Green Tea (Camellia sinensis) 19124972
Green tea (Camellia sinensis) extract does not alter cytochrome P450 3A4 or 2D6 activity in healthy volunteers. CSV JSON

Green tea extract is a widely used dietary supplement. The objective of this study was to assess the influence of a decaffeinated green tea (DGT; Camellia sinensis) extract on the activity of the drug-metabolizing enzymes cytochrome P-450 2D6 and 3A4. Probe drugs dextromethorphan (30 mg, CYP2D6 activity) and alprazolam (ALPZ; 2 mg, CYP3A4 activity) were administered orally to healthy volunteers (n = 11) at baseline, and again after treatment with four DGT capsules/day for 14 days. Each DGT capsule contained 211 +/- 25 mg of green tea catechins and <1 mg of caffeine. Dextromethorphan metabolic ratios (DMRs) and alprazolam pharmacokinetics were determined at baseline and after DGT treatment. There were no significant differences in ALPZ pharmacokinetics at baseline and after DGT treatment (all P values >/= 0.05; maximum concentration in plasma, 33 +/- 8 versus 34 +/- 13 ng/ml; time to reach maximum concentration in plasma, 1.4 +/- 1.2 versus 1.4 +/- 1.2 h; area under the plasma concentration versus time curve, 480 +/- 119 versus 510 +/- 107 h. ng. ml(-1); half-life of elimination, 12.3 +/- 1.7 versus 13.1 +/- 3.4 h). The DMR was 0.053 +/- 0.045 at baseline and 0.041 +/- 0.032 after DGT supplementation (P > 0.05). The plasma concentration of the green tea flavonoid, (-)-epigallocatechin gallate, reached 1.3 +/- 1.8 microM 2 h after DGT treatment. Our results indicate that DGT is unlikely to alter the disposition of medications primarily dependent on the CYP2D6 or CYP3A4 pathways of metabolism.

1 . In vivo NPDI experiment (id=NPDI-_MbFQg)

In Vivo Interaction Study

No Effect (based on bioequivalence limits) was detected.

alprazolam 781039

  • CYP3A4 4306811

Results

Compound measured Measurement Value Study sequence Additional information N replicates

Experimental Conditions

Fixed-sequence

Population

Healthy volunteers

Nonsmokers

CYP2D6 normal metabolizer

11

six women and five men; seven white; two Asian, two black, with a mean (+/- S.D.) age of 35 +/- 9 years

Pharmacokinetic (PK) Sampling Information

0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 24, 36, 48, and 60 h

0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 24, 36, 48, and 60 h

Drug or Natural Product Administration

Object Administration — alprazolam

Oral

tablet

2 mg

single dose, before and after administration of green tea extract

Precipitant Administration — green tea leaf extract

Oral

Capsule of Decaffeinated Super Green Tea Extract

844 mg of green tea catechins and <4 mg of caffeine

4 capsules/day

14 days

Natural Product Characteristics

Life Extension; Fort Lauderdale, FL

No

2003

2 . CYP2D6 inhibition experiment (id=NPDI-cY8J6A)

In Vivo Interaction Study

No Effect (based on bioequivalence limits) was detected.

dextromethorphan 1119510

  • CYP2D6 4173631

Results

Compound measured Measurement Value Study sequence Additional information N replicates

Experimental Conditions

Fixed-sequence

Population

Healthy volunteers

Nonsmokers

CYP2D6 normal metabolizer

11

six women and five men; seven white; two Asian, two black, with a mean (+/- S.D.) age of 35 +/- 9 years

Pharmacokinetic (PK) Sampling Information

0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 24, 36, 48, and 60 h

0.5, 1, 1.5, 2, 3, 4, 6, 8, 12, 24, 36, 48, and 60 h

Drug or Natural Product Administration

Object Administration — dextromethorphan

Oral

suspension (Robitussin cough syrup; Wyeth-Ayerst, Princeton, NJ)

30 mg

single dose, before and after administration of green tea extract

Precipitant Administration — green tea leaf extract

Oral

Capsule of Decaffeinated Super Green Tea Extract

844 mg of green tea catechins and <4 mg of caffeine

4 capsules/day

14 days

Natural Product Characteristics

Life Extension; Fort Lauderdale, FL

No

2003