Busulfan
Busulfan is an alkylating chemotherapy drug used for chronic myelogenous leukemia (CML), either as a daily tablet for symptom relief or as an IV infusion to prepare the body for a stem cell transplant.
🧬 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 9 clinical label sets 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 →
Busulfan is an older alkylating chemotherapy (it attaches to DNA and damages fast-growing cells) for chronic myelogenous leukemia (CML), given as Myleran tablets to ease the disease or by IV with cyclophosphamide before a donor stem cell transplant; on the U.S. market since about 1954 and available generically, it is now used mostly in that transplant setting, since newer targeted drugs largely replaced the tablets. It is hard on the body, and nausea, vomiting, mouth sores and poor appetite are common. Its boxed warning is severe, prolonged bone marrow suppression (very low blood counts), so expect frequent blood tests and report fever, bleeding, breathing changes or yellowing skin right away.
Clinical pearls
- Avoid acetaminophen (Tylenol) for 72 hours before and during a busulfan infusion, since it may slow busulfan clearance.
- Anti-seizure medicine is given before the infusion because busulfan can cause seizures, so mention any seizure history or head injury.
- Tell every prescriber you are on busulfan; metronidazole, itraconazole and iron chelators like deferasirox can raise its levels and toxicity.
- A new cough or breathlessness months or years later can signal busulfan lung scarring, so report it even after treatment ends.
⚠️ FDA Boxed Warning — the FDA’s strongest safety alert ▾
Myleran can severely suppress the bone marrow, so it should only be used for firmly diagnosed CML and under a doctor experienced with chemotherapy.
The risk is a dangerous drop in blood cells. Your doctor should lower or stop the dose at the first sign of an unusual fall in any blood cell type, and may check the bone marrow if the picture is unclear. Busulfan has also been linked to leukemia and other cancers.
Patient information guide A plain-language walkthrough of Busulfan, written from its FDA label.
What Busulfan is used for
▾
Busulfan is used for chronic myelogenous leukemia (CML), with product-specific roles.
- Myleran (oral tablet): palliative treatment of CML.
- Busulfex and Busulfan Injection (IV): used with cyclophosphamide as a conditioning regimen before allogeneic hematopoietic progenitor cell (stem cell) transplantation for CML.
How Busulfan works
▾
Busulfan is a bifunctional alkylating agent. In water it breaks down and releases reactive pieces that attach to DNA. The resulting DNA damage is thought to be responsible for much of its cell-killing effect.
Busulfan dosage
▾
The two forms are used very differently.
- Myleran tablets are taken by mouth, usually daily. Your doctor adjusts treatment by watching white blood cell counts, and stops it before they reach the normal range.
- Busulfex and Busulfan Injection are given by your care team as a 2-hour IV infusion through a central line, every 6 hours for 4 days, with cyclophosphamide afterward.
- You get anti-seizure and anti-nausea medicine before the injection.
Follow your prescriber and the product label.
Dosing details from the FDA-approved label
From the Busulfan prescribing information (“Dosage and Administration”). Doses are set by your prescriber for your product, condition, kidney function and age — never change a dose on your own.
- Busulfex / busulfan injection (intravenous) in adults, conditioning regimen prior to bone marrow or peripheral blood progenitor cell replacement, given in combination with cyclophosphamide
- 0.8 mg per kg (ideal body weight or actual body weight, whichever is lower) intravenously via a central venous catheter as a two-hour infusion every six hours for four consecutive days for a total of 16 doses (Days -7, -6, -5 and -4)
- Cyclophosphamide 60 mg per kg intravenously as a one-hour infusion on each of two days beginning no sooner than six hours fol
- For patients weighing more than 12 kg; for obese or severely obese patients, base dosing on adjusted ideal body weight (AIBW = IBW + 0.25 x (actual weight - IBW)); premedicate with anticonvulsants and antiemetics
- Myleran (oral busulfan), remission induction in adults
- 4 to 8 mg, total dose, daily
- On a weight basis approximately 60 mcg/kg of body weight or 1.8 mg/m2 of body surface, daily (same for pediatric patients and adults)
- Daily doses exceeding 4 mg per day should be reserved for patients with the most compelling symptoms; withhold the drug when the total leukocyte count has declined to approximately 15,000/mcL
- Myleran (oral busulfan), maintenance therapy when remission is shorter than 3 months
- 1 to 3 mg daily
- Treatment is resumed with the induction dosage when the total leukocyte count reaches approximately 50,000/mcL
Read the label’s full dosing text
2 DOSAGE AND ADMINISTRATION Pre-medicate with anticonvulsants (e.g. benzodiazepines, phenytoin, valproic acid or levetiracetam) and antiemetic ( 2.1 , 5.2 ) Dilute and administer as intravenous infusion. Do not administer as intravenous push or bolus ( 2.1 , 2.3 ) Recommended adult dose: 0.8 mg per kg of ideal body weight or actual body weight, whichever is lower, administered intravenously via a central venous catheter as a two-hour infusion every six hours for four consecutive days for a total of 16 doses ( 2.1 ) 2.1 Initial Dosing Information • Administer busulfan injection in combination with cyclophosphamide as a conditioning regimen prior to bone marrow or peripheral blood progenitor cell replacement. For patients weighing more than 12 kg, the recommended doses are: o Busulfan injection 0.8 mg per kg (ideal body weight or actual body weight, whichever is lower) intravenously via a central venous catheter as a two-hour infusion every six hours for four consecutive days for a total of 16 doses (Days -7, -6, -5 and -4). o Cyclophosphamide 60 mg per kg intravenously as a one-hour infusion on each of two days beginning no sooner than six hours following the 16 th dose of busulfan injection (Days -3 and -2). o Administer hematopoietic progenitor cells on Day 0. • Premedicate patients with anticonvulsants (e.g., benzodiazepines, phenytoin, valproic acid or levetiracetam) to prevent seizures reported with the use of high dose busulfan injection. Administer anticonvulsants 12 hours prior to busulfan injection to 24 hours after the last dose of busulfan injection [see Warnings and Precautions (5.2) ]. • Administer antiemetics prior to the first dose of busulfan injection and continue on a fixed schedule through busulfan injection administration. • Busulfan injection clearance is best predicted when the busulfan injection dose is administered based on adjusted ideal body weight. Dosing busulfan injection based on actual body weight, ideal body weight or other factors can produce significant differences in busulfan injection clearance among lean, normal and obese patients.
Excerpted — the section continues on the label. Read the full Dosage and Administration section on DailyMed →
Busulfan side effects
▾
Side effects are common and often significant, especially with the IV form used before transplant.
Common side effects
- Severe drop in blood counts (myelosuppression)
- Nausea and vomiting
- Mouth sores (stomatitis)
- Loss of appetite and diarrhea
- Trouble sleeping and anxiety
- Fever and headache
- Abdominal pain
- Low magnesium or potassium, and high blood sugar
When to get medical help
- Call your care team right away about fever, signs of infection, unusual bruising or bleeding, or severe tiredness. These can signal low blood counts.
- Get help for a new cough, shortness of breath, or low-grade fever. This can be a rare lung problem that may appear months to years later.
- Report yellowing of the skin or eyes, belly pain or swelling, or weight gain. These can signal a serious liver blood vessel problem (hepatic veno-occlusive disease).
- Seek help for seizures or confusion.
- Report abdominal pain with vomiting, chest pain, or trouble breathing right away. Cardiac tamponade (fluid squeezing the heart) has been reported, mostly in children with thalassemia.
- Tell your doctor about blood in the urine or pain when urinating.
Busulfan warnings and precautions
▾
- Bone marrow suppression is the biggest risk. Blood counts are monitored closely.
- Seizures have been reported, so anti-seizure medicine is given before the injection.
- Hepatic veno-occlusive disease (a blocked liver blood vessel problem) can be life threatening. Liver tests are checked often.
- Lung scarring (bronchopulmonary dysplasia with pulmonary fibrosis) is rare but serious and can appear years later.
- Cardiac tamponade has been reported in children with thalassemia.
- Busulfan may cause secondary cancers and leukemia.
- It can harm an unborn baby and affect fertility.
Busulfan interactions
▾
Several drugs change how fast your body clears busulfan.
- Metronidazole: slows clearance and has been tied to more toxicity.
- Itraconazole: slows clearance by up to 25%.
- Iron chelating agents (such as deferasirox): can raise busulfan exposure.
- Acetaminophen: may slow clearance if used within 72 hours before or during the injection.
- Phenytoin: speeds clearance by 15% or more.
Interactions listed in the FDA-approved label
From the Busulfan prescribing information (“Drug Interactions”): what the manufacturer studied or reported to the FDA.
- Itraconazole: Itraconazole decreases busulfan clearance by up to 25%.
- Metronidazole: Metronidazole decreases the clearance of busulfan to a greater extent than does itraconazole; coadministration has been associated with increased busulfan toxicity.
- Fluconazole: Fluconazole (200 mg) has been used with Busulfan Injection.
- Deferasirox / iron chelating agents: Decreased clearance of busulfan was observed with concomitant use with deferasirox; the mechanism is not fully elucidated. Discontinue iron chelating agents well in advance of administration of Busulfan Injection to avoid increased exposure to busulfan.
- Acetaminophen: Use prior to (less than 72 hours) or concurrent with Busulfan Injection may result in reduced busulfan clearance, because acetaminophen decreases glutathione levels in the blood and tissues.
- Phenytoin: Phenytoin increases the clearance of busulfan by 15% or more, possibly due to induction of glutathione-S-transferase; clearance at the recommended dose may be lower and exposure (AUC) higher in patients not treated with phenytoin.
Read the label’s full interactions text
7 DRUG INTERACTIONS Drugs that Decrease Busulfan Injection Clearance: Metronidazole, itraconazole, iron chelating agents, acetaminophen. ( 7.1 ) Drugs that Increase Busulfan Injection Clearance: Phenytoin. ( 7.2 ) 7.1 Drugs that Decrease Busulfan Injection Clearance Itraconazole decreases busulfan clearance by up to 25%. Metronidazole decreases the clearance of busulfan to a greater extent than does itraconazole; metronidazole coadministration has been associated with increased busulfan toxicity. Fluconazole (200 mg) has been used with Busulfan Injection. Decreased clearance of busulfan was observed with concomitant use with deferasirox. The mechanism of this interaction is not fully elucidated. Discontinue iron chelating agents well in advance of administration of Busulfan Injection to avoid increased exposure to busulfan. Because busulfan is eliminated from the body via conjugation with glutathione, use of acetaminophen prior to (less than 72 hours) or concurrent with Busulfan Injection may result in reduced busulfan clearance based upon the known property of acetaminophen to decrease glutathione levels in the blood and tissues. 7.2 Drugs that Increase Busulfan Injection Clearance Phenytoin increases the clearance of busulfan by 15% or more, possibly due to the induction of glutathione-S-transferase. Since the pharmacokinetics of Busulfan Injection were studied in patients treated with phenytoin, the clearance of Busulfan Injection at the recommended dose may be lower and exposure (AUC) higher in patients not treated with phenytoin.
Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.
Before taking Busulfan
▾
- Do not use if you are allergic to busulfan or any ingredient.
- Myleran should not be used unless CML is firmly diagnosed.
- Tell your doctor about prior radiation or chemotherapy.
- Tell your doctor about seizure disorders, head injury, or seizure-triggering medicines.
- Use effective contraception during treatment. The injection label advises 6 months afterward for women and 3 months for men.
- Do not breastfeed during treatment with the injection.
- Fertility may be affected, temporarily or permanently.
Busulfan overdose
▾
There is no known antidote to busulfan. The main toxic effects are bone marrow depression and very low blood counts. Blood counts should be watched closely with strong supportive care, and dialysis may be considered.
What Busulfan does in the body
▾
Busulfan damages DNA in rapidly dividing cells. This suppresses the bone marrow, which is why blood counts fall. With Myleran, white cell counts typically do not drop in the first 10 to 15 days and may keep falling for over a month after stopping.
How your body processes Busulfan
▾
Oral busulfan is absorbed almost completely from the gut. It is cleared quickly, with a half-life of about 2.6 hours. It is mostly broken down in the liver, and less than 2% leaves in the urine unchanged. The injection reaches the cerebrospinal fluid at levels about equal to the blood.
How to store Busulfan
▾
stored under refrigerated conditions between 2° to 8°C (36° to 46°F). refrigerated conditions (2° to 8°C) for up to 12 hours but the infusion must be completed within that time.
Written from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
Supplements & herbs that interact with Busulfan
148 supplements and herbal products have documented interactions with Busulfan 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 · 104
- Minor · 41
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.
Nutrient depletion considerations
Busulfan has been associated with lower levels of 1 nutrient in the clinical literature. This does not mean a deficiency will occur — it means these may be worth discussing with your pharmacist or healthcare provider, especially with long-term use.
Educational information from a licensed clinical database (Natural Medicines) — not medical advice. Do not start or stop medications or supplements without professional guidance.
Busulfan: pharmacist answers to common questions
Quick, plain-English answers to the questions patients ask most about Busulfan — the kind of thing our pharmacy team would talk through with you at the counter.
What is busulfan for?
▾
How will I get it?
▾
What side effects should I expect?
▾
When should I call my doctor?
▾
Do I need to avoid any medicines?
▾
Is it safe in pregnancy?
▾
Is Busulfan available over the counter?
▾
When was Busulfan first available?
▾
Who makes Busulfan?
▾
Answers drafted from the FDA-approved label with AI and reviewed by our pharmacy team. How we use AI →
More about Busulfan on HelloPharmacist
Busulfan forms and strengths (how it comes)
Busulfan is available in 2 forms. 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
- Busulfex and Busulfan Injection are used with cyclophosphamide before an allogeneic stem cell transplant for chronic myelogenous leukemia.
- Busulfex and Busulfan Injection are diluted and given as an IV infusion through a central venous catheter, never as an IV push.
- Busulfex and Busulfan Injection are given over 2 hours every 6 hours for 4 days, followed by cyclophosphamide.
- Anti-seizure and anti-nausea medicines are given before Busulfex and Busulfan Injection.
Tablet
How this form is used
- Myleran is used for the palliative treatment of chronic myelogenous leukemia.
- Myleran is taken by mouth, usually once daily.
- Myleran dosing is guided by white blood cell counts, and it is stopped before counts fall into the normal range.
- Myleran patients are checked about monthly during remission.
Busulfan on the U.S. market: products, makers and brands
How Busulfan 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.
8 companies list 9 Busulfan product records with the FDA, mostly as injection, tablet; the earliest marketing or approval year on record is 1954. Brand names on the directory include Myleran; the rest are generics.
FDA-listed product records by dose form (tablet variants merged) — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
Also listed with the FDA, not a patient dose form: Powder (6) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
Compare Busulfan products
A representative set of FDA-listed product records for Busulfan — 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 | ||||
| 6 mg/mL | Intravenous | Accord Healthcare, Inc | ANDA | View NDC → |
| 6 mg/mL | Intravenous | Amneal Pharmaceuticals LLC | ANDA | View NDC → |
| 6 mg/mL | Intravenous | Eugia US LLC | ANDA | View NDC → |
| 6 mg/mL | Intravenous | Hospira, Inc. | ANDA | View NDC → |
| 6 mg/mL | Intravenous | Meitheal Pharmaceuticals Inc. × 2 listings | ANDA | View NDC → |
| 6 mg/mL | Intravenous | Pharmascience Inc. | ANDA | View NDC → |
| 6 mg/mL | Intravenous | Sagent Pharmaceuticals | ANDA | View NDC → |
| 💊Tablet | ||||
| 2 mg | Oral | Waylis Therapeutics LLC | NDA | View NDC → |
Showing 9 of 9 products — FDA National Drug Code Directory. See every product, package size and price: browse all 9 Busulfan NDCs →
Busulfan side effects reported to the 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 Busulfan — 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 Busulfan 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.
Busulfan FDA approval history
How Busulfan went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
Busulfan 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.
The FDA’s enforcement reports list one Busulfan recall since July 2021. It is still ongoing. A recall names specific lots from one company, so check the lot number on your own bottle rather than assuming every product is affected; your pharmacist can check whether your supply came from an affected lot.
- Busulfan Injection, 60 mg per 10 mL (6 mg per mL), 8x10 mL Single-Dose Vials, Rx only, Mfd. for Sagent Pharmaceuticals, Schaumburg, IL 60195, Made in Canada, NDC 25021-241-10. Lots: Lot #: 656412, Exp. Date 08/31/2026; 659646, Exp. Date 03/31/2027. FDA record D-0539-2026 →
Source: FDA enforcement (recall) reports, via openFDA; our copy was last updated Sep 24, 2026.
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 1828 2 dose forms · 2 strengths
-
Dose form (SCDF) Injection RxCUI 1729351In current FDA listingsClinical drug / strength (SCD) 10 ML busulfan 6 MG/MLRxCUI 253113 -
Dose form (SCDF) Oral Tablet RxCUI 371165In current FDA listingsClinical drug / strength (SCD) 2 MGRxCUI 197422
Look up RxCUI 1828 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.
Busulfan supply and shortage status
Whether Busulfan 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.
Busulfan brand names
Busulfan is sold under one brand name in the FDA directory — Myleran. A brand and its generic contain the same active ingredient; the brand name belongs to one company's product.
Who makes Busulfan: manufacturers and labelers
8 companies list Busulfan products with the FDA. By number of product records, the largest are Meitheal Pharmaceuticals Inc., Accord Healthcare, Inc, Amneal Pharmaceuticals LLC. Labelers include manufacturers and repackagers; the product in your bottle depends on which one your pharmacy stocks.
Busulfan drug class (RxNorm)
Busulfan belongs to the Alkylating Drug 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.
Sources for this Busulfan page
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 this page is built
HelloPharmacist combines public FDA and NLM records and does not author the underlying clinical facts. The plain-language sections are written with AI from the FDA-approved label text and reviewed by our pharmacy team before publication. Accord Healthcare, Inc is the representative DailyMed label linked for verification and dates. This is general education, not medical advice: always talk to your doctor or pharmacist about your own medicines. How we build and review drug pages →