Corticosteroids: antenatal steroids: 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 · Corticosteroids: antenatal steroids

Sample item

A woman at 30 weeks of gestation has threatened preterm labour. Which corticosteroid is chosen to accelerate fetal lung maturity, and why?

APrednisolone, because it crosses the placenta unchangedBHydrocortisone, because it has the highest fetal transferCBetamethasone, because it crosses the placenta in active formDFludrocortisone, because it has strong glucocorticoid action

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

The answer and the reasoning

C. Betamethasone, because it crosses the placenta in active form

Betamethasone and dexamethasone are fluorinated steroids that are poorly inactivated by placental 11-beta-hydroxysteroid dehydrogenase type 2, so active drug reaches the fetus and induces surfactant synthesis. Prednisolone and hydrocortisone are largely converted to inactive forms in the placenta.

Option by option

A. Prednisolone, because it crosses the placenta unchanged
Prednisolone is mostly inactivated by the placental enzyme, so little reaches the fetus.
B. Hydrocortisone, because it has the highest fetal transfer
Hydrocortisone is converted to cortisone by the placenta and has little fetal effect.
C. Betamethasone, because it crosses the placenta in active form (correct)
Correct. Placental transfer of active drug lets it act on fetal lung maturation.
D. Fludrocortisone, because it has strong glucocorticoid action
Fludrocortisone is a mineralocorticoid with little role in fetal lung maturation.

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 C, Betamethasone, because it crosses the placenta in active form. Betamethasone and dexamethasone are fluorinated steroids that are poorly inactivated by placental 11-beta-hydroxysteroid dehydrogenase type 2, so active drug reaches the fetus and induces surfactant synthesis.

Why is "Prednisolone, because it crosses the placenta unchanged" not the answer?

Prednisolone is mostly inactivated by the placental enzyme, so little reaches the fetus.

Why is "Hydrocortisone, because it has the highest fetal transfer" not the answer?

Hydrocortisone is converted to cortisone by the placenta and has little fetal effect.

Why is "Fludrocortisone, because it has strong glucocorticoid action" not the answer?

Fludrocortisone is a mineralocorticoid with little role in fetal lung maturation.

What concept does this question test?

It tests Corticosteroids: antenatal steroids in Pharmacology. Prednisolone and hydrocortisone are largely converted to inactive forms in the placenta.

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 Corticosteroids: antenatal steroids?

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.