Drugs Affecting Blood and Blood Formation — MCQs

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

Question 91: Which drug is contraindicated in hemophilia?

A. Aspirin (Correct Answer)
B. Penicillin
C. Aminocaproic acid
D. Diphenylhydantoin

Explanation: **Explanation:** **Aspirin (Correct Answer):** Hemophilia is a genetic bleeding disorder characterized by a deficiency of clotting factors (Factor VIII in Hemophilia A; Factor IX in Hemophilia B), which impairs the **secondary hemostasis** (fibrin clot formation). Aspirin is a non-selective COX inhibitor that irreversibly inhibits platelet aggregation by blocking Thromboxane A2 (TXA2) synthesis. This impairs **primary hemostasis**. In a hemophilic patient, whose secondary hemostasis is already compromised, the addition of an antiplatelet agent like Aspirin can lead to catastrophic, life-threatening hemorrhage. Therefore, it is strictly contraindicated. **Incorrect Options:** * **Penicillin:** This is a beta-lactam antibiotic. While high doses of certain penicillins (like Carbenicillin) can occasionally interfere with platelet function, standard Penicillin G or V does not pose a specific contraindication in hemophilia. * **Aminocaproic acid:** This is an antifibrinolytic agent. It is actually used **therapeutically** in hemophilia (especially during dental extractions) to stabilize clots by inhibiting plasminogen activation. * **Diphenylhydantoin (Phenytoin):** This is an antiepileptic drug. While it has many side effects (gingival hyperplasia, hirsutism), it does not directly interfere with the coagulation cascade or platelet aggregation in a way that contraindicates its use in hemophilia. **High-Yield Clinical Pearls for NEET-PG:** * **Safe Analgesic:** **Paracetamol (Acetaminophen)** is the drug of choice for pain relief in hemophilic patients as it does not affect platelet function. * **Avoid IM Injections:** Intramuscular injections should be avoided in hemophiliacs to prevent hematoma formation; subcutaneous or intravenous routes are preferred. * **Desmopressin (DDAVP):** Used in Mild Hemophilia A to release stored Factor VIII and von Willebrand factor from endothelial Weibel-Palade bodies.

Question 92: Bone marrow aplasia is seen with all of the following drugs except:

A. Methicillin (Correct Answer)
B. Chloramphenicol
C. Alpha methyl hydantoin
D. Phenylbutazone

Explanation: **Explanation:** The question asks to identify the drug that does **not** typically cause bone marrow aplasia (aplastic anemia). **1. Why Methicillin is the Correct Answer:** Methicillin, a penicillinase-resistant penicillin, is classically associated with **Interstitial Nephritis** (a type IV hypersensitivity reaction), not bone marrow suppression. While it can rarely cause neutropenia, it is not a recognized cause of generalized bone marrow aplasia. Therefore, it is the "except" in this list. **2. Analysis of Incorrect Options (Drugs that cause Aplasia):** * **Chloramphenicol:** This is the most notorious drug associated with bone marrow toxicity. It causes two types: a dose-dependent, reversible suppression and a dose-independent, **idiosyncratic irreversible aplastic anemia** (often fatal). * **Alpha methyl hydantoin (Mephenytoin):** Hydantoin derivatives used in epilepsy are well-documented triggers for idiosyncratic bone marrow failure. * **Phenylbutazone:** An older NSAID that is now rarely used due to its high risk of causing severe, often fatal, aplastic anemia and agranulocytosis. **3. NEET-PG High-Yield Pearls:** * **Gold Standard for Aplastic Anemia:** Other high-yield drugs to remember include **Gold salts, Penicillamine, Carbamazepine, and Sulfa drugs.** * **Methicillin Side Effect:** Always associate Methicillin with **Acute Interstitial Nephritis (AIN)**—look for symptoms like fever, rash, and eosinophiluria in clinical vignettes. * **Chloramphenicol:** Remember the "Gray Baby Syndrome" (due to deficient glucuronidation) and its mechanism of inhibiting the 50S ribosomal subunit. * **Agranulocytosis vs. Aplasia:** While aplasia affects all three cell lines (pancytopenia), **Clozapine and Antithyroid drugs (PTU/Methimazole)** are more specifically associated with isolated agranulocytosis.

Question 93: All are true about Romiplostim except?

A. It is recombinant erythropoietin. (Correct Answer)
B. It has a protein component in its structure.
C. Its half-life is variable.
D. It is given subcutaneously.

Explanation: ### Explanation **Romiplostim** is a novel **thrombopoietin (TPO) receptor agonist**, often referred to as a "peptibody." It is used primarily to treat chronic immune thrombocytopenic purpura (ITP). **1. Why Option A is the Correct Answer (The "Except" statement):** Romiplostim is **not** recombinant erythropoietin. Recombinant erythropoietin (e.g., Epoetin alfa) stimulates red blood cell production. Romiplostim, instead, mimics the action of endogenous thrombopoietin by binding to the TPO receptor (Mpl), which stimulates megakaryopoiesis and increases **platelet count**. **2. Analysis of Other Options:** * **Option B (Protein component):** Romiplostim is a fusion protein consisting of a bioactive peptide sequence linked to an IgG1 Fc domain. This structure allows it to activate the TPO receptor without sharing sequence homology with native TPO, reducing the risk of neutralizing antibodies. * **Option C (Variable half-life):** The pharmacokinetics of Romiplostim are non-linear. Its half-life is inversely proportional to the serum concentration and varies based on the individual’s platelet count (target-mediated drug disposition). * **Option D (Subcutaneous administration):** It is administered once weekly via **subcutaneous injection**, making it convenient for chronic management of ITP. **Clinical Pearls for NEET-PG:** * **Mechanism:** It is a TPO-mimetic "peptibody." * **Indication:** Chronic ITP in patients who have had an insufficient response to corticosteroids, immunoglobulins, or splenectomy. * **Comparison:** Unlike **Eltrombopag** (which is an oral, small-molecule non-peptide TPO agonist), Romiplostim must be injected. * **Side Effects:** Headache is common; risk of bone marrow reticulin deposition and rebound thrombocytopenia upon discontinuation.

Question 94: Urgent reversal of warfarin therapy can be achieved by the administration of which of the following?

A. Cryoprecipitate
B. Platelets
C. Fresh frozen plasma (Correct Answer)
D. Packed red blood cells

Explanation: **Explanation:** The correct answer is **Fresh Frozen Plasma (FFP)**. **1. Why Fresh Frozen Plasma (FFP) is Correct:** Warfarin acts as a Vitamin K antagonist, inhibiting the synthesis of clotting factors II, VII, IX, and X. In cases of life-threatening bleeding or the need for urgent surgery, the goal is to immediately replace these deficient factors. **FFP** contains all coagulation factors in their active forms, providing an immediate (though temporary) reversal of the anticoagulant effect. While **Prothrombin Complex Concentrate (PCC)** is technically the fastest and preferred method in modern guidelines, FFP remains the standard answer among the provided options for urgent reversal. **2. Why Other Options are Incorrect:** * **A. Cryoprecipitate:** This is rich in Factor VIII, von Willebrand factor, and Fibrinogen. It is used for Hemophilia A, von Willebrand disease, or hypofibrinogenemia, but it lacks the specific Vitamin K-dependent factors (II, VII, IX, X) required to reverse warfarin. * **B. Platelets:** Warfarin affects the coagulation cascade (humoral immunity), not platelet count or function. Platelet transfusion is indicated for thrombocytopenia or platelet dysfunction. * **D. Packed Red Blood Cells (PRBCs):** These are used to restore oxygen-carrying capacity in patients with symptomatic anemia or acute blood loss. They do not contain plasma or clotting factors. **3. High-Yield Clinical Pearls for NEET-PG:** * **Antidote for Warfarin:** Vitamin K (Phytonadione) is the specific antidote, but it takes 6–24 hours to work (requires new protein synthesis in the liver). * **Fastest Reversal:** Prothrombin Complex Concentrate (PCC) is faster than FFP and does not carry the risk of volume overload. * **Monitoring:** Warfarin therapy is monitored using **PT/INR**. * **Mechanism:** Inhibits **Vitamin K Epoxide Reductase (VKOR)**. * **Teratogenicity:** Warfarin is contraindicated in pregnancy (causes Fetal Warfarin Syndrome); Heparin is the preferred anticoagulant for pregnant women.

Question 95: Relative to filgrastim (G-CSF), what is a characteristic of sargramostim (GM-CSF)?

A. Has greater oral bioavailability
B. Is more likely to cause thrombocytopenia
C. Is more likely to elicit an allergic reaction
D. Stimulates production of a wider variety of hematopoietic stem cells (Correct Answer)

Explanation: ### Explanation **1. Why Option D is Correct:** The primary difference between these two myeloid growth factors lies in their lineage specificity. **Filgrastim (G-CSF)** is highly specific; it acts primarily on the proliferation and differentiation of **neutrophils** only. In contrast, **Sargramostim (GM-CSF)** is a multipotential growth factor. It stimulates the proliferation and differentiation of a broader range of progenitor cells, including **neutrophils, eosinophils, monocytes, and macrophages** [1]. It also acts synergistically with Interleukin-3 to stimulate megakaryocyte and erythroid progenitors [1]. **2. Analysis of Incorrect Options:** * **Option A:** Both Filgrastim and Sargramostim are proteins (recombinant cytokines). They are degraded by gastric enzymes and therefore have **zero oral bioavailability**. They must be administered parenterally (IV or SC). * **Option B:** Sargramostim actually tends to *increase* or maintain platelet counts rather than cause thrombocytopenia. A common side effect of Sargramostim at high doses is the "first-dose reaction" (hypotension and tachycardia), but not specific thrombocytopenia. * **Option C:** While both are recombinant proteins and can theoretically cause hypersensitivity, Sargramostim is not specifically characterized by a higher rate of allergic reactions [2]. **3. NEET-PG High-Yield Pearls:** * **Filgrastim (G-CSF):** Used primarily to reduce the duration of neutropenia after chemotherapy and for peripheral blood stem cell (PBSC) mobilization [1]. * **Sargramostim (GM-CSF):** Used in bone marrow transplantation and to accelerate myeloid recovery in patients with AML [2], [3]. * **Side Effects:** Filgrastim commonly causes **medullary bone pain**. Sargramostim at high doses can cause **Capillary Leak Syndrome** (edema, pleural/pericardial effusions). * **Pegfilgrastim:** A pegylated form of G-CSF with a much longer half-life, allowing for once-per-chemotherapy-cycle dosing.

Question 96: What is the earliest response to iron therapy?

A. Increase in Hemoglobin percentage
B. Reticulocytes (Correct Answer)
C. Increased Packed Cell Volume
D. Increased neutrophils

Explanation: In iron deficiency anemia, the administration of iron provides the essential substrate for erythropoiesis. The sequence of response follows a predictable physiological timeline: **Why Reticulocytes is the correct answer:** The earliest objective laboratory sign of response to iron therapy is **reticulocytosis** (an increase in young, immature red blood cells) [1]. After starting iron, the bone marrow begins producing new RBCs rapidly. The reticulocyte count starts rising within **3 to 7 days**, reaching a peak between **7 to 10 days**. This indicates that the marrow is functional and responding to the treatment [1]. **Explanation of Incorrect Options:** * **A & C (Hemoglobin and PCV):** While these parameters will eventually normalize, they are lagging indicators. Hemoglobin typically begins to rise after the first week, usually at a rate of approximately **1 g/dL per week** [1]. It takes about 1–2 months to reach normal levels. * **D (Increased Neutrophils):** Iron therapy specifically targets the erythroid cell line. It does not cause a significant or diagnostic increase in the neutrophil count. **High-Yield Clinical Pearls for NEET-PG:** * **Subjective Improvement:** The very first response (often within 24–48 hours) is a subjective sense of well-being and improved appetite, due to the restoration of iron-containing enzymes (like cytochromes). * **Duration of Therapy:** Iron therapy must be continued for **3 to 6 months** *after* hemoglobin normalizes to replenish the depleted iron stores (measured by Serum Ferritin). * **Parenteral Iron:** If a patient cannot tolerate oral iron or has malabsorption, IV iron (e.g., Iron Sucrose or Ferric Carboxymaltose) is used, but the *rate* of hemoglobin rise is generally the same as oral iron.

Question 97: A 55-year-old man with unstable angina is treated with an intravenously administered glycoprotein IIb/IIIa inhibitor. What is the mechanism of action of this agent?

A. Dilate coronary arteries
B. Inhibit platelet aggregation (Correct Answer)
C. Inhibit platelet adhesion
D. Inhibit atherogenesis

Explanation: **Explanation:** **Mechanism of Action (Why B is correct):** Glycoprotein (GP) IIb/IIIa inhibitors (e.g., **Abciximab, Eptifibatide, and Tirofiban**) are potent antiplatelet agents. The GP IIb/IIIa receptor is the most abundant receptor on the platelet surface. When platelets are activated, these receptors undergo a conformational change, allowing them to bind to **fibrinogen** and **von Willebrand factor**. Fibrinogen acts as a bridge between two GP IIb/IIIa receptors on adjacent platelets, leading to **platelet aggregation** (the "final common pathway" of platelet activation). By blocking this receptor, these drugs prevent the cross-linking of platelets, regardless of the initial stimulus (ADP, Thromboxane A2, or Collagen). **Why other options are incorrect:** * **Option A:** Coronary vasodilation is the primary mechanism of Nitrates and Calcium Channel Blockers, not GP IIb/IIIa inhibitors. * **Option C:** Platelet **adhesion** (platelets sticking to the vessel wall) is mediated primarily by GP Ib receptors binding to von Willebrand factor on exposed subendothelial collagen. GP IIb/IIIa inhibitors specifically target **aggregation** (platelets sticking to each other). * **Option D:** Atherogenesis is a chronic inflammatory process involving lipid deposition and plaque formation. While antiplatelet therapy prevents acute thrombotic events, it does not inhibit the underlying process of atherogenesis (which is managed by statins and lifestyle changes). **High-Yield Clinical Pearls for NEET-PG:** * **Abciximab:** A chimeric monoclonal antibody; it is non-competitive and has the longest biological half-life (irreversible binding). * **Eptifibatide & Tirofiban:** Competitive and reversible inhibitors. * **Route:** Administered only **intravenously**. * **Major Side Effect:** Bleeding and **thrombocytopenia**. * **Indications:** Acute Coronary Syndrome (ACS) and during Percutaneous Coronary Intervention (PCI).

Question 98: Which of the following classes of drugs is generally precluded from administration via the intramuscular route?

A. Anti-hypertensives
B. Anti-diabetics
C. Anticoagulants (Correct Answer)
D. Anti-fibrinolytics

Explanation: The correct answer is **Anticoagulants**. **Why Anticoagulants are precluded from IM administration:** The primary reason for avoiding the intramuscular (IM) route for anticoagulants (such as Heparin or Warfarin) is the high risk of **hematoma formation**. Skeletal muscle is highly vascular; when a needle punctures these vessels in a patient with impaired coagulation, it leads to significant local bleeding. This can result in large, painful hematomas, potential nerve compression, and erratic drug absorption. Therefore, Heparin is administered intravenously (IV) or subcutaneously (SC) [1], [2], but never IM. **Analysis of Incorrect Options:** * **Anti-hypertensives:** Many can be given IM in emergencies (e.g., Hydralazine or Labetalol), though IV is preferred for rapid titration. * **Anti-diabetics:** While Insulin is typically SC, certain preparations can be given IM if necessary, and Glucagon (used for hypoglycemia) is frequently administered via the IM route. * **Anti-fibrinolytics:** Drugs like Tranexamic acid are primarily given IV or Orally. While IM is not the standard route, they do not carry the specific risk of causing uncontrollable bleeding/hematoma at the injection site. **High-Yield Clinical Pearls for NEET-PG:** * **Heparin vs. Warfarin:** Heparin is the anticoagulant of choice in pregnancy (does not cross the placenta), while Warfarin is teratogenic [3]. * **Monitoring:** Monitor Heparin with **aPTT** (Intrinsic pathway) and Warfarin with **PT/INR** (Extrinsic pathway). * **Antidotes:** The antidote for Heparin is **Protamine Sulfate** [1]; for Warfarin, it is **Vitamin K** (slow) or **Fresh Frozen Plasma** (rapid) [3]. * **Absorption:** Subcutaneous administration of Heparin is preferred over IM because the smaller needle and slower absorption profile reduce the risk of massive tissue hemorrhage.

Question 99: All of the following are true about Heparin except?

A. Argatroban is the drug of choice for Heparin-induced thrombocytopenia.
B. Unfractionated Heparin induces antibodies against PF4 and leads to platelet aggregation.
C. Heparin can lead to arterial thrombosis more than venous thrombosis. (Correct Answer)
D. Unfractionated Heparin is safer in renal failure.

Explanation: **Explanation:** The correct answer is **C**, as Heparin-Induced Thrombocytopenia (HIT) is paradoxically characterized by a much higher risk of **venous thrombosis** (e.g., DVT, PE) than arterial thrombosis. While arterial "white clot syndrome" can occur, venous thromboembolism is 4x more common in HIT patients. **Analysis of Options:** * **Option A (Incorrect):** Argatroban, a parenteral direct thrombin inhibitor (DTI), is indeed the drug of choice for treating HIT. It does not require Antithrombin III and does not cross-react with HIT antibodies. * **Option B (Incorrect):** This describes the pathophysiology of **HIT Type II**. Heparin binds to **Platelet Factor 4 (PF4)**, forming a complex. IgG antibodies develop against this complex, which then bind to the Fc receptors on platelets, leading to massive platelet activation, consumption (thrombocytopenia), and a hypercoagulable state. * **Option D (Incorrect):** Unfractionated Heparin (UFH) is primarily cleared by the reticuloendothelial system and liver, making it **safer in renal failure**. In contrast, Low Molecular Weight Heparin (LMWH) is renally excreted and contraindicated in severe renal impairment (CrCl <30 ml/min). **High-Yield Clinical Pearls for NEET-PG:** * **HIT Type I:** Non-immunogenic, occurs within 2 days, transient, and not clinically significant. * **HIT Type II:** Immunogenic, occurs 5–14 days after starting heparin, and is a **pro-thrombotic emergency**. * **Monitoring:** UFH is monitored by **aPTT** (intrinsic pathway), while LMWH generally does not require monitoring (except in pregnancy/obesity via Anti-Xa levels). * **Antidote:** **Protamine sulfate** (1 mg neutralizes 100 units of UFH; only partially neutralizes LMWH).

Question 100: What is the anticoagulant of choice for heparin-induced thrombocytopenia?

A. Lepirudin (Correct Answer)
B. Aprotinin
C. Abciximab
D. Plasminogen

Explanation: **Explanation:** **Heparin-Induced Thrombocytopenia (HIT)** is a prothrombotic state caused by IgG antibodies against the Heparin-Platelet Factor 4 (PF4) complex. When HIT occurs, all forms of heparin must be stopped immediately. The anticoagulant of choice must be a drug that does not cross-react with HIT antibodies. **1. Why Lepirudin is Correct:** Lepirudin is a recombinant derivative of hirudin and acts as a **Direct Thrombin Inhibitor (DTI)**. Unlike heparin, DTIs do not require Antithrombin III for their action and do not bind to PF4. Therefore, they do not trigger or worsen the immune-mediated platelet destruction seen in HIT. While Argatroban is also frequently used (especially in renal failure), Lepirudin remains a classic textbook answer for HIT management. **2. Why the Other Options are Incorrect:** * **B. Aprotinin:** An antifibrinolytic agent (serine protease inhibitor) used to reduce blood loss during surgery. It promotes clotting rather than preventing it. * **C. Abciximab:** A Glycoprotein IIb/IIIa receptor antagonist. It is an antiplatelet drug, not an anticoagulant, and is used primarily in percutaneous coronary interventions (PCI). * **D. Plasminogen:** The inactive precursor of plasmin. It is part of the fibrinolytic system (clot-dissolving) and is not used as an anticoagulant. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice for HIT:** Direct Thrombin Inhibitors (e.g., **Argatroban, Lepirudin, Bivalirudin, Desirudin**). * **Argatroban** is preferred in patients with **renal impairment** (metabolized by the liver). * **Lepirudin** is preferred in patients with **hepatic impairment** (excreted by the kidneys). * **Avoid Warfarin** in the acute phase of HIT until the platelet count recovers, as it can precipitate venous limb gangrene due to a rapid drop in Protein C levels.

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