Natural Medicines Newsletter

Volume 1, Issue 45, 11/26/2009

Question

What Indonesian herbal and natural medicines are known to inhibit the cytochrome P450 (CYP2D6) enzyme?

Answer

It is well known that the cytochrome (CYP) P450 enzyme system is involved in drug metabolism of many medications used in clinical practice and have been implicated in causing clinically relevant drug-drug interactions.(1,2)  There are a number of CYP450 enzymes involved in mediating drug interactions and commonly include CYP1A2, 2C9, 2C19, 2D6, and 3A4.(1)  If the number and level of complexity were not enough with prescription medications alone, the addition of the use of natural and herbal medicines, which are now known to inhibit CYP enzymes as well, is only going to make this worse.  In fact, the number of herbal or natural medicines that are known to inhibit CYP2D6 is growing and is of clinical importance when assessing the potential etiologies in adverse drug events that appear to be from a drug-drug interaction.  Due to the wide diversity of the public and type of patients clinicians can encounter on a daily basis, all clinicians, regardless of specialty or level of training, need to be aware of the herbal or natural medicines from various regions of the world.  This issue will focus on herbal products originating from plant sources in Indonesia. 

Several studies have been done on over 30 different herbal products or plants from Indonesia to determine the inhibitory potential on CYP2D6.(3-5)  Of these herbs, those noted in the table provided were identified as those Indonesian herbs that have the greatest chance for causing drug interactions with medications that require CYP2D6 for their metabolism.  Furthermore, it would appear that....

The complete answer to this question comes with a table summarizing the Indonesian herbs that are likely to cause drug interactions through CYP2D6 as well as their IC50's and type of inhibition.

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