Drugs Affecting Blood and Blood Formation Practice Questions

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

Deamino D Arginine vasopressin. **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.

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

Ciprofloxacin. **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).

Q: All of the following are anticoagulants, except?

Phytonadione. ### 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.

Q: Which drug causes megaloblastic anemia?

Pyrimethamine. 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].

Q: What is the most recent oral direct thrombin inhibitor?

Dabigatran. **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.

Question 1

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

Accepted Answer

A tolerable daily dose typically delivers 40 to 60 mg of elemental iron.

Answer

The mass of the total salt is more important than elemental iron content in determining the daily dose.

Answer

Treatment should be continued until a normal hemoglobin level is achieved and then stopped immediately.

Answer

The desired rate of hemoglobin improvement during treatment is 0.5 g/dL per day.

Question 2

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

Accepted Answer

Deamino D Arginine vasopressin

Answer

Epsilon amino caproic acid

Answer

Tranexamic acid

Answer

Avitene

Question 3

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

Accepted Answer

It is effective in lysing thrombi of myocardial infarction.

Answer

It is produced by recombinant DNA technology.

Answer

Induction of systemic lytic state is limited with its use.

Answer

It is a poor plasminogen activator in the absence of fibrin.

Question 4

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

Accepted Answer

2500 mg

Answer

1000 mg

Answer

2000 mg

Answer

3000 mg

Question 5

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

Accepted Answer

Epistaxis

Answer

Haematuria

Answer

Oral bleeding

Answer

Hemarthrosis

Question 6

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

Accepted Answer

Ciprofloxacin

Answer

Phenytoin

Answer

Methotrexate

Answer

Pyrimethamine

Question 7

What is given in case of pernicious anaemia?

Accepted Answer

Methyl cobalamin

Answer

Folic acid

Answer

Folinic acid

Answer

Erythropoietin

Question 8

All of the following are anticoagulants, except?

Accepted Answer

Phytonadione

Answer

Warfarin

Answer

Low molecular weight heparin

Answer

Lepirudin

Question 9

Which drug causes megaloblastic anemia?

Accepted Answer

Pyrimethamine

Answer

Isoniazid (INH)

Answer

Chloramphenicol

Answer

Methyldopa

Question 10

What is the most recent oral direct thrombin inhibitor?

Accepted Answer

Dabigatran

Answer

Ximelagatran

Answer

Indraparinux

Answer

Fondaparinux

Drugs Affecting Blood and Blood Formation — MCQs

Drugs Affecting Blood and Blood Formation — MCQs

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