[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Alkylating agents](https://durgical.com/en/pharmacology/classes/alkylating-agents/) › Busulfan

# Busulfan

## Alkylating agents?

Alkylating agents

## High 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.

Updated Nov 1, 2026

## Quick facts

**Group**
[Alkylating agents](https://durgical.com/en/pharmacology/classes/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.

On this page

- The basics Mechanism of action
- Indications
- Adverse effects
- Pharmacokinetics
- Memory aid

- Clinical What the labels mean

- Safety Contraindications
- Key interactions
- What is monitored
- Administration and safety
- Pregnancy and breastfeeding
- Nursing care

- Study Test yourself

- Connections Connections

## 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 →](https://durgical.com/en/conditions/chronic-myeloid-leukaemia/)

## Adverse effects

### Common

- Profound, prolonged myelosuppression (expected)
- Nausea, vomiting, mucositis
- Infections

### Serious (rare, important)

- Seizures
- Hepatic veno-occlusive disease (sinusoidal obstruction: weight gain, painful liver, jaundice)
- Bronchopulmonary dysplasia with pulmonary fibrosis («busulfan lung») with long-term use
- Cardiac tamponade reported in children with thalassaemia on high-dose busulfan with cyclophosphamide

## 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.

## Memory aid

«BUSulfan BUSts the marrow»: before a transplant, with seizure prophylaxis; watch the liver (veno-occlusive disease) and the lungs (fibrosis).

## 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).

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[More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology)

## What the labels mean

**High alert**
An error with this medicine can cause serious harm: double checks and protocols are used.

## Connections

## Related drugs 2

- [Cyclophosphamide](https://durgical.com/en/pharmacology/cyclophosphamide/)
- [Melphalan](https://durgical.com/en/pharmacology/melphalan/)

## Related conditions 1

- [Chronic myeloid leukaemia](https://durgical.com/en/conditions/chronic-myeloid-leukaemia/)

[← Back to the class: Alkylating agents](https://durgical.com/en/pharmacology/classes/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](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=086a715e-4958-4bb5-9ebd-86171e6b6203) (DailyMed (U.S. National Library of Medicine), 2026); [Busulfan: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a682248.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L01AB01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/busulfan/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/busulfan/