Ropeginterferon alfa-2b
Ropeginterferon alfa-2b is an interferon alfa medication used to treat adults with polycythemia vera and essential thrombocythemia, two blood disorders that cause the bone marrow to overproduce blood cells.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 1 clinical label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
BESREMi carries a serious warning: it can cause or worsen dangerous conditions involving mental health, the immune system, blood circulation, and infection. These include severe depression, suicidal thoughts, autoimmune reactions, reduced blood flow to organs, and serious infections. Some of these reactions can be fatal. Your doctor will monitor you closely with regular check-ups and lab tests. If your symptoms become severe or keep getting worse, BESREMi will need to be stopped. In many — but not all — cases, these problems go away after stopping the medication. Watch for signs like worsening depression, unusual thoughts, signs of infection, or new physical symptoms and report them to your doctor right away.
📖 Ropeginterferon alfa-2b: Patient Information Guide
A plain-language walkthrough of Ropeginterferon alfa-2b — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Ropeginterferon alfa-2b is an interferon alfa medication approved for two related blood disorders in adults:
- Polycythemia vera — BESREMi is used to treat adults with this condition, where the bone marrow overproduces red blood cells, raising the risk of blood clots and other complications
- Essential thrombocythemia — BESREMi is used to treat adults with this condition, where the bone marrow overproduces platelets, which can lead to clotting or bleeding problems
⚙️How it works▾
Ropeginterferon alfa-2b belongs to a family of proteins called type I interferons. It works by binding to a specific receptor on bone marrow cells called IFNAR (interferon alfa receptor). This binding sets off a cascade of signals inside the cell — activating enzymes known as JAK1 and TYK2, and proteins called STATs — that travel to the cell's nucleus and change which genes are active. The end result is a reduction in the overproduction of blood cells that defines polycythemia vera and essential thrombocythemia. The complete picture of how all these effects produce the therapeutic benefit is still being studied.
💊How it's taken▾
BESREMi is given as a subcutaneous injection (under the skin) every two weeks, with the dose gradually increased over the first several weeks until blood counts are stabilized. For polycythemia vera, patients transitioning from hydroxyurea follow a specific overlap and tapering schedule guided by their doctor. Once blood counts have been stable for at least one year on a steady dose, the schedule may be extended to every four weeks.
- No specific food restrictions are noted, but follow your prescriber's instructions for timing
- Blood counts must be checked every two weeks during dose adjustment and every three to six months during the maintenance phase
- If a dose is interrupted due to side effects, your doctor will guide you on when and how to resume
🤒Side effects — in detail▾
The most commonly reported side effects vary somewhat by condition but generally include:
- Elevated liver enzymes (seen on routine blood tests)
- Flu-like symptoms: fever, chills, and muscle aches
- Fatigue and general feeling of being unwell
- Itching (pruritus)
- Joint pain (arthralgia)
- Anemia (low red blood cell count)
- Hair loss (alopecia)
- Nausea, diarrhea, or headache
- Low white blood cell counts (leukopenia)
More serious reactions — including severe depression, blood clots, heart problems, thyroid disorders, liver toxicity, and serious infections — require prompt medical attention and may mean the drug needs to be paused or stopped.
⚠️Warnings & precautions▾
The most critical warning is the risk of serious neuropsychiatric, autoimmune, ischemic, and infectious disorders — some of which can be fatal. Depression and mood disturbances were seen in a notable portion of patients in clinical trials. BESREMi must not be started in anyone with a history of severe depression, suicidal thoughts, or prior suicide attempt.
- Mental health: Watch for worsening depression, suicidal thoughts, aggression, or confusion — these can appear even in people with no prior psychiatric history
- Thyroid: Hypothyroidism, hyperthyroidism, and autoimmune thyroiditis have all been reported; thyroid function should be checked if symptoms develop
- Cardiovascular: Blood clots, irregular heart rhythms, and reduced blood flow to the heart have occurred; BESREMi should be avoided in patients with severe or unstable heart disease
- Liver: Liver enzyme elevations are common; serious liver toxicity requires dose reduction or discontinuation
- Fetal harm: BESREMi can harm an unborn baby — a pregnancy test is required before starting, and effective contraception must be used throughout treatment
- Other serious risks: Pancreatitis, colitis, lung toxicity, kidney toxicity, and serious eye problems have also been reported and may require stopping the drug
🔀What it interacts with▾
BESREMi can interact with several types of medications, so always give your doctor and pharmacist a full list of everything you take:
- CYP450 substrates with a narrow therapeutic index (such as certain blood thinners or seizure medications) — BESREMi may slow how the body processes these drugs, raising their levels and risk of side effects; your doctor may need to adjust those doses
- Myelosuppressive agents (drugs that suppress bone marrow, like certain chemotherapy medications or hydroxyurea) — combining them with BESREMi can dangerously lower blood counts; avoid unless closely monitored
- Narcotics, sedatives, and sleep aids — combining these with BESREMi can intensify central nervous system side effects such as confusion, excessive sedation, or mood problems; avoid where possible
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Severe psychiatric history: BESREMi is contraindicated if you have or have had severe depression, suicidal thoughts, or a suicide attempt
- Autoimmune disease: Do not use BESREMi if you have an active, serious, or untreated autoimmune condition
- Liver impairment: BESREMi is contraindicated in moderate (Child-Pugh B) or severe (Child-Pugh C) liver impairment
- Organ transplant: BESREMi must not be used by immunosuppressed transplant recipients
- Allergy to interferons: Do not use if you have had a hypersensitivity reaction to any interferon product or to any ingredient in BESREMi
- Heart or vascular disease: Tell your doctor if you have cardiovascular disease, a history of blood clots, recent heart attack, or recent stroke — you will need closer monitoring or may need to avoid BESREMi
- Pregnancy: BESREMi can harm a fetus; a pregnancy test is required before starting, and effective contraception must be used throughout treatment
- Breastfeeding: Breastfeeding is not recommended while using BESREMi
- Kidney problems: BESREMi should be avoided if you develop severe kidney impairment during treatment; your doctor will monitor kidney function
🚑If you take too much▾
Taking too much BESREMi may cause flu-like symptoms or worsen other known side effects. There is no antidote. If an overdose is suspected, seek medical attention and monitor closely for adverse reactions. Contacting the Poison Help line at 1-800-222-1222 or a medical toxicologist is recommended for guidance.
📡Pharmacodynamics — effects in the body▾
The effectiveness of BESREMi depends on its ability to bring blood counts back into a normal range — specifically stabilizing hematocrit (the proportion of red blood cells in the blood), platelet counts, and white blood cell counts. In polycythemia vera, the target is a hematocrit below 45%, platelets below a certain threshold, and normalized white cell counts. Achieving and maintaining this hematological stability is the measure of the drug working as intended.
🔬Pharmacokinetics — how your body processes it▾
After a subcutaneous injection, BESREMi is absorbed slowly — in polycythemia vera patients, peak levels are reached within about 2 to 5 days, while in essential thrombocythemia patients, peak levels occur roughly 62 to 123 hours after dosing. The drug has a long half-life of approximately 7 days in polycythemia vera patients, meaning it stays in the body for an extended period, which supports the every-two-week dosing schedule. BESREMi is broken down through a combination of receptor-mediated degradation and other elimination pathways, with a clearance rate that can vary by dose. Age, sex, body surface area, and JAK2 mutation status do not significantly affect how the body handles the drug.
📦How to store it▾
Store in the refrigerator between 36°F to 46°F (2°C to 8°C) in the original carton to protect from light. DO NOT FREEZE.
📄 Written from Ropeginterferon alfa-2b’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
Supplements & herbs that interact with Ropeginterferon alfa-2b
57 supplements and herbal products have documented interactions with Ropeginterferon alfa-2b in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.
- Major · 3
- Moderate · 53
- Minor · 1
Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Ropeginterferon alfa-2b — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is BESREMi being used to treat — is it a type of cancer? ▾
How do I take this medication — do I have to go to a clinic every time? ▾
What side effects should I expect, and which ones mean I need to call my doctor? ▾
Can I take my other medications while on BESREMi? ▾
Is it safe to get pregnant or breastfeed while on BESREMi? ▾
How will my doctor know the medication is working? ▾
Is Ropeginterferon alfa-2b available over the counter? ▾
When was Ropeginterferon alfa-2b first available? ▾
💬 Answers drafted from Ropeginterferon alfa-2b’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Ropeginterferon alfa-2b comes
Ropeginterferon alfa-2b is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Injection
How this form is used
- BESREMi is used to treat adults with polycythemia vera (a disorder causing too many red blood cells)
- BESREMi is used to treat adults with essential thrombocythemia (a disorder causing too many platelets)
- BESREMi is given as an injection under the skin (subcutaneous), typically every two weeks; after sustained blood count stability, your doctor may extend this to every four weeks
- BESREMi dosing is started at a low level and gradually increased based on your blood counts and how well you tolerate the medication
- BESREMi Pen is one of the available delivery options for the subcutaneous injection — follow your prescriber's or pharmacist's instructions for proper use
- Keep all scheduled blood count monitoring appointments — testing is required every two weeks during dose adjustment and every three to six months during the maintenance phase
📊 Ropeginterferon alfa-2b across the U.S. market
How Ropeginterferon alfa-2b appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
📈 How widely Ropeginterferon alfa-2b is used
A general measure of how commonly Ropeginterferon alfa-2b is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Ropeginterferon alfa-2b is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Ropeginterferon alfa-2b prescribed? Of the 1,596 medications we measure, Ropeginterferon alfa-2b ranks #1,341 by Medicaid prescriptions — more than 16% of them.
Utilization by Ropeginterferon alfa-2b product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
1 ML ropeginterferon alfa-2b-njft 0.5 MG/ML Prefilled Syringe
Summed across the 1 of 1 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 2587064
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Ropeginterferon alfa-2b, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 1 of 1 listed Ropeginterferon alfa-2b NDCs with Medicaid activity.
🔍 Compare Ropeginterferon alfa-2b products
A representative set of FDA-listed product records for Ropeginterferon alfa-2b — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Injection | ||||
| 500 mcg/0.5 mL | Subcutaneous | PharmaEssentia USA × 2 listings | BLA | View NDC → |
| 500 mcg/mL | Subcutaneous | PharmaEssentia USA × 5 listings | BLA | View NDC → |
Showing 7 of 7 products — FDA National Drug Code Directory. See every product, package size and price: browse all 7 Ropeginterferon alfa-2b NDCs →
📈 What people report — real-world data (FDA FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Ropeginterferon alfa-2b — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Ropeginterferon alfa-2b in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
🏛️ The road to your pharmacy
How Ropeginterferon alfa-2b went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
Source: openFDA drug enforcement (recall) reports.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 2587059 2 dose forms · 2 strengths
-
Dose form (SCDF) Pen Injector RxCUI 2748663In current FDA listingsClinical drug / strength (SCD) 0.5 ML ropeginterferon alfa-2b-njft 1 MG/MLRxCUI 2748665 -
Dose form (SCDF) Prefilled Syringe RxCUI 2587063No current FDA listingClinical drug / strength (SCD) 1 ML ropeginterferon alfa-2b-njft 0.5 MG/MLRxCUI 2587064
Look up RxCUI 2587059 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
📦 Supply & shortage status
Whether Ropeginterferon alfa-2b is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
🏷️ Sold under these brand names
🏭 Manufacturers & labelers
RxNorm drug class
Ropeginterferon alfa-2b belongs to the Interferon alfa-2b class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
🔬 Where this comes from
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 1 FDA-filed SPL label set within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. PharmaEssentia USA is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.