Vinblastine for Dogs

Vinblastine for Dogs: a Vinca Alkaloid

Like its cousin vincristine, vinblastine is a vinca alkaloid isolated from the plant Catharanthus roseus (a type of periwinkle)¹ Vinblastine is an injectable anti-cancer drug. It is a human-labeled product, so vinblastine for dogs is technically used off-label. How amazing it is that a chemotherapeutic drug was made from such a pretty garden plant?

Although vincristine and vinblastine are distilled from the same plant their chemistry and mechanisms of action as well as their toxic effects are different. These factors influence which of these drugs might be chosen to treat your pet.

Brand Names

Vinblastine is available as a generic medication. However, it is also known as:

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Blastovin^®

Cellblastijn^®

Cytoblastin^®

Fabla^®

Lemblastine^®

Periblastine^®

Serovin^®

Solblastin^®

Velban^®

Velbe^®

Velsar^®

Xintoprost^®

How Vinblastine for Dogs Works

Vinblastine binds to cell proteins and prevents cell division (cell growth) and interferes with cellular amino acid metabolism, causing a disruption in normal cellular function.¹

Vinblastine is given intravenously (IV). It becomes heavily bound to proteins in the blood and does not distribute into the central nervous system. It is metabolized in the liver and largely excreted in bile and feces, but, to a lesser extent, also is excreted in the urine.¹

Common Uses of Vinblastine for Dogs with Cancer

Vinblastine is often used in combination with other drugs. The type and stage of your dog’s cancer, the location of the cancer, and other characteristics all play a role, not only in the choice of using vinblastine, but success of vinblastine in managing your dog’s disease.

Please note that the use of vinblastine to treat your dog is based on a discussion between you and your veterinary oncologist. There may be instances when the tumors discussed below may be better treated with other drugs. Or there may be on-going research that has found other uses for vinblastine that are appropriate for your pet. Be sure to discuss the pros and cons of these choices with your veterinarian.

Lymphoma

Vinblastine typically has fewer side effects than vincristine and can be substituted for vincristine in multidrug protocols (eg. CHOP), however higher doses of vinblastine are necessary.²

Vinblastine is not superior to vincristine in its antitumor action and is typically selected to avoid worsening signs or development of peripheral nerve damage and gastrointestinal upset often caused by vincristine. However, vinblastine can cause greater bone marrow suppression than vincristine.³

Mast Cell Cancer

Vinblastine has been used in combination with Palladia^® (toceranib phosphate) to treat aggressive mast cell neoplasia.^3,4 A 2021 study found this treatment protocol well tolerated, but found no improvement in tumor control, compared to other treatment protocols. Further study is indicated.⁶

Using vinblastine as a single agent was not as successful as using vinblastine in combination with other medications.^7,8 Other medications used to treat mast cell cancer in combination with vinblastine include CCNU,⁸ prednisone,⁹ cyclophosphamide and prednisone,^10,11 prednisone and radiation therapy.¹¹

Transitional Cell Carcinoma

In one study vinblastine was found to have anti-tumor activity for transitional cell carcinoma as a single agent and in combination with a non-steroidal anti-inflammatory drug (piroxicam).¹²

When to Not Use Vinblastine

Vinblastine should not be used or the dose reduced in patients with liver dysfunction, decreased white blood cell counts, or bacterial infections.¹

Vinblastine should be used with caution in dogs that have the MDR1 gene mutation (Collies, Australian Sheperd, and other herding breeds may have this mutation)^.1 Testing may be done prior to identify the individuals with this mutation.

The following drugs may be contraindicated when your dog is given vinblastine. Let your veterinarian know if your pet is taking these medications and discuss whether the medication should be administered at the same time.

• Ototoxic drugs (drugs that damage hearing) – examples: cisplatin, carboplatin.
• Immunosuppressive drugs – examples: azathioprine, cyclophosphamide, steroids.
• Macrolide antibiotics.
• Myelosuppressive drugs – drugs that suppress the bone marrow.
• Vaccines – immunosuppression with vinblastine will diminish the efficacy of vaccines and may increase the likelihood of reactions.¹

How to Give Vinblastine

Vinblastine is administered intravenously (IV) with the benefit of an intravenous catheter. It is typically administered every 1-2 weeks, often as part of a combined protocol with other drugs.¹

What If I Miss a Dose?

Your doctor will let you know how to proceed if a dose is missed.

Storage and Handling

Vinblastine is a strictly intravenous (IV) injectable medication that will not be stored in your home but kept in a veterinary facility and administered by a veterinarian.

Vinblastine should be administered through an IV catheter to prevent potential injection of the medication outside the vein. Injection outside the vein can cause severe tissue irritation.¹

Vinblastine Safety

After your dog receives vinblastine, for 3-5 days afterwards, the drug may be excreted in urine, feces or vomit. Wear chemotherapy resistant gloves when cleaning and place everything in sealed plastic bags and dispose of the materials.¹ Persons pregnant, nursing or attempting to conceive should not clean the pet’s waste.¹ Precautions should be taken when handling dog toys and food and water bowls as well.¹

Vinblastine Side Effects

Decreased appetite, vomiting and diarrhea are possible side effects of most chemotherapy drugs. To help with side effects, your veterinarian can prescribe supportive medications to make your pet feel better. If side effects are persistent or severe, they should be reported to your veterinarian.¹ Difficulty breathing, neurologic signs, irritation or skin sloughing at the injection site are rare side effects and should be reported immediately to your veterinarian.¹

Since Vinblastine suppresses the rapidly dividing cells in the bone marrow, it can cause an increased chance of infection.¹ Persistent lethargy, fever, inappetence or any other changes in demeanor should be reported to your veterinarian.

Dog lovers sometimes worry about using potent drugs like vinblastine. While this fear is normal, keep in mind that veterinary oncologists always aim to give doses low enough to keep side effects extremely low, and if possible, nonexistent. We do not use Maximum Tolerated Doses in dogs that we use in human medicine.

Monitoring

A baseline CBC (complete blood count) should be done prior to every treatment to ensure that your pet has enough white blood cells and platelets present to safely treat. Monitoring liver enzymes periodically is a good idea as well.¹ These tests will help your dog avoid side effects due to continued dosing.