Pharmacokinetic Interactions of a Licorice Dietary Supplement with Cytochrome P450 Enzymes in Female Participants

• Published in: Drug metabolism and disposition Vol. 51; no. 2; pp. 199 - 204
• Main Authors: Liu, Jialin, Banuvar, Suzanne, Viana, Marlos, Barengolts, Elena, Chen, Shao-Nong, Pauli, Guido F, van Breemen, Richard B
• Format: Journal Article
• Language: English
• Published: United States The American Society for Pharmacology and Experimental Therapeutics 01-02-2023
• Subjects: Caffeine - pharmacokinetics; Cytochrome P-450 CYP1A2; Cytochrome P-450 CYP2C9; Cytochrome P-450 CYP2D6; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme System; Dietary Supplements; Female; Glycyrrhiza - chemistry; Glycyrrhizic Acid; Humans; Tolbutamide
• ISSN: 0090-9556; 1521-009X
• DOI: 10.1124/dmd.122.001050

Licorice, the roots and rhizomes of
L., has been used as a medicinal herb, herbal adjuvant, and flavoring agent since ancient times. Recently, licorice extracts have become popular as dietary supplements used by females to alleviate menopausal symptoms. Exposure to licorice products containing high levels of glycyrrhizic acid can cause hypokalemia, but independent from this effect, preclinical data indicate that licorice can inhibit certain cytochrome P450 (P450) enzymes. To evaluate whether clinically relevant pharmacokinetic interactions of licorice with P450 enzymes exist, a phase 1 clinical investigation was carried out using a licorice extract depleted in glycyrrhizic acid (content <1%) and a cocktail containing caffeine, tolbutamide, alprazolam, and dextromethorphan, which are probe substrates for the enzymes CYP1A2, CYP2C9, CYP3A4/5, and CYP2D6, respectively. The botanically authenticated and chemically standardized extract of roots from
was consumed by 14 healthy menopausal and postmenopausal female participants twice daily for 2 weeks. The pharmacokinetics of each probe drug were evaluated immediately before and after supplementation with the licorice extract. Comparison of the average areas under the time-concentration curves (AUCs) for each probe substrate in serum showed no significant changes from licorice consumption, whereas time to reach peak concentration for caffeine and elimination half-life for tolbutamide showed small changes. According to the US Food and Drug Administration guidance, which is based on changes in the AUC of each probe substrate drug, the investigated licorice extract should not cause any clinically relevant pharmacokinetic interactions with respect to CYP3A4/5, CYP2C9, CYP2D6, or CYP1A2. SIGNIFICANCE STATEMENT: Despite generally-recognized-as-safe status, the licorice species
has been associated with some toxicity. Preclinical studies suggest that
might cause pharmacokinetic drug interactions by inhibiting several cytochrome P450 enzymes. This phase 1 clinical study addressed these concerns by evaluating clinically relevant effects with respect to CYP3A4/5, CYP2C9, CYP2D6, and CYP1A2. These results showed that a standardized
extract did not cause any clinically relevant pharmacokinetic drug interactions with four major cytochrome P450 enzymes.