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Chlorambucil

Prescription
Alkylating agent (nitrogen mustard) — antineoplastic
Last reviewed 19 Apr 2026 · PetCare.AI Editorial Team
Species
Dog, Cat
Brands
2 available
Interactions
2 documented
Formulations
1

Mechanism of action

Cross-links DNA strands via alkylation, inhibiting DNA replication and transcription in rapidly dividing cells; also has immunosuppressive properties

At a glance

Class
Alkylating agent (nitrogen mustard) — antineoplastic
Schedule
Prescription
Storage
Refrigerate at 2–8°C; handle with gloves (cytotoxic)

Dosing

🐕

Dog

Chronic lymphocytic leukemia (CLL) / Low-grade lymphoma / Immune-mediated disease
Dose
4–6 mg/m²
Route
PO
Frequency
SID (continuous) or pulse 20 mg/m² every 14 days
Max dose
12 mg
Duration: Per oncology protocol; months to years for CLL
🐈

Cat

Small cell GI lymphoma / IBD (refractory) / Immune-mediated disease
Dose
2 mg per cat
Route
PO
Frequency
Every 48–72h (pulsed protocol)
Max dose
2 mg
Duration: Long-term; often combined with prednisolone for GI lymphoma
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Formulations

💊

Tablet — 1

Strength
2mg
Available in India

Storage

Refrigerate at 2–8°C; handle with gloves (cytotoxic)

Safety

Absolute contraindications — do not use

  • Severe bone marrow suppression

Use with caution

  • Concurrent myelosuppressive drugs
    Additive marrow toxicity

Adverse effects

Common
Mild myelosuppression
GI upset
Serious
Severe leukopenia/thrombocytopenia
Secondary infections
Hepatotoxicity (rare)

Monitoring parameters

CBC every 2 weeks initially, then monthlyHepatic enzymes
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Interactions

Major — 1

Azathioprine
major
Both myelosuppressive: chlorambucil (alkylating) + azathioprine (purine analog). Severe additive bone marrow suppression.
Management: Do not combine unless under oncologist supervision with frequent CBC monitoring.

Minor — 1

Prednisolone
minor
Common therapeutic combination but corticosteroids may increase immunosuppression risk
Management: Standard COP protocol combination. Monitor CBC regularly for myelosuppression.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

Brands

International

Leukeran
Aspen/GSK

India

Chlorambucil
Celon Labs

FAQs

Frequently asked questions

›What is Chlorambucil?
Chlorambucil is a alkylating agent (nitrogen mustard) — antineoplastic used in pets. Cross-links DNA strands via alkylation, inhibiting DNA replication and transcription in rapidly dividing cells; also has immunosuppressive properties
›What is Chlorambucil used for in pets?
Chlorambucil is used in veterinary medicine for: Chronic lymphocytic leukemia (CLL) / Low-grade lymphoma / Immune-mediated disease; Small cell GI lymphoma / IBD (refractory) / Immune-mediated disease.
›What is the Chlorambucil dose for dogs?
For dogs, Chlorambucil is typically dosed as follows — Chronic lymphocytic leukemia (CLL) / Low-grade lymphoma / Immune-mediated disease: 4–6 mg/m² PO SID (continuous) or pulse 20 mg/m² every 14 days. Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What is the Chlorambucil dose for cats?
For cats, Chlorambucil is typically dosed as follows — Small cell GI lymphoma / IBD (refractory) / Immune-mediated disease: 2 mg per cat PO Every 48–72h (pulsed protocol). Always consult your veterinarian for a dose tailored to your pet's weight, age, and condition.
›What are the side effects of Chlorambucil?
Common: Mild myelosuppression, GI upset. Serious (call your vet immediately): Severe leukopenia/thrombocytopenia, Secondary infections, Hepatotoxicity (rare).
›Does Chlorambucil need a prescription?
Yes. Chlorambucil is a prescription medication and should only be administered under veterinary supervision.
›When should Chlorambucil not be used?
Do not use Chlorambucil if: Severe bone marrow suppression.
Educational reference only
This information is provided for educational purposes and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult a qualified veterinarian before administering any medication to your pet. Find a vet near you →

References

References

The PetCare.AI drug reference is built from 13 authoritative sources cited across 580 drug monographs.

Textbooks & handbooks — 5

  • Plumb's Veterinary Drug Handbook
  • Withrow & MacEwen's Small Animal Clinical Oncology
  • Merck Veterinary Manual
  • NRC Nutrient Requirements of Dogs and Cats
  • Veterinary Pharmacology and Therapeutics (Riviere & Papich)

Clinical guidelines & consensus — 4

  • ASPCA Animal Poison Control Center Guidelines
  • AAHA Diabetes Management Guidelines
  • ASPCA Poison Control Guidelines
  • RECOVER CPR Guidelines

Journals & peer-reviewed studies — 2

  • EPIC Study (J Vet Intern Med 2016)
  • JVIM FAT CAT Study

Regulatory & approvals — 1

  • CDSCO Veterinary Drug Approval Registry (1969–2026)

Databases — 1

  • Washington State University VCPL MDR1 Database

Related medicines

Other medicines in the same class (Alkylating agent).

Busulfan
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Bifunctional alkylating agent that crosslinks DNA strands via alkylation of guanine N-7 positions, interfering with DNA replication and transcription. Has remarkable specificity for myeloid cells (myeloablative) at high doses, used for conditioning before bone marrow transplant.
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Cyclophosphamide
Rx
Prodrug metabolized by hepatic P450 to active phosphoramide mustard, which cross-links DNA; also immunosuppressive via lymphocyte depletion
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Melphalan
Rx
Bifunctional alkylating nitrogen mustard derivative of phenylalanine that forms intrastrand and interstrand DNA crosslinks, preventing replication. Incorporated into tumor cells via amino acid transport systems.
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