Drugs Affecting Blood and Blood Formation Practice Questions

Q: Which of the following is given to treat thrombocytopenia secondary to anticancer therapy and is known to stimulate progenitor megakaryocytes?

Oprelvekin. ***Oprelvekin*** - **Oprelvekin** is a recombinant form of **interleukin-11 (IL-11)**, which is a **thrombopoietic growth factor**. - It stimulates the proliferation and maturation of **megakaryocyte progenitors**, leading to an increase in platelet production. *Filgrastim* - **Filgrastim** is a **granulocyte colony-stimulating factor (G-CSF)**, primarily used to stimulate the production of **neutrophils** to counteract **neutropenia**. - It does not directly affect **megakaryocyte** or **platelet production**. *Erythropoietin* - **Erythropoietin** is a **hematopoietic growth factor** that specifically stimulates the production of **red blood cells (erythropoiesis)**. - It is used to treat **anemia**, particularly in patients with **chronic kidney disease** or those undergoing **chemotherapy**. *Anagrelide* - **Anagrelide** is an **antiplatelet agent** that works by reducing platelet production, often used to treat **thrombocythemia**. - Its action is the opposite of what is required to treat **thrombocytopenia**.

Q: Which agent is used for the treatment of heparin-induced thrombocytopenia?

Argatroban. ***Argatroban*** - **Argatroban** is a **direct thrombin inhibitor** and is a primary agent used for the treatment of **heparin-induced thrombocytopenia (HIT)**. - Its short half-life and independent metabolism from renal function make it suitable for patients with **renal impairment**. *Abciximab* - **Abciximab** is a **glycoprotein IIb/IIIa inhibitor** used to prevent platelet aggregation in conditions like percutaneous coronary intervention. - It is not indicated for HIT and can further exacerbate **thrombocytopenia** in certain situations. *Warfarin* - **Warfarin** is a **vitamin K antagonist** used for long-term anticoagulation, but it is **contraindicated in acute HIT**. - Initiating warfarin in acute HIT can worsen **thrombosis** due to initial protein C and S depletion, leading to a prothrombotic state. *Alteplase* - **Alteplase** is a **thrombolytic agent** (tissue plasaminogen activator) used to dissolve existing clots in conditions like acute ischemic stroke or pulmonary embolism. - It is not an anticoagulant for HIT and could increase the risk of **bleeding** without addressing the underlying prothrombotic state of HIT.

Q: What is the effect of nicotinic acid on cholesterol levels?

Increases HDL. ***Increases HDL*** - **Nicotinic acid**, or niacin, effectively **raises high-density lipoprotein (HDL)** cholesterol levels, which is beneficial for cardiovascular health. - It achieves this by decreasing the **hepatic uptake of HDL-apoA-I**, thus prolonging the half-life of HDL particles. *Increased triglyceride synthesis* - Nicotinic acid actually **reduces triglyceride synthesis** and secretion by the liver. - It **inhibits diacylglycerol acyltransferase 2 (DGAT2)**, a key enzyme in triglyceride synthesis. *Type II hyperlipoproteinemia* - **Type II hyperlipoproteinemia** is characterized by elevated **LDL cholesterol**. - While nicotinic acid can lower LDL, its primary effect and a key distinguishing feature is its ability to significantly **raise HDL**, not cause hyperlipoproteinemia. *Decreased hydrolysis of VLDL* - Nicotinic acid **enhances the clearance of VLDL** (very-low-density lipoprotein) and IDL (intermediate-density lipoprotein) from plasma. - It **decreases VLDL synthesis and secretion** rather than decreasing its hydrolysis.

Q: Which of the following is true about iron dextran except?

It binds to transferrin. ***It binds to transferrin*** - This statement is **false** because **iron dextran** is a stable complex designed to release iron slowly and does **not directly bind to transferrin** in its dextran-bound form. - The iron from iron dextran is taken up by the **reticuloendothelial system**, processed, and then released into the plasma to bind with transferrin. *It is a parenteral iron preparation* - **Iron dextran** is indeed administered parenterally, typically via **intravenous (IV)** or **intramuscular (IM)** injection, bypassing the gastrointestinal tract. - This route is preferred for patients who cannot tolerate oral iron or have severe iron deficiency. *It can be given either IV or IM* - **Iron dextran** can be administered both **intravenously (IV)** and **intramuscularly (IM)**, offering flexibility based on patient needs and clinical situations. - The IV route is often preferred due to better absorption and fewer local reactions compared to IM injections. *It is not excreted* - The iron component of **iron dextran** is primarily **recycled** within the body and is not readily excreted, reflecting iron's crucial role in various metabolic processes. - While trace amounts may be lost, significant excretion does not occur, and the iron is stored or utilized for erythropoiesis.

Q: Which of the following is a univalent direct thrombin inhibitor?

Argatroban. ***Argatroban*** - **Argatroban** is a **synthetic L-arginine derivative** that acts as a **direct thrombin inhibitor** and binds only to the catalytic site of thrombin, making it univalent. - It is used particularly in patients with **heparin-induced thrombocytopenia (HIT)** due to its independent mechanism from heparin [2]. *Hirudin* - **Hirudin** is a **bivalent direct thrombin inhibitor** originally isolated from leech saliva. - It binds to both the **catalytic site** and the **exosite 1 (fibrinogen-binding site)** of thrombin, preventing its enzymatic activity. *Bivalirudin* - **Bivalirudin** is a **synthetic peptide** that acts as a **bivalent direct thrombin inhibitor** [1]. - It binds reversibly to both the **catalytic site** and the **exosite 1** of thrombin [1]. *Lepirudin* - **Lepirudin** is a **recombinant hirudin derivative**, making it a **bivalent direct thrombin inhibitor** [2]. - Like hirudin, it binds to both the **catalytic site** and **exosite 1** of thrombin.

Q: The following factors are inhibited by heparin except?

VIIa. ***VIIa*** - Heparin, through its activation of **antithrombin III**, primarily inhibits factors **IIa (thrombin)**, **Xa**, **IXa**, **XIa**, and **XIIa**. - **Factor VIIa** is part of the extrinsic pathway and is not directly inhibited by the heparin-antithrombin III complex. *IIa* - **Factor IIa (thrombin)** is a direct target for inhibition by the **heparin-antithrombin III complex**. - Its inhibition is crucial for heparin's anticoagulant effect, as thrombin plays a central role in amplifying coagulation and converting fibrinogen to fibrin. *IXa* - **Factor IXa** is part of the intrinsic pathway and is effectively inhibited by the **heparin-antithrombin III complex**. - Inhibition of IXa prevents the activation of factor X, thereby disrupting the coagulation cascade. *Xa* - **Factor Xa** is a key component in the common pathway of coagulation and is potently inhibited by the **heparin-antithrombin III complex**. - Its inhibition is a primary mechanism by which both unfractionated heparin and low molecular weight heparins exert their anticoagulant effects.

Q: A patient with a malignancy is undergoing chemotherapy. The platelet counts were reduced after the previous cycle of chemotherapy. Which of the following drugs can be used to treat this patient?

Oprelvekin (IL-11) - stimulates platelet production. ***Oprelvekin (IL-11) - stimulates platelet production*** - **Oprelvekin** is a recombinant interleukin-11 (IL-11) that directly stimulates the proliferation and maturation of **megakaryocytes**, leading to increased platelet production. - It is specifically indicated for the prevention of **severe thrombocytopenia** and the reduction of the need for platelet transfusions following myelosuppressive chemotherapy. *Filgrastim - stimulates white blood cell production* - **Filgrastim** is a **granulocyte colony-stimulating factor (G-CSF)** that primarily acts on neutrophil precursors, promoting their proliferation and maturation. - It is used to prevent and treat **neutropenia** and reduce the incidence of febrile neutropenia, but it does not significantly affect platelet counts. *Amifostine - protects against chemotherapy toxicity* - **Amifostine** is a **cytoprotective agent** that reduces toxicities associated with chemotherapy and radiation by preferentially protecting non-malignant cells. - It does not directly stimulate blood cell production but rather acts as a **free radical scavenger** to mitigate damage from cytotoxic treatments. *Erythropoietin - stimulates red blood cell production* - **Erythropoietin** is a **hematopoietic growth factor** that specifically stimulates the production of **red blood cells** by promoting the proliferation and differentiation of erythroid progenitor cells. - It is used to treat **anemia**, particularly in patients with chronic kidney disease or those undergoing chemotherapy, but it has no role in managing thrombocytopenia.

Q: Which of the following clotting factors in a patient on Warfarin therapy would show the earliest decrease in functional activity?

Factor VII. ***Factor VII*** - Factor VII has the **shortest half-life** (approximately 6 hours) among the vitamin K-dependent clotting factors, meaning its functional activity decreases **most rapidly** after starting warfarin therapy. - Warfarin inhibits vitamin K epoxide reductase, preventing gamma-carboxylation of **all vitamin K-dependent factors** (II, VII, IX, X). However, Factor VII's short half-life means pre-existing functional Factor VII is depleted first. - This is why **PT/INR** (which measures the extrinsic pathway dependent on Factor VII) rises before aPTT in warfarin therapy. - Reduced gamma-carboxylation impairs Factor VII's ability to bind calcium and phospholipids, essential for its activation in the extrinsic coagulation pathway. *Factor IX* - Factor IX is a **vitamin K-dependent factor** affected by warfarin, but its longer half-life (approximately 24 hours) means functional activity decreases more slowly than Factor VII. - It plays a key role in the **intrinsic coagulation pathway**. *Factor X* - Factor X is a **vitamin K-dependent clotting factor** whose gamma-carboxylation is inhibited by warfarin. - Its half-life (approximately 40 hours) is longer than Factor VII, resulting in a **slower decline in functional activity**. *Prothrombin (Factor II)* - Prothrombin (Factor II) is a **vitamin K-dependent factor** affected by warfarin. - It has the **longest half-life** (60-72 hours) among vitamin K-dependent factors, meaning its functional levels decrease most slowly after initiating warfarin therapy.

Q: Which drug requires continuous monitoring of prothrombin time?

Coumadin. ***Coumadin*** - **Coumadin (warfarin)** is an oral anticoagulant that inhibits vitamin K epoxide reductase, thereby reducing the synthesis of **vitamin K-dependent clotting factors** (II, VII, IX, X). - Its narrow therapeutic index and significant variability in dosage requirements necessitate continuous monitoring of the **prothrombin time (PT)**, reported as the **International Normalized Ratio (INR)**, to ensure efficacy and prevent bleeding complications. *Aspirin* - **Aspirin** is an antiplatelet agent that irreversibly inhibits cyclooxygenase-1 (COX-1), preventing the synthesis of thromboxane A2, which is crucial for platelet aggregation. - It does not directly affect the coagulation cascade or prothrombin time; its antiplatelet effects are typically monitored by patient response and bleeding time, though routine monitoring is not usually required for standard antiplatelet therapy. *Digoxin* - **Digoxin** is a cardiac glycoside used to treat heart failure and atrial fibrillation by increasing myocardial contractility and slowing AV nodal conduction. - Its therapeutic effects and potential toxicity are monitored through serum digoxin levels, electrolyte balance (especially potassium), and electrocardiograms for signs of dysrhythmias, not by prothrombin time. *Lepirudin* - **Lepirudin** is a direct thrombin inhibitor (DTI) used in patients with heparin-induced thrombocytopenia (HIT). - Its anticoagulant effect is typically monitored using the **activated partial thromboplastin time (aPTT)**, not prothrombin time.

Question 1

Which of the following is given to treat thrombocytopenia secondary to anticancer therapy and is known to stimulate progenitor megakaryocytes?

Accepted Answer

Oprelvekin

Answer

Filgrastim

Answer

Erythropoietin

Answer

Anagrelide

Question 2

Which agent is used for the treatment of heparin-induced thrombocytopenia?

Accepted Answer

Argatroban

Answer

Abciximab

Answer

Warfarin

Answer

Alteplase

Question 3

What is the effect of nicotinic acid on cholesterol levels?

Accepted Answer

Increases HDL

Answer

Increased triglyceride synthesis

Answer

Type II hyperlipoproteinemia

Answer

Decreased hydrolysis of VLDL

Question 4

Which of the following is true about iron dextran except?

Accepted Answer

It binds to transferrin

Answer

It can be given either IV or IM

Answer

It is a parenteral iron preparation

Answer

It is not excreted

Question 5

Which of the following is a univalent direct thrombin inhibitor?

Accepted Answer

Argatroban

Answer

Hirudin

Answer

Bivalirudin

Answer

Lepirudin

Question 6

Which of the following statements accurately compares low molecular weight heparin to high molecular weight heparin?

Accepted Answer

Monitoring is generally not required for low molecular weight heparin compared to high molecular weight heparin.

Answer

Low molecular weight heparin is less likely to be filtered at the glomerulus compared to high molecular weight heparin.

Answer

Low molecular weight heparin interacts with plasma proteins similarly to high molecular weight heparin.

Answer

Low molecular weight heparin requires twice daily subcutaneous administration, unlike high molecular weight heparin which is given once daily.

Question 7

The following factors are inhibited by heparin except?

Accepted Answer

VIIa

Answer

IIa

Answer

IXa

Answer

Xa

Question 8

A patient with a malignancy is undergoing chemotherapy. The platelet counts were reduced after the previous cycle of chemotherapy. Which of the following drugs can be used to treat this patient?

Accepted Answer

Oprelvekin (IL-11) - stimulates platelet production

Answer

Filgrastim - stimulates white blood cell production

Answer

Amifostine - protects against chemotherapy toxicity

Answer

Erythropoietin - stimulates red blood cell production

Question 9

Which of the following clotting factors in a patient on Warfarin therapy would show the earliest decrease in functional activity?

Accepted Answer

Factor VII

Answer

Factor IX

Answer

Factor X

Answer

Prothrombin (Factor 2)

Question 10

Which drug requires continuous monitoring of prothrombin time?

Accepted Answer

Coumadin

Answer

Digoxin

Answer

Aspirin

Answer

Lepirudin

Drugs Affecting Blood and Blood Formation — MCQs

Drugs Affecting Blood and Blood Formation — MCQs

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