Anticholinergics: bladder antimuscarinics in the elderly: 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 · Anticholinergics: bladder antimuscarinics in the elderly

Sample item

A 78-year-old woman with overactive bladder has been taking oxybutynin for two months. Her urgency has improved, but her daughter reports new forgetfulness and confusion, along with a dry mouth. Which alternative antimuscarinic is least likely to cause central effects?

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

The answer and the reasoning

C. Trospium

Trospium is a quaternary ammonium compound that is charged and crosses the blood-brain barrier poorly, so cognitive adverse effects are minimal. Tertiary amines such as oxybutynin readily enter the brain and can cause confusion in older people. Anticholinergic load is a recognised cause of drug-induced delirium and memory impairment.

Option by option

  • A. Imipramine

    Imipramine has strong antimuscarinic activity and readily enters the brain, so it would worsen confusion.

  • B. Hyoscine hydrobromide

    Hyoscine hydrobromide is a tertiary amine that crosses the blood-brain barrier and causes sedation and amnesia.

  • C. Trospium (correct)

    Trospium is quaternary and charged, so little reaches the brain while bladder M3 blockade is retained.

  • D. Atropine

    Atropine is a tertiary amine with prominent central effects in the elderly, including delirium.

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.

More Pharmacology questions

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is C, Trospium. Trospium is a quaternary ammonium compound that is charged and crosses the blood-brain barrier poorly, so cognitive adverse effects are minimal.

Why is "Imipramine" not the answer?

Imipramine has strong antimuscarinic activity and readily enters the brain, so it would worsen confusion.

Why is "Hyoscine hydrobromide" not the answer?

Hyoscine hydrobromide is a tertiary amine that crosses the blood-brain barrier and causes sedation and amnesia.

Why is "Atropine" not the answer?

Atropine is a tertiary amine with prominent central effects in the elderly, including delirium.

What concept does this question test?

It tests Anticholinergics: bladder antimuscarinics in the elderly in Pharmacology. Tertiary amines such as oxybutynin readily enter the brain and can cause confusion in older people. Anticholinergic load is a recognised cause of drug-induced delirium and memory impairment.

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 Anticholinergics: bladder antimuscarinics in the elderly?

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.