- Natural product: Green tea (Camellia sinensis)
- Associated study: Testing Green Tea as a Precipitant of Natural Product-Drug Interactions Using Raloxifene as the Object Drug
In Vivo Interaction Study
Results
- A pharmacokinetic interaction was observed between a well-characterized green tea and the intestinal UGT substrate raloxifene, as reflected by the geometric mean raloxifene AUC0-96h and Cmax decreasing to below the pre-defined no effect range (0.75-1.33).
- The unaltered raloxifene and glucuronide terminal half-lives, combined with unaltered ratios of glucuronide-to-raloxifene AUC0-96h, in the presence of green tea, suggested inhibition of intestinal UGT activity was not responsible for the observed interaction, different from the IVIVE prediction.
- The greater decrease in raloxifene geometric mean Cmax relative to AUC0-96h further suggested that green tea alters primarily processes in the intestine, which could include permeability, transport and/or physicochemical processes involved in raloxifene absorption.
- Note: all means are geometric and ratios are geometric mean ratios
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Fixed-sequence
Females
Healthy volunteers
Males
Nonsmokers
Asian
Not Hispanic or Latino
White
18 subjects enrolled and 16 completed the study
0, 0.25, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 24, 48, 72, and 96 h
0, 0.25, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 24, 48, 72, and 96 h
One ml of plasma was mixed with 20 μl of ascorbic acid (20%, w/v) to stabilize catechins
Drug or Natural Product Administration
Oral
Tablet
60 mg
single dose
Oral
tea bag
Acute study: three bags of green tea
Acute study: three bags of green tea daily for 1 day
three bags daily for 1 day
Yes
2016