What type of chemotherapy drugs target the S phase of the cell cycle?

Antimetabolites are the correct category of chemotherapy drugs that specifically target the S phase of the cell cycle. The S phase, or synthesis phase, is when DNA replication occurs, and antimetabolites function by mimicking the normal substrates or metabolites that cells need to synthesize DNA. By interfering with this process, antimetabolites can inhibit DNA production, leading to cell death, particularly in rapidly dividing cancer cells.

Alkaloids, on the other hand, primarily affect the M phase of the cell cycle by disrupting microtubule function, which is essential for cell division. Vinca drugs, such as vincristine and vinblastine, also target the M phase, preventing the mitotic spindle formation necessary for mitosis. Corticosteroids are not classified as chemotherapy agents that target specific phases of the cell cycle; instead, they generally have immunosuppressive and anti-inflammatory effects that can impact lymphocyte proliferation but do not directly target the S phase of the cell cycle like antimetabolites do.