Vincristine
Vincristine sulfate
Also known as: Oncovin · Vincasar PFS · leurocristine sulfate · VCR · LCR compound 37231 · NSC-67574 · 22oxovincaleukoblastine sulphate · sulfato de vincristina · vincristini sulfas · Vincristine sulfate
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Neoplastic diseases (usually in combination protocols) | 0.5-0.75 mg/m2 | IV | every 1-2 weeks | — | 🌎 NA |
| Transmissible venereal tumor (TVT) | 0.5 mg/m2 (maximum dose 1 mg) | IV | once weekly | for 4-6 weeks | 🌎 NA |
| Adjunctive treatment of immune-mediated thrombocytopenia (IMT) | 0.5 mg/m2 | IV | once | — | 🌎 NA |
| Adjunctive treatment of immune-mediated thrombocytopenia (IMT) refractory to prednisone | 0.5-0.7 mg/m2 | IV | once | — | 🌎 NA |
| Adjunctive treatment of immune-mediated thrombocytopenia (IMT) | 0.02 mg/kg | IV | once | — | 🌎 NA |
| Neoplastic diseases (particularly lymphoproliferative disorders), immune-mediated thrombocytopenia, transmissible venereal tumour | See Appendix for chemotherapy protocols and conversion of body weight to body surface area. | IV | Not specified | Not specified | 🌍 EU |
- Neoplastic diseases (usually in combination protocols): Dosed in mg/m2, NOT mg/kg. Consultation with an oncologist recommended.
- Transmissible venereal tumor (TVT): Used as sole therapy.
- Adjunctive treatment of immune-mediated thrombocytopenia (IMT): If platelet count <10-20,000 cells/mcL or bleeding; consider bone marrow aspiration to document megakaryocytes.
- Adjunctive treatment of immune-mediated thrombocytopenia (IMT) refractory to prednisone: Given as an IV bolus or as an infusion over 4-6 hours.
- Adjunctive treatment of immune-mediated thrombocytopenia (IMT): Generally single use.
- Neoplastic diseases (particularly lymphoproliferative disorders), immune-mediated thrombocytopenia, transmissible venereal tumour: Must be administered i.v. through a carefully pre-placed catheter.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Neoplastic diseases | 0.5-0.75 mg/m2 | IV | every 1-3 weeks | — | 🌎 NA |
| Neoplastic diseases (particularly lymphoproliferative disorders) | See Appendix for chemotherapy protocols and conversion of body weight to body surface area. | IV | Not specified | Not specified | 🌍 EU |
- Neoplastic diseases: Dosed in mg/m2, NOT mg/kg. Consultation with an oncologist recommended.
- Neoplastic diseases (particularly lymphoproliferative disorders): Must be administered i.v. through a carefully pre-placed catheter.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Neoplastic diseases | 0.5 mg/m2 (usually 2.5-3 mg total dose per horse) | IV | weekly | — | 🌎 NA |
- Neoplastic diseases: Often used in CAP protocol with cytarabine and cyclophosphamide.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Vincristine is a cell-cycle specific (M-phase) antineoplastic agent derived from the periwinkle plant (Catharanthus roseus). It is a cornerstone in veterinary oncology, primarily utilized in combination chemotherapy protocols (such as CHOP) for lymphoid and hematopoietic neoplasms like lymphoma.
Key clinical highlights:
- Bone Marrow Sparing: Unlike many other chemotherapeutics (e.g., its analog vinblastine), vincristine is notably sparing to the bone marrow at standard doses, making it highly valuable in combination protocols.
- Transmissible Venereal Tumors (TVT): It is highly efficacious as a single agent for TVT in dogs.
- Immune-Mediated Thrombocytopenia (IMT): Vincristine is uniquely used to treat refractory IMT. It promotes the fragmentation of megakaryocytes, leading to a rapid release of platelets into circulation.
- Vesicant: It is a severe tissue vesicant; strict intravenous administration via a perfectly placed catheter is mandatory to prevent devastating extravasation injuries.
Mechanism of action
Vincristine is a cell-cycle specific agent that acts during the M-phase (mitosis).
- Antineoplastic Action: It binds specifically to tubulin dimers → inhibits microtubule polymerization → prevents the formation of the mitotic spindle → arrests cell division in metaphase, ultimately leading to apoptosis.
- Metabolic Effects: It interferes with amino acid metabolism by inhibiting glutamic acid utilization and preventing purine synthesis, citric acid cycle, and urea formation.
- Thrombocytosis: The exact mechanism is unknown, but it is believed to stimulate megakaryocyte fragmentation, accelerating the release of platelets into the peripheral blood.
- Immunosuppression: Exhibits mild immunosuppressive activity, which may contribute to its efficacy in immune-mediated conditions.
Safety & warnings
Contraindications
- Preexisting neuromuscular disease
- Severe leukopenia
- Uncontrolled infection
- No specific absolute contraindications listed, but requires extreme caution in specific disease states
Adverse effects
- Peripheral neuropathy (proprioceptive deficits, spinal hyporeflexia)
- Paralytic ileus and severe constipation
- Mild leukopenia
- Tissue necrosis and sloughing (if extravasated)
- Anorexia, vomiting, diarrhea
- Impaired platelet aggregation
- Increased liver enzymes
- Syndrome of inappropriate ADH secretion (SIADH)
- Jaw pain
- Alopecia
- Stomatitis
- Seizures
- Pulmonary edema (rare, reported in cats)
- GI tract toxicity
- Severe local irritation/tissue necrosis (if administered perivascularly)
- Myelosuppression (potential)
Precautions
Extravasation Warning: Vincristine is a potent vesicant. It must be given strictly IV. Use a different needle for injection than the one used to draw the drug from the vial. If extravasation occurs, stop immediately, apply moderate heat (or ice, depending on protocol), and consider topical DMSO or hyaluronidase injections.
- ABCB1 (MDR1) Mutation: Herding breeds (e.g., Collies, Australian Shepherds) with this mutation are highly susceptible to severe bone marrow suppression and GI toxicity. Reduce dose by 25-30% in mutant/normal or mutant/mutant dogs.
- Hepatic Impairment: Extensively metabolized by the liver. Consider a 50% dose reduction if serum bilirubin is > 2 mg/dL.
- Neurotoxicity: Cats are particularly sensitive to neurotoxicity, which can manifest as paralytic ileus, severe constipation, and reversible axon swelling.
- Handling: Wear gloves and protective clothing. Wash thoroughly with soap and water if skin exposure occurs.
- Pregnancy: Potentially teratogenic and embryotoxic (FDA Category D).
Drug interactions
Additive neurotoxicity may occur; less common if asparaginase is administered after vincristine.
Severe bronchospasm has occurred in humans receiving mitomycin-C with Vinca alkaloids.
Inhibits P-glycoprotein; may increase vincristine toxicity, especially in MDR1/ABCB1 mutant dogs.
Inhibits P-glycoprotein; may increase vincristine toxicity.
Inhibits P-glycoprotein; may increase vincristine toxicity.
Inhibits P-glycoprotein; may increase vincristine toxicity.
Inhibits P-glycoprotein; may increase vincristine toxicity.
Inhibits P-glycoprotein; may increase vincristine toxicity.
Inhibits P-glycoprotein; may increase vincristine toxicity.
Inhibits P-glycoprotein; may increase vincristine toxicity.
Inhibits P-glycoprotein; may increase vincristine toxicity.
Inhibits P-glycoprotein; may increase vincristine toxicity.
Inhibits P-glycoprotein; may increase vincristine toxicity.
Decreased metabolism of vincristine and increased toxicity
Reduced clearance of vincristine and increased toxicity if given with or before vincristine (vincristine should be given 12-24 hours before L-asparaginase)
Monitoring
- Efficacy (tumor burden reduction or platelet count)
- Peripheral neuropathic clinical signs (e.g., gait abnormalities, constipation)
- Complete blood counts (CBC) with platelets
- Liver function tests (prior to therapy and repeated as necessary)
- Serum uric acid
- Complete Blood Count (CBC) prior to each dose
- IV catheter site for any signs of extravasation during administration
- Gastrointestinal signs (monitoring for ileus or severe constipation)
- Neurological exams (monitoring for peripheral neuropathy, e.g., dragging paws, loss of reflexes)
Pharmacokinetics
Half-life
Absorption
Unpredictably absorbed from the GI tract; must be administered IV.
Distribution
Rapidly distributed to tissues after injection. In humans, ~75% is bound to tissue proteins. Does not appreciably enter the CNS.
Metabolism
Extensively metabolized, presumably by the liver.
Elimination
Primarily excreted in the bile/feces; lesser amounts are eliminated in the urine.
Overdose
Vincristine has a narrow therapeutic index.
- Dogs: The maximally tolerated dose is reported as 0.06 mg/kg every 7 days for 6 weeks. Toxicity signs include slight anemia, leukopenia, increased liver enzymes, and neuronal shrinkage in the peripheral and central nervous systems.
- Cats: The lethal dose is reportedly 0.1 mg/kg. Toxic signs include weight loss, seizures, leukopenia, and general debilitation. A reported 10X overdose (5 mg/m2) resulted in death within 72 hours despite intensive care (including calcium folinate).
- Treatment: Primarily supportive. Includes cardiovascular and hematologic monitoring, anticonvulsants for seizures, and prevention of ileus. Fluid restriction and loop diuretics may be needed to manage SIADH. Leucovorin calcium has been used in humans, but efficacy is unconfirmed.
Available products
Formulations
- Injection
- Injectable: 1 mg, 2 mg, 5 mg vials
Human-labeled
- Vincristine Sulfate Injection: 1 mg/mL in 1 mL, 2 mL & 5 mL vials and flip-top vials (Vincasar PFS; generic)
- Oncovin
- Vincristine 1 mg, 2 mg, 5 mg vials
Regulatory status
POM (Prescription Only Medicine)
POM (Prescription Only Medicine)
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Protect from light and store in the refrigerator (2-8°C).
Client information
Vincristine is a potent chemotherapy drug used to treat cancer and certain immune system disorders.
- Toxicity Risks: While generally well-tolerated, severe side effects can occur. Contact your veterinarian immediately if your pet shows profound depression, abnormal bleeding or bruising, bloody diarrhea, severe constipation, or difficulty walking (neuropathy).
- Safety Precautions at Home: The drug and its breakdown products are excreted in your pet's bodily fluids. Avoid direct contact with your pet's urine, saliva, or feces for up to 7 days after treatment. Wear gloves when cleaning up waste, and wash your hands thoroughly afterward.
- Missed Doses: Chemotherapy schedules are very strict. If you miss an appointment, contact your veterinarian immediately to reschedule.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.