Drugs Affecting Blood and Blood Formation — MCQs

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

Question 111: Oral anticoagulants cause all except?

A. Interference with synthesis of vitamin K dependent clotting factors
B. Anticoagulant effect both in vivo and in vitro (Correct Answer)
C. Hematuria
D. Internal haemorrhage

Explanation: **Explanation:** The core concept tested here is the mechanism of action of **Oral Anticoagulants** (like Warfarin) versus **Parenteral Anticoagulants** (like Heparin). **Why Option B is the correct answer (The "Except" statement):** Oral anticoagulants act as **Vitamin K antagonists**. They inhibit the enzyme *Vitamin K Epoxide Reductase (VKOR)*, preventing the gamma-carboxylation of glutamate residues on clotting factors II, VII, IX, and X. This process occurs exclusively in the **liver**. Therefore, oral anticoagulants are effective only **in vivo** (inside a living body). They have no effect **in vitro** (in a test tube) because the clotting factors already present in the blood sample are already functional and do not require hepatic synthesis. In contrast, Heparin works both *in vivo* and *in vitro* by activating Antithrombin III. **Analysis of Incorrect Options:** * **Option A:** This is the primary mechanism. By inhibiting VKOR, they interfere with the synthesis of functional Vitamin K-dependent factors (II, VII, IX, X) and proteins C and S. * **Options C & D:** These are common adverse effects. The most significant toxicity of oral anticoagulants is bleeding, which can manifest as **hematuria** (microscopic or gross), ecchymosis, or life-threatening **internal hemorrhage** (e.g., intracranial or GI bleed). **High-Yield Clinical Pearls for NEET-PG:** * **Monitoring:** Warfarin is monitored using **PT/INR** (Extrinsic pathway), while Heparin is monitored using **aPTT** (Intrinsic pathway). * **Antidote:** The specific antidote for Warfarin overdose is **Vitamin K1 (Phytonadione)**. For immediate reversal, **Fresh Frozen Plasma (FFP)** or Prothrombin Complex Concentrate (PCC) is used. * **Teratogenicity:** Warfarin is contraindicated in pregnancy (causes **Fetal Warfarin Syndrome**); Heparin is the anticoagulant of choice as it does not cross the placenta. * **Warfarin-Induced Skin Necrosis:** Occurs due to a rapid depletion of Protein C (a natural anticoagulant) before the procoagulant factors decline.

Question 112: All of the following are irreversible ADP inhibitors except?

A. Ticlopidine
B. Clopidogrel
C. Prasugrel
D. Cangrelor (Correct Answer)

Explanation: ### Explanation The question tests your knowledge of **P2Y12 receptor antagonists** (ADP inhibitors), which are classified based on their chemical structure and the nature of their binding to the platelet receptor. #### Why Cangrelor is the Correct Answer ADP inhibitors are divided into two main categories: 1. **Thienopyridines:** These are **irreversible** inhibitors. They are prodrugs that require hepatic metabolism to form active metabolites which bind covalently to the P2Y12 receptor. 2. **Non-thienopyridines (CPTPs):** These are **reversible** inhibitors. They bind directly to the receptor without requiring metabolic activation. **Cangrelor** (along with **Ticagrelor**) belongs to the non-thienopyridine class. It is a direct-acting, intravenous agent that binds reversibly to the P2Y12 receptor. Because it is not a prodrug and binds reversibly, it has an ultra-rapid onset and a very short half-life (3–6 minutes), making it ideal for percutaneous coronary intervention (PCI). #### Why the Other Options are Incorrect * **A, B, and C (Ticlopidine, Clopidogrel, Prasugrel):** These are all **Thienopyridines**. They are prodrugs that undergo hepatic conversion (via CYP enzymes) to create an active metabolite. This metabolite forms a permanent covalent disulfide bond with the P2Y12 receptor, leading to **irreversible** inhibition for the lifespan of the platelet (7–10 days). #### High-Yield Clinical Pearls for NEET-PG * **Ticagrelor vs. Cangrelor:** Both are reversible, but Ticagrelor is **oral**, while Cangrelor is **intravenous**. * **Genetic Polymorphism:** Clopidogrel's efficacy is significantly affected by **CYP2C19** polymorphisms (poor metabolizers have increased risk of cardiovascular events). * **Prasugrel Contraindication:** It is contraindicated in patients with a history of **Stroke or TIA** due to a high risk of intracranial hemorrhage. * **Ticlopidine Side Effect:** Rarely used now due to the risk of **Neutropenia** and TTP (Thrombotic Thrombocytopenic Purpura).

Question 113: Which of the following is given with iron to increase its absorption?

A. Milk
B. Antacids
C. Citrus fruits (Correct Answer)
D. Alkalies

Explanation: **Explanation:** The absorption of oral iron occurs primarily in the duodenum and proximal jejunum. Iron is absorbed in the **ferrous (Fe²⁺) state** more efficiently than the ferric (Fe³⁺) state. **Why Citrus Fruits are Correct:** Citrus fruits are rich in **Vitamin C (Ascorbic acid)**. Vitamin C enhances iron absorption through two mechanisms: 1. It acts as a reducing agent, converting dietary ferric iron (Fe³⁺) to the more soluble ferrous iron (Fe²⁺). 2. It forms a soluble iron-ascorbate complex that prevents iron from precipitating in the alkaline environment of the small intestine. **Why Other Options are Incorrect:** * **Milk:** Contains calcium and phosphates which form insoluble complexes with iron, significantly reducing its bioavailability. * **Antacids & Alkalies:** Iron requires an acidic gastric environment to remain in its soluble ferrous form. Antacids and alkalies neutralize gastric acid, leading to the formation of insoluble iron salts, thereby inhibiting absorption. **NEET-PG High-Yield Pearls:** * **Promoters of Iron Absorption:** Ascorbic acid (Vitamin C), Gastric HCl, and amino acids (meat). * **Inhibitors of Iron Absorption:** Phytates (cereals), Oxalates (spinach), Phosphates, Carbonates, Tetracyclines, and Tannins (Tea/Coffee). * **Clinical Tip:** Patients should be advised to take iron supplements on an empty stomach with orange juice and avoid tea, coffee, or milk for at least 2 hours before and after the dose.

Question 114: Epogen can be given in which of the following conditions?

A. Anemia of chronic renal failure (Correct Answer)
B. Aplastic anemia
C. Hemolytic anemia
D. Anemia of chronic disease

Explanation: **Explanation:**1. Why Option A is Correct: **Epogen (Epoetin alfa)** is a recombinant human erythropoietin (rhEPO) [1, 2, 3]. Erythropoietin is a glycoprotein hormone primarily produced by the peritubular interstitial cells of the kidney [1, 2, 3]. In **Chronic Renal Failure (CRF)**, the kidneys fail to produce sufficient erythropoietin, leading to normocytic, normochromic anemia [1, 2, 3]. Epogen acts as replacement therapy, stimulating the bone marrow to produce red blood cells, making it the treatment of choice for anemia in CRF patients [1, 3].2. Why Other Options are Incorrect:* **B. Aplastic Anemia:** This involves a primary bone marrow failure where the "factory" itself is damaged. While EPO levels are usually already high in these patients, the marrow cannot respond to it. Treatment typically requires immunosuppressants or bone marrow transplant.* **C. Hemolytic Anemia:** This is caused by the premature destruction of RBCs. The kidneys are functional and endogenous EPO levels are already maximally elevated to compensate; adding exogenous Epogen provides no benefit.* **D. Anemia of Chronic Disease (ACD):** While EPO can sometimes be used in specific cases (like cancer-related anemia), the primary pathology in ACD is iron sequestration due to high **hepcidin** levels. The first-line management is treating the underlying inflammatory condition.High-Yield NEET-PG Pearls:* **Target Hb:** When using Epogen, the target Hemoglobin should not exceed **11–12 g/dL**. Exceeding this increases the risk of hypertension, stroke, and tumor progression [1].* **Side Effects:** The most common side effect is **hypertension** and encephalopathy. It can also cause pure red cell aplasia (PRCA) due to antibody formation.* **Requirement:** For Epogen to be effective, the patient must have adequate **iron, B12, and folate stores**.* **Other Indications:** Anemia due to HIV (Zidovudine therapy) and chemotherapy-induced anemia.

Question 115: Which of the following agents has demonstrated antithrombotic properties?

A. Gelatin
B. Dextran 40 (Correct Answer)
C. Dextran 100
D. Hetastarch

Explanation: ### Explanation The correct answer is **Dextran 40**. **Why Dextran 40 is correct:** Dextran 40 (Low Molecular Weight Dextran) is a plasma expander that possesses unique **antithrombotic properties** beyond simple volume expansion. It reduces blood viscosity and inhibits erythrocyte aggregation (sludging). Most importantly, it coats the vascular endothelium and platelets, increasing their negative charge, which leads to decreased platelet adhesiveness and aggregation. It also alters the structure of fibrin clots, making them more susceptible to fibrinolysis. These properties make it useful in preventing deep vein thrombosis (DVT) and improving microcirculation in peripheral vascular surgery. **Why the other options are incorrect:** * **Dextran 100:** This is a high molecular weight dextran. While it expands plasma volume, it can actually promote the "rouleaux" formation of RBCs and interfere with blood grouping/cross-matching more significantly than Dextran 40. It does not share the same beneficial microcirculatory profile. * **Gelatin (e.g., Polygeline):** These are polypeptides derived from bovine collagen. They are used for volume expansion but lack specific antiplatelet or antithrombotic activity. They have a shorter duration of action and a higher risk of hypersensitivity reactions. * **Hetastarch (Hydroxyethyl Starch):** This is a complex polysaccharide. While it is an effective volume expander, its primary side effect is actually a *risk* of coagulopathy (by reducing Factor VIII/vWF levels) rather than a therapeutic antithrombotic effect. It is also associated with a risk of acute kidney injury in critically ill patients. **High-Yield Clinical Pearls for NEET-PG:** * **Dextran 40** is the preferred dextran for improving **microcirculation** and preventing postoperative thromboembolism. * **Side Effects of Dextrans:** They can cause **anaphylactoid reactions**, interfere with blood grouping (by coating RBCs), and may prolong bleeding time. * **Contraindication:** Dextrans should be avoided in patients with severe renal failure or congestive heart failure due to the risk of osmotic nephrosis and volume overload.

Question 116: A patient on Warfarin has an INR of 8. What is the next best step?

A. Restart Warfarin at a lower dose once the INR is in the therapeutic range.
B. Administer oral Vitamin K1. (Correct Answer)
C. Administer fresh frozen plasma.
D. Transfuse fresh blood.

Explanation: ### Explanation The management of Warfarin-induced elevation of INR is based on the **severity of the elevation** and the **presence of bleeding**. **1. Why Option B is Correct:** According to standard guidelines (ACCP), for a patient with an **INR between 4.5 and 10 without clinically significant bleeding**, the recommended management is to omit the next few doses of Warfarin and administer **low-dose oral Vitamin K1 (Phytonadione)**. Oral administration is preferred over subcutaneous (unpredictable absorption) or intravenous (risk of anaphylaxis) routes in non-emergency settings. Vitamin K acts as a cofactor for the gamma-carboxylation of factors II, VII, IX, and X, reversing Warfarin's effect within 24–48 hours. **2. Why Other Options are Incorrect:** * **Option A:** Simply restarting at a lower dose is insufficient for an INR as high as 8, as it leaves the patient at a prolonged high risk of spontaneous hemorrhage. * **Option C:** Fresh Frozen Plasma (FFP) or Prothrombin Complex Concentrate (PCC) is indicated only in cases of **serious/life-threatening bleeding** or when immediate surgery is required, regardless of the INR. * **Option D:** Fresh blood transfusion is not the standard of care for reversing anticoagulation; it is used for volume replacement and oxygen-carrying capacity in massive hemorrhage. **3. NEET-PG High-Yield Pearls:** * **INR < 4.5 (No bleeding):** Skip dose; monitor. * **INR 4.5 – 10 (No bleeding):** Hold Warfarin + Oral Vitamin K (1–2.5 mg). * **INR > 10 (No bleeding):** Hold Warfarin + Higher dose oral Vitamin K (3–5 mg). * **Serious Bleeding (Any INR):** Hold Warfarin + IV Vitamin K (10 mg) + **4-factor PCC** (preferred) or FFP. * **Mechanism:** Warfarin inhibits **Vitamin K Epoxide Reductase (VKOR)**. * **Monitoring:** PT/INR is used for Warfarin; aPTT is used for Unfractionated Heparin.

Question 117: Which of the following substances can be used as an antidote to fibrinolytics?

A. Epsilon amino caproic acid (Correct Answer)
B. Protamine
C. Alteplase
D. Dabigatran

Explanation: ### Explanation **Correct Option: A. Epsilon amino caproic acid (EACA)** Fibrinolytics (like Streptokinase or Alteplase) work by converting plasminogen into **plasmin**, an enzyme that degrades fibrin clots. Excessive plasmin activity can lead to severe systemic bleeding. **Epsilon amino caproic acid (EACA)** and **Tranexamic acid** act as antifibrinolytics by competitively inhibiting plasminogen activation and binding to fibrin. They occupy the lysine-binding sites on plasminogen/plasmin, preventing it from binding to and degrading fibrin, thereby stabilizing the clot and reversing the effect of fibrinolytics. **Analysis of Incorrect Options:** * **B. Protamine:** This is the specific antidote for **Heparin** overdose. It is a strongly basic protein that neutralizes acidic heparin through ionic bonding. * **C. Alteplase:** This is a recombinant tissue plasminogen activator (rt-PA). It is a **fibrinolytic agent** itself, used to dissolve clots in MI or stroke, not an antidote. * **D. Dabigatran:** This is an **oral direct thrombin inhibitor (DTI)**. Its specific reversal agent (antidote) is **Idarucizumab**. **High-Yield Clinical Pearls for NEET-PG:** * **Antifibrinolytics:** EACA and Tranexamic acid are used in fibrinolytic overdose, post-prostatectomy bleeding, and heavy menstrual bleeding. * **Tranexamic acid** is roughly 10 times more potent than EACA. * **Specific Antidotes Summary:** * **Warfarin:** Vitamin K (slow), Fresh Frozen Plasma (rapid). * **Heparin:** Protamine Sulfate. * **Dabigatran:** Idarucizumab. * **Rivaroxaban/Apixaban:** Andexanet alfa. * **Fibrinolytics:** EACA or Tranexamic acid.

Question 118: Which anticoagulant does not require routine coagulation profile monitoring post dosing?

A. Warfarin
B. Dabigatran etexilate (Correct Answer)
C. Argatroban
D. Phenprocoumon

Explanation: **Explanation:** The correct answer is **Dabigatran etexilate**. This drug belongs to the class of **Direct Oral Anticoagulants (DOACs)**. Unlike traditional anticoagulants, DOACs have a predictable pharmacokinetic and pharmacodynamic profile, a wide therapeutic window, and fixed dosing schedules. Consequently, they do not require routine laboratory monitoring (like PT/INR or aPTT) to adjust the dose. Dabigatran specifically acts as a **direct thrombin (Factor IIa) inhibitor**. **Analysis of Options:** * **Warfarin (Option A) & Phenprocoumon (Option D):** These are Vitamin K Antagonists (VKAs). They have a narrow therapeutic index and their efficacy is affected by diet, genetics, and drug interactions. They require frequent monitoring of the **International Normalized Ratio (INR)** to prevent bleeding or treatment failure. * **Argatroban (Option C):** This is a parenteral direct thrombin inhibitor used primarily in patients with Heparin-Induced Thrombocytopenia (HIT). Because it is administered intravenously and has a short half-life, it requires monitoring of the **activated Partial Thromboplastin Time (aPTT)** to ensure safe therapeutic levels. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Dabigatran inhibits both free and clot-bound thrombin. * **Reversal Agent:** The specific reversal agent for Dabigatran is **Idarucizumab** (a monoclonal antibody fragment). * **Excretion:** Dabigatran is primarily eliminated by the **kidneys** (80%); thus, it is contraindicated in severe renal failure. * **Monitoring Exception:** While not routine, if monitoring is required (e.g., emergency surgery or overdose), the **Ecarin Clotting Time (ECT)** or Dilute Thrombin Time (dTT) are the most sensitive tests.

Question 119: Which of the following statements is not true for heparin?

A. Acts by activating anti-thrombin III
B. Protamine sulphate antagonizes its action
C. Requires aPTT monitoring in patients
D. Has only in vivo anticoagulant action (Correct Answer)

Explanation: **Explanation:** The correct answer is **D**. Heparin is an anticoagulant that works both **in vivo** (inside the body) and **in vitro** (outside the body, such as in blood collection tubes or during dialysis). This is because heparin acts directly by activating plasma antithrombin III, which does not require a functioning physiological system to exert its effect. In contrast, oral anticoagulants like **Warfarin** act only *in vivo* because they interfere with the hepatic synthesis of clotting factors, a process that cannot occur in a test tube. **Analysis of other options:** * **Option A:** Heparin binds to **Antithrombin III (AT-III)**, inducing a conformational change that accelerates the inactivation of Thrombin (IIa) and Factor Xa by 1000-fold. * **Option B:** **Protamine sulphate** is a strongly basic protein that ionically binds to acidic heparin to form a stable, inactive complex. It is the specific antidote for heparin overdose. * **Option C:** Unfractionated Heparin (UFH) has an unpredictable dose-response; therefore, the **activated Partial Thromboplastin Time (aPTT)** is monitored to maintain a therapeutic range (typically 1.5–2.5 times the control). **High-Yield Clinical Pearls for NEET-PG:** * **LMWH (Low Molecular Weight Heparin):** Unlike UFH, LMWH mainly inhibits Factor Xa, has better bioavailability, and does **not** require routine aPTT monitoring. * **Side Effects:** The most common side effect is bleeding; the most unique is **Heparin-Induced Thrombocytopenia (HIT)**, caused by antibodies against the Heparin-Platelet Factor 4 complex. * **Safe in Pregnancy:** Heparin does not cross the placenta (due to high molecular weight and negative charge), making it the anticoagulant of choice during pregnancy.

Question 120: What is the drug of choice for neutropenia due to cancer chemotherapy?

A. Vitamin B-12
B. IL 11
C. Filgrastim (Correct Answer)
D. Erythropoietin

Explanation: **Explanation:** **Filgrastim** is the drug of choice for chemotherapy-induced neutropenia [1]. It is a recombinant human **Granulocyte Colony-Stimulating Factor (G-CSF)** [1]. It works by binding to specific receptors on myeloid progenitor cells, stimulating the proliferation, differentiation, and activation of **neutrophils** [3]. By accelerating neutrophil recovery, it reduces the duration of neutropenia and the risk of life-threatening febrile neutropenia episodes [2]. **Analysis of Incorrect Options:** * **Vitamin B-12 (Cyanocobalamin):** Used to treat megaloblastic anemia caused by B12 deficiency. While B12 deficiency can cause pancytopenia, it is not the treatment for drug-induced bone marrow suppression. * **IL-11 (Oprelvekin):** This is a recombinant interleukin used specifically for **thrombocytopenia** (low platelet count). It stimulates megakaryocytopoiesis but has no significant effect on neutrophil counts [1]. * **Erythropoietin (Epoetin alfa):** This hormone stimulates the production of red blood cells (erythropoiesis). It is used for anemia associated with chronic kidney disease or chemotherapy, not for neutropenia. **NEET-PG High-Yield Pearls:** * **Sargramostim:** A recombinant **GM-CSF** (Granulocyte-Macrophage CSF) that stimulates both neutrophils and macrophages [4]. * **Pegfilgrastim:** A pegylated form of Filgrastim with a much longer half-life, allowing for once-per-chemotherapy-cycle dosing [1]. * **Common Side Effect:** The most frequent side effect of G-CSF therapy is **bone pain** (due to marrow expansion). * **Timing:** G-CSF should generally not be administered within 24 hours of chemotherapy, as it may increase myelotoxicity by stimulating rapidly dividing cells.

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

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Blood Transfusion and Alternatives

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