Chlorambucil for Cats - Uses, Dose and Side Effects

Chlorambucil is an aromatic derivative of nitrogen mustard compound. It is the active ingredient in certain chemotherapy drugs and acts as a bifunctional alkylating agent. This means it attaches itself to the DNA of cancer cells, resulting in cross-linking and breaking the the structure of the DNA. The cells cannot replicate and will eventually die.

In addition to interfering with cellular DNA replication, it causes apoptosis of cells by generating an accumulation of p53 in their cytosol. Subsequently, this activates an apoptosis promoter known as Bax. In other words, it induces cell death.

Chlorambucil is also an immunosuppressive agent. For the reasons mentioned, it acts as an antitumor agent. By preventing cell replication and triggering cell death, it severely affects tumor cells which are characterized by rapid division.

Learn more about feline immunosuppression with our article on autoimmune skin disease in cats.

Due to its alkylating effects on tumor cells which cause damage to DNA chains and induce apoptosis, chlorambucil is used in metronomic chemotherapy protocols in cats. This means they are used at a relatively low dose and are administered over an extended period. This helps to reduce tumor size, but can minimize the side effects of other chemotherapy protocols. Most specifically, it is used in the treatment of the following feline cancers:

• Lymphoma
• Leukemia
• Multiple myeloma

Chlorambucil is not only used as a chemotherapy agent, but is also widely used in cats to treat inflammatory diseases, autoimmune diseases and other immune-mediated diseases. For example:

• Inflammatory bowel disease
• Immune-mediated hemolytic anemia
• Systemic lupus erythematosus
• Pemphigus
• Lymphoplasmacytic stomatitis
• Feline eosinophilic granuloma

In many cases, chlorambucil is combined with prednisolone. It may also be used when the latter is not effective or is insufficient to treat the disease from which the cat is affected.

Discover more about a drug related to prednisolone with our article on prednisone for cats.

As we have explained, chlorambucil in cats is used to treat various diseases. For this reason, its dose will depend on what is being treated, as well as other factors to be determined by the veterinarian. The following are only examples of chlorambucil for cats doses and are not a replacement for veterinary advice:

• Chemotherapy protocol: the dose is usually 20 mg/m²/day every two weeks, 2 mg every two to three days, or 15 mg/m²/day administered for four days at a frequency of every three weeks.
• Autoimmune disease treatment: a dose of 0.1-0.2 mg/kg per day is usually administered, which is then adjusted to administration every 48 hours.
• Inflammatory disease treatment: when used for inflammation of the digestive tract, the recommended dose is 2 mg/cat every 72 hours if the cat weighs less than 4 kg or 2 mg/cat every 48 hours if it weighs more than 4 kg. Alternatively, 4 mg per cat can be administered every 15 days.

As you can see, there are many determining factors when determining the chlorambucil dosage for cats. Never give this drug to your cat without express veterinary prescription.

It is important to be careful when administering chlorambucil to cats. In particular, it is a teratogenic agent that can affect developing fetuses. For this reason, it should not be handled by pregnant or breastfeeding women. In addition, chlorambucil can be irritating to the eyes, respiratory tract and skin, so it is essential to use gloves, a mask and other appropriate personal protective equipment (PPE) when handling the drug.

After administration, we must always properly dispose of any waste properly. While chlorambucil is often administered clinically, it can be given at home under strict medical guidance. The drug is administered orally and can be mixed with a little food. Breaking the tablets into smaller pieces is not recommended due to the risk of toxicity.

The price of chlorambucil varies depending on the formulation, brand and other factors. Location is important since different countries have different pricing guidelines. As a general guide, chlorambucil costs around $4 to $10 per tablet in the USA. This means that monthly administration can cost around $60 to $150, but this will depend on the individual cat and their specific needs.

Learn about the dose, side effects and cost of Solensia for cats in our related article.

Chlorambucil should not be used in pregnant or lactating cats due to the teratogenic effects, meaning it can result in birth defects or developmental disorders. It also needs to be avoided in immunosuppressed cats. It should not be administered in combination with other immunosuppressive drugs or live attenuated vaccines. In addition, its use is contraindicated in cats with allergy or hypersensitivity to chlorambucil, as well as other alkylating agents.

Learn about the symptoms and treatment of cat skin cancer in our related article.

As with any drug, chlorambucil has potential side effects. Chemotherapy drugs are particularly known for their side effects. This is because the alkylating action does not exclusively affect cancer cells. It also affects healthy cells, mainly those which carry out a similar form of rapid division. This is why they commonly affect bone marrow cells, hair follicles and those of the digestive tract, among others.

However, chlorambucil is considered to be less aggressive than many other chemotherapy agents. When we consider that it is also used in metronomic doses, the side effects tend to be less severe. Taking this into consideration, the following are potential side effects of chlorambucil for cats:

• Anorexia
• Anemia
• Thrombocytopenia
• Leukopenia
• Hemorrhages
• Dyspnea
• Lethargy
• Cerebellar toxicity
• Vomiting
• Diarrhea
• Other gastrointestinal issues

These side effects are usually transient and appear one to two weeks after starting treatment with chlorambucil. They tend to resolve within 7 to 14 days after cessation of administration. The effects on the immune system can also make the cat vulnerable to secondary infections. Although less frequent, another potential side effect is a low neutrophil count or neutropenia, which usually appears late and is reversible.

Learn about why a cat might have a low white blood cell count with our related article.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

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