Inrebic (fedratinib) is a medication used to treat a rare type of blood cancer called myelofibrosis (MF) in adults. It’s a JAK inhibitor that helps stop abnormal blood cells from growing too much. This medication is a tablet that you take by mouth once a day. But common side effects include diarrhea, nausea, and anemia (low red blood cells). There’s also a risk of a serious brain problem called Wernicke encephalopathy.
Inrebic (fedratinib) is a JAK inhibitor. It blocks proteins in the body called Janus kinase, or JAK. In people with myelofibrosis, these proteins don’t work properly and cause abnormal blood cells to grow.
By blocking JAK, Inrebic (fedratinib) helps stop abnormal blood cells from growing out of control.
| Common Brands | Inrebic |
|---|---|
| Drug Class | JAK inhibitor |
| Controlled Substance Classification | Not a controlled medication |
| Generic Status | No lower-cost generic available |
| Availability | Prescription only |
The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Contact your healthcare provider immediately if you experience any of the following.
Side effects that you should report to your care team as soon as possible:
Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):
Inrebic (fedratinib) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
It’s rare, but some people taking Inrebic (fedratinib) developed a serious brain problem called encephalopathy. One type, called Wernicke encephalopathy, can happen when vitamin B1 (thiamine) levels are too low.
Before starting Inrebic (fedratinib), your oncologist or hematologist will check your vitamin B1 levels. If they’re low, you’ll need to take vitamin B1 supplements first to get them back up before you can start treatment.
While you’re taking Inrebic (fedratinib), you’ll need to take vitamin B1 supplements. This will help prevent your levels from getting too low. Your care team will check your vitamin B1 levels as needed.
Watch for symptoms of Wernicke encephalopathy while taking Inrebic (fedratinib) . This can include trouble speaking or walking, confusion, or memory loss. It can also cause fast back-and-forth eye movements or double vision. If you notice any of these symptoms, get medical help right away.
Inrebic (fedratinib) can cause anemia, or low red blood cell count. It can sometimes drop dangerously low. On average, red blood cell counts go down during the first few months of treatment. Then, they can go back up a little and stay steady months later.
Inrebic (fedratinib) can also cause low platelet levels. This can sometimes be serious.
To help keep you safe, your hematologist or oncologist will check your blood counts with a blood test. This is done before you start Inrebic (fedratinib) and as needed during treatment. If your blood counts are too low, you might need to take a break from the medication or take a lower dose. If it’s serious, you also might need blood transfusions to keep your blood counts in a safe range.
Anemia can make you feel more tired than usual. And low platelets can make you bleed and bruise more easily. If this happens while you’re taking Inrebic (fedratinib), let your care team know. Get medical help right away if you have bleeding that’s hard to stop or blood in your urine or stool. These can be signs of serious bleeding.
Common side effects of Inrebic (fedratinib) include nausea, vomiting, and diarrhea. These are usually mild or moderate but can still be uncomfortable. They often start in the first 2 weeks of treatment, sometimes even on the first day.
Talk to your care team about ways to help prevent stomach problems while taking Inrebic (fedratinib). Taking the medication with a high-fat meal might help with nausea and vomiting. Your oncologist or hematologist might also give you an antiemetic medication, like ondansetron (Zofran). For diarrhea, they might suggest taking over-the-counter medication like loperamide (Imodium A-D).
If these side effects don’t get better within 2 days of trying to manage them yourself, call your care team. You might need to take a break from Inrebic (fedratinib) and then restart at a lower dose later.
Inrebic (fedratinib) can sometimes cause higher liver enzyme levels. These lab results can be a sign of liver damage or irritation. It’s usually mild or moderate and rarely severe. Most times, these lab changes can happen about 1 month or so after starting the medication.
Before starting Inrebic (fedratinib), your oncologist or hematologist will check your liver enzyme levels with lab tests. They’ll keep checking periodically during treatment and as needed. If your test results are abnormal, you might need to pause treatment and then restart the medication later at a lower dose.
If you notice yellowing of your skin, yellowing of the whites of your eyes, or new belly pain, let your care team know. These can be signs of liver problems.
It’s not common, but some people taking Inrebic (fedratinib) had high levels of certain digestive proteins. This includes high amylase and lipase levels. These lab changes can happen within the first month of treatment. Having high digestive protein levels can mean that your pancreas is irritated. If it gets too irritated, it might lead to pancreatitis or an inflamed pancreas.
Your oncologist or hematologist will check your amylase and lipase levels with lab tests. They’ll check before you start Inrebic (fedratinib), during treatment, and as needed. If your levels are high, you might need to stop the medication for a short time so you can recover. Then, you might restart the medication later at a lower dose.
It’s not common, but some people taking Inrebic (fedratinib) have had inflammation inside the eye (uveitis). This has happened several months after starting the medication and can come back. It can be mild or more serious.
Watch for signs of eye inflammation while taking Inrebic (fedratinib). This can include eye pain, redness, sensitivity to light, floaters, or unclear vision. If this happens, tell your care team. They’ll probably send you to an eye specialist. Treatment often includes steroid eye drops or other steroid medications.
People with rheumatoid arthritis (RA) who took a similar JAK inhibitor had a higher risk of serious health problems. These included heart-related death, heart attack, and stroke.
It’s important to know about this risk, even though Inrebic (fedratinib) isn’t used for RA. Tell your oncologist or hematologist about all your medical conditions and if you’ve smoked before. They can help decide if Inrebic (fedratinib) is safe for you. Talk to your oncologist or hematologist if you have concerns about this risk.
Call 911 right away if you have any signs of a heart attack or stroke. A heart attack can look like sudden chest pain, nausea, or sweating. And a stroke can cause a droopy face, sudden weakness on one side of the body, a sudden headache, or trouble walking or talking.
Some people with rheumatoid arthritis (RA) who took a similar JAK inhibitor had blood clots during treatment. This included deep vein thrombosis (DVT) and pulmonary embolism (PE).
Although Inrebic (fedratinib) isn’t used for RA, it works in a similar way and might have the same risk. Watch for symptoms of a blood clot like swelling or tenderness in one arm or leg, sudden chest pain, or trouble breathing. If this happens, get medical help right away.
Some people with rheumatoid arthritis (RA) who took a different JAK inhibitor have had a higher risk of developing new cancers, such as lymphoma. The risk of having a new cancer appears to be higher in people who smoke.
Inrebic (fedratinib) isn’t approved for RA. But it’s important to be aware of the risk of possible new cancers during treatment. Tell your care team if you have cancer, are a smoker, or are a past smoker. They can discuss with you about the risks and benefits of taking Inrebic (fedratinib). Talk with your oncology or hematology care team if you’re worried about the risk of a new cancer.
Don’t pause or stop taking Inrebic (fedratinib) without talking to your oncologist or hematologist. Your MF symptoms can get worse if you stop. This can include fever, breathing problems, low blood pressure, or other serious problems.
Your oncologist or hematologist can help decide if pausing or stopping Inrebic (fedratinib) is right for you. If it’s needed for other reasons besides serious side effects, your care team can tell you how to do this in a safe way. They'll lower your dose slowly before you can stop.
The typical dose is 400 mg by mouth once a day.
Your dose might be different if you have kidney problems. It also might be different if you take certain medications that interact with Inrebic (fedratinib).
Your oncologist or hematologist can adjust the dose if you have serious or bothersome side effects.
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No, Inrebic isn’t a traditional chemotherapy medication. It’s a targeted therapy. It works by blocking a protein in the body called JAK. In myelofibrosis, this protein tells abnormal blood and immune cells to grow. By blocking JAK, Inrebic helps stop these abnormal cells from growing. This is different from traditional chemotherapy, which destroys all fast-growing cells in the body.
Your oncologist or hematologist will have you take vitamin B1 (thiamine) while taking Inrebic. Some people have had a rare but serious brain problem called Wernicke encephalopathy during treatment. This brain problem is usually caused by low vitamin B1. To help your vitamin levels stay high enough, you’ll usually take 100 mg of vitamin B1 (thiamine) by mouth each day. Talk to your care team if you have questions about this risk or which vitamin B1 supplement to take.
Take Inrebic for as long as your oncologist or hematologist tells you to. You usually keep taking it as long as it’s helping you and not causing bothersome or serious side effects. Your care team will check how well Inrebic is working with lab tests and by asking you about your symptoms. They’ll also watch for side effects and check your blood counts, digestive protein levels, and vitamin levels. This helps them check that the medication is still safe for you to take. Don’t stop taking Inrebic without talking to your care team first. Stopping it suddenly can make your MF symptoms come back. Talk to your care team if you have questions about how long to take Inrebic.
If you have kidney problems, talk to your oncologist or hematologist before you start Inrebic. They can make sure it’s safe for you. Your kidneys help remove the medication from your body. If your kidneys don’t work well, the medication can stay in the body longer, build up, and raise your risk of side effects. If you have severe kidney problems, your prescriber will have you take a lower dose to help keep you safe.
Inrebic and Jakafi are both JAK inhibitors used to treat myelofibrosis (MF). They can help shrink the spleen and improve symptoms. Both are pills that are taken by mouth. But Inrebic is taken once a day, while Jakafi is taken twice a day. In general, Jakafi is often considered first in treatment. Both medications can cause low blood cell counts and anemia. But Inrebic also has a rare but serious risk of a brain problem called Wernicke encephalopathy. Talk to your oncologist or hematologist to compare and see which best fits your needs.
We don’t know if Inrebic is safe to take while pregnant. There isn’t enough information, but animal studies suggest it might harm an unborn baby. If you can become pregnant, are planning to be, or get pregnant during treatment, talk to your oncologist or hematologist. They can explain the risks and benefits of taking Inrebic and help choose the safest option.
Don’t breastfeed while taking Inrebic and for at least 1 month after your last dose. We don’t know if the medication can pass into breast milk and what effects it could have on your milk supply or your baby. But there’s a potential for serious side effects to your baby. Talk to your oncologist, hematologist, or a lactation specialist about safer feeding options.
