Drugs Affecting Blood and Blood Formation

Drugs Affecting Blood and Blood Formation Indian Medical PG Question 1: Which of the following is not a contraindication for the use of rtPA in stroke management?

• A. BP >185/110 mm Hg
• B. Heparin in the past 24 hrs
• C. Lesion occupying >1/3 of middle cerebral artery territory
• D. Presence of coma (Correct Answer)

Drugs Affecting Blood and Blood Formation Explanation: ***Presence of coma*** - While a severe neurological deficit, **coma itself is not an absolute contraindication** for rtPA if the stroke is acute ischemic and within the treatment window, and other contraindications are absent. - The decision to administer rtPA in comatose patients is complex and based on careful assessment of neurological impairment due to **ischemia**, not just a state of reduced consciousness. *BP >185/110 mm Hg* - **Elevated blood pressure** above 185/110 mmHg is a **major contraindication** for rtPA because it significantly increases the risk of **intracranial hemorrhage**. - Blood pressure must be **controlled below this threshold** before rtPA can be safely administered. *Heparin in the past 24 hrs* - Recent use of **anticoagulants**, especially heparin, within 24 hours, indicates a higher **risk of bleeding** if rtPA is given. - This significantly raises the potential for **hemorrhagic transformation** of the ischemic stroke. *Lesion occupying >1/3 of middle cerebral artery territory* - A **large ischemic lesion** (e.g., >1/3 of MCA territory) on initial imaging is a **contraindication** due to increased risk of **hemorrhagic conversion** and **edema** after reperfusion [1]. - Giving rtPA to such large lesions is associated with poorer outcomes and higher mortality [1].

Drugs Affecting Blood and Blood Formation Indian Medical PG Question 2: What is the mechanism of action of ticagrelor?

• A. PAR1 activator
• B. P2Y12 inhibitor (Correct Answer)
• C. P2Y12 activator
• D. PAR1 inhibitor

Drugs Affecting Blood and Blood Formation Explanation: ***P2Y12 inhibitor*** - Ticagrelor is an **oral antiplatelet agent** that works by reversibly binding to the **P2Y12 receptor** on platelets. - This binding prevents adenosine diphosphate (ADP) from activating the P2Y12 receptor, which is crucial for **platelet aggregation** and **thrombus formation**. *PAR1 inhibitor* - **PAR1 inhibitors** (e.g., vorapaxar) block the thrombin receptor on platelets, leading to antiplatelet effects. - This mechanism is distinct from ticagrelor's action on the P2Y12 receptor. *PAR1 activator* - Activating **PAR1** would promote platelet aggregation and activation, which is the opposite effect of an antiplatelet medication like ticagrelor. - This mechanism would increase the risk of thrombosis. *P2Y12 activator* - Activating the **P2Y12 receptor** would lead to increased platelet aggregation and is not the mechanism of action for an antiplatelet drug. - Drugs that activate P2Y12 would promote the formation of blood clots.

Drugs Affecting Blood and Blood Formation Indian Medical PG Question 3: Absolute contraindication to thrombolytic therapy is:

• A. Patients on nitrates
• B. Hypertension
• C. Pregnancy
• D. History of hemorrhagic stroke in past one year (Correct Answer)

Drugs Affecting Blood and Blood Formation Explanation: **History of hemorrhagic stroke in past one year** - A **history of hemorrhagic stroke** is an **absolute contraindication** to thrombolytic therapy due to the significantly increased risk of recurrent and fatal intracranial hemorrhage. [1] - Thrombolytic agents dissolve clots, and in a vessel weakened by prior hemorrhage, this can lead to catastrophic re-bleeding. [1] *Pregnancy* - Pregnancy is generally considered a **relative contraindication** but not an absolute one, as the risk-benefit decision depends on the specific clinical scenario and urgent need for thrombolysis. - The primary concern is fetal exposure to radiation and the potential for maternal and fetal bleeding complications. *Patients on nitrates* - Being on nitrates has **no direct contraindication** to thrombolytic therapy. [2] - Nitrates are commonly used in cardiac patients for vasodilation and symptom relief, and their use does not increase the risk of hemorrhage from thrombolysis. [2] *Hypertension* - **Uncontrolled severe hypertension** (e.g., systolic BP >185 mmHg or diastolic BP >110 mmHg) is a relative contraindication to thrombolysis, as it increases the risk of intracranial hemorrhage. - However, isolated hypertension without other risk factors, or hypertension that can be controlled, is not an absolute contraindication.

Drugs Affecting Blood and Blood Formation Indian Medical PG Question 4: All of the following are antiplatelet agents except which of the following?

• A. Tranexamic acid (Correct Answer)
• B. Clopidogrel
• C. Ticagrelor
• D. Aspirin

Drugs Affecting Blood and Blood Formation Explanation: ***Tranexamic acid*** - **Tranexamic acid** is an **antifibrinolytic agent** that inhibits plasminogen activation, thereby preventing clot breakdown. - It works to **promote clot stability** and is used to reduce bleeding, rather than inhibit platelet aggregation. *Aspirin* - **Aspirin** is an **antiplatelet agent** that irreversibly inhibits **cyclooxygenase-1 (COX-1)**, reducing thromboxane A2 production. - This effectively prevents platelet aggregation and is used for primary and secondary prevention of cardiovascular events. *Clopidogrel* - **Clopidogrel** is a **P2Y12 inhibitor**, an antiplatelet agent that selectively and irreversibly blocks the ADP receptor on platelets. - This inhibition prevents activation of the GP IIb/IIIa complex, thereby reducing **platelet aggregation**. *Ticagrelor* - **Ticagrelor** is a **P2Y12 inhibitor**, an antiplatelet agent that reversibly binds to the ADP receptor on platelets. - It provides a rapid and potent inhibition of **platelet aggregation**, similar to clopidogrel but with a faster onset and offset of action.

Drugs Affecting Blood and Blood Formation Indian Medical PG Question 5: Which of the following is the platinum-based chemotherapeutic agent used as first-line treatment for ovarian carcinoma?

• A. Cyclophosphamide
• B. Methotrexate
• C. Cisplatin (Correct Answer)
• D. Dacarbazine

Drugs Affecting Blood and Blood Formation Explanation: ***Cisplatin*** - **Cisplatin** is a platinum-based chemotherapy drug that forms **DNA cross-links**, inhibiting DNA synthesis and leading to the death of rapidly dividing cells, making it highly effective against **ovarian carcinoma**. - It is a cornerstone of chemotherapy regimens for ovarian cancer, often used in combination with other agents such as paclitaxel. *Methotrexate* - **Methotrexate** is an **antimetabolite** that inhibits dihydrofolate reductase, thereby interfering with DNA synthesis. - While it is used in various cancers like leukemia, lymphoma, and some solid tumors (e.g., breast cancer, gestational trophoblastic disease), it is **not a primary recommended drug for ovarian carcinoma**. *Cyclophosphamide* - **Cyclophosphamide** is an **alkylating agent** that causes DNA damage, leading to cell death. - It is used in many cancers, including lymphoma, breast cancer, and some leukemias, but it is **not a first-line or primary agent for ovarian carcinoma** in contemporary treatment guidelines. *Dacarbazine* - **Dacarbazine** is an **alkylating agent** primarily used in the treatment of **malignant melanoma** and Hodgkin lymphoma. - It is **not indicated for the treatment of ovarian carcinoma**.

Drugs Affecting Blood and Blood Formation Flashcard 1 of 5

Question: Thrombolytics result in an _____ PT and elevated PTT

Answer: elevated

Drugs Affecting Blood and Blood Formation Flashcard 2 of 5

Question: Concomitant measurement of _____ and anti-factor Xa level distinguishes pseudo-resistance and true-resistance to heparin.

Answer: aPTT

Drugs Affecting Blood and Blood Formation Flashcard 3 of 5

Question: _____ is an erythroid maturation agent, recently approved by the FDA for the treatment of transfusion-dependent thalassemia.

Answer: Luspatercept

Drugs Affecting Blood and Blood Formation Flashcard 4 of 5

Question: Immune thrombocytopenia can be treated with the TPO receptor agonists _____ and romiplostim

Answer: eltrombopag

Drugs Affecting Blood and Blood Formation Flashcard 5 of 5

Question: _____ is a competitive antagonist of _____ and inhibits thrombin-induced platelet aggregation.

Answer: Vorapaxar; PAR-1