Myleran (Busulfan)

Busulfan is an alkylating antineoplastic agent used in hematologic malignancies and transplant conditioning.

• Chronic myeloid leukemia: reduces leukemic cell proliferation and helps achieve disease control.
• Acute myeloid leukemia (pre‑transplant conditioning): eradicates residual malignant cells before hematopoietic stem cell transplantation.
• Bone marrow transplantation conditioning: provides myeloablation to facilitate engraftment of donor stem cells.

• Busulfan exerts its antineoplastic effect by alkylating DNA bases, creating interstrand cross‑links that block DNA replication and transcription. The resulting DNA damage triggers apoptosis in rapidly dividing hematopoietic cells, leading to myeloablation and suppression of malignant clones.

Busulfan may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Nausea and vomiting: gastrointestinal upset commonly reported during therapy.
• Oral mucositis: painful inflammation of the mouth lining.
• Fever and chills: may indicate early infection or cytokine release.
• Alopecia: temporary hair loss during treatment.
• Skin rash: mild erythematous eruptions.

Serious or Rare Side Effects

• Pulmonary fibrosis: progressive scarring of lung tissue that can impair breathing.
• Hepatic veno‑occlusive disease: blockage of small hepatic veins leading to liver dysfunction.
• Seizures: central nervous system events, especially at high plasma concentrations.
• Severe bone marrow suppression: pancytopenia with heightened infection and bleeding risk.
• Secondary malignancies: rare development of new cancers after prolonged exposure.
• Life‑threatening infections: opportunistic infections due to profound immunosuppression.

Before initiating Busulfan therapy, several safety measures should be observed.

• Monitor blood counts: perform regular complete blood count assessments to detect myelosuppression.
• Assess liver function: check hepatic enzymes and bilirubin prior to and during treatment.
• Evaluate pulmonary status: obtain baseline lung function tests, especially in patients with prior lung disease.
• Avoid use in known hypersensitivity: discontinue if allergic reactions occur.
• Use effective contraception: advise patients to employ reliable birth control during treatment and for a defined period afterward.
• Store at ambient temperature: keep below 25°C in the original packaging, protect from moisture.

Busulfan interacts with several medicines that can alter its efficacy or toxicity.

Major Interactions (Avoid)

• Concomitant thiotepa: combined myeloablation increases risk of severe toxicity.
• Azathioprine: additive myelosuppressive effect may lead to profound pancytopenia.
• Phenytoin: enzyme induction reduces Busulfan plasma levels, compromising efficacy.
• High‑dose cyclophosphamide: overlapping toxicities heighten organ damage risk.

Moderate Interactions (Monitor Closely)

• Antifungal azoles (e.g., fluconazole): may raise Busulfan concentrations, requiring level monitoring.
• Anticonvulsants such as carbamazepine: can modify Busulfan metabolism.
• Non‑steroidal anti‑inflammatory drugs (NSAIDs): may affect platelet function and increase bleeding tendency.