Complementary and Alternative Medicine: Lack of Pharmacokinetic Interaction Between St. John's Wort and Prednisone

• Published in: The Annals of pharmacotherapy 2007-11, Vol.41 (11), p.1819-1824
• Main Authors: Bell, Edward C, Ravis, William R, Chan, Hui Min, Lin, Yuh-Jing
• Format: Article
• Language: English
• ISSN: 1060-0280; 1542-6270
• DOI: 10.1345/aph.1K316

Background: St. John's wort (SJW) is a popular dietary supplement involved in numerous dietary supplement–drug interactions with prescription and nonprescription drugs. The supplement has been shown to affect the metabolism of various CYP3A4 substrates. The CYP3A4 pathway mediates the metabolism of a large number of drug entities, including the corticosteroids prednisone and prednisolone. Objective: To examine the effects of long-term SJW administration on the pharmacokinetics of prednisone and its reversible metabolite prednisolone in male subjects. Methods: Eight male subjects participated in this single-dose study. The pharmacokinetics of prednisone and prednisolone were evaluated before and after 28 days of SJW administration. Plasma corticosteroid concentrations were determined using a normal phase high-performance liquid chromatography assay. Model-independent methods were used to evaluate corticosteroid pharmacokinetics. Results: Twenty-eight days of SJW treatment resulted in no significant alterations in the pharmacokinetic parameters for prednisone or prednisolone. Oral administration of prednisone resulted in prednisone mean ± SD area under the curves (AUCs) of 115.89 ± 39.52 μg•h/L prior to SJW treatment and 128.76 ± 32,71 μg•h/L after 28 days of treatment. Prednisolone mean AUCs were 714.19 ± 153.29 μg•h/L before SJW administration and 700.74 ± 89.68 μg•h/L after treatment. Conclusions: Concurrent administration of SJW had no significant effect on the single-dose pharmacokinetics of prednisone or metabolic prednisolone in male subjects