CYP3A4 Interactions with Hawthorn

Introduction to CYP3A4 Interactions

The American College of Cardiology and other guideline societies discuss various substances that interact with CYP3A4, including strong inhibitors (ketoconazole, ritonavir, clarithromycin) and inducers (rifampin, St. John's wort) 1, 2, 3
St. John's wort is specifically identified as a CYP3A4 inducer by the American Heart Association 1, 3

Hawthorn is not listed in any of the guidelines as having significant CYP3A4 interaction potential, according to the American College of Chest Physicians 1, 3
Ketoconazole can increase rivaroxaban AUC by approximately 2.5-fold, highlighting the potential for significant CYP3A4 interactions, as noted by the American College of Chest Physicians 3

When prescribing medications metabolized by CYP3A4 to patients taking hawthorn, it would be prudent to monitor for unexpected changes in drug efficacy or toxicity, consider the possibility of additive pharmacodynamic effects with cardiovascular medications, and be particularly cautious with drugs that have a narrow therapeutic index, as recommended by the European Society of Cardiology 1, 2, 3
If a patient is taking both hawthorn and medications that are sensitive CYP3A4 substrates, closer monitoring may be warranted initially, especially for cardiovascular effects, according to the American Heart Association 1, 3