Pubmed screenshot: Objectives: Ciclosporin and sirolimus, two immunosuppressive agents with narrow therapeutic windows, are mainly metabolized by Cytochrome 3A4 (CYP3A4). A clinical case [highlighted] of toxic blood levels of these drugs after the consumption of a '24-flavours' tea was reported. This study aims to identify the causative ingredients [end highlight] of the 24-flavour herbal tea in the inhibition of CYP3A4 metabolism. Methods: Two commercially available 24- flavour tea products purchased in Hong Kong and the six plant constituents were tested for their CYP3A4 inhibitory effects utilizing an in- vitro fluorometric assay. Key findings: Of the commercially available teas available in Hong Kong, the most potent inhibitory effect was observed with the tea consumed in the initial clinical case. Of the six universal constituents, [highlight] chrysanthemum 5 the greatest inhibitory effect, iW LEW C50 of 95.7 ug/ml. Dandelion, liquorice and bishop's weed have IC50 of 140.6, 148.4 and 185.5 pg/ml, respectively. Field mint and Japanese honeysuckle have wearker inhibitory effect on CYP3A4 with IC50 of 1153.3 and 1466.6 ug/ml.

Pubmed screenshot: Objectives: Ciclosporin and sirolimus, two immunosuppressive agents with narrow therapeutic windows, are mainly metabolized by Cytochrome 3A4 (CYP3A4). A clinical case [highlighted] of toxic blood levels of these drugs after the consumption of a '24-flavours' tea was reported. This study aims to identify the causative ingredients [end highlight] of the 24-flavour herbal tea in the inhibition of CYP3A4 metabolism. Methods: Two commercially available 24- flavour tea products purchased in Hong Kong and the six plant constituents were tested for their CYP3A4 inhibitory effects utilizing an in- vitro fluorometric assay. Key findings: Of the commercially available teas available in Hong Kong, the most potent inhibitory effect was observed with the tea consumed in the initial clinical case. Of the six universal constituents, [highlight] chrysanthemum 5 the greatest inhibitory effect, iW LEW C50 of 95.7 ug/ml. Dandelion, liquorice and bishop's weed have IC50 of 140.6, 148.4 and 185.5 pg/ml, respectively. Field mint and Japanese honeysuckle have wearker inhibitory effect on CYP3A4 with IC50 of 1153.3 and 1466.6 ug/ml.