Vincristine is a cytostatic drug used to treat cancer. The alkaloid acts as a mitosis inhibitor.
What is vincristine?
Vincristine is a cytostatic drug used to treat cancer. Vincristine is an alkaloid. Alkaloids are chemical heterogeneous substances that occur naturally. They are usually nitrogenous and are formed in the secondary metabolism of plants or animals. Secondary metabolites are chemical substances that are produced by plants, bacteria, or fungi, but are not needed by these organisms for growth or survival. Secondary metabolites such as vincristine are also called secondary metabolites. Vincristine is an alkaloid extracted from the pink catharanth (Catharantus roseus or Vinca rosea). It thus belongs to the semisynthetic vinca alkaloids. Vinca alkaloids are active ingredients obtained from plants of the dog poison genus. Vincristine is a cytostatic drug used to treat cancer. For this purpose, it is administered intravenously as part of chemotherapy.
Pharmacologic action
Vinca alkaloids such as vincristine have the property of attaching to the protein tubulin. Tubulins are proteins found in eukaryotic cells. After vincristine attaches, microtubules can no longer form. Microtubules are tubular intracellular organelles. They are responsible for chromosome assembly within mitosis. In the phase of mitosis, the cell nucleus divides in the cell cycle and the DNA is split. Subsequently, in cell division, the genetic material is distributed from a single cell to two daughter cells. If the microtubules cannot perform their task within the mitosis phase, the formation of new functioning cells is no longer possible. Cells are formed, but they undergo cell death (apoptosis) quite rapidly. Within a tumor, cells divide particularly rapidly. Mitosis is therefore particularly affected in cancer cells by the use of vincristine. Thus, cancer growth can be effectively inhibited or at least slowed down. Furthermore, vincristine inhibits or interferes with DNA synthesis and RNA production within the cells. Thus, protein formation and cell proliferation are not possible.
Medical application and use
Vincristine is a cytostatic agent administered as part of chemotherapy. It interferes with the mitosis of all cells. However, rapidly progressing mitoses are more likely to be affected. Therefore, vincristine can be used to treat all malignant (malignant) tumor diseases. Vincristine is especially commonly used to treat acute leukemia. Other malignancies of the lymphatic system, such as Hodgkin’s disease or non-Hodgkin’s lymphoma, are also treated with vincristine. Furthermore, vincristine is used for rhabdomyosarcoma, neuroblastoma and osteosarcoma. Malignant melanoma is also an indication for the cytostatic drug. In children, Wilms’ tumor, an embryonal malignant mixed tumor of the kidney, is treated with vincristine. Ten percent of all childhood malignancies are nephroblastomas. Women with cervical cancer are also frequently treated with vincristine. Other indications for the use of the cytostatic agent include small cell lung carcinoma, Ewing’s sarcoma and Werlhof’s disease. Werlhof’s disease is not a cancer, but an autoimmune disease associated with the destruction of platelets in the spleen. Due to the lack of platelets, patients experience hemorrhage. However, in Werlhof’s disease, also known as idiopathic thrombocytopenic purpura (ITP), vincristine is only used when patients do not respond to short-term therapy with corticosteroids or splenectomy. Vincristine is a chemotherapeutic agent that should only be used under the strictest medical supervision. Misuse or overdose can have fatal consequences. Adults receive between one and two milligrams of vincristine per square meter of body surface area per week. For children and adolescents, the daily dose is two milligrams per square meter of body surface area. Patients who have elevated direct bilirubin levels in their blood serum receive a much lower dose of vincristine.
Risks and side effects
Vincristine has many side effects.The bone marrow can be damaged so that anemia, leukopenia and thrombocytopenia can develop. In anemia, there are too few red blood cells in the blood. In leukopenia, white blood cells are absent. Thrombocytopenia is associated with a lack of platelets. Rarely, patients react to vincristine with allergic shock. More commonly, they develop skin rashes or edema. There may be a disturbance in ADH secretion. A deficiency of the antidiuretic hormone is noticeable by the excretion of large amounts of water in the urine. This phenomenon is also known as diabetes insipidus. Along with the water, sodium is also lost through the kidneys. In addition, patients taking vincristine may experience nerve pain and paresthesias such as tingling. The neurological deficits may be irreversible. Furthermore, gait disturbances, cranial nerve palsies, and myalgias are observed. Muscle atrophy, hypertension, constipation and colicky abdominal pain are other adverse effects of the cytostatic drug. Since the cells of the oral mucosa are also affected by the chemotherapeutic agent, those affected suffer from severe pain in the oral cavity and throat. They may also exhibit paralysis or spasm of the airways with severe shortness of breath. In some cases, atrophy of the optic nerve occurs. This results in temporary blindness. Rarely, oral ulceration and necrosis of the intestine occur. In addition, a common and characteristic side effect of vincristine is hair loss.
