Drugs Affecting Blood and Blood Formation Practice Questions

Q: Which drug is contraindicated in hemophilia?

Aspirin. **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.

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

Methicillin. **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.

Q: All are true about Romiplostim except?

It is recombinant erythropoietin.. ### 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.

Q: What is the earliest response to iron therapy?

Reticulocytes. 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.

Q: 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?

Inhibit platelet aggregation. **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).

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

Anticoagulants. 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.

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

Lepirudin. **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.

Question 1

Which drug is contraindicated in hemophilia?

Accepted Answer

Aspirin

Answer

Penicillin

Answer

Aminocaproic acid

Answer

Diphenylhydantoin

Question 2

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

Accepted Answer

Methicillin

Answer

Chloramphenicol

Answer

Alpha methyl hydantoin

Answer

Phenylbutazone

Question 3

All are true about Romiplostim except?

Accepted Answer

It is recombinant erythropoietin.

Answer

It has a protein component in its structure.

Answer

Its half-life is variable.

Answer

It is given subcutaneously.

Question 4

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

Accepted Answer

Fresh frozen plasma

Answer

Cryoprecipitate

Answer

Platelets

Answer

Packed red blood cells

Question 5

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

Accepted Answer

Stimulates production of a wider variety of hematopoietic stem cells

Answer

Has greater oral bioavailability

Answer

Is more likely to cause thrombocytopenia

Answer

Is more likely to elicit an allergic reaction

Question 6

What is the earliest response to iron therapy?

Accepted Answer

Reticulocytes

Answer

Increase in Hemoglobin percentage

Answer

Increased Packed Cell Volume

Answer

Increased neutrophils

Question 7

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?

Accepted Answer

Inhibit platelet aggregation

Answer

Dilate coronary arteries

Answer

Inhibit platelet adhesion

Answer

Inhibit atherogenesis

Question 8

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

Accepted Answer

Anticoagulants

Answer

Anti-hypertensives

Answer

Anti-diabetics

Answer

Anti-fibrinolytics

Question 9

All of the following are true about Heparin except?

Accepted Answer

Heparin can lead to arterial thrombosis more than venous thrombosis.

Answer

Argatroban is the drug of choice for Heparin-induced thrombocytopenia.

Answer

Unfractionated Heparin induces antibodies against PF4 and leads to platelet aggregation.

Answer

Unfractionated Heparin is safer in renal failure.

Question 10

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

Accepted Answer

Lepirudin

Answer

Aprotinin

Answer

Abciximab

Answer

Plasminogen

Drugs Affecting Blood and Blood Formation — MCQs

Drugs Affecting Blood and Blood Formation — MCQs

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