Chemotherapy: nitrosoureas: practice question

A Pharmacology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pharmacology · Chemotherapy: nitrosoureas

Sample item

A man with glioblastoma receives a lipid-soluble alkylating agent that crosses the blood-brain barrier. Four to six weeks later his counts fall, and after cumulative dosing he develops pulmonary fibrosis. Which drug is it?

ACarmustineBChlorambucilCCyclophosphamideDMelphalan

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Carmustine

Carmustine and lomustine are nitrosoureas that are highly lipophilic and cross into the CNS, so they are used in brain tumours. They cause delayed and prolonged myelosuppression and dose-related pulmonary fibrosis. The other alkylators are less lipid soluble and do not cause this pattern.

Option by option

A. Carmustine (correct)
Correct. A lipophilic nitrosourea with delayed myelosuppression and pulmonary fibrosis.
B. Chlorambucil
Chlorambucil is used in chronic lymphocytic leukaemia and does not cause this pattern.
C. Cyclophosphamide
Cyclophosphamide is a prodrug causing haemorrhagic cystitis and does not enter the brain well.
D. Melphalan
Melphalan is used in myeloma and does not cross the blood-brain barrier appreciably.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is A, Carmustine. Carmustine and lomustine are nitrosoureas that are highly lipophilic and cross into the CNS, so they are used in brain tumours.

Why is "Chlorambucil" not the answer?

Chlorambucil is used in chronic lymphocytic leukaemia and does not cause this pattern.

Why is "Cyclophosphamide" not the answer?

Cyclophosphamide is a prodrug causing haemorrhagic cystitis and does not enter the brain well.

Why is "Melphalan" not the answer?

Melphalan is used in myeloma and does not cross the blood-brain barrier appreciably.

What concept does this question test?

It tests Chemotherapy: nitrosoureas in Pharmacology. They cause delayed and prolonged myelosuppression and dose-related pulmonary fibrosis. The other alkylators are less lipid soluble and do not cause this pattern.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Chemotherapy: nitrosoureas?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.