Cytostatic agents are substances that inhibit cell growth and / or cell division. They are used primarily in the context of chemotherapy for cancer. Because cytostatics attack cells that divide quickly. This is the case for cancer cells that multiply through uncontrolled cell division, but also for some healthy body cells. These cells include, among others, the mucosal cells in the mouth and gastrointestinal tract, the cells in the bone marrow and the hair cells. Cells that do not divide during treatment are usually not affected by the drugs.
Cytostatic agents inhibit cell division
Cytostatic agents ensure that the division and uncontrolled growth of tumor cells are inhibited and the cells die off. Some substances incorporate errors in the DNA of the tumor cells or inhibit the copying of the genome, which is essential for the division of the cell. Other cytotoxic drugs influence the metabolism of the cell.
The damaged or dead cells are recognized and degraded by an endogenous control mechanism. If the therapy starts, the tumor becomes smaller or at least does not grow any further. Whether chemotherapy is successful or not, however, can not be detected overnight: It usually takes a few days or even weeks before it becomes clear whether the treatment will work.
The success of the treatment is controlled at regular intervals. A treatment is considered successful if the tumor no longer grows, it has become smaller or completely disappeared. Likewise, an improvement in the subjective well-being of the patient is considered a success.
Various active ingredients
Many different cytotoxic drugs are available for chemotherapy. Which drug is used in an individual case depends, among other things, on the type of cancer. Below is a list of the most important cytotoxic drugs.
Alkylating agents prevent the duplication of the genetic material in the tumor cells, which is absolutely necessary for cell division. This prevents the proliferation of cells and the growth of the tumor. The group of alkylating agents include, among others, agents such as busulfan, cyclophosphamide and ifosfamide.
Among the alkylating agents in a broader sense also the so-called platinum analogues are counted. They fight the tumor cells by connecting to the genetic information in the tumor cells and thereby destroy them. In addition, they inhibit those enzymes that could repair the damage caused to the DNA.
Since platinum analogues can cause severe nausea, concomitant medications are usually administered. Active substances from this group are cisplatin, carboplatin and oxaliplatin.
Antibiotics, like cytostatic drugs, inhibit the growth and proliferation of cells. However, most antibiotics are directed against foreign cells. Only a few inhibit the proliferation of endogenous cells and can therefore be counted among the cytostatic drugs.
These antitumoral antibiotics cause breaks in the DNA in the tumor cells and cause changes in the cell membrane. As they not only work during the cell division phase, they usually have more side effects than other cytotoxic drugs. The group of antitumoral antibiotics includes drugs such as doxorubicin and epirubicin.
Antimetabolites destroy the genome of the cells by introducing themselves into the DNA of the cells as false building blocks. They work during cell division and have relatively little side effects compared to other cytostatics.
The group of antimetabolites includes active ingredients such as:
Strictly speaking, hormones are not cytostatic drugs. However, as part of chemotherapy, they may be helpful in those tumors whose growth is stimulated by hormones. For example, female sex hormones promote the growth of breast cancer and male sex hormones promote prostate cancer. The use of the respective antagonists can stem the growth of the tumors. Depending on the type of cancer, for example, antiestrogens or antiandrogens are administered.
Mitosis inhibitors prevent the cell nuclei from dividing into tumor cells. If this process is blocked, an increase of the cells is not possible. The mitosis inhibitors include many plant substances, including the vinca alkaloids and the taxanes.
- Vinca alkaloids: They are obtained from the plant periwinkle (Vinca). Examples of active substances from this group are vinblastine and vincristine.
- Taxanes: They are extracted from yew bark. Examples of drugs from this group are docetaxel and paclitaxol.
Topoisomerase inhibitors block the enzyme topoisomerase, which allows the proliferation of cells. If the topoisomerases of the cancer cells are inhibited, the tumor can no longer grow. Examples of topoisomerase inhibitors are etoposide, irinotecan and topotecan.