Drugs Affecting Blood and Blood Formation Practice Questions

Q: Which of the following drugs inhibit platelet cyclooxygenase reversibly?

Ibuprofen. ***Ibuprofen*** - Ibuprofen is a non-steroidal anti-inflammatory drug (**NSAID**) that **reversibly inhibits** both **COX-1** and **COX-2** enzymes. - Its inhibitory effect on platelet function is temporary and wears off as the drug is metabolized and cleared from the body. *Alprostadil* - **Alprostadil** is a synthetic **prostaglandin E1 (PGE1)** analogue; it does not inhibit cyclooxygenase. - It works by directly activating **prostaglandin receptors**, leading to vasodilation and inhibition of platelet aggregation. *Aspirin* - **Aspirin** *irreversibly inhibits* platelet cyclooxygenase (specifically **COX-1**) by **acetylation** of a serine residue. - This irreversible inhibition means that the effect on platelets lasts for their entire lifespan, requiring new platelets to be produced for normal function. *Prednisolone* - **Prednisolone** is a **corticosteroid** that works by inhibiting **phospholipase A2**, thereby preventing the release of arachidonic acid, the precursor for prostaglandins. - It does not directly inhibit cyclooxygenase enzymes, but rather acts upstream in the inflammatory pathway.

Q: All are antiplatelet drugs except:

Aprotinin. ***Aprotinin*** - **Aprotinin** is a **serine protease inhibitor** used to reduce bleeding during complex surgeries, particularly cardiac surgery. - It works by inhibiting kallikrein and plasmin, thereby **preserving platelets** and **reducing fibrinolysis**, rather than inhibiting platelet aggregation. *Clopidogrel* - **Clopidogrel** is a **P2Y12 receptor inhibitor** that prevents platelet activation and aggregation. - It is commonly used in patients with **acute coronary syndrome** and for the prevention of thrombotic events. *Abciximab* - **Abciximab** is a **glycoprotein IIb/IIIa receptor antagonist** that blocks the final common pathway of platelet aggregation. - It is primarily used during **percutaneous coronary intervention (PCI)** to prevent ischemic complications. *Ticlopidine* - **Ticlopidine** is another **P2Y12 receptor inhibitor** that inhibits platelet aggregation similar to clopidogrel. - It is associated with a higher risk of **hematologic side effects** like neutropenia and thrombotic thrombocytopenic purpura (TTP) compared to clopidogrel.

Q: Which one of the following is used for the preservation of blood for transfusions?

Citrate phosphate dextrose. ***Citrate phosphate dextrose*** - This anticoagulant solution is commonly used for blood preservation in blood banks because **citrate** chelates **calcium ions**, preventing coagulation. - The **phosphate** acts as a buffer to maintain pH, and **dextrose** provides energy for red blood cell metabolism during storage. - **CPD** allows blood storage for up to **21 days**, and when adenine is added (CPDA-1), storage can be extended to **35 days**. *Heparin* - **Heparin** is an anticoagulant that works by enhancing the activity of **antithrombin III**, but it is generally not used for long-term blood storage for transfusion due to its short half-life and potential to activate platelets upon prolonged contact. - While effective as an anticoagulant, heparin is not suitable for routine blood bank storage as it does not adequately support the viability of red blood cells over extended periods. *Thrombin* - **Thrombin** is a procoagulant enzyme involved in the final stages of the coagulation cascade, converting fibrinogen to fibrin, thus promoting clot formation. - Using thrombin would cause immediate blood clotting, making it entirely unsuitable for preserving blood for transfusion purposes. *EDTA* - **EDTA (Ethylenediaminetetraacetic acid)** is a chelating anticoagulant commonly used in **laboratory samples** for hematological testing (e.g., CBC). - However, it is **not used for blood transfusion** because it can cause morphological changes in cells and is toxic when transfused, making it unsuitable for therapeutic blood storage.

Q: Which of the following is a non-peptide GP IIb/IIIa antagonist?

Tirofiban. **Tirofiban** is the correct answer as it is a **non-peptide GP IIb/IIIa antagonist**. ***Tirofiban*** - Tirofiban is a **non-peptide GP IIb/IIIa antagonist** (tyrosine derivative) that blocks the binding of **fibrinogen** to the receptor, thereby inhibiting platelet aggregation. - Its **small molecular weight** and **reversible binding** allow for rapid onset and offset of action. - Used in acute coronary syndromes and during percutaneous coronary interventions. *Abciximab* - Abciximab is the **Fab fragment** of a **monoclonal antibody** directed against the GPIIb/IIIa receptor, making it a **peptide-based** (antibody-based) antagonist. - It has high affinity for the receptor and a relatively **long duration of action** due to its antibody nature. *Eptifibatide* - Eptifibatide is a **cyclic heptapeptide** that mimics the RGD (arginine-glycine-aspartate) sequence found in fibrinogen, classifying it as a **peptide-based** antagonist. - It selectively binds to the **GPIIb/IIIa receptor**, preventing platelet aggregation. *Prasugrel* - Prasugrel is a **thienopyridine P2Y12 inhibitor**, which acts by irreversibly blocking the **ADP receptor** on platelets, preventing their activation and aggregation. - It is distinct from GP IIb/IIIa inhibitors as it targets a **different pathway of platelet activation** (not a GP IIb/IIIa antagonist at all).

Q: Which of the following vitamins can be used in high doses to treat hypercholesterolemia?

Niacin. ***Niacin*** - **Niacin** (Vitamin B3) in pharmacological doses effectively lowers **LDL cholesterol** and triglycerides while raising **HDL cholesterol**. - Its mechanism involves inhibiting **hepatic VLDL secretion** and decreasing the catabolism of **HDL**. *Vitamin B2* - **Vitamin B2** (riboflavin) is crucial for **cellular energy production** and acts as a cofactor in various enzyme reactions. - It does not have a significant role in **lipid metabolism** or in treating **hypercholesterolemia** at high doses. *Vitamin B5* - **Vitamin B5** (pantothenic acid) is a component of **coenzyme A**, essential for **fatty acid synthesis** and breakdown. - While involved in metabolism, it is not used therapeutically to manage **hypercholesterolemia**. *Vitamin B1* - **Vitamin B1** (thiamine) is vital for **carbohydrate metabolism** and **nerve function**. - There is no evidence supporting its use in treating **hypercholesterolemia**.

Q: A patient with hemophilia and rheumatoid arthritis may be prescribed which drug to relieve pain?

Acetaminophen. ***Acetaminophen*** - **Acetaminophen** is a preferred pain reliever for patients with hemophilia because it has **no antiplatelet effect** and thus does not increase the risk of bleeding. - It effectively manages mild to moderate pain associated with **rheumatoid arthritis** without impacting coagulation. *Acetylsalicylic acid* - **Acetylsalicylic acid** (aspirin) is an **NSAID** and a potent **antiplatelet agent**, which would significantly increase the risk of bleeding in a patient with hemophilia. - Its use is contraindicated in hemophilia due to the high risk of **hemorrhage**. *Phenylbutazone* - **Phenylbutazone** is an **NSAID** that is rarely used due to severe side effects such as **aplastic anemia** and **agranulocytosis**. - Like other NSAIDs, it inhibits platelet aggregation, posing a significant **bleeding risk** for hemophiliac patients. *Naproxen* - **Naproxen** is another **NSAID** that inhibits cyclooxygenase enzymes, which not only provides pain relief but also **impairs platelet function**. - Its use is contraindicated in hemophilia because it increases the risk of **gastrointestinal and other bleeding episodes**.

Q: Which of the following is most likely to be used in a young child with chronic renal insufficiency?

Erythropoietin (EPO). ***Erythropoietin (EPO)*** - **Chronic renal insufficiency** leads to decreased production of **erythropoietin** by the kidneys, resulting in **anemia**. - Administering exogenous **EPO** stimulates red blood cell production, correcting the anemia common in these patients. *Desferrioxamine* - This is a **chelating agent** used to treat **iron overload**, which can occur in patients receiving multiple blood transfusions or those with certain genetic disorders. - While some chronic renal patients may receive transfusions, **iron overload** is not the primary or most common issue addressed by this medication in the context of general renal insufficiency. *Filgrastim (G-CSF)* - **Granulocyte colony-stimulating factor (G-CSF)** is used to stimulate the production of **neutrophils**, typically in patients with **neutropenia** (low white blood cell count) due to chemotherapy or certain bone marrow disorders. - It does not directly address the primary hematological complications of chronic renal insufficiency, which is mainly **anemia**. *Cyanocobalamin (Vitamin B12)* - **Vitamin B12** is essential for red blood cell formation and neurological function; its deficiency can cause **megaloblastic anemia**. - While renal insufficiency can affect nutrient absorption, **B12 deficiency anemia** is not the most common or direct hematological complication of chronic kidney disease, which is primarily due to EPO deficiency.

Q: Fish oil is not used in the treatment of:

Type 2A Hyperlipoproteinemia. ***Type 2A Hyperlipoproteinemia*** - **Fish oil** (omega-3 fatty acids) primarily lowers **triglyceride** levels. - In **Type 2A hyperlipoproteinemia**, the main lipid abnormality is elevated **LDL cholesterol**, with normal triglycerides, making fish oil less effective as a primary treatment. *Type 2B Hyperlipoproteinemia* - This condition involves elevated **LDL cholesterol** and moderately elevated **triglycerides**. - **Fish oil** can be beneficial in managing the elevated triglyceride component. *Type 5 Hyperlipoproteinemia* - Characterized by very high **triglyceride** levels and elevated **chylomicrons** and **VLDL**. - **Fish oil** is a key therapeutic agent for significantly reducing triglycerides in this severe form of hyperlipidemia. *Type 3 Hyperlipoproteinemia* - Also known as **familial dysbetalipoproteinemia**, this condition involves elevated **chylomicron remnants** and **VLDL remnants**. - **Fish oil** can help lower the triglyceride-rich lipoproteins seen in this disorder.

Q: What is the mechanism of action of Clopidogrel?

Inhibition of ADP-mediated platelet activation. ***Inhibition of ADP-mediated platelet activation*** - Clopidogrel is an **antiplatelet agent** that works by a direct antagonistic action at the **P2Y12 receptor** on the surface of platelets. - This binding prevents adenosine diphosphate (ADP) from binding to its receptor, thereby inhibiting the activation of the **GP IIb/IIIa receptor complex** and subsequent platelet aggregation. *Inhibition of Thromboxane A2* - This mechanism of action is characteristic of **aspirin**, which inhibits the enzyme **cyclooxygenase-1 (COX-1)**. - COX-1 inhibition leads to reduced production of **Thromboxane A2**, a potent platelet aggregator and vasoconstrictor. *Inhibition of GP IIb/IIIa receptors* - While Clopidogrel ultimately affects the activation of **GP IIb/IIIa receptors**, it does not directly inhibit them. - Drugs like **abciximab**, **eptifibatide**, and **tirofiban** are direct inhibitors of the GP IIb/IIIa receptors, preventing fibrinogen binding and platelet aggregation. *No effect on platelet activation* - This statement is incorrect as Clopidogrel is a well-established **antiplatelet drug**. - Its therapeutic effect is specifically to **reduce platelet activation** and aggregation, thus preventing thrombotic events.

Q: Folic acid deficiency is precipitated by:

Methotrexate. ***Methotrexate*** - **Methotrexate** is an **antimetabolite** that acts as a **folic acid analog**, competitively inhibiting **dihydrofolate reductase (DHFR)**, the enzyme responsible for converting dihydrofolate to tetrahydrofolate. - This inhibition blocks **DNA synthesis** and cell proliferation, leading to the therapeutic effects of methotrexate but also causing **severe folic acid deficiency** by preventing the formation of its active form. - **Most direct and potent** cause of drug-induced folate deficiency, requiring **leucovorin rescue** in high-dose therapy. *Phenytoin* - **Phenytoin** is an **antiepileptic drug** that **interferes with folate absorption** by inhibiting **intestinal conjugase enzyme** and affecting folate transport mechanisms. - Chronic use can lead to **clinically significant folate deficiency** and **megaloblastic anemia**, making it an important recognized cause. - However, compared to methotrexate, the mechanism is **indirect** (absorption interference) rather than direct enzyme inhibition, and the onset is more gradual. *Trimethoprim* - **Trimethoprim** also inhibits **dihydrofolate reductase**, but its affinity for **bacterial DHFR** is significantly higher (thousands of times) than for human DHFR. - While prolonged high-dose use can rarely cause **folate deficiency** in humans, it is much less common and clinically significant than with methotrexate or phenytoin. *Cyclosporin* - **Cyclosporin** is an **immunosuppressant** that primarily acts by inhibiting **calcineurin**, thereby preventing the activation of **T-lymphocytes**. - Its mechanism of action does not directly involve **folic acid metabolism**, and it is **not known** to cause folic acid deficiency.

Question 1

Which of the following drugs inhibit platelet cyclooxygenase reversibly?

Accepted Answer

Ibuprofen

Answer

Alprostadil

Answer

Prednisolone

Answer

Aspirin

Question 2

All are antiplatelet drugs except:

Accepted Answer

Aprotinin

Answer

Clopidogrel

Answer

Abciximab

Answer

Ticlopidine

Question 3

Which one of the following is used for the preservation of blood for transfusions?

Accepted Answer

Citrate phosphate dextrose

Answer

Heparin

Answer

Thrombin

Answer

EDTA

Question 4

Which of the following is a non-peptide GP IIb/IIIa antagonist?

Accepted Answer

Tirofiban

Answer

Abciximab

Answer

Eptifibatide

Answer

Prasugrel

Question 5

Which of the following vitamins can be used in high doses to treat hypercholesterolemia?

Accepted Answer

Niacin

Answer

Vitamin B2

Answer

Vitamin B5

Answer

Vitamin B1

Question 6

A patient with hemophilia and rheumatoid arthritis may be prescribed which drug to relieve pain?

Accepted Answer

Acetaminophen

Answer

Acetylsalicylic acid

Answer

Phenylbutazone

Answer

Naproxen

Question 7

Which of the following is most likely to be used in a young child with chronic renal insufficiency?

Accepted Answer

Erythropoietin (EPO)

Answer

Desferrioxamine

Answer

Filgrastim (G-CSF)

Answer

Cyanocobalamin (Vitamin B12)

Question 8

Fish oil is not used in the treatment of:

Accepted Answer

Type 2A Hyperlipoproteinemia

Answer

Type 2B Hyperlipoproteinemia

Answer

Type 5 Hyperlipoproteinemia

Answer

Type 3 Hyperlipoproteinemia

Question 9

What is the mechanism of action of Clopidogrel?

Accepted Answer

Inhibition of ADP-mediated platelet activation

Answer

Inhibition of Thromboxane A2

Answer

Inhibition of GP IIb/IIIa receptors

Answer

No effect on platelet activation

Question 10

Folic acid deficiency is precipitated by:

Accepted Answer

Methotrexate

Answer

Phenytoin

Answer

Trimethoprim

Answer

Cyclosporin

Drugs Affecting Blood and Blood Formation — MCQs

Drugs Affecting Blood and Blood Formation — MCQs

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