Drugs Affecting Blood and Blood Formation Practice Questions

Q: Which of the following belongs to antifibrinolytic drugs?

Aprotinin. **Explanation:** The core concept here is the distinction between **fibrinolytics** (which break down clots) and **antifibrinolytics** (which prevent the breakdown of clots). **Why Aprotinin is Correct:** **Aprotinin** is a potent protease inhibitor that inhibits **plasmin**, the enzyme responsible for fibrinolysis (clot dissolution). By blocking plasmin and its precursor kallikrein, it stabilizes existing fibrin clots and reduces bleeding. It is clinically used to reduce blood loss during major surgeries, such as coronary artery bypass grafting (CABG). Other common antifibrinolytics include **Tranexamic acid** and **Epsilon-aminocaproic acid (EACA)**, which work by blocking the lysine-binding sites on plasminogen. **Why the Other Options are Incorrect:** * **Alteplase (A):** This is a recombinant Tissue Plasminogen Activator (rt-PA). It converts plasminogen to plasmin, thereby promoting the lysis of clots. It is used in acute ischemic stroke and MI. * **Urokinase (B):** An enzyme naturally produced by the kidneys that directly converts plasminogen to plasmin. It is a fibrinolytic agent. * **Reteplase (D):** A second-generation recombinant plasminogen activator (a derivative of t-PA) with a longer half-life than Alteplase. Like the others, it is a fibrinolytic used to dissolve thrombi. **High-Yield NEET-PG Pearls:** * **Mechanism Check:** Fibrinolytics = Plasminogen Activators; Antifibrinolytics = Plasmin Inhibitors/Plasminogen Activation Blockers. * **Tranexamic Acid:** 10 times more potent than EACA; widely used in trauma and postpartum hemorrhage (PPH). * **Aprotinin Caution:** Though effective, its use is limited due to risks of anaphylaxis and renal dysfunction. * **Antidote:** If a patient bleeds excessively due to Fibrinolytics (like Alteplase), the specific antidote is an Antifibrinolytic (like Tranexamic acid).

Q: Which of the following therapies is known to stimulate progenitor megakaryocytes and is used in the treatment of cancer chemotherapy-induced thrombocytopenia?

IL-11. **Explanation:** **Correct Option: D (IL-11)** Interleukin-11 (Oprelvekin) is a recombinant cytokine that acts directly on the **progenitor megakaryocytes** in the bone marrow. It stimulates their proliferation and maturation, leading to increased platelet production. It is the only FDA-approved cytokine specifically indicated for the prevention of severe **chemotherapy-induced thrombocytopenia (CIT)** in patients with non-myeloid malignancies. **Incorrect Options:** * **A (IL-2):** Also known as Aldesleukin, it primarily stimulates T-cell proliferation and NK cell activity. It is used in the treatment of metastatic renal cell carcinoma and malignant melanoma, not for platelet stimulation. * **B (IL-6):** While IL-6 does have some thrombopoietic activity, it is a potent pro-inflammatory cytokine. Its clinical use is limited by systemic toxicity (fever, acute phase response). Clinically, we use IL-6 *antagonists* (e.g., Tocilizumab) for Rheumatoid Arthritis and Cytokine Release Syndrome. * **C (IL-8):** This is a potent chemotactic factor for neutrophils. It plays a role in inflammation and angiogenesis but has no role in megakaryocytopoiesis. **High-Yield Clinical Pearls for NEET-PG:** * **Oprelvekin (IL-11) Side Effects:** The most characteristic side effect is **fluid retention** (leading to peripheral edema, dyspnea, and pleural effusion) and transient atrial arrhythmias. * **Romiplostim & Eltrombopag:** These are newer **Thrombopoietin (TPO) receptor agonists**. Romiplostim is a "peptibody" (SC route), while Eltrombopag is an oral non-peptide. They are primarily used for Chronic ITP. * **Filgrastim (G-CSF):** Used for chemotherapy-induced **neutropenia**, not thrombocytopenia.

Q: Relative contraindication to thrombolytic therapy includes all the following except?

Hypotension. **Explanation:** The core concept behind contraindications to thrombolytic therapy (like Streptokinase, Alteplase, or Tenecteplase) is the **risk of life-threatening hemorrhage**. Contraindications are strictly divided into Absolute and Relative. **Why Hypotension is the Correct Answer:** Hypotension is **not** a contraindication; rather, it is often an **indication** for thrombolysis, particularly in cases of Massive Pulmonary Embolism. In the context of Acute MI, hypotension (cardiogenic shock) is a high-risk feature where rapid reperfusion via thrombolytics (if PCI is unavailable) is life-saving. It does not increase the risk of bleeding, which is the primary concern with these drugs. **Analysis of Incorrect Options (Relative Contraindications):** * **Recent Surgery:** Major surgery within the last 3 weeks is a relative contraindication because the drug may dissolve the "hemostatic plugs" at the surgical site, leading to internal hemorrhage. * **Active Peptic Ulcer:** Thrombolytics can cause massive upper GI bleeding from an existing ulcerated lesion. * **Pregnancy:** It is a relative contraindication due to the risk of placental abruption and maternal hemorrhage, though it may be considered in life-threatening maternal scenarios. **High-Yield NEET-PG Pearls:** * **Absolute Contraindications:** Any prior intracranial hemorrhage (ICH), known structural cerebral vascular lesion (AVM), ischemic stroke within 3 months, active internal bleeding (excluding menses), or suspected aortic dissection. * **Most common side effect:** Bleeding (specifically ICH). * **Antidote:** Epsilon-aminocaproic acid or Tranexamic acid can be used to manage fibrinolytic states. * **Streptokinase:** Cannot be repeated within 6 months due to high antistreptococcal antibody titers.

Q: Which monoclonal antibody is useful in the treatment of paroxysmal nocturnal hemoglobinuria?

Eculizumab. **Explanation:** **Eculizumab** is the correct answer because it is a humanized monoclonal antibody that targets the **C5 complement protein**. **Mechanism of Action:** Paroxysmal Nocturnal Hemoglobinuria (PNH) is caused by an acquired mutation in the *PIGA* gene, leading to a deficiency of GPI-anchored proteins like **CD55 and CD59** (complement regulatory proteins) on red blood cells. Without these "shields," the body’s own complement system—specifically the **Membrane Attack Complex (MAC)**—destroys the RBCs. Eculizumab binds to C5, preventing its cleavage into C5a and C5b, thereby inhibiting the formation of the MAC and stopping intravascular hemolysis. **Analysis of Incorrect Options:** * **Rituximab (Option A):** A monoclonal antibody against **CD20** found on B-cells. It is used in Non-Hodgkin Lymphoma, CLL, and Rheumatoid Arthritis. * **Infliximab (Option C) & Adalimumab (Option D):** These are **TNF-alpha inhibitors**. They are primarily used in chronic inflammatory conditions like Crohn’s disease, Ulcerative Colitis, and Rheumatoid Arthritis. **High-Yield Clinical Pearls for NEET-PG:** * **Black Box Warning:** Eculizumab significantly increases the risk of **Meningococcal infections** (Neisseria meningitidis) because complement is essential for clearing encapsulated bacteria. Patients **must** be vaccinated against Meningococcus before starting therapy. * **Ravulizumab:** A newer, long-acting C5 inhibitor now also used for PNH. * **Other Indications for Eculizumab:** Atypical Hemolytic Uremic Syndrome (aHUS) and Myasthenia Gravis.

Q: Which of the following drugs is used postoperatively to reverse the effect of heparin used intraoperatively in cardiac surgery?

Protamine sulfate. **Explanation:** **Correct Answer: A. Protamine Sulfate** Protamine sulfate is the specific pharmacological antagonist used for the rapid reversal of heparin. It is a highly basic (cationic) protein derived from salmon sperm. Heparin is a highly acidic (anionic) molecule. When administered, protamine binds to heparin through **electrostatic interaction**, forming a stable, inactive salt complex. This mechanism is known as **chemical antagonism**. It is routinely used post-cardiopulmonary bypass to neutralize the systemic anticoagulation required during surgery. **Why other options are incorrect:** * **B. Vitamin K:** This is the antidote for **Warfarin** (coumarin derivatives). It acts by promoting the hepatic synthesis of clotting factors II, VII, IX, and X. It has no effect on heparin and takes several hours to work. * **C. Tranexamic acid:** This is an **antifibrinolytic** agent. It inhibits the activation of plasminogen to plasmin. It is used to control bleeding by preventing clot dissolution, not by neutralizing heparin. * **D. Factor VIII concentrate:** This is used in the management of **Hemophilia A**. While it aids coagulation, it does not neutralize the heparin molecule. **High-Yield NEET-PG Pearls:** * **Dosing:** 1 mg of protamine neutralizes approximately 100 units of heparin. * **The "Protamine Paradox":** In high doses, protamine itself has weak anticoagulant effects (it inhibits platelets and interacts with fibrinogen). * **Side Effects:** Rapid IV injection can cause histamine release, leading to hypotension, bradycardia, and pulmonary hypertension. * **Monitoring:** The effectiveness of reversal is monitored using the **Activated Clotting Time (ACT)** or aPTT.

Question 1

Which of the following belongs to antifibrinolytic drugs?

Accepted Answer

Aprotinin

Answer

Alteplase

Answer

Urokinase

Answer

Reteplase

Question 2

Which of the following therapies is known to stimulate progenitor megakaryocytes and is used in the treatment of cancer chemotherapy-induced thrombocytopenia?

Accepted Answer

IL-11

Answer

IL-2

Answer

IL-6

Answer

IL-8

Question 3

Relative contraindication to thrombolytic therapy includes all the following except?

Accepted Answer

Hypotension

Answer

Recent surgery

Answer

Active peptic ulcer

Answer

Pregnancy

Question 4

Which monoclonal antibody is useful in the treatment of paroxysmal nocturnal hemoglobinuria?

Accepted Answer

Eculizumab

Answer

Rituximab

Answer

Infliximab

Answer

Adalimumab

Question 5

Which of the following drugs is used postoperatively to reverse the effect of heparin used intraoperatively in cardiac surgery?

Accepted Answer

Protamine sulfate

Answer

Vitamin K

Answer

Tranexamic acid

Answer

Factor VIII concentrate

Drugs Affecting Blood and Blood Formation — MCQs

Drugs Affecting Blood and Blood Formation — MCQs

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