Antimetabolites are a class of drugs that interfere with the normal metabolism of cells, particularly during the process of cell division. They mimic the structure of natural metabolites, which are essential for DNA and RNA synthesis. By doing so, they disrupt the production of nucleic acids, leading to the inhibition of cell growth and replication. This makes them particularly useful in treating certain types of cancer, as rapidly dividing cancer cells are more affected by these drugs. Common examples of antimetabolites include methotrexate, 5-fluorouracil, and cytarabine. These medications are often used in chemotherapy regimens to target and kill cancer cells. However, because they can also affect normal, healthy cells, they may cause side effects such as nausea, fatigue, and increased risk of infection.