Plant alkaloids make up a group of chemotherapy medications used to treat cancer. These medications are divided into three subgroups based on what type of plant they come from. Vinca alkaloids come from the periwinkle plant, epipodophyllotoxins come from the may apple plant, and taxanes come from the Pacific yew tree. All of these types of chemotherapy work in similar ways to attack cancer cells and cause them to die.
History
According to Drs. Vincent Devita and Edward Chu of Yale University, vinca alkaloids date to 1963 when they were first discovered. The discovery of etoposide, a epipodophyllotoxin, occurred in 1971. The discovery of the taxane group took place in 1975. All of the plant alkaloids are commonly used to treat many cancers.
Subgroups and Action
The oldest of the three groups of medications are the vinca alkaloids. Medications in this group include vinblastine, vincristine and vinerolbine. Etoposide and teniposide make up the epipodophyllotoxin group. The taxane group of plant alkaloids includes paclitaxel, protein-bound paclitaxel and docetaxel. These medications interfere with the cancer cells' DNA, preventing the cells from replicating and dividing. Without the ability to grow and divide, the tumor cells eventually die.
Administration
Alkaloid administration typically involves intravenous infusion. Once mixed for IV infusion, these medications appear to be clear liquid substances, with the exception of protein-bound paclitaxel, which appears milky white. Nurses place an IV line in a vein and administer the medications over a period of time. Normal administration time of the vinca alkaloids ranges from a few minutes to 1/2 hour. Typical infusion of the other alkaloids ranges from 1/2 hour to four hours.
Side Effects
Side effects for these medications include nausea, vomiting, mouth sores, lowered blood counts, diarrhea, constipation and nail bed changes. According to the Chemotherapy Source Book, paclitaxel and docetaxel cause numbness of the hands and feet, known as peripheral neuropathy, in approximately 40 percent of patients. Vinca alkaloids also cause peripheral neuropathy to a lesser extent. Allergic reaction is also common with the use of taxanes, and low blood pressure is seen with the use of etoposide.
Common Uses
Plant alkaloid uses vary widely. Vinerolbine commonly treats non-small cell lung cancer but also treats breast and ovarian cancers. Vinblastine treatment includes lymphomas, germ cell tumors, Kaposi sarcoma, band reast and renal cancers. Vincristine is often used to treat lymphomas, sarcomas, thyroid cancer and some leukemias. Breast cancer treatments commonly include use of the taxanes. In addition, taxanes use includes treatment of ovarian, lung, esophageal, bladder and head and neck cancers. The Chemotherapy Source Book lists typical uses for epipodophyllotoxins to include treatment of lung, gastric and ovarian cancers, as well as lymphomas.
References
- Chemocare: Types of Chemotherapy Agents
- Cancer Research: A History of Cancer Chemotherapy
- "The Chemotherapy Source Book"; Michael C. Perry MD.; 2008
