Cardiovascular drugs: streptokinase antigenicity: 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.

Try it

Pharmacology · Cardiovascular drugs: streptokinase antigenicity

Sample item

A 60-year-old man in a district hospital with no catheterisation facility has an inferior ST-elevation infarction 2 hours after onset. He received streptokinase for a previous infarction 8 months ago. Which is the best reperfusion option?

ATenecteplase, as antibodies from the earlier exposure make streptokinase unsuitableBIntravenous heparin infusion aloneCStreptokinase again at a higher doseDAspirin alone, as fibrinolytics are contraindicated after any prior lytic

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

The answer and the reasoning

A. Tenecteplase, as antibodies from the earlier exposure make streptokinase unsuitable

Streptokinase is a bacterial protein that is antigenic, and neutralising antibodies persist for months after exposure or after a streptococcal infection. A repeat course is not advised between about 5 days and 12 months because of reduced efficacy and allergic reactions. Fibrin-specific agents such as tenecteplase or alteplase do not have this problem and are the alternative when primary PCI is unavailable.

Option by option

A. Tenecteplase, as antibodies from the earlier exposure make streptokinase unsuitable (correct)
Correct. A non-antigenic fibrin-specific lytic achieves reperfusion without neutralisation or allergy.
B. Intravenous heparin infusion alone
Heparin alone does not lyse the occlusive thrombus.
C. Streptokinase again at a higher dose
Antibodies neutralise streptokinase, and a higher dose raises the risk of allergy and hypotension.
D. Aspirin alone, as fibrinolytics are contraindicated after any prior lytic
Only streptokinase is avoided after prior use; other lytics are not contraindicated by it.

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, Tenecteplase, as antibodies from the earlier exposure make streptokinase unsuitable. Streptokinase is a bacterial protein that is antigenic, and neutralising antibodies persist for months after exposure or after a streptococcal infection.

Why is "Intravenous heparin infusion alone" not the answer?

Heparin alone does not lyse the occlusive thrombus.

Why is "Streptokinase again at a higher dose" not the answer?

Antibodies neutralise streptokinase, and a higher dose raises the risk of allergy and hypotension.

Why is "Aspirin alone, as fibrinolytics are contraindicated after any prior l…" not the answer?

Only streptokinase is avoided after prior use; other lytics are not contraindicated by it.

What concept does this question test?

It tests Cardiovascular drugs: streptokinase antigenicity in Pharmacology. A repeat course is not advised between about 5 days and 12 months because of reduced efficacy and allergic reactions. Fibrin-specific agents such as tenecteplase or alteplase do not have this problem and are the alternative when primary PCI is unavailable.

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 Cardiovascular drugs: streptokinase antigenicity?

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.