Which of the following medications is a mitotic inhibitor?

DSSSB October 2024

Pharmacology

Easy

Appeared in: DSSSB October 2024

Explanation

Vincristine is a plant alkaloid belonging to the vinca alkaloid class of chemotherapy agents.
Its primary mechanism of action is to inhibit cell division (mitosis) by binding to tubulin.
This binding disrupts the formation of microtubules, which are essential components of the mitotic spindle required for chromosome segregation during metaphase.
By arresting the cell cycle in the M-phase, Vincristine induces apoptosis (cell death) in rapidly dividing cancer cells.

Option A: Cyclophosphamide is an alkylating agent, not a mitotic inhibitor. It works by adding an alkyl group to DNA, which causes the DNA to be damaged and prevents cancer cells from replicating.
Option C: Daunorubicin is an antitumor antibiotic of the anthracycline class. It works by intercalating with DNA, inhibiting the enzyme topoisomerase II, and producing free radicals that damage the cells' DNA and membranes.
Option D: Etoposide is a topoisomerase II inhibitor. It works by forming a complex with the topoisomerase II enzyme and DNA, which leads to breaks in the DNA strand and prevents cancer cells from dividing.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification and mechanism of action of antineoplastic drugs as background academic context rather than a clinical decision trigger.
Understanding the classification of chemotherapy drugs is crucial for nurses to anticipate specific side effects. For Vincristine, the primary concern is neurotoxicity (peripheral neuropathy), which is different from the primary toxicities of other drug classes.
Nurses must be aware that Vincristine is a potent vesicant. Extravasation (leakage into surrounding tissue) can cause severe pain and tissue necrosis, requiring immediate intervention.
A critical patient safety issue with Vincristine is its route of administration. It is for IV use ONLY. Accidental intrathecal administration is fatal, and many safety protocols, such as dispensing the drug in a small IV bag rather than a syringe, are in place to prevent this error.

How to Approach the Question

First, identify the key term in the question stem, which is "mitotic inhibitor". This asks for a drug that specifically interferes with the process of mitosis.
Recall or look up the major classes of antineoplastic (chemotherapy) drugs and their general mechanisms of action.
Evaluate each option based on its classification:
Cyclophosphamide: Is it a mitotic inhibitor? No, it's an alkylating agent.
Vincristine: Is it a mitotic inhibitor? Yes, it's a classic example of a vinca alkaloid that works on microtubules during mitosis.
Daunorubicin: Is it a mitotic inhibitor? No, it's an antitumor antibiotic (anthracycline).

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