7 Verzenio Interactions and How to Manage Them

Radiation, surgery, and medications are all possible treatment options for breast cancer. Between them, the best treatment(s) depend on the type of breast cancer you have and how far along it is, among other factors.

If you have HR+/HER2- breast cancer, you may receive a prescription for Verzenio (abemaciclib). It's an oral prescription-only medication that you can take alone or in combination with other medications.

You'll likely take Verzenio twice a day with or without food. However, your recommended dosage may be adjusted up or down due to possible changes in lab tests, side effects, or drug interactions. Several medications, supplements, and foods can interact with Verzenio.

Managing interactions is one part of prioritizing your health on your journey to beating breast cancer. Here are the top seven Verzenio interactions to keep in mind if you're new to the treatment.

1. Azole antifungals like ketoconazole

Verzenio interacts with several azole antifungals. One example is ketoconazole (Nizoral), which treats various fungal infections. Other notable azole antifungals include fluconazole (Diflucan), itraconazole (Sporanox), and posaconazole (Noxafil).

These medications are well known for causing drug interactions. The interaction happens because azole antifungals make it harder for your liver to break down (metabolize) medications like Verzenio. This raises Verzenio levels in your blood, increasing the risk of side effects such as nausea, diarrhea, and others.

If you need to take Verzenio and an azole antifungal, your oncologist may lower your dose of Verzenio to keep things safe. For example, your oncologist may recommend you take Verzenio 100 mg twice daily if you were previously taking 200 mg twice daily. However, your instructions may be different if you already had to lower your Verzenio dose due to side effects. You may find yourself taking Verzenio 50 mg twice daily if you were previously taking 100 mg twice daily, in this case.

The opposite is also true. Your oncologist may increase your Verzenio dose once you stop taking a medication like posaconazole (after your infection has resolved).

Never take more Verzenio than your oncologist has prescribed, even if you think it may help. Speak to your oncologist if you have any concerns about combining azole antifungals with Verzenio.

Good to know: It's important that your oncologist knows about all medications you're taking, including those that are unrelated to your cancer treatment. Share an updated list of all the medications you take, including over-the-counter (OTC) medications and supplements, with your oncologist so they can check for interactions.

2. Paxlovid and other ritonavir-containing medications

Paxlovid is a treatment option to lessen the severity of COVID-19. It's a combination medication containing two different active ingredients. One of them, ritonavir, interacts with many medications.

Ritonavir slows the breakdown of Verzenio. This increases Verzenio levels in your blood when the two medications are taken at the same time.

Ritonavir is also found in several HIV treatment regimens. One example is Kaletra (lopinavir / ritonavir). It used to be an ingredient in certain hepatitis C medications, too, but those products have since been discontinued.

Speak with your oncologist if you're prescribed ritonavir or any ritonavir-containing medication. They'll likely want to adjust your dose of Verzenio to ensure you're getting one that is safe for you.

3. Certain heart medications

Diltiazem (Cardizem) and verapamil (Calan SR, Verelan) are two medications that treat different heart conditions. This includes arrhythmias (abnormal heart rhythms) and chest pain. Some people take them to treat high blood pressure too, but it's not as common. Amiodarone (Pacerone) is another medication that treats arrhythmias, but it works in a different way.

All three medications can cause drug interactions. Diltiazem, verapamil, and amiodarone affect how your body breaks down Verzenio. Again, they can slow down Verzenio's breakdown, causing Verzenio to accumulate. Side effects are more likely to happen as a result.

Make sure your oncologist is aware of your heart conditions and heart medications. They can adjust your Verzenio dose to ensure you stay safe, especially if you're already stable on your current cardiac regimen. Alternatively, your cardiologist may be able to change your heart medication to a different one that doesn't interact with Verzenio. These types of changes are made on a case-by-case basis.

4. Grapefruit

Grapefruit is a food you may want to think twice about the next time you peruse the produce at your local grocery store. It can cause a similar interaction as some of the medications above. Think of grapefruit as something that can "boost" your medication dose more than intended.

Verzenio is no exception to this. Eating or drinking grapefruit products can affect Verzenio, making medication levels escalate in your body. This increases the risk of Verzenio side effects. It's a good idea to avoid grapefruit products entirely while you're taking Verzenio.

You can opt for other related options, though. Apple juice, orange juice, and tomato juice don't interact with Verzenio and are great alternatives to grapefruit. Your oncologist can tell you more about foods and drinks to avoid while taking Verzenio or other cancer medications.

5. Anti-seizure medications

Carbamazepine (Tegretol, Equetro), phenobarbital (Luminal), and phenytoin (Dilantin) are prescription medications that treat specific types of seizures. But they may also impact other medications that you take, such as Verzenio.

Anti-seizure medications are effective for their given uses. However, they can have the unintended effect of speeding up how quickly your liver processes and removes Verzenio from your body. When your liver works faster, Verzenio levels drop. The treatment may not be as effective against breast cancer as a result.

There's no best choice for managing both seizures and cancer. It's a balancing act, as everyone's experiences with seizures and cancer are unique. Your oncologist and neurologist will likely work together to find the treatment approach that's best for you.

6. Select antibiotics

Antibiotics treat infections caused by bacteria. Most of them play well with Verzenio, but certain antibiotics can be problematic when paired with it. Clarithromycin (Biaxin XL) and erythromycin (Ery-Tab) are two examples.

These antibiotics slow down the breakdown of Verzenio, causing it to build up in your body. Again, this increases the risk of side effects such as nausea, diarrhea, and more.

Your prescriber should prescribe an antibiotic that doesn't interact with Verzenio. However, if your antibiotic can't be changed from clarithromycin or erythromycin, your oncologist may temporarily adjust your Verzenio dose. Alternatively, they may monitor you for side effects.

Thankfully, antibiotics are usually taken for a short period of time. Your oncologist will likely adjust your Verzenio dose back to normal after you complete your antibiotic course.

7. St. John's wort

St. John's wort is a dietary supplement that some people take for depression and anxiety. Many people think supplements are safe because they come from natural sources. But it can meaningfully affect other medications you take. It's known for causing interactions - even though it's readily available over the counter (OTC).

St. John's wort can affect how well Verzenio works. Taking St. John's wort can decrease your body's Verzenio levels. Verzenio may not be effective for treating cancer if Verzenio levels drop in your blood.

Speak to your oncologist if you're experiencing symptoms of anxiety or depression. They can refer you to a psychiatrist or psychologist to help you weigh safe and effective treatment options, such as prescription medications and/or cognitive behavioral therapy.