Can Skullcap Safely Be Taken With Orgovyx?

Quick Answer

Evidence suggests that Baikal skullcap may inhibit a protein known as p-glycoprotein, which plays a role in the absorption and distribution of Orgovyx. Combining Baikal skullcap with Orgovyx may increase concentrations of Orgovyx in the body, potentially increasing the risk of side effects. Although this interaction has not been seen in humans, the combination should be used cautiously and only under the supervision of your doctor.

Detailed Answer

Thanks for reaching out!

You don't specify in your question which species of the Scutellaria genus you are referring to. There are several, with the two most common being the American skullcap (Scutellaria lateriflora) and Baikal skullcap (Scutellaria baicalensis).

Both American skullcap and Baikal skullcap contain a variety of active compounds, including flavonoids, phenolic acids, and essential oils.

However, Baikal skullcap is particularly known for its high concentration of baicalin, which has potent antioxidant and anti-inflammatory properties. On the other hand, American skullcap contains scutellarin, which is thought to have sedative and anticonvulsant effects.

Based on their individual constituents, American skullcap is often used to treat anxiety and insomnia, while Baikal skullcap is commonly used as a source of antioxidants to treat inflammatory conditions. Nevertheless, there is some overlap in their uses and both plants have been studied for a range of health benefits.

I'll consider both American skullcap and Baikal skullcap for your interaction question (it should be noted that Baikal skullcap is the more often utilized species for dietary supplements).

Skullcap Interaction With Orgovyx (Relugolix)?

Orgovyx (relugolix) is a medicine used to treat a type of cancer that starts in the prostate gland. It belongs to a group of medicines called gonadotropin-releasing hormone (GnRH) receptor antagonists.

It works by lowering the level of testosterone. Prostate cancer cells need testosterone to grow, so reducing its production can slow down or stop the cancer from spreading.

It is important to note that Orgovyx is a substrate of P-glycoprotein (P-gp), a protein that is often referred to as a drug transporter.

When a medication is a P-gp substrate, it means that P-gp is involved in the way the medication is absorbed, distributed, metabolized, and eliminated in the body.

In the case of Orgovyx, being a P-gp substrate means that the medication can be affected by other drugs that interact with P-gp. For example, drugs that inhibit P-gp activity can increase the concentration of Orgovyx in the body, leading to a higher risk of side effects.

The prescribing information for Orgovyx states the following regarding drug interactions with other medications that affect P-gp:

Co-administration of ORGOVYX with a P-gp inhibitor increases the AUC [area under the curve] and the maximum concentration (Cmax) of relugolix, which may increase the risk of adverse reactions associated with ORGOVYX. Avoid co-administration of ORGOVYX with oral P-gp inhibitors. If co-administration is unavoidable, take ORGOVYX first, separate dosing by at least 6 hours, and monitor patients more frequently for adverse reactions.

Evidence Suggests That Baikal skullcap May Affect P-glycoprotein

Several investigations conducted on cells and animals indicate that certain compounds present in Baikal skullcap, as opposed to American skullcap, may possess the ability to inhibit P-glycoprotein (as detailed on our interaction page for this combination).

Specifically, baicalein and Oroxylin A, both compounds that occur naturally in Baikal skullcap, have demonstrated an inhibitory effect on P-glycoprotein.

Nevertheless, it is important to note that this effect has not yet been observed in humans. All available research on this topic has either been performed in a laboratory setting using isolated cells or tissues, or in animals. Whether this effect translates to humans remains unknown.

The conclusions of various studies have also been inconsistent. Some propose that inhibiting P-glycoprotein can be beneficial in certain situations, as it can increase the sensitivity of cancer cells to drugs. By inhibiting P-glycoprotein, these drugs will not be removed from the cells too quickly, meaning that more of the drugs can accumulate within the cancer cells and potentially destroy them more effectively.

However, it is essential to consider that elevated concentrations can also lead to severe side effects.

How To Manage The Interaction

This is a tough one to definitively say one way or the other how to manage this potential interaction due to the lack of data available in humans.

From the perspective of "better to be safe than sorry" and out of an abundance of caution, I would recommend avoiding taking Baikal skullcap if you are currently taking Orgovyx.

This is based on the evidence I discussed above that Baikal skullcap may inhibit P-glycoprotein, which could increase the risk of side effects of Orgovyx (such as hot flushes, cardiac abnormalities, increased blood glucose, musculoskeletal pain, liver dysfunction, and gastrointestinal effects).

If you do decide you want to take Baikal skullcap, please be sure to let your doctor know so you can be appropriately monitored.

I would also suggest following the guidance given in the Orgovyx prescribing information, which states to take Orgovyx first and separate dosing with the P-glycoprotein inhibitor (Baikal skullcap in this case) by at least 6 hours.

Final Words

Thanks so much for reaching out to HelloPharmacist! This was a great question and I really enjoyed putting an answer together for you.