Drugs Affecting Blood and Blood Formation — MCQs

Drugs Affecting Blood and Blood Formation Indian Medical PG Practice Questions and MCQs

Question 41: Oprelvekin is a:

A. IL-1 analogue
B. IL-6 analogue
C. IL-11 analogue (Correct Answer)
D. IL-13 analogue

Explanation: **Explanation:** **Oprelvekin** is a recombinant form of **Interleukin-11 (IL-11)**. It is a potent thrombopoietic growth factor that stimulates the proliferation of hematopoietic stem cells and megakaryocyte progenitor cells, ultimately increasing platelet production. **Why the correct answer is right:** * **IL-11 Analogue (Option C):** Oprelvekin mimics the action of endogenous IL-11. It is FDA-approved for the **prevention of severe thrombocytopenia** in patients receiving myelosuppressive chemotherapy for non-myeloid malignancies. By stimulating megakaryocytopoiesis, it reduces the need for platelet transfusions. **Why the other options are wrong:** * **IL-1 Analogue (Option A):** IL-1 is a pro-inflammatory cytokine. **Anakinra** is the relevant drug here; it is an IL-1 receptor antagonist used in Rheumatoid Arthritis. * **IL-6 Analogue (Option B):** While IL-6 also stimulates platelet production, Oprelvekin specifically targets the IL-11 pathway. **Tocilizumab** is a well-known drug related to IL-6, but it is an antagonist (receptor blocker). * **IL-13 Analogue (Option D):** IL-13 is involved in allergic inflammation and B-cell responses. There are no commonly tested analogues used for blood formation in this category. **High-Yield Clinical Pearls for NEET-PG:** 1. **Side Effects:** The most characteristic side effect of Oprelvekin is **fluid retention** (edema, dyspnea, and pleural effusion) due to sodium and water retention. It can also cause transient **atrial arrhythmias** (fibrillation/flutter). 2. **Comparison:** While Oprelvekin is an IL-11 analogue, **Romiplostim** (peptibody) and **Eltrombopag** (oral non-peptide) are **Thrombopoietin (TPO) receptor agonists** used for ITP. 3. **Route:** It is administered via the subcutaneous route.

Question 42: What is the primary indication for eptifibatide?

A. Angina (Correct Answer)
B. HIV
C. Congestive Cardiac Failure (CCF)
D. Hypertension

Explanation: **Explanation:** **Eptifibatide** is a potent **Glycoprotein (GP) IIb/IIIa inhibitor**. Its primary indication is the management of **Acute Coronary Syndromes (ACS)**, specifically **Unstable Angina** and Non-ST Elevation Myocardial Infarction (NSTEMI), as well as for patients undergoing Percutaneous Coronary Intervention (PCI). **Why Angina is Correct:** The underlying mechanism involves blocking the GP IIb/IIIa receptor on the platelet surface. This receptor is the "final common pathway" for platelet aggregation, as it serves as the binding site for fibrinogen and von Willebrand factor. By preventing fibrinogen bridges between platelets, eptifibatide inhibits thrombus formation, thereby maintaining coronary blood flow in patients with unstable angina. **Why Other Options are Incorrect:** * **HIV:** Antiretroviral drugs (like Protease Inhibitors or RTIs) are used here. Eptifibatide has no antiviral properties. * **Congestive Cardiac Failure (CCF):** CCF is managed with diuretics, ACE inhibitors, and beta-blockers to reduce preload/afterload. Eptifibatide does not improve myocardial contractility or fluid status. * **Hypertension:** Antihypertensives (like CCBs or ARBs) target peripheral resistance or cardiac output. Eptifibatide does not lower blood pressure. **High-Yield NEET-PG Pearls:** * **Structure:** Eptifibatide is a cyclic heptapeptide derived from rattlesnake venom (Barbourin). * **Reversibility:** It is a **reversible** inhibitor with a short half-life (approx. 2 hours). * **Other GP IIb/IIIa Inhibitors:** **Abciximab** (monoclonal antibody - irreversible) and **Tirofiban** (non-peptide - reversible). * **Major Side Effect:** Bleeding (especially at the access site) and thrombocytopenia. * **Excretion:** Primarily renal; dose adjustment is required in chronic kidney disease.

Question 43: Which of the following drugs produces neutrophilia?

A. Chlorambucil
B. Glucocorticoids (Correct Answer)
C. Sulfonamides
D. Chloramphenicol

Explanation: **Explanation:** The correct answer is **Glucocorticoids (Option B)**. While most drugs that affect the bone marrow cause a decrease in cell counts, glucocorticoids are unique because they cause an **increase** in the absolute neutrophil count (neutrophilia). **Mechanism of Glucocorticoid-induced Neutrophilia:** Glucocorticoids produce neutrophilia through three primary mechanisms: 1. **Demargination:** They decrease the expression of adhesion molecules (like L-selectin) on neutrophils, causing them to detach from the vascular endothelium (the "marginal pool") and enter the "circulating pool." 2. **Delayed Apoptosis:** They extend the lifespan of mature neutrophils in the blood. 3. **Increased Bone Marrow Release:** They stimulate the release of neutrophils from the bone marrow storage pool. *Note: While they increase neutrophils, glucocorticoids simultaneously cause lymphopenia, eosinopenia, and monocytopenia.* **Why the other options are incorrect:** * **Chlorambucil (Option A):** An alkylating agent used in chemotherapy; it causes generalized myelosuppression (neutropenia/leukopenia). * **Sulfonamides (Option C):** These are common causes of idiosyncratic drug-induced agranulocytosis (severe neutropenia). * **Chloramphenicol (Option D):** Notorious for causing dose-dependent bone marrow suppression and idiosyncratic **aplastic anemia**, leading to pancytopenia (low RBCs, WBCs, and platelets). **High-Yield NEET-PG Pearls:** * **The "Rule of Up and Down":** Glucocorticoids increase **N**eutrophils, **R**BCs, and **P**latelets, but decrease **L**ymphocytes, **E**osinophils, and **B**asophils (Mnemonic: **NRP** goes up; **LEB** goes down). * **Steroid-induced Lymphopenia:** This occurs primarily due to the redistribution of lymphocytes from the blood into other lymphoid compartments (e.g., bone marrow). * **Clinical Correlation:** When a patient on steroids presents with a high WBC count, it may be a drug effect rather than a sign of new infection.

Question 44: A patient receiving coumarin therapy for three years recently developed a bleeding tendency. How will you reverse the effect of coumarin therapy?

A. Protamine injection
B. Vitamin K injection (Correct Answer)
C. Infusion of fibrinogen
D. Whole blood transfusion

Explanation: **Explanation:** **Mechanism of Action & Correct Answer:** Coumarin derivatives (like Warfarin) are oral anticoagulants that act as **Vitamin K antagonists**. They inhibit the enzyme **Vitamin K Epoxide Reductase (VKOR)**, preventing the conversion of inactive Vitamin K epoxide to its active hydroquinone form. This results in the depletion of active Vitamin K, which is essential for the γ-carboxylation (activation) of clotting factors **II, VII, IX, and X**. Therefore, the physiological and direct pharmacological antidote to reverse coumarin-induced bleeding is **Vitamin K injection** (Phytonadione), which bypasses the inhibition and restores clotting factor synthesis. **Analysis of Incorrect Options:** * **A. Protamine injection:** This is the specific antidote for **Heparin** overdose. It is a basic protein that neutralizes acidic heparin through ionic bonding. * **C. Infusion of fibrinogen:** Fibrinogen (Factor I) is used in specific deficiency states or DIC, but it does not address the multi-factor deficiency (II, VII, IX, X) caused by coumarins. * **D. Whole blood transfusion:** While it can replace volume, it is not the standard of care for reversing anticoagulation. If immediate reversal is required (life-threatening bleed), **Fresh Frozen Plasma (FFP)** or **Prothrombin Complex Concentrate (PCC)** is preferred over whole blood. **NEET-PG High-Yield Pearls:** * **Immediate Reversal:** Vitamin K takes 6–24 hours to work (requires new protein synthesis). For **emergency** reversal, use **FFP** or **PCC**. * **Monitoring:** Warfarin therapy is monitored using **PT/INR** (Extrinsic pathway). * **Teratogenicity:** Warfarin is contraindicated in pregnancy (causes Fetal Warfarin Syndrome); Heparin is the anticoagulant of choice for pregnant women.

Question 45: All of the following are false regarding prasugrel, except?

A. Minimal metabolism in the body
B. Slower onset of action than clopidogrel
C. Reversible inhibitors of ADP
D. Contraindicated in cerebrovascular accident (Correct Answer)

Explanation: **Explanation:** Prasugrel is a third-generation **thienopyridine** derivative and a potent P2Y12 receptor antagonist used to inhibit platelet aggregation. **Why Option D is Correct:** Prasugrel is associated with a significantly higher risk of major bleeding compared to clopidogrel. It is strictly **contraindicated** in patients with a history of **Cerebrovascular Accident (CVA)** or **Transient Ischemic Attack (TIA)** because it markedly increases the risk of intracranial hemorrhage in these individuals. **Analysis of Incorrect Options:** * **Option A:** Prasugrel is a **prodrug**. Unlike clopidogrel, which requires a complex two-step hepatic activation, prasugrel undergoes rapid hydrolysis by intestinal esterases followed by a single CYP-dependent step. It undergoes extensive metabolism, not minimal. * **Option B:** Because its metabolic activation is more efficient and less dependent on genetic polymorphisms (like CYP2C19), prasugrel has a **faster onset of action** and provides more consistent platelet inhibition than clopidogrel. * **Option C:** Like all thienopyridines (clopidogrel, ticlopidine), prasugrel binds **irreversibly** to the P2Y12 ADP receptor for the lifespan of the platelet. Only non-thienopyridines like Ticagrelor and Cangrelor are reversible inhibitors. **High-Yield Clinical Pearls for NEET-PG:** * **TRITON-TIMI 38 Trial:** Demonstrated prasugrel's superiority over clopidogrel in reducing MI but highlighted the increased bleeding risk. * **Dosing Caution:** Use with caution or reduced dose in patients weighing **<60 kg** or those aged **>75 years** due to bleeding risk. * **Drug Interactions:** Unlike clopidogrel, prasugrel's efficacy is not significantly affected by Proton Pump Inhibitors (PPIs) like omeprazole.

Question 46: Which of the following statements about oral anticoagulants is FALSE?

A. They interfere with an early step in the synthesis of clotting factors (Correct Answer)
B. Irrespective of the dose administered, their anticoagulant effect has a latency of onset of 1-3 days
C. Their dose is adjusted by repeated measurement of prothrombin time
D. They are contraindicated during pregnancy

Explanation: **Explanation** **1. Why Option A is the correct (False) statement:** Oral anticoagulants like Warfarin do not interfere with an "early step" in the synthesis of clotting factors. Instead, they interfere with the **final step** of synthesis—the **$\gamma$-carboxylation** of glutamate residues on Factors II, VII, IX, and X. This process requires reduced Vitamin K. Warfarin inhibits the enzyme **Vitamin K Epoxide Reductase (VKOR)**, preventing the regeneration of reduced Vitamin K. Consequently, the liver produces "PIVKA" (Proteins Induced by Vitamin K Absence), which are biologically inactive precursors. **2. Analysis of other options:** * **Option B (Latency of onset):** This is **true**. Even with high doses, the effect is delayed (1–3 days) because Warfarin does not affect factors already circulating in the blood. The clinical effect appears only after the pre-existing clotting factors are naturally degraded (Factor VII has the shortest half-life, while Factor II has the longest). * **Option C (Prothrombin Time):** This is **true**. The dose is titrated using **PT/INR** (International Normalized Ratio). Since Warfarin affects the extrinsic and common pathways, PT is the most sensitive marker. * **Option D (Pregnancy):** This is **true**. Warfarin is **teratogenic** (causes Fetal Warfarin Syndrome, including chondrodysplasia punctata) and can cause fetal hemorrhage. Heparin is the preferred anticoagulant in pregnancy as it does not cross the placenta. **High-Yield Clinical Pearls for NEET-PG:** * **Antidote:** For immediate reversal, use **Fresh Frozen Plasma (FFP)** or Prothrombin Complex Concentrate (PCC). For non-emergency reversal, use **Vitamin K1 (Phytonadione)**. * **Warfarin-Induced Skin Necrosis:** Occurs due to a rapid decline in **Protein C** (which has a short half-life), leading to a transient hypercoagulable state. * **Drug Interactions:** Enzyme inhibitors (e.g., Erythromycin, Cimetidine) increase Warfarin's effect, while enzyme inducers (e.g., Rifampicin, Phenytoin) decrease it.

Question 47: Which of the following statements about TXA2 is incorrect?

A. It is formed in platelets.
B. It is formed from PGG2/H2.
C. It is prothrombotic.
D. It has platelet anti-aggregatory activity. (Correct Answer)

Explanation: Thromboxane A2 (TXA2) is a potent eicosanoid derived from arachidonic acid that plays a central role in hemostasis. **1. Why Option D is the Correct Answer (The Incorrect Statement):** TXA2 is a powerful **platelet aggregator**, not an anti-aggregatory agent [4]. It acts via the TP receptor (Gq-coupled) to increase intracellular calcium, leading to the activation of the GPIIb/IIIa receptor, which facilitates platelet-to-platelet binding via fibrinogen [4]. It also acts as a potent **vasoconstrictor**. **2. Analysis of Incorrect Options (Correct Statements):** * **Option A:** TXA2 is primarily synthesized in **platelets** by the enzyme Thromboxane Synthase [2]. * **Option B:** The biosynthetic pathway involves the conversion of Arachidonic acid to cyclic endoperoxides (**PGG2 and PGH2**) by the enzyme Cyclooxygenase (COX-1) [1]. These endoperoxides are then converted into TXA2. * **Option C:** Because it promotes both platelet aggregation and vasoconstriction, TXA2 is fundamentally **prothrombotic**, aiding in the formation of a stable blood clot. **Clinical Pearls for NEET-PG:** * **Aspirin’s Mechanism:** Low-dose Aspirin irreversibly inhibits **COX-1** in platelets [1]. Since platelets are anuclear and cannot synthesize new enzymes, TXA2 production is inhibited for the lifetime of the platelet (7–10 days) [2]. * **The Balance:** While platelets produce TXA2 (pro-aggregatory), vascular endothelial cells produce **PGI2 (Prostacyclin)**, which is a potent vasodilator and **anti-aggregatory** agent [3]. The balance between these two determines vascular patency. * **TXA2 vs. PGI2:** Remember "TXA2 = **T**hrombosis" and "PGI2 = **I**nhibits aggregation."

Question 48: Which of the following is NOT a true statement about heparin?

A. It prolongs aPTT.
B. Hyperkalemia is not seen. (Correct Answer)
C. It can result in alopecia.
D. It can cause thrombocytopenia.

Explanation: ### Explanation **Correct Answer: B. Hyperkalemia is not seen.** **Why Option B is the correct answer:** This statement is **false** because heparin **can cause hyperkalemia**. Heparin inhibits the synthesis of aldosterone in the adrenal cortex (by reducing the number and affinity of angiotensin II receptors in the zona glomerulosa). Since aldosterone is responsible for potassium excretion, its suppression leads to potassium retention. This effect can occur even with low-dose heparin and is more significant in patients with diabetes mellitus or chronic renal failure. **Analysis of Incorrect Options:** * **A. It prolongs aPTT:** This is a **true** statement. Unfractionated Heparin (UFH) acts primarily by accelerating Antithrombin III, which inactivates Thrombin (IIa) and Factor Xa. The activated Partial Thromboplastin Time (aPTT) is the standard clinical test used to monitor its therapeutic effect. * **C. It can result in alopecia:** This is a **true** statement. Alopecia (hair loss) is a recognized, though less common, side effect of long-term heparin therapy. It is usually reversible upon discontinuation. * **D. It can cause thrombocytopenia:** This is a **true** statement. Heparin-Induced Thrombocytopenia (HIT) is a serious immune-mediated reaction (Type II hypersensitivity) where antibodies form against the Heparin-Platelet Factor 4 complex, leading to platelet activation and paradoxical thrombosis. **NEET-PG High-Yield Pearls:** * **Antidote:** Protamine sulfate (a basic drug that neutralizes acidic heparin via chemical antagonism). * **Safe in Pregnancy:** Heparin does not cross the placenta, making it the anticoagulant of choice during pregnancy (unlike Warfarin, which is teratogenic). * **Osteoporosis:** Long-term use of heparin (usually >6 months) can lead to decreased bone density and spontaneous fractures. * **LMWH vs. UFH:** Low Molecular Weight Heparins (e.g., Enoxaparin) have a more predictable response, longer half-life, and do not require routine aPTT monitoring.

Question 49: Heparin-induced thrombocytopenia is due to antibodies against which of the following?

A. Platelet factor 1
B. Platelet factor 2
C. Platelet factor 3
D. Platelet factor 4 (Correct Answer)

Explanation: **Explanation:** **Heparin-Induced Thrombocytopenia (HIT)** is a life-threatening clinico-pathological syndrome caused by an immune-mediated reaction to heparin therapy. **Why Option D is Correct:** The pathogenesis of HIT (specifically Type II) involves the formation of IgG antibodies against the **Heparin-Platelet Factor 4 (PF4) complex**. 1. PF4 is a cationic protein stored in the alpha-granules of platelets. 2. When heparin (anionic) binds to PF4, it causes a conformational change, creating a neoantigen. 3. IgG antibodies bind to this Heparin-PF4 complex, forming immune complexes. 4. These complexes then bind to the **FcγRIIa receptors** on the surface of other platelets, leading to massive platelet activation, prothrombotic state, and subsequent consumption (thrombocytopenia). **Why Other Options are Incorrect:** * **Platelet Factor 1:** This is actually Factor V (proaccelerin) adsorbed onto the platelet surface; it is not involved in HIT. * **Platelet Factor 2:** Also known as thrombin-accelerator, it sensitizes fibrinogen to thrombin; it has no role in heparin-related immune reactions. * **Platelet Factor 3:** This refers to the platelet membrane phospholipids (like phosphatidylserine) that provide a surface for the assembly of coagulation complexes (tenase and prothrombinase). **High-Yield Clinical Pearls for NEET-PG:** * **Type II HIT** is the clinically significant form, typically occurring **5–10 days** after starting heparin. * **Paradoxical Thrombosis:** Despite low platelet counts, HIT is a **hypercoagulable state**. Patients are at high risk for venous and arterial thrombosis. * **Management:** Immediately stop all heparin products (including LMWH). Switch to direct thrombin inhibitors like **Argatroban** (drug of choice in renal failure) or **Lepirudin/Bivalirudin**. * **Gold Standard Test:** Serotonin Release Assay (SRA). The most common screening test is the ELISA for PF4 antibodies.

Question 50: Coumarin necrosis occurs due to:

A. Heparin
B. Low molecular weight heparin
C. Warfarin (Correct Answer)
D. Clopidogrel

Explanation: **Explanation:** **Warfarin-induced skin necrosis** is a rare but severe complication occurring typically within 3 to 10 days of starting therapy. **Why Warfarin is the correct answer:** Warfarin acts by inhibiting Vitamin K epoxide reductase, leading to a decrease in Vitamin K-dependent clotting factors (II, VII, IX, X) and anticoagulant proteins (Protein C and Protein S). Protein C has a significantly shorter half-life (~6 hours) compared to procoagulant factors like Factor X and II. Consequently, during the initial phase of treatment, Protein C levels drop rapidly while procoagulant levels remain high. This creates a transient **prothrombotic state**, leading to microvascular thrombosis in the subcutaneous fat, resulting in skin necrosis. This risk is significantly higher in patients with pre-existing Protein C or S deficiency. **Why other options are incorrect:** * **Heparin & LMWH:** These drugs act via Antithrombin III and do not cause a rapid depletion of Protein C. In fact, "Heparin bridging" is used specifically to prevent warfarin-induced necrosis. * **Clopidogrel:** This is an antiplatelet drug (P2Y12 inhibitor) and does not affect the Vitamin K-dependent coagulation cascade. **High-Yield Clinical Pearls for NEET-PG:** * **Prevention:** Always "bridge" warfarin with Heparin for the first 4–5 days until the INR reaches the therapeutic range. * **Management:** If necrosis occurs, immediately stop Warfarin, administer **Vitamin K**, and provide **Protein C concentrates** or Fresh Frozen Plasma (FFP). * **Common Site:** Areas with high fat content (breasts, thighs, and buttocks). * **Teratogenicity:** Warfarin is contraindicated in pregnancy (causes Fetal Warfarin Syndrome/Chondrodysplasia punctata); Heparin is the drug of choice.

Practice by Chapter

Hematopoietic Growth Factors

Practice Questions

Iron Preparations and Management of Iron Deficiency

Practice Questions

Vitamin B12 and Folic Acid

Practice Questions

Anticoagulants: Heparins and Direct Inhibitors

Practice Questions

Oral Anticoagulants

Practice Questions

Antiplatelet Drugs

Practice Questions

Thrombolytic Agents

Practice Questions

Hemostatic Drugs

Practice Questions

Plasma Expanders

Practice Questions

Blood Transfusion and Alternatives

Practice Questions

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free