RxMnemonic High-Yield Pharmacology Practice Quiz

Question 1

A 58-year-old woman with hypertension and type 2 diabetes is started on lisinopril. Three weeks later she develops a persistent dry cough. Which mechanism is most directly responsible for this adverse

Accepted Answer

ACE inhibitors block the conversion of angiotensin I to II, but ACE also degrades bradykinin. Bradykinin accumulation in the lungs triggers prostaglandin-mediated cough. ARBs block the AT1 receptor instead and do not affect bradykinin, so they are used when ACE inhibitor cough develops.

Question 2

A 34-year-old pregnant woman at 18 weeks gestation is found to have worsening hypertension. Her prior antihypertensive was lisinopril. Which is the most important reason to switch medications?

Accepted Answer

ACE inhibitors are absolutely contraindicated in pregnancy (category D/X) because angiotensin II is critical for fetal kidney development. Exposure in the 2nd and 3rd trimesters causes fetal renal dysgenesis, oligohydramnios, limb contractures, and skull hypoplasia, collectively called ACE inhibitor fetopathy. Labetalol, nifedipine, or methyldopa are preferred.

Question 3

A 72-year-old man with metastatic prostate cancer is treated with long-term oral morphine. He develops tolerance to euphoria, sedation, and respiratory depression. Which opioid side effect does NOT de

Accepted Answer

Constipation is the one opioid side effect to which patients do NOT develop tolerance. This is because opioids act on mu receptors in the myenteric plexus of the gut, decreasing peristalsis, and this peripheral effect persists indefinitely. Tolerance develops to most CNS effects (euphoria, sedation, analgesia, respiratory depression, nausea). Miosis via Edinger-Westphal nucleus also shows minimal tolerance.

Question 4

A patient is brought to the ED unresponsive with a respiratory rate of 6/min, BP 90/60 mmHg, and pinpoint pupils. Empty fentanyl patches are found on his skin. Which is the most appropriate initial tr

Accepted Answer

This is classic opioid toxidrome: miosis, respiratory depression, unconsciousness. Naloxone (a competitive mu-opioid receptor antagonist) reverses it. Critically, fentanyl patches are long-acting; naloxone's half-life (30–90 min) is shorter than fentanyl's, so repeat doses or a continuous infusion are often needed. Flumazenil reverses benzodiazepines, not opioids.

Question 5

A 45-year-old chronic alcohol user is admitted after his last drink 48 hours ago. He develops tremors, diaphoresis, tachycardia, and a seizure. What is the mechanism of the first-line treatment for hi

Accepted Answer

Alcohol withdrawal results from rebound CNS excitation after chronic GABA potentiation and NMDA inhibition by alcohol. Benzodiazepines (first-line: lorazepam, diazepam, or chlordiazepoxide) are GABA-A positive allosteric modulators that increase chloride influx frequency and amplitude, reducing neuronal excitability and preventing seizures and delirium tremens.

Question 6

A 19-year-old presents with acute onset hyperthermia, agitation, diaphoresis, hypertension, and mydriasis after taking a pill at a party. Urine drug screen is positive for amphetamines. What is the pr

Accepted Answer

Amphetamines work primarily by reversing the direction of monoamine transporters (DAT, NET, SERT), acting as substrates that are transported inward while pushing dopamine, norepinephrine, and serotonin outward into the synapse. The resulting massive NE release causes the hypertension, tachycardia, and vasoconstriction. This mechanism is distinct from cocaine, which blocks reuptake without reversal.

Question 7

A 28-year-old woman with severe rheumatoid arthritis is started on methotrexate. She is counseled to also take folic acid supplementation. What is the primary mechanism by which methotrexate exerts it

Accepted Answer

Methotrexate inhibits dihydrofolate reductase (DHFR), preventing THF regeneration needed for purine and pyrimidine synthesis. At low doses used in RA, a major mechanism involves adenosine accumulation, which has potent anti-inflammatory effects. Folic acid supplementation reduces GI and hepatic toxicity without significantly reducing efficacy.

Question 8

A 67-year-old man takes nitroglycerin for stable angina. Which hemodynamic effect is primarily responsible for its anti-anginal benefit?

Accepted Answer

Nitroglycerin is converted to nitric oxide, which activates guanylate cyclase → cGMP → smooth muscle relaxation. At low doses (sublingual), the dominant effect is venodilation, reducing preload (venous return). Reduced preload decreases left ventricular end-diastolic pressure and wall stress, reducing myocardial oxygen demand. Coronary dilation also occurs but the preload reduction is the primary anti-anginal mechanism.

Question 9

A 24-year-old schizophrenia patient on haloperidol develops involuntary slow writhing movements of the face, tongue, and hands that persist even after the medication is tapered. What is the most likel

Accepted Answer

Tardive dyskinesia (TD) is a late-onset (months to years) movement disorder caused by prolonged D2 receptor blockade in the nigrostriatal pathway. Chronic blockade leads to receptor upregulation and supersensitivity; when dopaminergic tone fluctuates, hypersensitive receptors trigger uncontrolled choreiform or athetoid movements. TD is often irreversible. Treatment: valbenazine or deutetrabenazine (VMAT2 inhibitors).

Question 10

A patient taking hydrochlorothiazide for hypertension develops hypercalcemia. A nephrologist explains this is a known metabolic effect. What is the mechanism?

Accepted Answer

Thiazides block the NCC (Na-Cl cotransporter) in the distal convoluted tubule. The resulting intracellular sodium depletion stimulates the basolateral Na/Ca exchanger, which increases calcium reabsorption. This hypercalcemic effect is clinically useful; thiazides are first-line for calcium oxalate kidney stones. Contrast with loop diuretics, which cause hypocalciuria by different mechanisms.

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