Melphalan
4-[bis(2-chloroethyl)amino]-L-phenylalanine
Also known as: Alkeran · L-PAM · Phenylalanine mustard · L-sarcolysin
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Dosing by species
Dosing data for this drug is not yet available in the VetSheet formulary. Every other section below is complete. Consult the current product label before prescribing.
Overview
Melphalan is a cytotoxic alkylating agent primarily used in veterinary oncology for the treatment of multiple myeloma. It is also utilized as an alternative to cyclophosphamide in canine lymphoma rescue protocols and for the management of certain solid tumors, including ovarian carcinoma, osteosarcoma, and pulmonary or mammary neoplasia.
Clinical Warning: Melphalan is a potent cytotoxic drug. Strict safety and handling protocols must be followed to prevent accidental exposure to personnel and owners.
Mechanism of action
Melphalan acts as a bifunctional alkylating agent. It forms inter- and intrastrand cross-links with DNA → alters DNA structure → inhibits DNA synthesis and function, ultimately leading to cell death (apoptosis), particularly in rapidly dividing neoplastic cells.
Safety & warnings
Contraindications
- Bone marrow suppression
- Concurrent infection
- Impaired renal function
Adverse effects
- Myelosuppression (leucopenia, thrombocytopenia)
- Anorexia
- Nausea
- Vomiting
- Pulmonary infiltrates
- Pulmonary fibrosis
- Oral ulceration (reported in humans)
Precautions
Cytotoxic Handling: Melphalan is a cytotoxic drug; refer to specialist texts for safe handling and administration of chemotherapeutic agents.
Dosing Warning: Take extreme care when dosing small dogs using their body surface area (BSA). There is a significant risk of overdose due to the fixed tablet sizes. Tablets should not be split.
- Administration: Give tablets on an empty stomach to maximize absorption.
- Toxicity: Myelosuppression is the dose-limiting toxicity; its effects may be prolonged and cumulative.
Drug interactions
Decreases the oral bioavailability of melphalan
Enhance the antitumour effects of melphalan
Enhances the risk of renal toxicity (reported in humans)
Monitoring
- Complete Blood Count (CBC) - monitor for leucopenia and thrombocytopenia
- Renal function panel
- Gastrointestinal signs (anorexia, vomiting)
- Respiratory rate and effort (for pulmonary infiltrates/fibrosis)
Pharmacokinetics
Half-life
Absorption
Oral absorption is highly variable and incomplete. Administration with food significantly decreases bioavailability.
Distribution
Distributes rapidly into total body water; moderate protein binding.
Metabolism
Undergoes spontaneous chemical degradation (hydrolysis) rather than extensive hepatic metabolism.
Elimination
Eliminated primarily via the kidneys as inactive metabolites and some unchanged drug.
Overdose
Overdosage primarily manifests as severe myelosuppression (profound neutropenia and thrombocytopenia) and severe gastrointestinal toxicity (vomiting, diarrhea, ulceration). Treatment is supportive, including broad-spectrum antibiotics for neutropenia, antiemetics, and potentially blood transfusions or colony-stimulating factors.
Available products
Formulations
- Oral: 2 mg tablet
- Injection: 50 mg powder in vial plus diluent
Human-labeled
- Alkeran 2 mg tablets
- Alkeran 50 mg powder for injection
Regulatory status
Human-approved drug used off-label in veterinary medicine.
POM (Prescription Only Medicine). Human-approved drug used off-label under the cascade.
POM. Human-approved drug used off-label under the cascade.
No regulatory data for: 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Tablets should be stored in a closed, light-protected container under refrigeration (2-8°C).
Client information
- Safe Handling: This is a chemotherapy drug. Wear disposable gloves when handling the medication and when cleaning up your pet's waste (urine, feces, vomit) for several days after administration.
- Administration: Give this medication on an empty stomach. Do not crush, break, or split the tablets.
- Monitoring: Watch closely for signs of infection (fever, lethargy), unusual bleeding or bruising, loss of appetite, vomiting, or diarrhea. Contact your veterinarian immediately if these occur.
- Storage: Keep the tablets in the refrigerator (2-8°C) in a tightly closed, light-protected container.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.