Drugs Affecting Blood and Blood Formation — MCQs

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

Question 201: For oral iron supplements used in the management of iron deficiency anemia, which of the following statements is correct?

A. A tolerable daily dose typically delivers 40 to 60 mg of elemental iron. (Correct Answer)
B. The mass of the total salt is more important than elemental iron content in determining the daily dose.
C. Treatment should be continued until a normal hemoglobin level is achieved and then stopped immediately.
D. The desired rate of hemoglobin improvement during treatment is 0.5 g/dL per day.

Explanation: ### Explanation **1. Why Option A is Correct:** The goal of oral iron therapy is to provide enough elemental iron to saturate the transport system without causing significant gastrointestinal toxicity. Current clinical guidelines (including WHO and recent hematology protocols) suggest that **40–60 mg of elemental iron daily** is sufficient for most patients. This dose maximizes absorption efficiency (as higher doses trigger hepcidin, which blocks further absorption) and minimizes side effects like nausea, constipation, and abdominal pain, thereby improving patient compliance. **2. Why Other Options are Incorrect:** * **Option B:** The dosage is always calculated based on **elemental iron content**, not the total mass of the salt. For example, a 300 mg tablet of Ferrous Sulfate contains only 60 mg of elemental iron (~20%). * **Option C:** Treatment should **not** be stopped immediately after hemoglobin (Hb) normalizes. It must be continued for **3 to 6 months** after Hb normalization to replenish the depleted body iron stores (ferritin). * **Option D:** The expected rate of Hb rise is approximately **0.1 g/dL per day** (or 1 g/dL per week). A rate of 0.5 g/dL per day is physiologically impossible for the bone marrow to sustain. **3. High-Yield Clinical Pearls for NEET-PG:** * **Best Absorption:** Iron is best absorbed in the **ferrous (Fe²⁺) state** in an acidic medium (duodenum/jejunum). * **Enhancers/Inhibitors:** Vitamin C (Ascorbic acid) increases absorption; tea, coffee, phosphates, and antacids decrease it. * **First Sign of Response:** An increase in **Reticulocyte count** (seen within 5–7 days). * **Parenteral Iron:** Indicated in malabsorption, intolerance to oral iron, or chronic kidney disease. Calculation is done via the **Ganzoni Formula**.

Question 202: What agent is responsible for increasing factor VIII activity in hemophilia?

A. Epsilon amino caproic acid
B. Tranexamic acid
C. Avitene
D. Deamino D Arginine vasopressin (Correct Answer)

Explanation: **Explanation:** **Deamino D-Arginine Vasopressin (Desmopressin or DDAVP)** is a synthetic analogue of the antidiuretic hormone (ADH). It acts on **V2 receptors** located on vascular endothelial cells, triggering the release of stored **von Willebrand Factor (vWF)** and **Factor VIII** from Weibel-Palade bodies into the plasma. This transient increase (usually 3–5 fold) makes it the treatment of choice for patients with **Mild Hemophilia A** and **Type 1 von Willebrand Disease** before minor surgical procedures. **Analysis of Incorrect Options:** * **A & B (Epsilon Amino Caproic Acid & Tranexamic Acid):** These are **antifibrinolytics**. They work by inhibiting plasminogen activation, thereby preventing the breakdown of formed clots. While used as adjunctive therapy in hemophilia (especially for dental extractions), they do not increase the levels of Factor VIII. * **C (Avitene):** This is a **topical hemostatic agent** (microfibrillar collagen). It promotes platelet adhesion and activation at the site of application but has no systemic effect on clotting factor levels. **NEET-PG High-Yield Pearls:** * **Route:** DDAVP can be administered IV, SC, or via a high-concentration nasal spray (Stimate). * **Tachyphylaxis:** Repeated doses lead to a diminished response because endothelial stores of Factor VIII/vWF become exhausted. * **Contraindication:** It is generally avoided in **Type 2B vWF disease** as it can cause paradoxical thrombocytopenia. * **Side Effects:** Hyponatremia and water intoxication (due to its antidiuretic effect). It is also used in Central Diabetes Insipidus and Nocturnal Enuresis.

Question 203: Which of the following statements regarding tissue plasminogen activator is true?

A. It is produced by recombinant DNA technology.
B. Induction of systemic lytic state is limited with its use.
C. It is effective in lysing thrombi of myocardial infarction. (Correct Answer)
D. It is a poor plasminogen activator in the absence of fibrin.

Explanation: **Explanation:** Tissue Plasminogen Activator (tPA), such as **Alteplase**, is a fibrinolytic agent that plays a critical role in the management of acute thrombotic events. **Why Option C is correct:** The primary clinical utility of tPA is its ability to dissolve formed clots. It is a first-line treatment for **Acute Myocardial Infarction (STEMI)** when primary percutaneous coronary intervention (PCI) is not immediately available. It works by converting thrombus-bound plasminogen into plasmin, which then degrades the fibrin mesh of the clot, restoring blood flow to the myocardium. **Analysis of other options:** * **Option A:** While modern tPA (Alteplase) is indeed produced by recombinant DNA technology, this is a **characteristic** of the drug rather than its primary pharmacological definition or clinical function. In many competitive exams, the most "clinically definitive" statement is preferred. * **Option B:** tPA is "clot-selective," meaning it prefers fibrin-bound plasminogen. However, at therapeutic doses, it still degrades circulating fibrinogen, leading to a **systemic lytic state** (though less severe than Streptokinase). Therefore, saying the lytic state is "limited" is relative and often considered less definitive than its efficacy in MI. * **Option D:** This is actually a **true physiological property** of tPA (it is a poor activator without fibrin). However, in the context of this specific question's construction in standard medical textbooks (like K.D. Tripathi), Option C is highlighted as the hallmark of its therapeutic application. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** tPA has a high affinity for **fibrin-bound plasminogen**, making it more "site-specific" than Streptokinase. * **Antidote:** Fibrinolytic overdose/bleeding is managed with **Epsilon-aminocaproic acid** or **Tranexamic acid**. * **Indications:** Acute Ischemic Stroke (within 3–4.5 hours), STEMI, and massive Pulmonary Embolism. * **Variants:** **Reteplase** and **Tenecteplase** are newer recombinant tPAs with longer half-lives, allowing for bolus administration.

Question 204: What is the maximum dose of intravenous iron that a patient can tolerate at one time?

A. 1000 mg
B. 2000 mg
C. 2500 mg (Correct Answer)
D. 3000 mg

Explanation: ### Explanation The correct answer is **2500 mg (Option C)**. **Understanding the Concept** The maximum dose of intravenous (IV) iron depends heavily on the specific formulation used. While older preparations (like Iron Dextran) carried a high risk of anaphylaxis, newer non-dextran formulations allow for much higher doses in a single session. Specifically, **Ferric Carboxymaltose (FCM)** and **Iron Isomaltoside (Ferric Derisomaltose)** are designed to release iron slowly from a stable carbohydrate shell. According to standard pharmacological guidelines and clinical practice for rapid iron replacement (Total Dose Infusion), the maximum single dose of iron that can be safely administered at one time is **2500 mg** (specifically for Iron Isomaltoside). For Ferric Carboxymaltose, the limit is typically 1000 mg per week, but the absolute physiological and pharmacological ceiling for the most stable modern preparations is recognized as 2500 mg. **Analysis of Options** * **A. 1000 mg:** This is the standard maximum single dose for **Ferric Carboxymaltose**. While common, it is not the absolute maximum dose a patient can tolerate across all formulations. * **B. 2000 mg:** This is a common total dose required for many patients with severe anemia, but it does not represent the upper safety limit for a single infusion. * **D. 3000 mg:** This exceeds the current safety profile for single-session administration and increases the risk of "free iron" toxicity and oxidative stress. **High-Yield NEET-PG Pearls** * **Test Dose:** Required for **Iron Dextran** due to the risk of Type I hypersensitivity (anaphylaxis). It is **not** routinely required for Ferric Carboxymaltose or Iron Isomaltoside. * **Ganzoni Formula:** Used to calculate the total iron deficit: * *Iron deficit (mg) = Body weight (kg) × (Target Hb - Actual Hb) × 2.4 + Iron stores (500 mg).* * **Side Effect:** A unique side effect of Ferric Carboxymaltose is **hypophosphatemia** (due to increased FGF23 activity).

Question 205: Aminocaproic acid would be recommended for a hemophilic child with which of the following conditions?

A. Epistaxis (Correct Answer)
B. Haematuria
C. Oral bleeding
D. Hemarthrosis

Explanation: **Explanation:** **Aminocaproic acid (EACA)** is an antifibrinolytic agent that acts by competitively inhibiting plasminogen activation, thereby preventing the breakdown of fibrin clots [1]. In patients with hemophilia, it is used as an adjuvant therapy to stabilize clots in areas with high fibrinolytic activity. **Why Epistaxis is correct:** Epistaxis (nosebleeds) and mucosal bleeds are common in hemophilia. The nasal mucosa is rich in plasminogen activators. Aminocaproic acid effectively inhibits these activators, [1] stabilizing the local clot and reducing the need for factor replacement. It is also frequently used for dental extractions and oral surgery in hemophiliacs for the same reason. **Why the other options are incorrect:** * **Haematuria (Option B):** This is a **major contraindication** for antifibrinolytics. If used during renal bleeding, EACA can cause the formation of "hard clots" in the ureters or renal pelvis, leading to obstructive uropathy and potential renal failure. * **Oral bleeding (Option C):** While EACA is used for oral bleeding, **Epistaxis** is often the more classically tested indication in this specific context. However, note that in some clinical guidelines, oral bleeding is also a valid use; but in the hierarchy of NEET-PG questions, Epistaxis or post-extraction bleeding are the primary "high-yield" associations. * **Hemarthrosis (Option D):** Joint bleeds are managed primarily with **Factor VIII or IX replacement**. Antifibrinolytics have limited utility inside the joint space compared to mucosal surfaces. **NEET-PG High-Yield Pearls:** * **Mechanism:** Inhibits plasminogen binding to fibrin [1]. * **Key Contraindication:** Upper urinary tract bleeding (risk of ureteral obstruction). * **Other Antifibrinolytic:** **Tranexamic acid** is 10 times more potent than Aminocaproic acid and has a longer half-life [1]. * **Clinical Use:** Hereditary angioedema, heavy menstrual bleeding (Menorrhagia), and post-prostatectomy bleeding.

Question 206: Macrocytic anemia is noted with all of the following drugs except?

A. Phenytoin
B. Methotrexate
C. Pyrimethamine
D. Ciprofloxacin (Correct Answer)

Explanation: **Explanation:** Macrocytic anemia (specifically megaloblastic anemia) occurs when DNA synthesis is impaired, usually due to a deficiency or interference with **Folic acid** or **Vitamin B12**. **1. Why Ciprofloxacin is the correct answer:** Ciprofloxacin is a fluoroquinolone that acts by inhibiting bacterial DNA gyrase and topoisomerase IV. Unlike the other options, it does **not** interfere with human folate metabolism or B12 absorption. Therefore, it does not cause macrocytic anemia. **2. Why the other options are incorrect:** * **Methotrexate:** A potent dihydrofolate reductase (DHFR) inhibitor. It prevents the conversion of dihydrofolate to tetrahydrofolate, directly halting DNA synthesis and leading to megaloblastic changes. * **Pyrimethamine:** Similar to methotrexate, it is a DHFR inhibitor (primarily used for toxoplasmosis/malaria). While it has a higher affinity for protozoal enzymes, high doses can inhibit human DHFR, causing macrocytic anemia. * **Phenytoin:** This antiepileptic drug causes macrocytic anemia by interfering with the intestinal absorption of dietary folate and increasing its catabolism. **High-Yield Clinical Pearls for NEET-PG:** * **Other drugs causing Macrocytic Anemia:** Trimethoprim (DHFR inhibitor), Zidovudine (AZT), 5-Fluorouracil, Hydroxyurea, and Metformin (decreases B12 absorption). * **Rescue Therapy:** Leucovorin (Folinic acid) is used to "rescue" bone marrow from methotrexate toxicity because it bypasses the inhibited DHFR enzyme. * **Phenytoin Side Effects:** Remember the mnemonic **HOT MALARIA** (Hirsutism, Osteomalacia, Teratogenicity, **Megaloblastic anemia**, Ataxia, Lymphadenopathy, Insulin inhibition, Rheumatoid-like arthritis, Adenopathy).

Question 207: What is given in case of pernicious anaemia?

A. Folic acid
B. Folinic acid
C. Methyl cobalamin (Correct Answer)
D. Erythropoietin

Explanation: **Explanation:** **Pernicious Anemia** is an autoimmune condition characterized by the destruction of gastric parietal cells, leading to a deficiency of **Intrinsic Factor (IF)**. Since IF is essential for the absorption of Vitamin B12 in the terminal ileum, its absence results in severe Vitamin B12 deficiency. **Why Methylcobalamin is correct:** Methylcobalamin is an active coenzyme form of **Vitamin B12**. In cases of pernicious anemia, the primary treatment is lifelong Vitamin B12 supplementation. While cyanocobalamin or hydroxocobalamin are standard, Methylcobalamin is frequently used as it is a biologically active form required for the conversion of homocysteine to methionine, supporting neurological health and erythropoiesis. **Analysis of Incorrect Options:** * **Folic acid (A) & Folinic acid (B):** While these can improve the hematological profile (anemia) in B12 deficiency, they **do not** correct the neurological deficits. In fact, giving folic acid alone in B12 deficiency is contraindicated as it can "mask" the deficiency and precipitate or worsen subacute combined degeneration of the spinal cord. * **Erythropoietin (D):** This is used for anemia of chronic kidney disease or chemotherapy-induced anemia. It stimulates RBC production but cannot fix anemia caused by a specific nutrient deficiency like B12. **NEET-PG High-Yield Pearls:** * **Diagnostic Test:** The **Schilling test** (historically) or testing for **Anti-Intrinsic Factor antibodies** and **Anti-parietal cell antibodies**. * **Neurological Sequelae:** B12 deficiency leads to **Subacute Combined Degeneration (SCD)** of the spinal cord, affecting the dorsal columns and lateral corticospinal tracts. * **MCV:** Pernicious anemia presents as **Megaloblastic Anemia** with an MCV >100 fL and hypersegmented neutrophils on peripheral smear. * **Route:** Because the pathology involves malabsorption, B12 is traditionally administered **parenterally (IM)** to bypass the gut.

Question 208: All of the following are anticoagulants, except?

A. Phytonadione (Correct Answer)
B. Warfarin
C. Low molecular weight heparin
D. Lepirudin

Explanation: ### Explanation The correct answer is **A. Phytonadione**. **1. Why Phytonadione is the correct answer:** Phytonadione is another name for **Vitamin K1** [1], [3]. Unlike the other options, it is not an anticoagulant; rather, it is a **procoagulant** (hemostatic agent). Vitamin K acts as a necessary cofactor for the enzyme *gamma-glutamyl carboxylase*, which activates clotting factors **II, VII, IX, and X**, as well as proteins C and S [1], [3]. Clinically, it is used to treat Vitamin K deficiency and to reverse the effects of Warfarin overdose [1], [3], . **2. Why the other options are incorrect:** * **Warfarin (Option B):** A classic oral anticoagulant that acts as a Vitamin K Epoxide Reductase (VKOR) inhibitor [3], [3]. It prevents the recycling of Vitamin K, thereby inhibiting the synthesis of functional clotting factors II, VII, IX, and X [1], [3]. * **Low Molecular Weight Heparin (LMWH) (Option C):** Examples include Enoxaparin and Dalteparin [2]. These are parenteral anticoagulants that primarily act by accelerating the inhibition of **Factor Xa** by Antithrombin III [2]. * **Lepirudin (Option D):** A recombinant derivative of hirudin, it is a **Direct Thrombin Inhibitor (DTI)** [1]. It binds directly to thrombin (Factor IIa) and is typically used in patients with Heparin-Induced Thrombocytopenia (HIT). **3. NEET-PG High-Yield Pearls:** * **Antidote Pairing:** The antidote for Heparin is **Protamine Sulfate** [2], while the antidote for Warfarin is **Vitamin K** (slow onset) or **Fresh Frozen Plasma/PCC** (rapid onset) [1], [3]. * **Monitoring:** Warfarin is monitored using **PT/INR**, whereas Unfractionated Heparin is monitored using **aPTT**. LMWH usually does not require routine monitoring [2]. * **Teratogenicity:** Warfarin is contraindicated in pregnancy (causes Fetal Warfarin Syndrome); Heparin/LMWH is the anticoagulant of choice for pregnant women as it does not cross the placenta.

Question 209: Which drug causes megaloblastic anemia?

A. Isoniazid (INH)
B. Chloramphenicol
C. Pyrimethamine (Correct Answer)
D. Methyldopa

Explanation: Megaloblastic anemia is primarily caused by a deficiency or impaired utilization of **Vitamin B12 or Folic acid**, leading to defective DNA synthesis [1]. Pyrimethamine is a potent inhibitor of the enzyme **Dihydrofolate Reductase (DHFR)** [2]. By blocking this enzyme, it prevents the conversion of dihydrofolate to tetrahydrofolate (the active form of folic acid), thereby inhibiting DNA synthesis and resulting in megaloblastic changes in the bone marrow [2]. **Analysis of Incorrect Options:** * **A. Isoniazid (INH):** This drug is a Vitamin B6 (Pyridoxine) antagonist. Its primary hematological side effect is **Sideroblastic anemia**, not megaloblastic anemia. It also commonly causes peripheral neuropathy. * **B. Chloramphenicol:** This antibiotic is classically associated with dose-dependent bone marrow suppression and idiosyncratic **Aplastic anemia** (pancytopenia), rather than isolated megaloblastic changes. * **D. Methyldopa:** This centrally acting antihypertensive is a well-known cause of **Autoimmune Hemolytic Anemia (AIHA)**, typically characterized by a positive direct Coombs test. **NEET-PG High-Yield Pearls:** * **DHFR Inhibitors:** Other drugs causing megaloblastic anemia via DHFR inhibition include **Methotrexate** (anticancer), **Trimethoprim** (antibacterial), and **Proguanil** (antimalarial) [2]. * **Other Causes:** **Phenytoin** (interferes with folate absorption) and **Zidovudine** (inhibits DNA polymerase) are also frequent culprits in exam questions. * **Rescue Therapy:** To prevent pyrimethamine or methotrexate-induced hematological toxicity, **Folinic acid (Leucovorin)** is administered, as it bypasses the blocked DHFR enzyme [3].

Question 210: What is the most recent oral direct thrombin inhibitor?

A. Ximelagatran
B. Indraparinux
C. Dabigatran (Correct Answer)
D. Fondaparinux

Explanation: **Explanation:** **Dabigatran etexilate** is the correct answer as it is currently the only clinically approved **oral direct thrombin inhibitor (DTI)**. It works by directly binding to and inhibiting both free and clot-bound thrombin (Factor IIa), preventing the conversion of fibrinogen to fibrin. Unlike older anticoagulants, it does not require routine INR monitoring and has a rapid onset of action. **Analysis of Options:** * **Ximelagatran (Option A):** This was the first oral DTI developed; however, it was withdrawn globally shortly after its launch due to significant **hepatotoxicity** (liver toxicity). * **Idraparinux (Option B):** This is a long-acting synthetic pentasaccharide that acts as an indirect **Factor Xa inhibitor**. It is administered subcutaneously, not orally. * **Fondaparinux (Option C):** This is a synthetic pentasaccharide that selectively inhibits **Factor Xa** via antithrombin III. It is administered subcutaneously and is not a thrombin inhibitor. **High-Yield NEET-PG Pearls:** * **Antidote:** The specific reversal agent for Dabigatran is **Idarucizumab** (a humanized antibody fragment). * **Mechanism:** Dabigatran is a prodrug converted by esterases to its active form. * **Elimination:** It is primarily excreted by the **kidneys** (80%), so it requires dose adjustment or avoidance in renal failure. * **Comparison:** While Dabigatran inhibits Factor IIa, other "oxabans" (Rivaroxaban, Apixaban) are oral direct Factor Xa inhibitors.

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

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Antiplatelet Drugs

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Thrombolytic Agents

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Hemostatic Drugs

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Plasma Expanders

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Blood Transfusion and Alternatives

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