USMLE Step 1 Pharmacology Review Flashcards
Learning the basics
You are currently employed as a clinical researcher working on clinical trials of a new drug to be used to treat Parkinson disease. You have already determined the safe clinical dose of the drug in a healthy patient and you have now begun to study the drug in a relatively small group of patients who have the target disease to determine the drug’s efficacy. Which clinical trial phase are you currently conducting?
Phase 2
While studying the metabolism of a novel drug X, the researcher identifies a molecule “A” that inhibits the metabolism of X by binding with enzyme E, which is involved in the metabolism of X. Molecule A inhibits enzyme E by reversibly binding at the same active site on the enzyme where drug X binds. What would be the effects of molecule A on Vmax and Km on the metabolic reactions of the novel drug?
Value of Vmax is unchanged but value of Km is increased
An experimental drug (SD27C) is being studied. This novel drug delivers insulin via the intranasal route. Diabetic participants who are taking insulin as their current treatment regimen are asked to participate in a clinical trial. Five hundred patients have given their informed consent and are divided into 2 groups, and a double-blind clinical trial is conducted. One group receives the new formulation (SD27C), while the second group receives regular insulin via subcutaneous injection. The results show that the treatment outcomes in both groups are the same. SD27C is currently under investigation in which phase of the clinical trial?
Phase III
A patient who weighs 70 kg (154 lb) requires intravenous antibiotics for the treatment of pneumonia. The desired target plasma concentration of the antibiotic is 4.5 mg/L. The patient is estimated to have a volume of distribution of 30 L and a clearance rate of 60 mL/min. How many milligrams of the drug should be administered for the initial dose to reach the desired target plasma concentration?
135mg
A pharmacology student is a member of a team that is conducting research related to the elimination of multiple anticoagulant medications. His duty as a member of the team is to collect serum samples of the subjects every 4 hours and send them for analysis of serum drug levels. He is also supposed to collect, document, and analyze the data. For 1 of the subjects, he notices that the subject is eliminating 0.5 mg of the drug every 4 hours. Which of the following anticoagulants did this patient most likely consume?
Warfarin
A 45-year-old man presents with a chief complaint of pain in the great toe. He has a history of gout, which is under control. He was diagnosed with diabetes 5 years ago and is currently taking metformin. He was recently diagnosed with hypertension and was placed on a hypertensive drug. He is a non-smoker and does not abuse alcohol. The family history is significant for ischemic heart disease in his father. His current blood pressure is 136/84 mm Hg and the pulse is 78/min. The physical examination did not reveal any abnormalities. He uses over-the-counter multivitamin supplements. Which class of drugs could have resulted in these symptoms?
Thiazide diuretics
A 58-year-old man presents to the physician due to difficulty initiating and sustaining erections which has lasted for a year. According to the patient, he has a loving wife and he is still attracted to her sexually. While he still gets an occasional erection, he has not been able to maintain an erection throughout intercourse. He no longer gets morning erections. He is happy at work and generally feels well. His past medical history is significant for angina and he takes isosorbide dinitrate as needed for exacerbations. His pulse is 80/min, respirations are 14/min, and blood pressure is 130/90 mm Hg. The physical examination is unremarkable. Nocturnal penile tumescence testing reveals the absence of erections during the night. The patient expresses a desire to resume sexual intimacy with his spouse. What is the next best step for treating this patient?
Check testosteron levels
A 56-year-old man presents to the office complaining of a dry cough for the past 2 months. His medical history includes a recent myocardial infarction (MI), after which he was placed on several medications. He is currently on ramipril, clopidogrel, digoxin, lovastatin, and nitroglycerin. He does not smoke cigarettes and does not drink alcohol. He denies a history of bronchial asthma. The examination of the chest is within normal limits. Which medication may have caused his symptoms?
Ramipril
A 45-year-old man was shown to have a blood pressure of 142/90 mm Hg at a health fair. Despite modifying his lifestyle, his blood pressure remained elevated on 2 separate subsequent occasions. He was prescribed an anti-hypertensive medication. After 3 weeks, he complained of swelling of his lips. What medication was the most likely cause of this finding?
Lisinopril
A 60-year-old man presents to the office for a scheduled follow-up visit. He has had hypertension for the past 30 years and his current antihypertensive medications include lisinopril (40 mg/day) and hydrochlorothiazide (50 mg/day). He follows most of the lifestyle modifications recommended by his physician but is concerned about the occasional occipital headaches that he has in the mornings. His blood pressure is 160/98 mm Hg. The physician adds another drug to his regimen which acts centrally as an α2-adrenergic agonist. Which other messenger is involved in the mechanism of action of this new drug?
Cyclic adenosine monophosphate
A 73-year-old man seeks evaluation for difficulty developing and maintaining erections. He has a medical history of hypertension and diabetes. There is no evidence of neurologic, vascular or phsychogenic causes for erectile dysfunction. He has recently made lifestyle modifications, such as losing 4.5 kg (10 lb), but his erectile symptoms have not improved. He was prescribed a drug that is first-line therapy treatment by his physician. Inhibition of which enzyme best describes this drug’s mechanism of action?
cGMP phosphodiesterase
A 44-year-old man presents to his physician’s office because he has been experiencing a problem with his sexual health for the past month. He says he does not get erections like he used to, despite feeling the urge. In addition to heart failure, he has angina and hypertension. His regular oral medications include amlodipine, atorvastatin, nitroglycerin, spironolactone, and losartan. After a detailed evaluation of his current medications, it is concluded that he has drug-induced erectile dysfunction. Which medication may have caused this patient’s symptoms?
Spironolactone
A 38-year-old woman presents to a physician’s office for progressive weakness and pallor over the last few weeks. She also complains of shortness of breath during her yoga class. She denies fever, cough, rhinorrhea, or changes in appetite or bowel and bladder habits. She is generally healthy except for an occasional migraine, which is relieved by acetaminophen. Last month, she began having more frequent migraine attacks and was started on prophylactic aspirin. Her vital signs include: pulse 102/min, respirations 18/min, and blood pressure 130/84 mm Hg. Her blood pressures on previous visits were 110/76 mm Hg, 120/78 mm Hg, and 114/80 mm Hg. The physical examination is otherwise unremarkable. Stool for occult blood is positive. In addition to a low hemoglobin concentration, which other abnormal laboratory finding is expected in this patient?
Prolonged bleeding time
A 65-year-old man presents with hypercholesterolemia. Family history is significant for multiple cardiac deaths and other cardiovascular diseases. The patient reports a 40-pack-year smoking history. The body mass index (BMI) is 28 kg/m^2. The total cholesterol is 255 mg/dL, and the low-density lipoprotein (LDL) is more than 175 mg/dL. Lifestyle and dietary modifications are recommended, and the patient is prescribed a hypolipidemic drug. He returns for follow-up 4 weeks later complaining of muscle pains. Laboratory findings are significant for a significant increase in serum transaminases. Which drug is most likely responsible for this patient’s symptoms on follow-up?
Atorvastatin
A 49-year-old man presents to a physician with a complaint of pain in the thigh after walking. He says that he is an office clerk with a sedentary lifestyle and usually drives to his office. On 2 occasions last month he had to walk to his office, which is less than a quarter of a mile from his home. On both occasions, soon after walking, he experienced pain in the right thigh which subsided spontaneously within a few minutes. His past medical history is negative for hypertension, hypercholesterolemia, or ischemic heart disease. He is a non-smoker and non-alcoholic. His father has ischemic heart disease. His physical examination is within normal limits, and the peripheral pulses are palpable in all extremities. A detailed diagnostic evaluation, including magnetic resonance angiography and exercise treadmill ankle-brachial index testing, suggests a diagnosis of peripheral vascular disease due to atherosclerosis of the right iliac artery. What is the best initial treatment option?
Exercise therapy
A 65-year-old man presents to the physician with pain in his right calf over the last 3 months. He mentions that the pain typically occurs after he walks for about 100 meters and subsides after he rests for 5 minutes. His medical history is significant for hypercholesterolemia, ischemic heart disease, and bilateral knee osteoarthritis. His current daily medications include aspirin and simvastatin, which he has taken for the last 2 years. Physical examination reveals diminished popliteal artery pulses on the right side. Which drug is most likely to improve this patient’s symptoms?
Cilostazol
A 50-year-old man with a history of paroxysmal atrial fibrillation presents to his cardiologist’s office for a follow-up visit. He recently started treatment with an antiarrhythmic drug to prevent future recurrences and he reports that he has been feeling well. A physical examination shows that the arrhythmia appears to have resolved; however, there is now mild bradycardia. In addition, an electrocardiogram shows a slight prolongation of the PR and QT intervals. Which drug was most likely used to treat this patient?
Sotalol
A 65-year-old man with a history of coronary artery disease presents to your office complaining of chest pain on exertion. The patient underwent a recent cardiac workup that showed no areas of acute ischemia. At the last visit, the patient was prescribed sublingual nitroglycerin for symptomatic relief of stable angina. On further questioning, the patient states that he has been swallowing the tablet whole instead of allowing it to dissolve because he “does not like the taste.” What is the cause of the patient’s persistent symptoms?
First pass metabolism of nitroglycerin
A 61-year-old man with longstanding diabetes and coronary artery disease presents to the ER with chest pain and dyspnea. Echocardiography reveals moderate-to-severe mitral regurgitation and an ejection fraction of 27%. A chest X-ray shows bibasilar infiltrates. A new drug is added to his medication regimen, and he is told by his physician that possible side effects include urinary frequency, increased breast tissue development, and erectile dysfunction. What is the mechanism of action of this drug?
Inhibits mineralcorticoid receptor in the cortical collecting duct
An 18-year-old boy is brought to the emergency department by his parents because he suddenly collapsed while playing football. His parents mention that he had complained of dizziness while playing in times past, but he has never fainted in the middle of a game. On physical examination, his blood pressure is 130/90 mm Hg, respirations are 15/min, and pulse is 110/min. The chest is clear, but a systolic ejection murmur is present. The remainder of the examination reveals no significant findings. An ECG is ordered, along with an echocardiogram. The patient is diagnosed with hypertrophic cardiomyopathy, and the physician lists all the precautions the patient must follow. Which class of drugs will be on the list of contraindicated substances?
Nitrates
Following gastric surgery, a 45-year-old woman complains of severe nausea and vomiting on the second postoperative day. On physical examination, her vitals are stable, and examination of the abdomen reveals no significant abnormality. The patient is already receiving the maximum dosage of ondansetron. She is given metoclopramide and experiences significant relief from the nausea and vomiting. What is the mechanism of action of metoclopramide?
Inhibition of dopamine receptors in the area postrema
The parents of a newly adopted 5-year-old child bring him to the pediatrician after he started to have intermittent bouts of diarrhea, flatulence, and feeling of abdominal bloating. The parents report that his symptoms seem to be worse after consuming dairy products. The patient has been otherwise healthy and has no further pertinent medical history. His immunization history is up to date. His height and weight are in the 60th and 70th percentiles, respectively. A physical examination is normal. What is the first-line therapy for the condition most likely affecting this patient?
Diet modification
A 28-year-old woman presents with severe diarrhea and abdominal pain. She says she has had 10 watery stools since the previous morning and is experiencing severe cramping in her abdomen. She reports similar past episodes of diarrhea with excruciating abdominal pain and mentions that she has taken diphenoxylate and atropine before, which had helped her diarrhea and pain but resulted in severe constipation for a week. Which receptors does diphenoxylate activate to cause the effects mentioned by this patient?
µ receptors
A 23-year-old woman presents to her primary care physician with complaints of flatulence and abdominal cramping after meals. For the last year, she has been feeling unwell after meals and sometimes has severe pain particularly after eating breakfast in the morning. She also experiences flatulence regularly and diarrhea on rare occasions. She reports eating either cereal or oats in the morning, which she usually consumes with a glass of milk. The patient is afebrile and vital signs are within normal limits. Physical examination is unremarkable. Which drug should be avoided in this patient?
Magnesium hydroxide
