Home/Medicines/Chlorambucil
All medicines

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

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

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.

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.

References

References

Textbooks & handbooks

  • Plumb, D.C. Plumb's Veterinary Drug Handbook. 10th ed., Wiley-Blackwell, 2023.
  • Vail, D.M., Thamm, D.H., & Liptak, J.M. (eds.). Withrow & MacEwen's Small Animal Clinical Oncology. 6th ed., Saunders/Elsevier, 2020.
  • Riviere, J.E., & Papich, M.G. (eds.). Veterinary Pharmacology and Therapeutics. 10th ed., Wiley-Blackwell, 2018.
  • National Research Council. Nutrient Requirements of Dogs and Cats. National Academies Press, Washington DC, 2006.
  • The Merck Veterinary Manual. Merck & Co., Online edition. https://www.merckvetmanual.com/

Clinical guidelines & consensus

  • Fletcher, D.J., Boller, M., Brainard, B.M., et al. "RECOVER Evidence and Knowledge Gap Analysis on Veterinary CPR." Journal of Veterinary Emergency and Critical Care, 2012;22(S1):S102–S131.
  • American Animal Hospital Association. 2018 AAHA Diabetes Management Guidelines for Dogs and Cats. AAHA Press.

Journals & peer-reviewed studies

  • Hogan, D.F., Fox, P.R., Jacob, K., et al. "Secondary prevention of cardiogenic arterial thromboembolism in the cat: The FAT CAT study." Journal of Veterinary Cardiology, 2015;17(Suppl 1):S306–S317.
  • Boswood, A., Häggström, J., Gordon, S.G., et al. "Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study — A Randomized Clinical Trial." Journal of Veterinary Internal Medicine, 2016;30(6):1765–1779.
  • ASPCA Animal Poison Control Center. Toxicology and Poison Management Guidelines. American Society for the Prevention of Cruelty to Animals. https://www.aspca.org/pet-care/animal-poison-control

Regulatory & approvals

  • Central Drugs Standard Control Organisation (CDSCO), Government of India. Veterinary Drug Approval Registry, 1969–2026. Directorate General of Health Services. https://cdsco.gov.in/

Databases

  • Washington State University, College of Veterinary Medicine. Veterinary Clinical Pharmacology Laboratory (VCPL) — MDR1 Multidrug Sensitivity Database. https://vcpl.vetmed.wsu.edu/
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 →

Related medicines

Other medicines in the same class (Alkylating agent).

Busulfan
Rx
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.
dogcat
Cyclophosphamide
Rx
Prodrug metabolized by hepatic P450 to active phosphoramide mustard, which cross-links DNA; also immunosuppressive via lymphocyte depletion
dogcat
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.
dogcat