Drugs Affecting Blood and Blood Formation Practice Questions

Q: Sargramostim is a:

GM-CSF. **Explanation:** **Sargramostim** is a recombinant human **Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF)**. It is produced using recombinant DNA technology in yeast [1]. It works by binding to specific receptors on hematopoietic progenitor cells, stimulating the proliferation and differentiation of neutrophils, monocytes/macrophages, and eosinophils [2]. **Analysis of Options:** * **A. GM-CSF (Correct):** Sargramostim is the pharmacological analog of GM-CSF [1]. It is primarily used to accelerate myeloid recovery in patients undergoing bone marrow transplantation or intensive chemotherapy [3]. * **B. G-CSF:** **Filgrastim** and **Pegfilgrastim** are the recombinant forms of Granulocyte Colony-Stimulating Factor (G-CSF). Unlike GM-CSF, G-CSF acts more selectively on the neutrophil lineage [2]. * **C. IL-11 analogue:** **Oprelvekin** is the recombinant Interleukin-11 used to treat chemotherapy-induced thrombocytopenia by stimulating megakaryocyte maturation. * **D. Erythropoietin analogue:** **Epoetin alfa** and **Darbepoetin alfa** are erythropoiesis-stimulating agents used to treat anemia associated with chronic kidney disease or chemotherapy. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Use:** Sargramostim is used to reduce the duration of neutropenia and the incidence of life-threatening infections following autologous bone marrow transplantation [1]. * **Side Effects:** A unique side effect of Sargramostim (GM-CSF) not typically seen with Filgrastim (G-CSF) is the **"First-dose reaction,"** characterized by hypotension, flushing, and tachycardia. It can also cause capillary leak syndrome (edema, pleural/pericardial effusions) at high doses. * **Mnemonic:** Sar**gram**ostim = **Granulocyte-Macrophage** (GM). Fil**g**rastim = **G**-CSF.

Q: Which of the following is not used for thromboprophylaxis?

Antithrombin III. **Explanation:** The goal of **thromboprophylaxis** is to prevent the formation of a thrombus in high-risk patients (e.g., post-surgery or prolonged immobilization). **Why Antithrombin III is the correct answer:** Antithrombin III (ATIII) is a naturally occurring endogenous anticoagulant. While ATIII concentrates are used as **replacement therapy** in patients with hereditary ATIII deficiency (to prevent or treat thromboembolism) or during heparin resistance, it is **not** used as a standard pharmacological agent for routine thromboprophylaxis in the general population. Its use is highly specific and restricted to replacement in deficient states. **Analysis of Incorrect Options:** * **Heparin (Option A):** Low-dose Unfractionated Heparin (UFH) or Low Molecular Weight Heparins (LMWH like Enoxaparin) are the "gold standard" for VTE prophylaxis in surgical and medical patients. * **Warfarin (Option B):** An oral vitamin K antagonist used for long-term thromboprophylaxis, particularly in patients with prosthetic heart valves or chronic atrial fibrillation. * **Aspirin (Option C):** An antiplatelet drug used for "arterial" thromboprophylaxis to prevent myocardial infarction and stroke in high-risk cardiovascular patients. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Heparin:** Heparin does not have intrinsic anticoagulant activity; it works by accelerating the action of **Antithrombin III** by 1000-fold. * **Heparin Resistance:** If a patient does not respond to heparin (monitored via aPTT), suspect **Antithrombin III deficiency**. * **Virchow’s Triad:** Remember the three factors predisposing to thrombus: Endothelial injury, Stasis, and Hypercoagulability. Prophylaxis targets these pathways. * **DOC for Pregnancy:** Heparin (LMWH) is the drug of choice for thromboprophylaxis in pregnancy as it does not cross the placenta, unlike Warfarin (which is teratogenic).

Q: Which of the following is the mechanism of action of Fondaparinux?

Factor Xa inhibition. **Explanation:** **Fondaparinux** is a synthetic pentasaccharide that acts as a **selective Factor Xa inhibitor**. Its mechanism is mediated through **Antithrombin III (AT-III)**. When Fondaparinux binds to AT-III, it induces a conformational change that increases the neutralization of Factor Xa by 300-fold. Unlike Heparin, the pentasaccharide chain of Fondaparinux is too short to bridge AT-III to Thrombin; therefore, it has **no activity against Thrombin (Factor IIa).** **Analysis of Options:** * **Option B (Correct):** Fondaparinux selectively accelerates the neutralization of Factor Xa. * **Option A & D (Incorrect):** These describe the action of Unfractionated Heparin (UFH). UFH inhibits both Xa and IIa (ratio 1:1). Low Molecular Weight Heparins (LMWH) also inhibit both, but with a higher selectivity for Xa (ratio 2:1 to 4:1). Fondaparinux is unique in its pure Xa selectivity. * **Option C (Incorrect):** Fondaparinux is an Antithrombin **activator/cofactor**, not an inhibitor. **High-Yield Clinical Pearls for NEET-PG:** 1. **HIT Safety:** Fondaparinux does not bind to Platelet Factor 4 (PF4); thus, it carries virtually **no risk of Heparin-Induced Thrombocytopenia (HIT)**. 2. **Pharmacokinetics:** It has a long half-life (~17 hours), allowing for once-daily subcutaneous dosing. 3. **Excretion:** It is primarily excreted unchanged by the kidneys; it is **contraindicated** in patients with severe renal impairment (CrCl <30 mL/min). 4. **Monitoring:** Unlike Warfarin (PT/INR) or UFH (aPTT), Fondaparinux does not require routine laboratory monitoring.

Q: Which of the following iron preparations is used for parenteral iron therapy?

Iron dextran. **Explanation:** **1. Why Iron Dextran is Correct:** Parenteral iron therapy is indicated when oral iron is not tolerated, ineffective (malabsorption), or when rapid replenishment of iron stores is required (e.g., chronic kidney disease or severe anemia in late pregnancy). **Iron dextran** is a complex of ferric hydroxide and dextran. It can be administered via deep intramuscular (IM) injection or slow intravenous (IV) infusion. It is a high-molecular-weight compound that allows for the delivery of large doses of iron in a single session (Total Dose Infusion). **2. Why the Other Options are Incorrect:** * **Ferrous sulfate, Ferrous fumarate, and Ferrous gluconate** are all **oral iron salts**. * These are the preferred first-line treatments for iron deficiency anemia due to their safety, low cost, and effectiveness. * Among these, Ferrous sulfate is the most commonly prescribed, while Ferrous fumarate contains the highest percentage of elemental iron (~33%). **3. High-Yield Clinical Pearls for NEET-PG:** * **Adverse Effects:** The most significant risk with Iron dextran is **anaphylaxis** (Type I hypersensitivity). A **test dose** is mandatory before the full therapeutic dose is administered. * **Z-track Technique:** When giving iron dextran intramuscularly, the Z-track technique must be used to prevent skin staining and local irritation. * **Newer Parenteral Agents:** Modern alternatives like **Iron Sucrose** and **Ferric Carboxymaltose** are often preferred over iron dextran because they carry a significantly lower risk of anaphylaxis and do not require a test dose. * **Calculation:** The dose of parenteral iron is calculated using the **Ganzoni Equation**: * *Iron deficit (mg) = Body weight (kg) × (Target Hb - Actual Hb) × 2.4 + Iron stores (500 mg).*

Q: Which of the following is NOT an antiplatelet drug?

Warfarin. ### Explanation The key to answering this question lies in distinguishing between **antiplatelet drugs** (which inhibit platelet aggregation) and **anticoagulants** (which inhibit the coagulation cascade). **1. Why Warfarin is the correct answer:** Warfarin is an **anticoagulant**, not an antiplatelet drug. It acts as a **Vitamin K antagonist**, inhibiting the enzyme Vitamin K Epoxide Reductase (VKOR). This prevents the γ-carboxylation of Vitamin K-dependent clotting factors (**II, VII, IX, and X**) and proteins C and S. It is primarily used to prevent venous thromboembolism and systemic embolism in patients with prosthetic valves or atrial fibrillation. **2. Why the other options are incorrect:** * **Aspirin:** An irreversible inhibitor of **COX-1**, preventing the synthesis of Thromboxane A2 (TXA2), a potent platelet aggregator. * **Clopidogrel:** A P2Y12 receptor antagonist. It prevents ADP from binding to its receptor on platelets, thereby inhibiting the activation of the GPIIb/IIIa complex. * **Dipyridamole:** A phosphodiesterase (PDE) inhibitor that increases cAMP levels within platelets, leading to the inhibition of platelet aggregation. It also has vasodilator properties. **3. NEET-PG High-Yield Pearls:** * **Monitoring:** Warfarin is monitored using **PT/INR**, whereas Heparin is monitored using **aPTT**. * **Teratogenicity:** Warfarin is contraindicated in pregnancy (causes **Fetal Warfarin Syndrome**); Heparin is the anticoagulant of choice. * **Resistance:** Clopidogrel is a prodrug activated by **CYP2C19**. Genetic polymorphisms or drugs like Omeprazole can reduce its efficacy. * **Abciximab:** Remember that this is a GPIIb/IIIa antagonist, often tested as the "final common pathway" inhibitor of platelet aggregation.

Q: Which of the following iron therapies is associated with the highest risk of anaphylaxis?

Iron dextran. The correct answer is **Iron dextran**. Among parenteral iron preparations, **Iron dextran** (specifically the high-molecular-weight formulation) carries the highest risk of severe Type I hypersensitivity reactions and anaphylaxis [2]. This is primarily due to the formation of antibodies against the **dextran polymer** component. Because of this risk, a **test dose** (usually 25 mg) is mandatory before administering the full therapeutic dose [2]. Patients must be monitored closely for at least an hour for signs of bronchospasm, hypotension, or urticaria [2]. **2. Why the other options are incorrect:** * **Ferric carboxymaltose (Option A):** This is a newer parenteral iron preparation designed with a non-dextran carbohydrate shell. It has a significantly lower risk of anaphylaxis compared to iron dextran and does not require a test dose [1]. It is preferred for rapid, high-dose replacement. * **Ferrous sulfate (Option C) and Ferrous fumarate (Option D):** These are **oral** iron salts. Anaphylaxis is a systemic reaction associated with intravenous administration; oral iron preparations typically cause gastrointestinal side effects rather than life-threatening allergic reactions [3]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Test Dose Requirement:** Iron dextran is the only iron preparation that strictly requires a test dose [2]. * **Iron Sucrose:** Another common IV option; it has a lower risk of allergy than dextran but can cause "free iron" toxicity if infused too rapidly. * **Management of Toxicity:** Acute iron poisoning is treated with **Deferoxamine** (IV/IM), while chronic iron overload (hemosiderosis) is managed with **Deferiprone** or **Deferasirox** (oral).

Question 1

All of the following features are common for both cangrelor and ticagrelor except?

Accepted Answer

Both drugs can be given orally.

Answer

They are antiplatelet drugs.

Answer

They reversibly inhibit ADP.

Answer

Both drugs have short half-lives.

Question 2

Sargramostim is a:

Accepted Answer

GM-CSF

Answer

G-CSF

Answer

IL-11 analogue

Answer

Erythropoietin analogue

Question 3

Which of the following is not used for thromboprophylaxis?

Accepted Answer

Antithrombin III

Answer

Heparin

Answer

Warfarin

Answer

Aspirin

Question 4

All of the following are complications of streptokinase, except?

Accepted Answer

Joint pain

Answer

Intracranial bleed

Answer

Fever

Answer

Anaphylaxis

Question 5

Which of the following is the mechanism of action of Fondaparinux?

Accepted Answer

Factor Xa inhibition

Answer

Factor Xa inhibition and Thrombin inhibition

Answer

Antithrombin inhibitor

Answer

Thrombin inhibition

Question 6

All of the following are target-specific oral anticoagulants except?

Accepted Answer

Betrixaban

Answer

Apixaban

Answer

Dabigatran

Answer

Rivaroxaban

Question 7

A pregnant mother is treated with oral anticoagulant. What is the likely congenital malformation that may result in the fetus?

Accepted Answer

Chondrodysplasia punctata

Answer

Long bones limb defect

Answer

Cranial malformation

Answer

Cardiovascular malformation

Question 8

Which of the following iron preparations is used for parenteral iron therapy?

Accepted Answer

Iron dextran

Answer

Ferrous sulfate

Answer

Ferrous fumarate

Answer

Ferrous gluconate

Question 9

Which of the following is NOT an antiplatelet drug?

Accepted Answer

Warfarin

Answer

Aspirin

Answer

Clopidogrel

Answer

Dipyridamole

Question 10

Which of the following iron therapies is associated with the highest risk of anaphylaxis?

Accepted Answer

Iron dextran

Answer

Ferric carboxymaltose

Answer

Ferrous sulfate

Answer

Ferrous fumarate

Drugs Affecting Blood and Blood Formation — MCQs

Drugs Affecting Blood and Blood Formation — MCQs

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