Drug interactions and adverse effects Practice Questions

Question 1

A student is reviewing the various effects that can be plotted on a dose-response curve. He has observed that certain drugs can work as an agonist and an antagonist at a particular site. He has plotted a particular graph (as shown below) and is checking for other responses that can be measured on the same graph. He learned that drug B is less potent than drug A. Drug B also reduces the potency of drug A when combined in the same solution; however, if additional drug A is added to the solution, the maximal efficacy (Emax) of drug A increases. He wishes to plot another curve for drug C. He learns that drug C works on the same molecules as drugs A and B, but drug C reduces the maximal efficacy (Emax) of drug A significantly when combined with drug A. Which of the following best describes drug C?

Accepted Answer

Non-competitive antagonist

Answer

Reversible antagonist

Answer

Competitive antagonist

Answer

Full agonist

Answer

Inverse agonist

Question 2

A 61-year-old man with a history of type 1 diabetes mellitus and depression is brought to the emergency department because of increasing confusion and fever over the past 14 hours. Four days ago, he was prescribed metoclopramide by his physician for the treatment of diabetic gastroparesis. His other medications include insulin and paroxetine. His temperature is 39.9°C (103.8°F), pulse is 118/min, and blood pressure is 165/95 mm Hg. Physical examination shows profuse diaphoresis and flushed skin. There is generalized muscle rigidity and decreased deep tendon reflexes. His serum creatine kinase is 1250 U/L. Which of the following drugs is most likely to also cause this patient's current condition?

Accepted Answer

Fluphenazine

Answer

Tranylcypromine

Answer

Desflurane

Answer

Methamphetamine

Answer

Nortriptyline

Question 3

A 76-year-old man comes to the physician for a follow-up examination. One week ago, he was prescribed azithromycin for acute bacterial sinusitis. He has a history of atrial fibrillation treated with warfarin and metoprolol. Physical examination shows no abnormalities. Compared to one month ago, laboratory studies show a mild increase in INR. Which of the following best explains this patient's laboratory finding?

Accepted Answer

Inhibition of cytochrome p450

Answer

Drug-induced hepatotoxicity

Answer

Depletion of intestinal flora

Answer

Increased gastrointestinal absorption of warfarin

Answer

Increased non-protein bound warfarin fraction

Question 4

After being warned by the locals not to consume the freshwater, a group of American backpackers set off on a week-long hike into a region of the Ecuadorean Amazon forest known for large gold mines. The group of hikers stopped near a small stream and used the water they filtered from the stream to make dinner. Within the next half hour, the hikers began to experience headaches, vertigo, visual disturbances, confusion, tachycardia, and altered levels of consciousness. Which of the following enzymes was most likely inhibited in this group of hikers?

Accepted Answer

Cytochrome c oxidase

Answer

NADH dehydrogenase

Answer

ATP synthase

Answer

Cytochrome bc1 complex

Answer

Succinate dehydrogenase

Question 5

A medical student is reviewing dose-response curves of various experimental drugs. She is specifically interested in the different factors that cause the curve to shift in different directions. From her study, she plots the following graph (see image). She marks the blue curve for drug A, which acts optimally on a receptor. After drawing the second (green) curve for drug B, she discovers that more of drug B is required to produce the same response as drug A, although drug B can still achieve the same maximum effect. Which of the following terms best describes the activity of drug B in comparison to drug A?

Accepted Answer

Lower potency

Answer

Decreased efficacy

Answer

Increased affinity

Answer

Higher potency

Answer

Higher efficacy

Question 6

You are currently employed as a clinical researcher working on clinical trials of a new drug to be used for the treatment of Parkinson's disease. Currently, you have already determined the safe clinical dose of the drug in a healthy patient. You are in the phase of drug development where the drug is studied in patients with the target disease to determine its efficacy. Which of the following phases is this new drug currently in?

Accepted Answer

Phase 2

Answer

Phase 4

Answer

Phase 1

Answer

Phase 0

Answer

Phase 3

Question 7

A researcher is currently working on developing new cholinergic receptor agonist drugs. He has formulated 2 new drugs: drug A, which is a selective muscarinic receptor agonist and has equal affinity for M1, M2, M3, M4, and M5 muscarinic receptors, and drug B, which is a selective nicotinic receptor agonist and has equal affinity for NN and NM receptors. The chemical structure and mechanisms of action of both drugs mimic acetylcholine. However, drug A does not have any nicotinic receptor activity and drug B does not have any muscarinic receptor activity. Which of the following statements is most likely correct regarding these new drugs?

Accepted Answer

Drug B acts by stimulating a receptor which is composed of 5 subunits

Answer

Drug B may produce some of its effects by activating the IP3-DAG (inositol triphosphate-diacylglycerol) cascade

Answer

Drug A acts by causing conformational changes in ligand-gated ion channels

Answer

Drug A acts on receptors located at the neuromuscular junctions of skeletal muscle

Answer

Drug A acts by stimulating a receptor which is composed of 6 segments

Question 8

A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?

Accepted Answer

"Can you tell me more about the symptoms you have been experiencing?"

Answer

"Does the diarrhea typically precede the constipation, or vice-versa?"

Answer

"Is the diarrhea foul-smelling?"

Answer

"Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"

Answer

"Are the symptoms worse in the morning or at night?"

Question 9

A 78-year-old man receives chemotherapy for advanced hepatocellular carcinoma. Despite appropriate therapy, he dies 4 months later. Histopathological examination of the cancer cells shows the presence of a transmembrane efflux pump protein that is known to cause decreased intracellular concentrations of chemotherapeutic drugs. Which of the following best describes this membrane protein?

Accepted Answer

P-glycoprotein

Answer

G protein

Answer

Cadherin

Answer

Tyrosine receptor

Answer

Channel protein

Question 10

A 63-year-old man with high blood pressure, dyslipidemia, and diabetes presents to the clinic for routine follow-up. He has no current complaints and has been compliant with his chronic medications. His blood pressure is 132/87 mm Hg and his pulse is 75/min and regular. On physical examination, you notice that he has xanthelasmas on both of his eyelids. He currently uses a statin to lower his LDL but has not reached the LDL goal you have set for him. You would like to add an additional medication for LDL control. Of the following, which statement regarding fibrates is true?

Accepted Answer

Fibrates can potentiate the risk of myositis when given with statins

Answer

Fibrates inhibit the rate-limiting step in cholesterol synthesis

Answer

Fibrates can cause significant skin flushing and pruritus

Answer

Fibrates can increase the risk of cataracts

Answer

The primary effect of fibrates is to lower LDL

Drug interactions and adverse effects

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Questions

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Pharmacokinetic interaction mechanisms

Pharmacodynamic interaction mechanisms

CYP450 inhibition and induction

P-glycoprotein interactions

QT prolongation and torsades de pointes

Serotonin syndrome

Neuroleptic malignant syndrome

DRESS syndrome and severe cutaneous reactions

Drug-induced liver injury

Drug-induced kidney injury

Drug-food interactions

Polypharmacy management

Pharmacovigilance principles

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