Chemotherapeutic

Chemotherapeutic Agents

Chemotherapeutic agents, commonly referred to as chemotherapy, are drugs used to treat cancer by inhibiting the growth of cancerous cells. These agents can be classified based on their mechanism of action, chemical structure, or their relationship to a specific phase of the cell cycle.

History

The use of chemotherapeutic agents began in the early 20th century. The first chemotherapeutic agent was mustard gas, which was found to have effects on rapidly dividing cells. This discovery led to the development of nitrogen mustards, the first class of chemotherapy drugs.

Mechanism of Action

Chemotherapeutic agents work by targeting rapidly dividing cells, a hallmark of cancer. However, they also affect normal cells that divide quickly, such as those in the bone marrow, gastrointestinal tract, and hair follicles, leading to side effects.

Alkylating Agents

Alkylating agents work by adding an alkyl group to the DNA molecule, which prevents the DNA from replicating and ultimately leads to cell death. Examples include cyclophosphamide and ifosfamide.

Antimetabolites

Antimetabolites interfere with DNA and RNA synthesis by mimicking the natural substances within the cell. They are most effective during the S phase of the cell cycle. Examples include methotrexate and 5-fluorouracil.

Anti-tumor Antibiotics

These agents intercalate into DNA, disrupting the function of enzymes involved in DNA replication. Doxorubicin and bleomycin are examples of anti-tumor antibiotics.

Plant Alkaloids

Derived from plants, these agents inhibit cell division by interfering with microtubule function. Vincristine and paclitaxel are examples of plant alkaloids.

Topoisomerase Inhibitors

These drugs interfere with the action of topoisomerase enzymes, which help to separate the strands of DNA so they can be copied. Examples include etoposide and irinotecan.

Administration

Chemotherapy can be administered in various ways, including orally, intravenously, intramuscularly, or topically. The method of administration depends on the type of cancer, the specific drug, and the patient's overall health.

Side Effects

Common side effects of chemotherapy include nausea, vomiting, hair loss, fatigue, and increased risk of infection. These occur because chemotherapy affects not only cancer cells but also normal, rapidly dividing cells.

Resistance

Cancer cells can develop resistance to chemotherapeutic agents through various mechanisms, such as drug efflux, DNA repair, and drug target alteration. Overcoming resistance is a significant challenge in cancer treatment.

Future Directions

Research is ongoing to develop more targeted chemotherapeutic agents that minimize damage to normal cells. Immunotherapy and targeted therapy are promising areas that aim to improve the specificity and efficacy of cancer treatment.

See Also

• Cancer treatment
• Radiation therapy
• Surgery

References

• DeVita, V. T., Lawrence, T. S., & Rosenberg, S. A. (2015). Cancer: Principles & Practice of Oncology. Wolters Kluwer Health.
• Chabner, B. A., & Longo, D. L. (2011). Cancer Chemotherapy and Biotherapy: Principles and Practice. Lippincott Williams & Wilkins.