Busulfan
Alkylating agents
Alkylating agentsHigh alert
An error with this medicine can cause serious harm: double checks and protocols are used.
An alkyl sulfonate that wipes out the bone marrow before a stem cell transplant. It can cause seizures, liver veno-occlusive disease and lung fibrosis.
Quick facts
- Group
- Alkylating agents
- Target
- DNA (guanine N7), cross-linked by the alkyl sulfonate
- Used for
- Conditioning
- Key effects
- Profound · Nausea · Infections
- Monitor
- Blood counts · Neurological status
- ATC
- L01AB01
No doses: the clinician sets them by the current guideline.
Mechanism of action
Busulfan has two methanesulfonate groups that leave easily, so each end of the molecule bonds to a guanine. It cross-links DNA strands and joins DNA to proteins. It is especially toxic to bone marrow stem cells, which is why it is used to empty the marrow (myeloablation) before a transplant.
- The two sulfonate groups leave, creating reactive ends
- Each end bonds to a guanine: DNA is cross-linked
- Bone marrow stem cells die (myeloablation)
Indications
- Conditioning, with cyclophosphamide, before allogeneic stem cell transplantation for chronic myeloid leukaemia. Chronic myeloid leukaemia →
Adverse effects
Common
- Profound, prolonged myelosuppression (expected)
- Nausea, vomiting, mucositis
- Infections
Contraindications
- Hypersensitivity to any of its components
Key interactions
- Itraconazole and metronidazole
- Reduce busulfan clearance; metronidazole has been linked to more toxicity.
- Deferasirox (iron chelators)
- Reduces busulfan clearance; chelators are stopped well before conditioning.
- Paracetamol (acetaminophen)
- Lowers glutathione, which busulfan needs for its elimination; used with caution around the infusion.
What is monitored
- Blood counts (marrow recovery after the transplant)
- Liver tests and bilirubin daily during conditioning (veno-occlusive disease)
- Neurological status (seizures)
- Weight and abdominal girth
Administration and safety
- Anticonvulsant prophylaxis is started before the first dose.
- Given only in transplant units with stem cells ready to infuse: without them the marrow damage can be fatal.
- Hazardous drug: chemotherapy handling precautions.
Pregnancy and breastfeeding
Can cause fetal harm; effective contraception is needed.
Nursing care
- Confirm that seizure prophylaxis was given before each dose.
- Weigh daily and check for painful liver enlargement, fluid gain or jaundice.
- Strict infection precautions during the period of no marrow function.
- Teaching: report breathlessness or a persistent cough, even months later.
Pharmacokinetics
- Absorption
- Intravenous for transplant conditioning; an oral form also exists.
- Distribution
- Crosses the blood–brain barrier, which explains the seizures.
- Metabolism
- Mostly conjugated with glutathione (spontaneously and by glutathione S-transferase), then oxidised in the liver.
- Elimination
- As metabolites in the urine.
Test yourself
Think of the answer, then tap the question to see it.
What is busulfan mainly used for today?
To destroy the bone marrow (conditioning) before a stem cell transplant.
Why is an anticonvulsant given before busulfan?
Busulfan crosses into the brain and can cause seizures.
Which liver complication of transplant conditioning is linked to busulfan?
Hepatic veno-occlusive disease (sinusoidal obstruction syndrome).
Connections
← Back to the class: Alkylating agents
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: DailyMed - BUSULFAN injection, solution, concentrate (DailyMed (U.S. National Library of Medicine), 2026); Busulfan: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.