Green tea (Camellia sinensis) extract does not alter cytochrome p450 3A4 or 2D6 activity in healthy volunteers.
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.
Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston 29425, USA.
Jennifer L
JL
Donovan
Kenneth D
KD
Chavin
C Lindsay
CL
Devane
Robin M
RM
Taylor
Jun-Sheng
JS
Wang
Ying
Y
Ruan
John S
JS
Markowitz
D000284:Administration, Oral; D000328:Adult; D000525:Alprazolam / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D028241:Camellia sinensis / Q000737:chemistry*; D002214:Capsules; D002392:Catechin / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000494:pharmacology*; D019389:Cytochrome P-450 CYP2D6 / Q000502:physiology*; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000502:physiology*; D003915:Dextromethorphan / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D019587:Dietary Supplements / Q000032:analysis; D004334:Drug Administration Schedule; D005260:Female; D006207:Half-Life; D006801:Humans; D008297:Male; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D013997:Time Factors
D002214:Capsules; D010936:Plant Extracts; D003915:Dextromethorphan; D002392:Catechin; D003577:Cytochrome P-450 Enzyme System; C045651:epigallocatechin gallate; C104464:CYP3A protein, human; D019389:Cytochrome P-450 CYP2D6; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D000525:Alprazolam