PHARMACOLOGY BLOCK B

48) A 37-year-old man comes to the emergency department because of difficulty breathing and a productive cough for the past 4 days. He is diagnosed with Pneumocystisjirovecii pneumonia and is found to be HIV positive with a reduced CD4+ cell count. He is placed on several medications to manage his condition. Three weeks later, his serum creatinine concentration has increased from 1.1 mg/dL to 2.8 mg/dL. Which of the following medications is the most likely cause of his increased serum creatinine? A. Abacavir B. Didanosine C. Enfuvirtide D. Tenofovir E. Zidovudine

*D. Tenofovir*

31) A 26-year-old man is brought to the emergency department after being found unresponsive in his apartment. He has no known medical conditions and does not take any medications. On examination, his temperature is 37.1°C (98.7°F), pulse is 55/min, respirations are 6/min, and blood pressure is 110/89 mm Hg. The patient's pupils are 2 mm in size and are nonreactive to light. Skin examination reveals evidence of injectable drug use on the patient's forearms. The patient's respiratory depression is most likely caused by which of the following mechanisms? A. Activation of κ opioid receptors B. Activation of μ opioid receptors C. Blockade of norepinephrine reuptake D. Inhibition of muscarinic receptor

*B. Activation of μ opioid receptors*

47) A 57-year-old immunocompromised man is hospitalized with pneumonia. He also is showing symptoms of central nervous system involvement, specifically headache and confusion. Bronchoalveolar lavage fluid is sampled, and culture results are shown. Intravenous medications are started and, 2 hours later, the patient experiences intense chills and spikes a fever Which of the following medications is most likely responsible for this patient's chills and fever? A. Amphotericin B B. Caspofungin C. Fluconazole D. Flucytosine E. Zidovudine

*A. Amphotericin B*

44) A 33-year-old man comes to the clinic because of a burning sensation in his mouth that started 3 weeks ago. It causes him severe pain with eating and swallowing; it also makes it difficult for him to taste food. Recently, the patient started experiencing night sweats and weight loss. His history is significant for alcohol and injectable drug use. Temperature is 37.90C (100.3'F). Physical examination of the oral mucosa is shown. Laboratory tests reveal a CD4+ cell count of 200 cells/mm. Which of the following is the mechanism of action of the drug this patient was most likely given? A. Binds ergosterol to form pores in membranes B. Binds tubulin to interfere with microtubule function C. Inhibits DNA polymerase by mimicking pyrophosphate D. Inhibits DNA replication E. Inhibits folate synthesis to impair DNA replication

*A. Binds ergosterol to form pores in membranes*

55) A 6-year-old boy is brought to the office by his parents with a 1 -day history of sore throat, fever, and headache. His temperature is 38.60C (1 01.50F). On examination, his tonsils are enlarged and have a white exudate. A rapid antigen test is positive. Which of the following is the mechanism of action of the most likely prescribed drug to treat this patient's condition? A. Blocks peptidoglycan polymerization B. Blocks protein synthesis at the 30S ribosomal subunit C. Blocks protein synthesis at the 50S ribosomal subunit D. Inhibits DNA gyrase E. Inhibits peptidoglycan polymer cross-linking

*A. Blocks peptidoglycan polymerization*

39) A 60-year-old woman comes to the office with fatigue and dyspnea for 1 week. She began receiving chemotherapy for breast cancer 3 months ago. She is otherwise healthy. Physical examination reveals an elevated jugular venous pressure, an S3 heart sound, crackles, and bilateral pitting edema. An x-ray of the chest reveals an enlarged cardiac silhouette. The x-ray was normal at the time of her breast cancer diagnosis. The chemotherapeutic agent she is most likely receiving has which of the following mechanisms of action? A. DNA intercalation B. Estrogen receptor modulation C. Inhibition of dihydrofolate reductase D. Inhibition of microtubule formation E. Inhibition of purine synthesis

*A. DNA intercalation*

42) A 37-year-old man with a history of HIV infection comes to the physician because of worsening pain on swallowing and oral thrush. His CD4+ cell count is 250/gL. He is prescribed a course of fluconazole and started on antiretroviral therapy. Over the next 3 months, he experiences intermittent nausea and diarrhea, and he notices a redistribution of fat on his body, predominately around his abdomen. The cause of this patient's fat redistribution is most likely which of the following medications? A. Darunavir B. Dolutegravir C. Emtricitabine D. Fluconazole E. Nevirapine

*A. Darunavir*

38) A 58-year-old man comes to the physician because of fatigue, fever, and joint pain for the past several weeks. He has a history of systolic heart failure treated with enalapril, which was discontinued because of angioedema. The patient was switched to isosorbide and an antihypertensive agent. On physical examination today, his knees and hands are edematous and tender to palpation. Laboratory studies are notable for positive antihistone antibodies and antinuclear antibodies. Which of the following best describes the mechanism of action of the newly prescribed antihypertensive agent that was paired with isosorbide? A. Dilates arterioles B. Inhibits the Na+/K+/2Cl— contransporter C. Inhibits the distal tubule Na+/Cl- cotransporter D. Prevents the influx of calcium into cardiac and smooth muscle cell

*A. Dilates arterioles*

59) A 19-year-old man taking a trek in Nepal takes a medication to assist adjusting to high altitudes. The medication is also used to treat glaucoma and inhibits an enzyme in renal proximal tubule cells. Which of the following is the most likely acid-base abnormality caused by this drug? A. Metabolic acidosis B. Metabolic alkalosis C. Mixed metabolic acidosis and respiratory alkalosis D. Respiratory acidosis E. Respiratory alkalosis

*A. Metabolic acidosis*

37) A 7-year-old girl is brought to the emergency department 10 hours after ingesting an unknown substance. The child appears uncomfortable and is seen holding both ears tightly. Temperature is 37.00C (98.60F), pulse is 90/min, respirations are 24/min, and blood pressure is 1 10/78 mm Hg. The physical examination is normal. Laboratory tests show: Arterial blood gas Pac02: 22 mm Hg Pa02: 110 mm Hg pH: 7.51 Serum Na+: 134 mEq/L C: 4.0 mEq/L cr: 98 mEq/L HC03-: 17 mEq/L. Ingestion of which of the following substances is the most likely cause of this patient's condition? A. Acetaminophen B. Aspirin C. Benzodiazepine D. Ethylene glycol E. Sodium hydroxide

*B. Aspirin*

57) A 27-year-old woman comes to her physician because of burning on urination. Her urine sample tests positive for leukocyte esterase and nitrite. She is treated with a first-line drug that inhibits bacterial topoisomerases. Which of the following adverse effects is this patient most likely to experience? A. Arrhythmia B. Diarrhea C. Hematuria D. Myalgia E. Ototoxicity

*B. Diarrhea*

58) A 35-year-old woman comes to the physician because of fever, night sweats, and fatigue. Biopsy specimen of an enlarged lymph node reveals Hodgkin lymphoma. The patient is treated with doxorubicin, bleomycin, vinblastine, and dacarbazine. This chemotherapeutic regimen increases the patient's risk for developing which of the following most likely adverse effects? A. Cushing syndrome B. Dilated cardiomyopathy C. Hemorrhagic cystitis D. Ototoxicity E. Thromboembolism

*B. Dilated cardiomyopathy*

56) A 28-year-old woman at 30 weeks of gestation with a 3-year history of HIV infection comes for consultation regarding the risk of HIV transmission to her child during delivery. She has been compliant with combined antiretroviral therapy since her diagnosis. HIV RNA viral load is 4 copies/mL. She is informed that zidovudine will be prescribed to her newborn after delivery. Which of the following best describes how zidovudine will inhibit HIV replication in the newborn? A. Competitively inhibits inosine-5'-monophosphate dehydrogenase B. Inhibits HIV reverse transcriptase C. Inhibits HIV-I integrase D. Inhibits viral DNA polymerase E. Upregulates the activity of cytochrome P450 enzymes

*B. Inhibits HIV reverse transcriptase*

41) A 48-year-old man develops hypertension 10 months after a renal transplant. His medications include trimethoprim-sulfamethoxazole, low-dose glucocorticoids, cyclosporine, cholecalciferol, and atorvastatin. Which of the following medications is most likely responsible for the patient's hypertension? A. Atorvastatin B. Cholecalciferol C. Cyclosporine D. Glucocorticoids E. Trimethoprim-sulfamethoxazole

*C. Cyclosporine*

35) A 38-year-old man is being treated for HIV-induced acquired immunodeficiency syndrome (AIDS). When abacavir therapy is begun, he develops a severe skin rash. Having which of the following allele might explain this skin rash? A. CYP2D6*3 B. CYP3A5*3 C. HLA-B*57:01 D. HLA- B27

*C. HLA-B*57:01*

50) A 38-year-old man comes to the clinic with blurry vision and intermittent floaters and flashes in his right eye. He is living with HIV. Fundoscopic examination reveals fluffy yellow-white lesions of the right retina with small areas of hemorrhage. Laboratory testing is significant for a CD4+ cell count of 35/mm3. Two weeks after initiating appropriate treatment, follow-up laboratory tests reveal an absolute neutrophil count of 400/gL and a creatinine level of 1.9 mg/dL. Which of the following is the most likely mechanism of action of the newly prescribed drug? A. Binding to the gp41 subunit of the viral envelope B. Inhibition of cleavage of viral polyproteins C. Inhibition of the incorporation of dGTP by viral DNA polymerase D. Inhibition of viral integrase E. Interference with the release of viral progeny

*C. Inhibition of the incorporation of dGTP by viral DNA polymerase*

52) A 49-year-old man comes to the outpatient clinic because of a 3-week history of ringing in his ears, stomach pain, and nausea. His past medical history is significant for chronic back pain, for which he takes an unknown analgesic agent. The physical examination shows epigastric tenderness. Which of the following describes the mechanism of action of this patient's most likely prescribed pain medication? A. Binding to central nervous system m-receptors B. Inhibition of cyclooxygenase (COX)-I , COX-2, and phospholipase A2 C. Irreversible cyclooxygenase (COX)-I and COX-2 inhibitor D. Reversible cyclooxygenase-2 inhibitor E. Reversible inhibition of cyclooxygenase (COX)-I and COX-2

*C. Irreversible cyclooxygenase (COX)-I and COX-2 inhibitor*

34) A 70-year-old patient with multiple cancer metastasis is prescribed extended- release morphine for pain management. To prevent constipation Sena glycoside and lactulose were tried but without any positive effect.. Which of the following medications should be prescribed for bowel regimen? A. Naloxone B. Naltrexone C. Methylnaltrexone D. Buprenorphine

*C. Methylnaltrexone*

51) A 32-year-old man who emigrated from Bolivia comes to the clinic because of fatigue, decreased appetite, and frequent nausea. He is otherwise healthy and takes one medication, which a doctor in Bolivia prescribed for 9 months after the patient's wife developed a severe cough. He drinks two beers each weekend. Physical examination shows mild right upper quadrant tenderness but is otherwise normal. Which of the following medications is the most likely cause of this patient's symptoms? A. Acetaminophen B. Dapsone C. Ethambutol D. Isoniazid E. Rifampin

*D. Isoniazid*

33) A 45-year-old man develops watery diarrhea after traveling and is prescribed a one-week course of an appropriate antibiotic drug for the infection. Three days later, his diarrhea is gone.That night while having dinner with friends, he experiences intense flushing, nausea, vomiting, and a racing pulse. The patient mentions that he didn't smoke and didn't consume any foods that he might be allergic to, but that he did drink alcohol. Which of the following antibiotics was most likely prescribed? A. Albendazole B. Azithromycin C. Levofloxacin D. Metronidazole E. Nitazoxanide

*D. Metronidazole*

49) A 33-year-old woman is diagnosed with HIV and started on antiretroviral medications, including enfuvirtide. Which of the following best describes the most likely mechanism of action of enfuvirtide? A. Blocking incorporation of the viral genome into the host cell genome B. Blocking translation of the viral messenger RNAS C. Interfering with posttranslational processing of viral proteins D. Preventing entry of viral particles into the target host cell E. Preventing synthesis of DNA from viral RNA

*D. Preventing entry of viral particles into the target host cell*

45) A 14-year-old girl is hospitalized with pneumonia. Bronchoalveolar lavage reveals Pseudomonas along with several other organisms. When no clinical improvement is observed after administration of several antibiotics, imipenem is administered alongside another agent to increase its efficacy. Which of the following mechanisms of action best describes the drug added to imipenem in this patient? A. Disruption of the bacterial cell wall B. Inhibition of DNA gyrase C. Inhibition of bacterial ß-lactamase D. Inhibition of bacterial folic acid synthesis E. Inhibition of renal drug metabolism

*E. Inhibition of renal drug metabolism*

46) A 69-year-old man comes to the physician because of ringing in his ears for the past week. He has a history of angina pectoris and underwent coronary artery stenting 1 month ago, after which he started taking medications to prevent myocardial infarction. He has early Alzheimer dementia and sometimes has difficulty taking his medications as prescribed, relying on his wife to help him. Physical examination is normal. Which of the following is the mechanism of action of the drug most likely causing this adverse effect? A. Blocks ßl- and h-adrenergic receptors B. Blocks activation of coagulation factors II, VII, IX, and X C. Inhibits 3-hydroxy-3-methylglutaryl coenzyme A reductase D. Inhibits conversion of fibrinogen to fibrin E. Inhibits cyclooxygenase F. Inhibits platelet aggregation via the ADP pathway G. Promotes the conversion of plasminogen to plasmin

*E. Inhibits cyclooxygenase*

32) A 34-year-old man with a history of ulcerative colitis is hospitalized after developing intense abdominal pain and passing loose bright red stools. The physician recommends initiating therapy with a drug to reduce inflammation and achieve remission of the patient's acute flare-ups. Treatment calls for a high dose followed by a slow taper. Which of the following adverse effects is most likely to arise from long-term use of this medication? A. Adrenal hyperplasia B. Agranulocytosis C. Hepatotoxicity D. Immune reconstitution inflammatory syndrome E. Osteoporosis

*E. Osteoporosis*

40) A 43-year-old man with a history of chronic renal insufficiency comes to the emergency department with a 5-day history of productive cough and shortness of breath. Physical examination reveals crackles in the left lower lobe. The patient begins taking oral levofloxacin. How does the dosing of levofloxacin for this patient differ from a patient with no underlying medical history? A. Higher loading dose, higher maintenance dose B. Higher loading dose, same maintenance dose C. Lower loading dose, lower maintenance dose D. Lower loading dose, same maintenance dose E. Same loading dose, higher maintenance dose F. Same loading dose, lower maintenance dose G. Same loading dose, same maintenance dose

*E. Same loading dose, higher maintenance dose*

F. 53) A 20-year-old man comes to the clinic because of worsening abdominal discomfort for the past 2 days. He does not report nausea or vomiting, has not traveled recently, and has no sick contacts. The patient reports recent intravenous heroin use. Abdominal examination is significant for diffuse, mild tenderness. There is no rebound or guarding. Needle tracks are noted on both arms. An image of the abdomen is shown. This patient's abdominal discomfort is best explained by which of the following mechanisms? A. Inhibition of K-receptors B. Inhibition of g-receptors C. Partial agonist action on g-receptors D. Stimulation of K-receptors E. Stimulation of g-receptors

*E. Stimulation of g-receptors*

60) A newborn is evaluated in the labor and delivery suite for excessive jaundice. His mother reports she took a medication for dysuria during her third trimester that she had used in prior episodes of urinary tract infections (UTIs) before she was pregnant. She was unaware that it might harm her baby. The baby's serum studies show a total bilirubin concentration of 1 0 mg/dL. Which of the following medications did the patient's mother most likely take? A. Amoxicillin B. Cephalexin C. Ciprofloxacin D. Gentamicin E. Trimethoprim-sulfamethoxazole

*E. Trimethoprim-sulfamethoxazole*

43) A 42-year-old woman is diagnosed with invasive ductal carcinoma of the breast. Imaging shows multiple masses in the liver. Chemotherapy is started, and the liver masses initially decrease in size but then grow rapidly. Molecular analysis of one of the tumors shows a mutation that prevents the assembly of ß-tubulin. Which of the following drugs in the chemotherapy regimen would be most affected? A. Busulfan B. Cisplatin C. Cyclophosphamide D. Doxorubicin E. Etoposide F. Paclitaxel

*F. Paclitaxel*

36) A 20-year-old man is brought to the emergency department by his friends after becoming agitated and aggressive at a party. He is belligerent and uncooperative upon arrival.Temperature is 99.50F (37.50C), pulse is 120/min, respirations are 16/min, and blood pressure is 156/90 mm Hg. Examination shows horizontal nystagmus and intense sensitivity to noises. His conjunctivae and pupil size are constricted. Elevated blood levels of which of the following substances are most likely responsible for this patient's clinical presentation? A. Alcohol B. Amphetamines C. Cocaine D. Lysergic acid diethylamide E. Morphine F. Phencyclidine G. Phenobarbital

*F. Phencyclidine*

54) A 43-year-old woman comes to the emergency department with severe headache, vomiting, blurry vision, and shortness of breath. She says she was at a cocktail party when the symptoms began. She has a history of type 2 diabetes mellitus. Respiratory rate is 22/min, blood pressure is 86/58 mm Hg, and heart rate is 115/min. Physical examination is significant for facial flushing. Which of the following medications is most likely responsible for this patient's reaction? A. Acarbose B. Glipizide C. Metformin D. Pioglitazone E. Sitagliptin F. Tolbutamide

*F. Tolbutamide*