Melphalan

What is this medication for?

• Multiple myeloma (drug of choice with prednisone); ovarian carcinoma, lymphoreticular neoplasms, osteosarcoma, mammary/pulmonary neoplasms; DMAC rescue protocol (relapsed multicentric lymphoma)
• Lymphoreticular neoplasms per protocol

How is it given?

Give exactly as your veterinarian prescribed — never change the dose or stop on your own unless your veterinarian has told you to.

• Myeloma package: melphalan + prednisone, response tracked by paraprotein (serum Ig/ globulins), indefinite low-dose continuation, relapse signaled by bone pain/bleeding/eye changes/Ig rise.

What if I miss a dose?

• Give it as soon as you remember — unless it is almost time for the next dose (then skip the missed one; never double up).
• Call your clinic if you miss more than one dose in a row.

Side effects — what should I watch for?

Effects listed as common in this handout

• stomach/intestinal (loss of appetite, vomiting, diarrhea) (Common)
• Allopurinol-requiring hyperuricemia (Tumor-lysis companion (myeloma))

Worth a phone call to your veterinarian

• Bone marrow depression (low red blood cell counts, low platelet counts, low white blood cell counts) (Dose-limiting; cumulative marrow toxicity with chronic therapy)
• Pulmonary infiltrates/fibrosis (Less common, serious)

⚠️ Contact your veterinarian or an emergency clinic IMMEDIATELY if you notice

• Trouble breathing, collapse, seizures, severe vomiting or diarrhea, facial swelling, or pale gums

Before starting (or refilling), tell your veterinarian if your pet:

• has or has had: Anemia/marrow depression (unless disease-related), infection, renal impairment, marrow infiltrated by tumor, prior chemo/radiation

• is pregnant, nursing, or used for breeding
• is taking any other medications, supplements, or flea/tick products, including:
  • Prednisone
  • Other myelosuppressives
  • Allopurinol

Storage and handling

Chemo handling; accurate dosing essential (tiny doses); refrigerate per label.

Good to know

• Myeloma package: melphalan + prednisone, response tracked by paraprotein (serum Ig/ globulins), indefinite low-dose continuation, relapse signaled by bone pain/bleeding/eye changes/Ig rise.
• No hepatic activation needed — the "clean" alkylator pharmacologically, but pays for it with cumulative marrow fibrosis (watch platelets over months).
• DMAC = the named rescue protocol (Dactinomycin-Melphalan-Ara-C + Dex) for relapsed lymphoma — melphalan's second job.