Pemazyre has possible interactions with some other drugs and certain supplements. Examples include phenytoin, diltiazem, and St. John’s wort. Talk with your doctor to avoid potentially harmful effects from Pemazyre interactions.

Pemazyre is prescribed to treat certain types of cancer in adults, including:

  • bile duct cancer* (cholangiocarcinoma) that has been previously treated and:
    • cannot be removed by surgery or has spread to other areas of the body
    • has specific changes in the fibroblast growth factor receptor 2 gene
  • a type of blood cancer called myeloid/lymphoid neoplasm (MLN) that hasn’t responded to treatment or has come back after past treatment and has specific changes in the fibroblast growth factor receptor 1 gene.

An interaction occurs when one substance causes another substance to have a different effect than expected.

By learning about possible Pemazyre interactions, you can work with your doctor to ensure Pemazyre will be safe and effective for you to take.

* For this use, Pemazyre has received accelerated approvalTrusted Source from the Food and Drug Administration (FDA). This means the drug has been approved for this purpose based on limited data from early clinical trials. A decision regarding full approval will be made once additional clinical trials have been completed.

Before you start treatment with Pemazyre, tell your doctor and pharmacist about any prescription, over-the-counter, and other medications you take. By sharing this information with them, you may help prevent possible interactions.

To learn whether Pemazyre interacts with supplements, herbs, or vitamins, see the “Pemazyre and other interactions” section.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Here’s a table of drugs that can interact with Pemazyre. Keep in mind this table doesn’t include all drugs that may interact with Pemazyre. Some of these interactions are described in detail in “Drug interactions in depth.”

Drug class or drug nameDrug examplesInteraction result with Pemazyre
certain antibiotics• clarithromycin
• erythromycin (Erythrocin, Ery-Tab, others)
• ciprofloxacin (Cipro)		can increase the risk of side effects from Pemazyre
certain antifungals• itraconazole (Sporanox, Tolsura)
• ketoconazole
• voriconazole (Vfend)
• fluconazole (Diflucan)		can increase the risk of side effects from Pemazyre
certain calcium channel blockers• verapamil (Verelan)
• diltiazem (Cartia XT, Cardizem CD, others)		can increase the risk of side effects from Pemazyre
certain HIV drugs• Ritonavir (Norvir)
• cobicistat (Tybost)		can increase the risk of side effects from Pemazyre
certain seizure medications• phenytoin (Dilantin)
• carbamazepine (Tegretol, Equetro, others)		can make Pemazyre less effective
certain cancer drugs• apalutamide (Erleada)
• enzalutamide (Xtandi)
• mitotane (Lysodren)
• dabrafenib (Tafinlar)		can make Pemazyre less effective
rifampin (Rimactane)–can make Pemazyre less effective
nefazodone–can increase the risk of side effects from Pemazyre
aprepitant (Emend)–can increase the risk of side effects from Pemazyre
cyclosporine (Gengraf, Neoral, others)– can increase the risk of side effects from Pemazyre

There are no known interactions between Pemazyre and alcohol. However, if you drink alcohol, your doctor may advise you to avoid or limit it during Pemazyre treatment.

This is because drinking alcohol while taking the drug may worsen some of Pemazyre’s side effects. For example, you may be more likely to experience:

  • nausea
  • vomiting
  • headache
  • dehydration
  • dizziness
  • mouth sores

If you have questions about drinking alcohol while taking Pemazyre, talk with your doctor.

Here’s a closer look at certain drug interactions of Pemazyre.

Certain calcium channel blockers

Taking Pemazyre with certain calcium channel blockers can increase the risk of side effects of Pemazyre. This is because some calcium channel blockers can cause your body to break down Pemazyre more slowly. When this happens, more of the drug stays in your system. This can lead to a higher risk of side effects from Pemazyre, such as fatigue, hair loss, and mouth sores.

Here are some calcium channel blockers that may interact with Pemazyre:

  • verapamil (Verelan)
  • diltiazem (Cartia XT, Cardizem CD, others)

Steps you or your doctor may take

Your doctor will likely avoid prescribing Pemazyre with certain calcium channel blockers. If you are taking a calcium channel blocker that interacts with Pemazyre, they may have you switch to a different medication before prescribing Pemazyre for you. However, if they decide you must take a calcium channel blocker that interacts with Pemazyre, your doctor will likely prescribe a lower dose of Pemazyre to reduce the risk of side effects.

Talk with your doctor or pharmacist if you have questions or concerns about taking Pemazyre with a calcium channel blocker.

Certain seizure medications

Taking Pemazyre with certain seizure medications can make Pemazyre less effective. This is because some seizure medications can cause your body to break down Pemazyre faster than usual, reducing the amount of drug in your system. As a result, Pemazyre may be less effective in treating your cancer.

Here are some seizure medications that may interact with Pemazyre:

  • phenytoin (Dilantin)
  • carbamazepine

Steps you or your doctor may take

Your doctor will likely avoid prescribing Pemazyre with certain seizure medications. If you are taking a seizure medication that interacts with Pemazyre, they may have you switch to a different medication to treat your seizures before prescribing Pemazyre for you.

Talk with your doctor or pharmacist. If you have questions or concerns about taking Pemazyre with a seizure medication.

Certain antifungal medications

Taking Pemazyre with certain antifungal medications can increase the risk of side effects of Pemazyre. This is because some antifungals can cause your body to break down Pemazyre more slowly. When this happens, more of the drug stays in your system. This can lead to a higher risk of side effects from Pemazyre, such as fatigue, hair loss, and mouth sores.

Here are some antifungals that may interact with Pemazyre:

  • itraconazole (Sporanox, Tolsura)
  • ketoconazole
  • voriconazole (Vfend)
  • fluconazole (Diflucan)

Steps you or your doctor may take

If you have a fungal infection, your doctor will likely try to avoid prescribing an antifungal medication that interacts with Pemazyre. But if they decide it’s necessary to use one of these antifungals, your doctor may lower your dose of Pemazyre while you’re taking the antifungal. After your infection has cleared and you stop taking the antifungal, your doctor will likely increase Pemazyre back to your original dosage.

Talk with your doctor or pharmacist if you have questions about taking Pemazyre with an antifungal drug.

Pemazyre may have other interactions, such as with supplements, foods, vaccines, or lab tests.

Here are some potential interactions with Pemazyre. Keep in mind that the following information does not include all possible Pemazyre interactions.

Pemazyre interactions with supplements

Before you start treatment with Pemazyre, tell your doctor and pharmacist about any supplements, herbs, and vitamins you take. By sharing this information with them, you may help prevent possible interactions.

If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Pemazyre interactions with herbs

Doctors will typically recommend that you avoid taking St. John’s wort with Pemazyre. St. John’s wort is an herbal supplement that some people use to treat depression and other conditions.

St. John’s wort may speed up the activity of an enzyme in your body called cytochrome P450 3A4 (CYP3A4). This enzyme helps break down Pemazyre.

By speeding up this enzyme, St. John’s wort can cause Pemazyre to break down more quickly. And this may lead to a low level of Pemazyre in your system. If the level of Pemazyre in your system is too low, the drug may not work to treat your cancer.

Your doctor may be able to suggest a treatment option other than St. John’s wort.

Pemazyre interactions with vitamins

There are no specific reports of vitamins interacting with Pemazyre. However, that doesn’t mean vitamin interactions won’t occur or be recognized in the future. Because of this, you should talk with your doctor or pharmacist before taking any vitamin product with Pemazyre.

Pemazyre interactions with food

Grapefruit and grapefruit juice can interact with Pemazyre. Specifically, grapefruit products can block the CYP3A4 enzyme, which helps to break down Pemazrye. This can raise the level of Pemazyre in your body, which increases your risk of side effects from Pemazyre. Due to this risk, your doctor may recommend not consuming grapefruit and grapefruit juice while taking the drug.

Pemazyre interactions with vaccines

There are no known interactions between Pemazyre and vaccines. Talk with your doctor or pharmacist to check whether you’re due for any vaccines.

Pemazyre interactions with lab tests

Pemazyre is not known to interact with lab tests. If you have concerns about this medication interacting with lab tests, talk with your doctor.

PEMAZYRE INTERACTION WITH CANNABIS OR CBD

Cannabis (often called marijuana) and cannabis products, such as cannabidiol (CBD), have not been specifically reported to interact with Pemazyre. However, as with any drug or supplement, talk with your doctor before using cannabis in combination with Pemazyre. The impact of cannabis may affect how well you stick to your Pemazyre treatment plan.

Note: Cannabis is illegal at a federal level but is legal in many states to varying degrees.

Certain medical conditions and other factors may increase the risk of interactions with Pemazyre. Before you take this drug, be sure to talk with your doctor about your health history. Pemazyre may not be the right treatment option if you have certain medical conditions or other factors affecting your health.

Health conditions or factors that might interact with Pemazyre include:

  • Severe liver or kidney problems: If you have severe liver or kidney problems, your body doesn’t get rid of Pemazyre as quickly as usual. This can cause the amount of drug to build up in your body, which may increase the risk of side effects. If you have severe liver or kidney problems, your doctor will likely prescribe a lower dosage of Pemazyre to reduce this risk.
  • Eye or vision problems: If you have dry eye syndrome or retinal pigment epithelial detachment, taking Pemazyre may worsen your condition. Before starting Pemazyre, talk with your doctor. They can determine if Pemazyre is safe for you to take and discuss possible risks.
  • Allergic reaction: If you’ve had an allergic reaction to Pemazyre or any of its ingredients, your doctor will likely not prescribe Pemazyre. Taking the drug could cause another allergic reaction. You can ask them about other treatments that may be better choices for you.
  • Breastfeeding: There isn’t enough information to determine whether the drug passes into breast milk or what effects Pemazyre may have on a child who is breastfed. If you’re breastfeeding or planning to, talk with your doctor before using Pemazyre. They can talk with you about treatment options and ways to feed a child other than breastfeeding.
  • Pregnancy: Pemazyre has not been shown to be safe to use during pregnancy. Animal studies show that the drug may cause congenital anomalies (commonly known as birth defects) or pregnancy loss. However, it’s important to note that animal studies don’t always indicate what may happen in humans. If you’re pregnant or planning to become pregnant, tell your doctor before starting Pemazyre. They can advise you on the right treatment plan for you.

Here are some frequently asked questions about Pemazyre and possible interactions.

Does Pemazyre interact with diabetes medications?

No, Pemazyre has not been reported to interact with diabetes medications. But it can cause side effects like loss of appetite or weight loss, which may affect blood sugar regulation. Pemazyre can also increase blood sugar in some people. If you have diabetes, your doctor may recommend monitoring your blood sugar levels more frequently while taking Pemazyre.

Talk with your doctor or pharmacist if you have questions about taking diabetes medication or monitoring your blood sugar during treatment with Pemazyre.

Do pain relievers like ibuprofen or acetaminophen interact with Pemazyre?

No, there weren’t any drug interactions reported with over-the-counter pain relievers like ibuprofen or acetaminophen. However, since Pemazyre can affect the liver, taking too much acetaminophen may increase the risk of liver damage. If you need to take acetaminophen, it’s best to use it in moderation and follow the recommended dosage.

If you have any questions about taking an over-the-counter pain medication, talk with your doctor or pharmacist.

You can take certain steps to help prevent interactions with Pemazyre. Your doctor and pharmacist are key resources, so reaching out to them before starting treatment is a helpful first step. For example, it’s important that you plan to do the following:

  • Let them know if you drink alcohol or use cannabis.
  • Tell them about any other medications you take, as well as any supplements, herbs, and vitamins.
  • Create a medication listTrusted Source, which your doctor and pharmacist can help you fill out.

It’s also important to read the Pemazyre label and other paperworkTrusted Source that may come with the drug. The label may have colored stickers that mention an interaction. The paperwork, sometimes called the medication guide or patient package insert, may contain details about interactions.

If Pemazyre doesn’t come with paperwork, you can ask your pharmacist to print a copy. If you need help reading or understanding this information, ask your doctor or pharmacist.

You can also help prevent interactions with Pemazyre by taking it exactly as your doctor prescribes.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.