1.
A 54-year-old woman suffering from asthma was brought to the emergency room because of a sudden offset of left side paresis. Imaging studies confirmed the diagnosis of thromboembolic stroke and the patient started a treatment that included a drug that
acts by blocking platelet ADP receptors. Which of the following drugs has this mechanism of action?
Correct Answer
D. Clopidogrel
Explanation
Clopidogrel is the correct answer because it acts by blocking platelet ADP receptors. By blocking these receptors, clopidogrel prevents platelets from aggregating and forming blood clots, which can help reduce the risk of further thromboembolic events, such as strokes. Warfarin, aminocaproic acid, alteplase, heparin, and aspirin do not have this specific mechanism of action.
2.
A 34-year-old man admitted to the hospital with the presumptive diagnosis of pulmonary thromboembolism started a treatment that included a drug that acts by accelerating the binding between antithrombin III and clotting factor proteases. Which of the following drugs has this mechanism of action?
Correct Answer
E. Heparin
Explanation
Heparin is a drug that acts by accelerating the binding between antithrombin III and clotting factor proteases. It inhibits the formation of fibrin clots by preventing the conversion of fibrinogen to fibrin. This mechanism of action makes it an effective treatment for conditions such as pulmonary thromboembolism, where there is a clot formation in the blood vessels of the lungs. Warfarin, Aminocaproic acid, Alteplase, Clopidogrel, and Aspirin have different mechanisms of action and are not used for this purpose.
3.
A 30-year-old woman presented to her family physician complaining of black, tarry stools. The woman had had a prosthetic valve replacement four months ago for severe aortic stenosis secondary to rheumatic disease and had been receiving daily anticoagulant therapy since then. Physical examination revealed subconjunctival hemorrhage and bruises on arms and legs. Which of the following drugs most likely caused the patient’s symptoms and signs?
Correct Answer
D. Warfarin
Explanation
The patient's symptoms and signs, including black, tarry stools, subconjunctival hemorrhage, and bruises, are consistent with bleeding complications. Warfarin is an anticoagulant medication that works by inhibiting vitamin K-dependent clotting factors, leading to an increased risk of bleeding. The patient's history of prosthetic valve replacement and daily anticoagulant therapy further supports the likelihood that warfarin is the cause of her symptoms and signs.
4.
A 42-year-old woman suffering from systemic lupus erythematosus was admitted to the hospital with substernal, non-radiating pain that awakened her from sleep. Physical examination showed a patient in moderate distress, complaining of chest pain that got
worse by thoracic motion. Vital signs included temperature 103° F, pulse 90 bpm, blood pressure 150/90 mm Hg, respirations 18/min. Auscultation revealed a precordial systolic and diastolic friction rub. Which of the following drug classes would be absolutely
contraindicated for this patient?
Correct Answer
B. Fibrinolytic drugs
Explanation
Fibrinolytic drugs would be absolutely contraindicated for this patient because she is exhibiting symptoms of pericarditis, including substernal chest pain, friction rub, and fever. Fibrinolytic drugs are used to dissolve blood clots, but in the case of pericarditis, there is no clot formation. Therefore, fibrinolytic drugs would not be effective and could potentially worsen the patient's condition.
5.
A 51-year-old man was admitted to the hospital because he found red blood in his stools and pink urine. Two weeks previously the man had started treatment with warfarin for recurrent deep venous thrombosis. On physical examination, the patient appeared pale and diaphoretic. Vital signs were: blood pressure 85/55 mm Hg, heart rate 105 bpm, respirations 20/min. Appropriate therapy was started. Which of the following drugs was most likely administered IV to the patient?
Correct Answer
E. Fresh frozen plasma
Explanation
Fresh frozen plasma is most likely administered IV to the patient in this scenario. The patient's symptoms of red blood in stools and pink urine, along with the physical examination findings of pale appearance and low blood pressure, suggest significant bleeding. Warfarin, which the patient started two weeks ago, is an anticoagulant that can increase the risk of bleeding. Fresh frozen plasma contains clotting factors and can help replace the depleted factors in the patient, helping to control the bleeding.
6.
A 32-year-old man suffering from hemophilia A was admitted to the dentist's office for a tooth extraction. The patient received an SC injection of desmopressin, a drug that was effective for the patient in the past, in preparation for minor surgery. Which of the following statements best explains why desmopressin was an appropriate therapy for the patient?
Correct Answer
A. It increases the plasma levels of factor VIII
Explanation
Desmopressin is an appropriate therapy for the patient because it increases the plasma levels of factor VIII. Hemophilia A is a genetic disorder characterized by a deficiency or dysfunction of factor VIII, a blood clotting factor. Desmopressin stimulates the release of factor VIII from storage sites in the body, increasing its concentration in the blood. This can help prevent or control bleeding episodes in patients with hemophilia A.
7.
Which of the following agents can act as an antidote to manage bleeding due to fibrinolytic therapy?
Correct Answer
E. Aminocaproic acid
Explanation
Aminocaproic acid can act as an antidote to manage bleeding due to fibrinolytic therapy. Fibrinolytic therapy involves the use of drugs like alteplase to dissolve blood clots. However, these drugs can sometimes cause excessive bleeding. Aminocaproic acid works by inhibiting the breakdown of blood clots and preventing further bleeding. It helps to stabilize the clot and control bleeding in patients receiving fibrinolytic therapy.
8.
A 62-year-old woman complained to her physician of nose bleeding and red eyes. The woman has been receiving warfarin for one month because of deep venous thrombosis.
Four days ago she started treatment with erythromycin for acute pharyngitis. Which of the following was most likely the reason for the patient‘s symptoms?
Correct Answer
B. Erythromycin-induced inhibition of warfarin metabolism
Explanation
The correct answer is "Erythromycin-induced inhibition of warfarin metabolism". Erythromycin is known to inhibit the metabolism of warfarin, which is a blood thinner. This can lead to an increase in the levels of warfarin in the body, resulting in an increased risk of bleeding. The patient's symptoms of nose bleeding and red eyes are consistent with this increased risk of bleeding due to the interaction between erythromycin and warfarin.
9.
A 56-year-old man, admitted to the hospital with myocardial infarction, underwent a percutaneous coronary angioplasty for the revascularization of his left coronary. Which of
the following drugs were most likely given IV during the procedure?
Correct Answer
F. Abciximab
Explanation
Abciximab,a glycoprotein IIb/IIIa receptor antagonist, is a platelet aggregation inhibitor mainly used during and after coronary artery procedures like angioplasty to prevent platelets from sticking together and causing thrombus (blood clot) formation within the coronary artery. It is a glycoprotein IIb/IIIa inhibitor. While Abciximab has a short plasma half-life, due to its strong affinity for its receptor on the platelets, it may occupy some receptors for weeks. In practice, platelet aggregation gradually returns to normal about 96 to 120 hours after discontinuation of the drug.
10.
A 64-year-old man, admitted to the hospital with the presumptive diagnosis of pulmonary embolism, started an appropriate emergency therapy. Three days later his finger became discolored and laboratory tests showed the following:
WBC 10.2 x 103/mm3 (normal 4.3-10.8),
RBC 4.8 x 106/mm3 (normal 3.5-5.0),
platelets 75 x 103/mm3 (normal 140-440).
Which of the following drugs most likely caused the patient’s symptoms and signs?
Correct Answer
C. Heparin
Explanation
The patient's symptoms and laboratory findings are consistent with heparin-induced thrombocytopenia (HIT), which is a known side effect of heparin therapy. HIT is characterized by a decrease in platelet count, as seen in this case, and can lead to the development of blood clots and tissue damage. The other drugs listed are not typically associated with these symptoms and signs.
11.
A 50-year-old man is found in a coma after he was admitted to the hospital following an acute myocardial infarction. CT scan of the head shows intracranial hemorrhage in the left hemisphere. Which of the following drugs is most likely to increase the risk of this hemorrhage?
Correct Answer
B. Warfarin
Explanation
Warfarin is a commonly used anticoagulant medication that works by inhibiting the synthesis of vitamin K-dependent clotting factors. This increases the risk of bleeding, including intracranial hemorrhage. In this case, the patient had an acute myocardial infarction and was found in a coma, indicating a severe condition. The CT scan showed intracranial hemorrhage in the left hemisphere, suggesting that the patient's condition was worsened by the use of warfarin, which increased the risk of bleeding in the brain. Aspirin, streptokinase, and ticlopidine are not typically associated with an increased risk of intracranial hemorrhage.
12.
A 58-year-old man with a history of unstable angina was given clopidogrel as a prophylactic treatment. Which of the following molecular actions most likely mediated the therapeutic effect of the drug in the patient’s disease?
Correct Answer
C. Irreversible blockade of platelet ADP receptors
Explanation
Clopidogrel is a medication that is commonly used as an antiplatelet agent to prevent blood clot formation in patients with cardiovascular diseases. It works by irreversibly blocking the ADP receptors on platelets, preventing platelet activation and aggregation. This inhibitory effect on platelets reduces the risk of clot formation and helps in preventing complications associated with unstable angina. Therefore, the irreversible blockade of platelet ADP receptors is the molecular action that most likely mediates the therapeutic effect of clopidogrel in the patient's disease.