Drugs in pregnancy: insulin and the placenta: 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 · Drugs in pregnancy: insulin and the placenta

Sample item

A woman with gestational diabetes not controlled by diet is started on insulin. Which property makes insulin suitable in pregnancy from the point of view of fetal exposure?

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

The answer and the reasoning

D. It is a large peptide that does not cross the placenta appreciably

Insulin is a large polypeptide of about 5800 daltons and does not cross the placenta in meaningful amounts, so it controls maternal glucose without direct fetal pharmacological effect. Small, lipid-soluble, unionised drugs cross readily.

Option by option

  • A. It is an unionised weak base that is trapped in the fetus

    Insulin is not a weak base, and ion trapping does not apply.

  • B. It is converted by the placenta into an inactive form

    The placenta does not inactivate insulin, and this is not why it is chosen.

  • C. It is highly lipid soluble and crosses freely

    Insulin is a polar peptide and is not lipid soluble.

  • D. It is a large peptide that does not cross the placenta appreciably (correct)

    Correct. Its size prevents significant transplacental passage.

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.

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Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is D, It is a large peptide that does not cross the placenta appreciably. Insulin is a large polypeptide of about 5800 daltons and does not cross the placenta in meaningful amounts, so it controls maternal glucose without direct fetal pharmacological effect.

Why is "It is an unionised weak base that is trapped in the fetus" not the answer?

Insulin is not a weak base, and ion trapping does not apply.

Why is "It is converted by the placenta into an inactive form" not the answer?

The placenta does not inactivate insulin, and this is not why it is chosen.

Why is "It is highly lipid soluble and crosses freely" not the answer?

Insulin is a polar peptide and is not lipid soluble.

What concept does this question test?

It tests Drugs in pregnancy: insulin and the placenta in Pharmacology. Small, lipid-soluble, unionised drugs cross readily.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Drugs in pregnancy: insulin and the placenta?

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.