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.
Donovan
Jennifer L
JL
Department of Psychiatry and Behavioral Sciences, Medical University of South Carolina, Charleston 29425, USA.
Chavin
Kenneth D
KD
Devane
C Lindsay
CL
Taylor
Robin M
RM
Wang
Jun-Sheng
JS
Ruan
Ying
Y
Markowitz
John S
JS
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