What is chlorambucil?
Chlorambucil (brand names: Leukeran®, Chloraminophene®, Linfolysin®) is an immunosuppressive and anticancer medication used to treat certain cancers, such as leukemia, lymphoma, and multiple myeloma. It can also be used as a supplemental treatment for some immune-mediated diseases such as inflammatory bowel disease.
It is used off label (extra label) to treat cancer and immune-mediated diseases in cats, dogs, and horses. Many drugs are commonly prescribed for off-label use in veterinary medicine. “Off label” means the drug is being used in a way that has not been reviewed or approved by the U.S. Food and Drug Administration (FDA) or Health Canada. In these instances, follow your veterinarian’s directions and cautions carefully, as they may be significantly different from those on the label.
How is chlorambucil given?
- Chlorambucil is given by mouth, in the form of a tablet or a specially compounded liquid.
- Chlorambucil should be given with food.
- Do not crush, split, or liquify this medication on your own.
- Measure liquid forms extremely carefully.
Chlorambucil is considered a hazardous drug. Humans administering this medication are at risk for exposure.
- Do not handle this medication if you are pregnant or nursing.
- Always wear gloves when giving this medication, and do not reuse gloves.
- Do not allow the medication to come into contact with your skin, eyes, or mouth.
- On the day you give this medication and for a few days afterward, handle your pet’s bodily fluids carefully and wear gloves; seal the gloves and any waste in a plastic bag before disposing of them in the trash.
- Do not allow your pet to lick your skin within an hour of administration; if this occurs, wash the area thoroughly with soap and water.
This medication can take a few weeks before full effects are noted, but side effects can occur immediately. Gradual improvements are usually noticeable after a few days.
What if I miss giving my pet the medication?
If you miss a dose, contact your veterinarian for further instructions, as this medication must be dosed very carefully.
Are there any potential side effects?
Side effects may include:
- Change in the hair coat
- Fur loss
Serious side effects may occur. If any of the following signs develop, stop giving Chlorambucil and contact your veterinarian immediately:
- Abnormal bleeding
- Agitation
- Bloody diarrhea
- Bruising
- Diarrhea
- Facial twitching
- Infection
- Lack of appetite
- Low energy/depression
- Seizures
- Shortness of breath
- Vomiting
This moderate-acting medication should stop working in a few days, although effects can be longer in pets with liver or kidney disease.
Are there any risk factors for this medication?
DO NOT USE chlorambucil in pets that:
- Are allergic to it or other alkylating medications
- Have bone marrow disease
- Have active infection
- Are pregnant or lactating (use milk replacer if it is necessary to use this medication during lactation)
USE WITH CAUTION in pets that:
- Are susceptible to infections, such as elderly pets or those with chronic disease.
Do not vaccinate your pet while using this medication unless it is recommended by your veterinarian.
Are there any drug interactions I should be aware of?
The following medications should be used with caution when given with chlorambucil:
- Myelosuppressive agents
- Vaccines
Be sure to tell your veterinarian about any medications (including vitamins, supplements, or herbal therapies) that your pet is taking before starting any new treatment.
Is any monitoring needed with this medication?
- Baseline complete blood counts, blood chemistry profiles, and urinalysis will be performed before your pet starts this medication.
- Follow-up blood counts and chemistry profiles will be done every 1-3 months.
- Your veterinarian may monitor your pet to be sure that the medication is working.
How do I store chlorambucil?
- Store chlorambucil in the refrigerator between 36°F and 46°F (2°C and 8°C) and protect from light.
- The tablets can be stored short-term, up to a week, in temperatures up to 86°F (30°C).
- Liquid formulations cannot be left outside of the refrigerator, even for only a few hours.
What should I do in case of emergency?
Any overdose, no matter how small, should be considered an emergency. If you suspect an overdose or an adverse reaction to the medication, call your veterinary office immediately. If they are not available, follow their directions in contacting an emergency facility. Be prepared to provide information about the product and your pet's weight and symptoms.
