 inhibited the in vitro transport activities of OCT1, OCT2, OAT3, and OATP1B1, with IC50 values of 106, 174, 48.1, and 273 μg/mL, respectively, while the other transporters were not inhibited by 300 μg/mL DA-9801. To investigate whether this inhibitory effect of DA-9801 on OCT1, OCT2, and OAT3 could change the pharmacokinetics of their substrates in vivo, we measured the pharmacokinetics of cimetidine, a substrate for OCT1, OCT2, and OAT3, and of furosemide, a substrate for OAT1 and OAT3, by co-administration of DA-9801 at a single oral dose of 1,000 mg/kg. Pre-dose of DA-9801 5 min or 2 h prior to cimetidine administration decreased the Cmax of cimetidine in rats. However, DA-9801 did not affect the elimination parameters such as half-life, clearance, or amount excreted in the urine, suggesting that it did not inhibit elimination process of cimetidine, which is governed by OCT1, OCT2, and OAT3. Moreover, DA-9801 did not affect the pharmacokinetic characteristics of furosemide, as evidenced by its unchanged pharmacokinetic parameters.

Conclusion

Inhibitory effects of DA-9801 on OCT1, OCT2, and OAT3 observed in vitro may not necessarily translate into in vivo herb-drug interactions in rats even at its maximum effective dose.

Keywords:
Transporter-mediated herb-drug interaction; DA-9801; OCT1; OCT2; OAT3; Cimetidine; Furosemide