BESREMi PEN
BESREMi is a prescription medicine that is used to treat adults with polycythemia vera
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Taking BESREMi
Taking BESREMi
Getting started with BESREMi and continuing treatment
BESREMi Pen™ is a single-dose prefilled pen that you administer once every 2 weeks.
Your doctor will prescribe BESREMi Pen through a specialty pharmacy, and your first prescription will be shipped directly to your home.
Storage
Store the BESREMi carton containing the prefilled pen in the refrigerator between 36°F to 46°F (2°C to 8°C).
Starting dose
Each time you use BESREMi Pen, be sure that you know your prescribed dose. Your doctor can tell you the correct dosage.
The recommended starting dosage of BESREMi Pen is 100 micrograms (or 50 micrograms in people currently taking hydroxyurea
Continuing treatment
Once you start taking BESREMi, your doctor will increase your prescribed dose until your blood cell counts are stable.
After maintaining stable blood levels for 1 year, your doctor may reduce your dosage to once every 4 weeks.
How to use BESREMi Pen: Prep. Click. Push.
Take control of your polycythemia vera (PV) with simplified administration in a ready-to-use pen. BESREMi Pen makes it easy to handle, set your dose, and self-administer.
To learn how to use BESREMi Pen, watch this video, follow step-by-step instructions, or speak to someone for guidance and assistance.
Watch the instructional video.
Read step-by-step instructions.
Speak to a healthcare provider:
- A PharmaEssentia SOURCE Case Manager
- A specialty pharmacy nurse
- Your doctor’s office
What to expect when starting BESREMi
Every person may have a different experience taking BESREMi. Because BESREMi is an
Talk with your doctor about taking acetaminophen to help reduce fever symptoms or ibuprofen to help reduce aches and pains.
Keep in mind that it may take a few months to see results with BESREMi because it targets PV at the source. By addressing the cause of PV in the bone marrow, BESREMi delivers long-term PV control.
Reaching When all blood cell counts and spleen size have returned to normal and there is an absence of thromboembolic events, typically after treatment for a blood-related condition.comprehensive disease control
10 weeks
About 27% of
patients achieved
comprehensive
disease control
at 10 weeks
on BESREMi.
7.8 months
Patients who
experienced
comprehensive
disease control
Months
Travel tips
BESREMi Pen is designed with you in mind to offer easier handling and simpler administration. It’s important to maintain your treatment routine even when you travel.
Be sure to tell the Transportation Security Administration (TSA) officer that you’re carrying a liquid pen. Ask the TSA officer for a visual inspection of your BESREMi Pen. Do not put BESREMi Pen through X-ray screening.
You’re allowed to carry BESREMi Pen in your carry-on bag. It doesn’t need to be placed in a separate clear plastic bag. It’s important to keep BESREMi Pen cold at all times in a cooler pack until you need it.
After your trip, any pens and needles that you used must be transported back in an FDA-cleared sharps disposal container. You can put the container in your checked bag or carry-on bag.
You can email or print out this Letter of Medical Necessity for Travel for your doctor to sign, indicating that you’re traveling with BESREMi Pen®.
Read this Important Safety Information carefully. It explains the serious risks of BESREMi and how to take it safely. Talk to your healthcare provider if you have any questions.
What is the most important information I should know about BESREMi®?
BESREMi® can cause serious side effects, including conditions that may cause death or may worsen certain serious diseases you may already have. If symptoms get worse, or become severe and continue, your healthcare provider may tell you to stop taking BESREMi permanently. These symptoms may go away in some people after they stop taking BESREMi.
Mental health problems, including suicide
BESREMi may cause mood or behavior problems that can get worse during treatment or after your last dose, including:
- Irritability (getting upset easily)
- Restlessness and agitation
- Confusion
- Depression (feeling low, hopeless, or bad about yourself)
- Unusually grand ideas
- Acting aggressive or impulsively
- Thoughts of hurting yourself or others, or thoughts of suicide
If you develop any of these symptoms, call your healthcare provider immediately.
New or worsening autoimmune problems
BESREMi may cause your immune system to attack healthy cells, leading to conditions such as thyroid disease, increased blood sugar (hyperglycemia), or type 1 diabetes. Call your healthcare provider if you experience:
- Extreme tiredness
- Frequent urination
- Excessive thirst
Heart problems
BESREMi may cause heart problems, including:
- Cardiomyopathy (heart muscle disease)
- Heart attack
- Irregular heartbeat (atrial fibrillation)
- Decreased blood flow to the heart
You should not take BESREMi if you have:
- Uncontrolled high blood pressure
- Congestive heart failure
- A serious abnormal heart rhythm
- Narrowing of the arteries to your heart
- Certain types of chest pain (angina)
- A recent stroke or heart attack
Who should not take BESREMi?
Do not take BESREMi if you:
- Have or had severe mental health problems, especially depression, suicidal thoughts, or attempted suicide
- Have or had a serious or untreated autoimmune disease
- Are allergic to interferon or any ingredient in BESREMi (symptoms may include itching, swelling, trouble breathing, dizziness, or chest pain)
- Have certain types of liver disease
- Have had a transplant and take immune-suppressing medication
Before using BESREMi, tell your healthcare provider about all of your medical conditions, including if you have any of the following:
Do not take BESREMi if you:
- A mental illness
- Type 1 diabetes
- Heart or bleeding problems
- Problems with your immune system
- Hepatitis B or HIV infection
- Kidney or liver problems
- Are pregnant or planning to become pregnant
- BESREMi may harm your unborn baby. Use effective birth control during treatment and for at least 8 weeks after your last dose
- BESREMi may affect your menstrual cycle and could stop your periods
- Do not breastfeed while taking BESREMi
What are the possible side effects of BESREMi? Serious side effects include:
- Low blood cell counts: taking BESREMi can lead to infections, anemia, or bleeding problems. Call your healthcare provider right away if you develop weakness and tiredness, bruising easily, nose bleeds often, fever, chills, burning and painful urination, urinating often, or coughing up yellow or pink mucus (phlegm)
- Serious allergic reactions: Get medical help right away if you get any of the following symptoms: skin rash or hives; itching; swelling of the face, eyes, lips, tongue, or throat; trouble breathing; chest pain; or feeling faint
- Eye problems: BESREMi can cause severe eye problems with your retinas that can lead to vision loss or blindness. You should have an eye exam before and during treatment with BESREMi if you have diabetes or high blood pressure and also have retinal problems
- Liver problems: BESREMi can cause increases in liver enzymes and liver damage. Your healthcare provider should do blood tests to monitor your liver enzymes and liver function before you start and during treatment with BESREMi
- Kidney problems: Your healthcare provider will do blood tests to check your kidney function before starting and during treatment with BESREMi. Tell your healthcare provider right away if you develop any symptoms of a kidney problem, including: changes in the amount or color of your urine, swelling in your ankles, blood in your urine, or loss of appetite
- Tooth and gum problems: BESREMi can cause tooth loss and/or dry mouth. It is important for you to brush your teeth well, two times each day and have regular dental examinations during treatment with BESREMi
- Skin reactions: BESREMi may cause reaction such as rash, itching, and hair loss
- Increased triglycerides: You may require blood tests to monitor levels
The most common side effects of BESREMi include:
- Flu-like symptoms, including tiredness, weakness, fever, chills, muscle aches, and joint pain
- Itching
- Sore throat
These are not all of the possible side effects of BESREMi.
Call your doctor for medical advice about side effects. You may report side effects to PharmaEssentia at 1-800-999-2449 or FDA at 1-800-FDA-1088.
Please see full Prescribing Information including Boxed Warning and Medication Guide for BESREMi.
Read this Important Safety Information carefully. It explains the serious risks of BESREMi and how to take it safely.
Talk to your healthcare provider if you have any questions.MORE 
What is the most important information I should know about BESREMi®?
BESREMi can cause serious side effects, including conditions that may cause death or may worsen certain serious diseases you may already have. If symptoms get worse, or become severe and continue, your healthcare provider may tell you to stop taking BESREMi permanently. These symptoms may go away in some people after they stop taking BESREMi.
Read this Important Safety Information carefully. It explains the serious risks of BESREMi and how to take it safely. Talk to your healthcare provider if you have any questions.MORE
What is the most important information I should know about BESREMi®?
BESREMi® may cause you to develop
Read this Important Safety Information carefully. It explains the serious risks of BESREMi and how to take it safely. Talk to your healthcare provider if you have any questions.MORE
What is the most important information I should know about BESREMi®?
BESREMi can cause serious side effects that may cause death or may worsen certain serious
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BESREMi, the BESREMi logo, and PharmaEssentia are registered trademarks of PharmaEssentia Corporation, and BESREMi Pen, the BESREMi Pen logo, the PharmaEssentia logo, PharmaEssentia SOURCE, and the PharmaEssentia SOURCE logo are trademarks of PharmaEssentia Corporation.
US-BSRM-2400203 (v2.0) 06/2025