Melphalan
Alkylating agents
Alkylating agentsHigh alert
An error with this medicine can cause serious harm: double checks and protocols are used.
Phenylalanine mustard for multiple myeloma, oral or intravenous (high doses before an autologous transplant). Myelosuppression is its main toxicity.
Also called: L-phenylalanine mustard, melphalan hydrochloride
Quick facts
- Group
- Alkylating agents
- Target
- DNA (guanine N7), cross-linked by the mustard
- Used for
- Multiple myeloma · Ovarian cancer
- Key effects
- Myelosuppression · Nausea · Hair loss
- Monitor
- Blood counts before each dose · Kidney function
- ATC
- L01AA03
No doses: the clinician sets them by the current guideline.
Mechanism of action
Melphalan is a nitrogen mustard attached to the amino acid phenylalanine. Its two chloroethyl arms bond to guanines on both DNA strands and cross-link them, blocking replication and transcription.
- Melphalan, a phenylalanine mustard, reaches the myeloma cell
- Its two arms bond to guanines on opposite strands
- Cross-linked DNA cannot be copied: myeloma cells die
Indications
- Multiple myeloma: oral or intravenous palliative treatment, and high-dose conditioning before an autologous stem cell transplant. Multiple myeloma →
- Ovarian cancer (oral). Ovarian cancer →
Adverse effects
Common
- Myelosuppression (leukopenia, thrombocytopenia)
- Nausea, vomiting, diarrhoea, mouth ulcers
- Hair loss
- Amenorrhoea and suppressed testicular function
Contraindications
- Previous hypersensitivity to melphalan
- Previous resistance to melphalan
Key interactions
- Nalidixic acid
- Severe haemorrhagic necrotic enterocolitis in children given intravenous melphalan.
- Ciclosporin
- Severe renal failure after intravenous melphalan followed by ciclosporin.
- Carmustine
- Intravenous melphalan may lower the threshold for carmustine lung toxicity.
What is monitored
- Blood counts before each dose
- Signs of hypersensitivity during intravenous infusion
- Kidney function
Administration and safety
- The intravenous form is not injected directly into a peripheral vein; it is infused into a running line, and a central line is considered when veins are poor.
- The reconstituted solution is unstable and is given promptly.
- Hazardous drug: chemotherapy handling precautions.
Pregnancy and breastfeeding
Can cause fetal harm; pregnancy is avoided during treatment.
Nursing care
- Watch closely during the first minutes of an intravenous infusion for hypersensitivity.
- Check the infusion site for extravasation.
- Infection and bleeding precautions during the low-count period.
- Teaching: infertility and second cancers are long-term risks; contraception during treatment.
Pharmacokinetics
- Absorption
- Oral (variable) or intravenous.
- Metabolism
- Mainly chemical hydrolysis to inactive mono- and dihydroxy forms; a small part leaves unchanged in the urine, so poor kidney function deepens myelosuppression.
Test yourself
Think of the answer, then tap the question to see it.
Which cancer is melphalan most associated with?
Multiple myeloma.
Which amino acid is part of melphalan's structure?
Phenylalanine (melphalan is L-phenylalanine mustard).
Why is intravenous melphalan not injected directly into a peripheral vein?
Extravasation can damage tissue; it is given into a running line or a central vein.
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 - MELPHALAN- melphalan hydrochloride kit (DailyMed (U.S. National Library of Medicine), 2026); Melphalan: 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.