Chemotherapy Biotherapy Certification ONS Practice Test 2025 - Free Practice Questions and Study Guide

Antimetabolites are classified as cell cycle phase-specific drugs because they primarily exert their effects during the S-phase of the cell cycle, a period when DNA synthesis occurs. These drugs mimic the natural metabolites and interfere with the synthesis of nucleic acids, thereby disrupting the replication of cancer cells. This specificity allows for more targeted therapy since the drugs are most effective when the cancer cells are actively dividing and synthesizing DNA.

In contrast, alkylating agents act on all phases of the cell cycle by damaging DNA directly, which does not limit their action to a specific phase. Hormonal agents, while they target specific pathways related to hormone receptors, are not categorized based on the cell cycle phases. Supportive care agents are not aimed at directly killing cancer cells or affecting their cycle; instead, they alleviate side effects of cancer treatments and improve patient quality of life.