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BCPS MCPS Part-1 study materials
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BCPS MCPS Part-1 practice questions

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Question 1Basic Sciences

Which organelle is the primary site of oxidative phosphorylation and ATP synthesis in eukaryotic cells?

  1. Lysosome
  2. Golgi apparatus
  3. Mitochondrion Correct answer.
  4. Smooth endoplasmic reticulum

Explanation

The inner mitochondrial membrane houses the electron transport chain and ATP synthase, which together carry out oxidative phosphorylation. Other organelles handle protein modification, degradation, or lipid synthesis rather than bulk ATP production.

Question 2Basic Sciences

A drug that competitively inhibits an enzyme will most likely have which effect on the enzyme's kinetic parameters?

  1. Increased Vmax with unchanged Km
  2. Decreased Vmax with unchanged Km
  3. Decreased Km and decreased Vmax
  4. Increased apparent Km with unchanged Vmax Correct answer.

Explanation

Competitive inhibitors bind the active site reversibly, so higher substrate concentrations can overcome inhibition, leaving Vmax unchanged while raising the apparent Km. Noncompetitive inhibitors instead reduce Vmax without altering Km.

Question 3Basic Sciences

Which molecule serves as the immediate precursor for synthesis of prostaglandins and thromboxanes?

  1. Arachidonic acid Correct answer.
  2. Sphingomyelin
  3. Palmitic acid
  4. Cholesterol

Explanation

Arachidonic acid is liberated from membrane phospholipids by phospholipase A2 and then converted by cyclooxygenase into prostaglandins, thromboxanes, and prostacyclin. Cholesterol and sphingomyelin are structural lipids, and palmitic acid is a saturated fatty acid not used for eicosanoid production.

Question 4Basic Sciences

During glycolysis, which reaction produces ATP through substrate-level phosphorylation?

  1. Conversion of fructose-6-phosphate to fructose-1,6-bisphosphate
  2. Conversion of pyruvate to acetyl-CoA
  3. Conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate Correct answer.
  4. Conversion of glucose to glucose-6-phosphate

Explanation

Substrate-level phosphorylation transfers a phosphate from a high-energy intermediate directly to ADP. The phosphoglycerate kinase step converts 1,3-bisphosphoglycerate to 3-phosphoglycerate while generating ATP. The other listed steps either consume ATP or occur outside glycolysis.

Question 5Basic Sciences

Which vitamin deficiency classically causes night blindness and xerophthalmia?

  1. Vitamin K
  2. Vitamin C
  3. Vitamin D
  4. Vitamin A Correct answer.

Explanation

Retinal, a vitamin A derivative, is essential for rhodopsin formation in rod photoreceptors, and deficiency impairs dim-light vision and corneal health. Vitamin C, D, and K deficiencies produce scurvy, rickets, and bleeding disorders respectively.

Question 6Basic Sciences

A patient's arterial blood gas shows pH 7.28, PaCO2 30 mmHg, and HCO3- 14 mEq/L. Which acid-base disorder is present?

  1. Metabolic acidosis with respiratory compensation Correct answer.
  2. Metabolic alkalosis with respiratory compensation
  3. Respiratory acidosis with metabolic compensation
  4. Respiratory alkalosis with metabolic compensation

Explanation

The low pH indicates acidosis, and the low bicarbonate points to a metabolic cause. The reduced PaCO2 reflects hyperventilation as respiratory compensation. A primary respiratory acidosis would instead show an elevated PaCO2.

Question 7Basic Sciences

Which immunoglobulin class is the first to be produced in a primary humoral immune response?

  1. IgM Correct answer.
  2. IgE
  3. IgA
  4. IgG

Explanation

Naive B cells initially secrete IgM, a pentameric antibody effective at complement activation. Class switching later produces IgG, IgA, or IgE, and IgG dominates secondary responses.

Question 8Basic Sciences

Which phase of mitosis is characterized by alignment of chromosomes along the metaphase plate?

  1. Anaphase
  2. Telophase
  3. Metaphase Correct answer.
  4. Prophase

Explanation

During metaphase, spindle fibers attach to kinetochores and align duplicated chromosomes at the cell equator. Prophase involves condensation, anaphase involves chromatid separation, and telophase involves nuclear reformation.

Question 9Basic Sciences

Which enzyme is the rate-limiting step in cholesterol biosynthesis?

  1. Carnitine palmitoyltransferase I
  2. Acetyl-CoA carboxylase
  3. Lipoprotein lipase
  4. HMG-CoA reductase Correct answer.

Explanation

HMG-CoA reductase converts HMG-CoA to mevalonate and is the committed, rate-limiting step of cholesterol synthesis, making it the target of statins. The other enzymes participate in fatty acid synthesis, lipoprotein processing, or fatty acid transport.

Question 10Basic Sciences

Which of the following best describes the mechanism of action of a nonsteroidal anti-inflammatory drug such as ibuprofen?

  1. Blockade of leukotriene receptors
  2. Irreversible inhibition of cyclooxygenase enzymes
  3. Activation of phospholipase A2
  4. Reversible inhibition of cyclooxygenase enzymes Correct answer.

Explanation

Ibuprofen reversibly competes with arachidonic acid at the cyclooxygenase active site, reducing prostaglandin synthesis. Aspirin is the classic irreversible cyclooxygenase inhibitor, and leukotriene receptor blockade is a different drug class.

Question 11Basic Sciences

Which of the following is the primary determinant of drug distribution into the central nervous system?

  1. Ability to cross the blood-brain barrier Correct answer.
  2. Degree of plasma protein binding only
  3. Renal tubular secretion rate
  4. Hepatic first-pass metabolism

Explanation

The blood-brain barrier restricts entry of polar and large molecules, so lipophilicity and transporter interactions determine CNS penetration. Plasma protein binding and metabolism influence systemic exposure but are not the primary gate for brain entry.

Question 12Basic Sciences

Which of the following describes the relationship between a drug's half-life and the time to reach steady state with continuous dosing?

  1. Steady state is reached after exactly one half-life
  2. Steady state is independent of half-life
  3. Steady state is reached after approximately four to five half-lives Correct answer.
  4. Steady state is reached after ten half-lives

Explanation

With repeated dosing, accumulation follows first-order kinetics, and approximately 94 percent of steady-state concentration is achieved after four to five half-lives. This relationship holds regardless of dose magnitude when kinetics are linear.

Question 13Basic Sciences

Which of the following receptor types is a ligand-gated ion channel?

  1. Nicotinic acetylcholine receptor Correct answer.
  2. Insulin receptor tyrosine kinase
  3. G protein-coupled adrenergic receptor
  4. Steroid hormone receptor

Explanation

The nicotinic acetylcholine receptor is a pentameric ion channel that opens directly upon acetylcholine binding, producing rapid depolarization. The other receptors signal through G proteins, intrinsic kinase activity, or nuclear transcription.

Question 14Basic Sciences

A 60-year-old man with chronic alcohol use presents with impaired gluconeogenesis and hypoglycemia. Which substrate is most directly depleted for hepatic glucose production?

  1. Lactate and alanine availability Correct answer.
  2. Circulating free fatty acids
  3. Intramuscular creatine phosphate
  4. Dietary sucrose intake

Explanation

Hepatic gluconeogenesis depends on precursors such as lactate, alanine, and glycerol. Chronic alcohol metabolism shifts the NADH/NAD+ ratio, impairing lactate conversion to pyruvate and limiting gluconeogenic flux, which can cause hypoglycemia.

Question 15Basic Sciences

Which of the following best explains why the sodium-potassium ATPase is electrogenic?

  1. It transports only sodium ions across the membrane
  2. It transports equal numbers of sodium and potassium ions
  3. It imports three sodium ions and exports two potassium ions per ATP
  4. It exports three sodium ions and imports two potassium ions per ATP Correct answer.

Explanation

Each cycle of the pump moves three Na+ out and two K+ in, producing a net extrusion of one positive charge. This contributes to the negative resting membrane potential. Equal or single-ion transport would not create this net charge separation.

Question 16Basic Sciences

Which of the following best describes the role of the sodium-potassium pump in maintaining resting membrane potential?

  1. It releases neurotransmitter at synapses
  2. It directly generates action potentials
  3. It regulates intracellular calcium storage
  4. It maintains ion gradients that underlie the resting potential Correct answer.

Explanation

The pump establishes high extracellular sodium and high intracellular potassium, and these gradients set the electrochemical driving forces that produce the resting potential. Action potentials arise from opening of voltage-gated channels rather than the pump itself.

Question 17Basic Sciences

Which of the following is the primary mechanism by which the kidney concentrates urine?

  1. Reabsorption of bicarbonate in the proximal tubule
  2. Active secretion of glucose into the collecting duct
  3. Filtration of plasma proteins at the glomerulus
  4. Establishment of a medullary osmotic gradient Correct answer.

Explanation

The loop of Henle generates a hypertonic medullary interstitium, allowing water reabsorption from collecting ducts under antidiuretic hormone control. Bicarbonate reabsorption and glucose handling affect acid-base and nutrient balance, not urine concentration.

Question 18Basic Sciences

Which of the following best describes the Frank-Starling relationship in cardiac muscle?

  1. Increased preload decreases end-diastolic volume
  2. Increased heart rate decreases contractility
  3. Increased preload increases stroke volume within physiologic limits Correct answer.
  4. Increased afterload increases stroke volume

Explanation

Greater ventricular filling stretches sarcomeres, increasing myofilament overlap and calcium sensitivity, which raises force generation and stroke volume. This relationship operates within a physiologic range before overstretch reduces efficiency.

Question 19Basic Sciences

Which of the following explains why the resting membrane potential of a neuron is close to but not identical to the potassium equilibrium potential?

  1. Chloride ions are actively pumped out of the cell
  2. Potassium channels are completely closed at rest
  3. Small resting sodium permeability depolarizes the membrane slightly Correct answer.
  4. The sodium-potassium pump is inactive at rest

Explanation

The membrane is highly permeable to potassium but has a small resting sodium conductance, so the potential sits slightly above the potassium equilibrium potential. The pump contributes a minor electrogenic effect but is not the main reason for the deviation.

Question 20Basic Sciences

Which of the following is the correct sequence of events in synaptic chemical transmission?

  1. Calcium influx, action potential, neurotransmitter binding, vesicle fusion
  2. Vesicle fusion, action potential, calcium influx, neurotransmitter binding
  3. Action potential, calcium influx, vesicle fusion, neurotransmitter binding to receptors Correct answer.
  4. Neurotransmitter binding, calcium influx, action potential, vesicle fusion

Explanation

Depolarization opens voltage-gated calcium channels at the terminal, calcium triggers vesicle fusion and exocytosis, and released transmitter binds postsynaptic receptors. This ordered sequence underlies fast chemical synaptic transmission.

Question 21Basic Sciences

Which of the following best explains why a drug with high hepatic first-pass metabolism has low oral bioavailability?

  1. Extensive metabolism occurs before the drug reaches systemic circulation Correct answer.
  2. The drug is rapidly excreted unchanged by the kidney
  3. The drug is not absorbed from the gastrointestinal tract
  4. The drug binds extensively to plasma proteins

Explanation

Orally absorbed drug travels through portal circulation to the liver, where metabolism can remove a large fraction before systemic delivery. This reduces the fraction reaching the systemic circulation even when absorption is complete.

Question 22Basic Sciences

Which of the following is the primary role of the sodium-glucose cotransporter in the proximal tubule?

  1. Secretion of glucose into urine
  2. Reabsorption of filtered amino acids
  3. Secretion of hydrogen ions
  4. Reabsorption of filtered glucose Correct answer.

Explanation

SGLT proteins in the proximal tubule couple sodium reabsorption with glucose reabsorption, reclaiming filtered glucose. Amino acid reabsorption and hydrogen secretion use separate transporters.

Question 23Basic Sciences

A 45-year-old woman has a mutation that abolishes the function of the enzyme phenylalanine hydroxylase. Which of the following is the most direct consequence?

  1. Accumulation of phenylalanine and deficiency of tyrosine Correct answer.
  2. Deficiency of branched-chain amino acid catabolism
  3. Accumulation of tyrosine and deficiency of phenylalanine
  4. Accumulation of homogentisic acid

Explanation

Phenylalanine hydroxylase converts phenylalanine to tyrosine, so loss of function causes phenylalanine accumulation and makes tyrosine conditionally essential. Homogentisic acid accumulation occurs in alkaptonuria, a defect further downstream in tyrosine degradation.

Question 24Basic Sciences

Which of the following best describes the mechanism by which a proton pump inhibitor reduces gastric acid secretion?

  1. Blockade of muscarinic receptors on parietal cells
  2. Neutralization of secreted acid in the gastric lumen
  3. Competitive antagonism at histamine H2 receptors
  4. Irreversible inhibition of the parietal cell hydrogen-potassium ATPase Correct answer.

Explanation

Proton pump inhibitors bind covalently to the hydrogen-potassium ATPase on the secretory canalicular membrane, shutting down the final step of acid secretion. H2 blockers and antimuscarinics act at upstream receptors, and antacids neutralize existing acid.

Question 25Basic Sciences

Which of the following best explains why myelination increases conduction velocity in axons?

  1. Myelin increases the intracellular sodium concentration
  2. Saltatory conduction reduces the need to regenerate action potentials along the entire membrane Correct answer.
  3. Myelin increases membrane capacitance and slows current flow
  4. Myelin opens more voltage-gated channels in the internodal membrane

Explanation

Myelin insulates internodal segments, lowering membrane capacitance and increasing resistance, so current spreads farther and triggers action potentials only at nodes of Ranvier. This saltatory conduction greatly speeds propagation.

Question 26Basic Sciences

During which phase of the cell cycle does DNA replication occur?

  1. G2 phase
  2. G1 phase
  3. S phase Correct answer.
  4. M phase

Explanation

DNA replication takes place during the S (synthesis) phase of interphase, ensuring that each daughter cell receives an identical copy of the genome. G1 and G2 are gap phases for growth and preparation, while M phase is when chromosomes segregate and the cell divides.

Question 27Basic Sciences

Which of the following best describes the mechanism by which a competitive inhibitor reduces the rate of an enzyme-catalyzed reaction?

  1. It binds to the enzyme-substrate complex and prevents product formation.
  2. It binds reversibly to the active site, competing with the substrate. Correct answer.
  3. It permanently modifies the active site through covalent bonding.
  4. It binds to an allosteric site and changes the shape of the active site.

Explanation

A competitive inhibitor structurally resembles the substrate and binds reversibly to the active site, preventing substrate binding. This inhibition can be overcome by increasing substrate concentration, and it increases the apparent Km without changing Vmax.

Question 28Basic Sciences

A 50-year-old man with type 2 diabetes mellitus has a fasting glucose of 180 mg/dL. Which of the following best explains the increased hepatic glucose output in this condition?

  1. Enhanced suppression of glucagon secretion
  2. Increased hepatic gluconeogenesis due to insulin resistance Correct answer.
  3. Increased insulin sensitivity in the liver
  4. Decreased availability of gluconeogenic substrates

Explanation

In type 2 diabetes, insulin resistance in the liver reduces the ability of insulin to suppress gluconeogenesis, leading to increased hepatic glucose production. This contributes to fasting hyperglycemia despite the presence of insulin.

Question 29Basic Sciences

Which of the following is the primary mechanism by which the kidney concentrates urine in the presence of antidiuretic hormone (ADH)?

  1. Active reabsorption of sodium chloride in the thin descending limb of the loop of Henle
  2. Increased filtration of water at the glomerulus
  3. Secretion of hydrogen ions into the tubular lumen
  4. Insertion of aquaporin-2 water channels into the apical membrane of collecting duct cells Correct answer.

Explanation

ADH binds to V2 receptors on collecting duct cells, stimulating cAMP and the insertion of aquaporin-2 channels into the apical membrane. This increases water permeability, allowing water to be reabsorbed down the medullary osmotic gradient and producing concentrated urine.

Question 30Basic Sciences

A 60-year-old woman with small cell lung cancer develops hyponatremia. Which of the following best explains the mechanism of her hyponatremia?

  1. Hyperglycemia-induced osmotic diuresis
  2. Primary polydipsia causing water intoxication
  3. Dilutional hyponatremia from syndrome of inappropriate ADH secretion Correct answer.
  4. Excessive renal sodium loss due to a tubular defect

Explanation

Small cell lung cancer can ectopically secrete ADH, leading to the syndrome of inappropriate antidiuretic hormone (SIADH). The excess ADH causes water retention and dilutional hyponatremia, with urine that is inappropriately concentrated relative to plasma osmolality.

Question 31Basic Sciences

Which of the following best explains why the resting membrane potential of a typical neuron is less negative than the equilibrium potential for potassium?

  1. The membrane is completely impermeable to sodium ions.
  2. Potassium ions are actively transported out of the cell against their gradient.
  3. The sodium-potassium pump transports equal numbers of sodium and potassium ions.
  4. There is a small resting permeability to sodium ions. Correct answer.

Explanation

At rest, the membrane is highly permeable to potassium but also has a small permeability to sodium. The inward leak of sodium slightly depolarizes the membrane, making the resting potential less negative than the potassium equilibrium potential.

Question 32Basic Sciences

A 45-year-old man has a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (HGPRT). Which of the following is the most likely consequence?

  1. Increased de novo purine synthesis and hyperuricemia Correct answer.
  2. Increased pyrimidine synthesis and orotic aciduria
  3. Decreased de novo purine synthesis and hypouricemia
  4. Impaired DNA repair and increased cancer risk

Explanation

HGPRT is a key enzyme in the purine salvage pathway. Its deficiency impairs salvage, leading to increased degradation of purines and increased de novo purine synthesis due to loss of feedback inhibition, resulting in hyperuricemia and conditions such as Lesch-Nyhan syndrome.

Question 33Basic Sciences

Which of the following best describes the role of the sarcoplasmic reticulum in skeletal muscle contraction?

  1. It generates ATP through oxidative phosphorylation.
  2. It provides the structural framework for the sarcomere.
  3. It synthesizes acetylcholine for release at the neuromuscular junction.
  4. It stores and releases calcium ions to trigger contraction. Correct answer.

Explanation

The sarcoplasmic reticulum is a specialized endoplasmic reticulum in muscle cells that stores calcium ions. Upon excitation, it releases calcium into the cytoplasm, which binds troponin and initiates the cross-bridge cycle leading to contraction.

Question 34Basic Sciences

Which of the following best explains why a drug that is highly protein-bound has a large volume of distribution?

  1. Protein binding increases the fraction of drug that is filtered by the kidney.
  2. Protein binding facilitates drug entry into the central nervous system.
  3. Protein binding traps the drug in the plasma, reducing its volume of distribution. Correct answer.
  4. Protein binding increases the apparent volume of distribution by enhancing tissue uptake.

Explanation

A drug that is highly bound to plasma proteins remains largely in the vascular compartment, which limits its distribution into tissues and results in a small volume of distribution. The unbound fraction is what distributes and exerts pharmacological effect.

Question 35Medicine

A 58-year-old man with chronic stable angina is prescribed sublingual nitroglycerin for acute attacks. Which instruction is most appropriate regarding its use?

  1. Take two tablets at once and lie flat to increase absorption
  2. Swallow the tablet whole with water for faster systemic effect
  3. Take one tablet at the onset of chest pain and repeat every 5 minutes up to three doses while sitting down Correct answer.
  4. Use the spray only after the pain has lasted 30 minutes

Explanation

Sublingual nitroglycerin is taken at the onset of anginal pain and may be repeated every five minutes for up to three doses; if pain persists, emergency care is needed. Patients should sit or lie down because vasodilation can cause hypotension and syncope. Sublingual absorption is rapid and bypasses first-pass metabolism, so swallowing the tablet defeats the purpose.

Question 36Medicine

Which laboratory parameter is most useful for monitoring adherence and glycemic control over the preceding two to three months in a patient with type 2 diabetes?

  1. Glycated hemoglobin (HbA1c) Correct answer.
  2. Serum fructosamine
  3. Fasting plasma glucose
  4. Random urine glucose

Explanation

HbA1c reflects average glucose exposure over the lifespan of red blood cells, roughly the prior two to three months, making it the standard measure of long-term control. Fasting glucose captures only a single moment. Fructosamine reflects a shorter period of about two to three weeks and is used when HbA1c is unreliable.

Question 37Medicine

A patient with an acute exacerbation of asthma presents with severe wheezing. Which medication is the first-line agent for rapid relief of bronchospasm?

  1. Inhaled short-acting beta-2 agonist Correct answer.
  2. Oral montelukast
  3. Inhaled corticosteroid
  4. Inhaled ipratropium

Explanation

Short-acting beta-2 agonists such as albuterol produce rapid bronchodilation by relaxing airway smooth muscle and are the cornerstone of acute symptom relief. Ipratropium is an adjunct, and corticosteroids address inflammation but do not bronchodilate immediately. Montelukast is a controller, not a rescue agent.

Question 38Medicine

Which mechanism best explains why low-dose aspirin is used for secondary prevention of cardiovascular events?

  1. Irreversible inhibition of platelet cyclooxygenase-1, reducing thromboxane A2 production Correct answer.
  2. Direct inhibition of thrombin activity
  3. Reversible blockade of platelet ADP receptors
  4. Activation of antithrombin III

Explanation

Aspirin acetylates cyclooxygenase-1 irreversibly in platelets, which cannot synthesize new enzyme, thereby suppressing thromboxane A2 and platelet aggregation for the platelet lifespan. This irreversible action underlies its once-daily low-dose antiplatelet effect. Other antiplatelet agents act at different targets such as ADP receptors or thrombin.

Question 39Medicine

A 70-year-old woman with hypertension and reduced renal function has a serum potassium of 5.9 mEq/L. Which antihypertensive class is most likely responsible and should be reconsidered?

  1. Loop diuretics
  2. Angiotensin-converting enzyme inhibitors Correct answer.
  3. Dihydropyridine calcium channel blockers
  4. Thiazide diuretics

Explanation

ACE inhibitors reduce aldosterone secretion, which decreases potassium excretion and can cause hyperkalemia, particularly with impaired renal function. Thiazide and loop diuretics generally promote potassium loss. Dihydropyridine calcium channel blockers do not raise potassium.

Question 40Medicine

Which adverse effect is classically associated with long-term systemic corticosteroid therapy?

  1. Hyperkalemia and hypertension
  2. Hypoglycemia and weight loss
  3. Bradycardia and heart block
  4. Osteoporosis and hyperglycemia Correct answer.

Explanation

Chronic glucocorticoid excess suppresses bone formation and increases resorption, causing osteoporosis, while promoting hepatic gluconeogenesis and insulin resistance that raise blood glucose. These effects are classic complications of prolonged systemic steroid use. Electrolyte and cardiac effects described in the other options are not typical of glucocorticoids.

Question 41Medicine

A patient is prescribed warfarin for atrial fibrillation. Which parameter is monitored to guide dosing?

  1. Activated partial thromboplastin time (aPTT)
  2. Bleeding time
  3. Platelet count
  4. Prothrombin time expressed as the international normalized ratio (INR) Correct answer.

Explanation

Warfarin inhibits vitamin K-dependent clotting factors, and its effect is monitored with the prothrombin time standardized as the INR. The aPTT is used to monitor unfractionated heparin, not warfarin. Platelet count and bleeding time do not reflect warfarin's anticoagulant intensity.

Question 42Medicine

Which therapy is most appropriate for a patient with an acute opioid overdose presenting with respiratory depression?

  1. Flumazenil
  2. Naloxone Correct answer.
  3. Atropine
  4. N-acetylcysteine

Explanation

Naloxone is a competitive opioid receptor antagonist that rapidly reverses opioid-induced respiratory depression and sedation. Flumazenil reverses benzodiazepines, atropine treats cholinergic toxicity, and N-acetylcysteine is the antidote for acetaminophen overdose. Matching the antidote to the intoxicant is essential.

Question 43Medicine

A 45-year-old woman with type 1 diabetes presents with nausea, abdominal pain, and deep rapid breathing. Blood glucose is 320 mg/dL and arterial pH is 7.18. Which initial fluid strategy is most appropriate?

  1. Hypertonic 3% saline
  2. Isotonic intravenous crystalloid such as 0.9% sodium chloride Correct answer.
  3. Oral rehydration with free water
  4. Rapid infusion of 5% dextrose in water

Explanation

Diabetic ketoacidosis involves profound volume depletion from osmotic diuresis, so initial resuscitation uses isotonic crystalloid such as 0.9% sodium chloride. Dextrose-containing fluids are added later once glucose falls to prevent hypoglycemia during insulin therapy. Hypertonic saline and oral free water are inappropriate in this acute setting.

Question 44Medicine

Which medication is contraindicated in a patient with a history of angioedema while taking an ACE inhibitor?

  1. Hydrochlorothiazide
  2. Sacubitril with valsartan Correct answer.
  3. Losartan
  4. Amlodipine

Explanation

Sacubitril is a neprilysin inhibitor that increases bradykinin levels, and combining it with an ACE inhibitor markedly raises the risk of serious angioedema. A 36-hour washout is required when switching. Amlodipine, hydrochlorothiazide, and even ARBs are not contraindicated on this basis, although ARBs are used cautiously after ACE inhibitor angioedema.

Question 45Medicine

A patient with chronic kidney disease and a creatinine clearance of 25 mL/min is prescribed a renally cleared drug. What is the most appropriate action?

  1. Double the dose to overcome reduced absorption
  2. Use the standard dose because renal function is only mildly reduced
  3. Reduce the dose or extend the dosing interval according to renal function Correct answer.
  4. Discontinue all renally cleared medications permanently

Explanation

When creatinine clearance is substantially reduced, renally eliminated drugs accumulate and can cause toxicity, so dose reduction or interval extension is required. Standard dosing risks adverse effects, while doubling the dose worsens accumulation. Not all renally cleared drugs must be stopped permanently; many can be dose-adjusted.

Question 46Medicine

Which finding is most characteristic of serotonin syndrome?

  1. Clonus, hyperreflexia, and agitation Correct answer.
  2. Dry skin, urinary retention, and mydriasis
  3. Pinpoint pupils, bradycardia, and hypoventilation
  4. Muscle rigidity with hyporeflexia and hyperthermia

Explanation

Serotonin syndrome presents with a triad of mental status changes, autonomic hyperactivity, and neuromuscular abnormalities such as clonus and hyperreflexia, often most prominent in the lower extremities. Pinpoint pupils and hypoventilation suggest opioid toxicity. Dry skin and urinary retention suggest anticholinergic toxicity.

Question 47Medicine

A patient with heart failure and reduced ejection fraction is started on a beta-blocker. Which agent has the strongest evidence for reducing mortality in this population?

  1. Nebivolol
  2. Atenolol
  3. Propranolol
  4. Carvedilol Correct answer.

Explanation

Carvedilol, metoprolol succinate, and bisoprolol are the beta-blockers with mortality benefit in heart failure with reduced ejection fraction. Carvedilol combines nonselective beta blockade with alpha-1 blockade. Atenolol, propranolol, and nebivolol lack the same outcome evidence in this setting.

Question 48Medicine

A patient on furosemide for heart failure develops muscle weakness and a serum potassium of 2.9 mEq/L. Which additional finding is most likely?

  1. Hypercalcemia
  2. Metabolic alkalosis Correct answer.
  3. Metabolic acidosis
  4. Hyperkalemia

Explanation

Loop diuretics increase distal sodium delivery and aldosterone-mediated potassium and hydrogen secretion, producing hypokalemia and metabolic alkalosis. The resulting volume contraction further sustains the alkalosis. Metabolic acidosis and hyperkalemia are not typical of loop diuretic use.

Question 49Medicine

Which drug interaction is most concerning when simvastatin is co-prescribed with clarithromycin?

  1. Loss of antibiotic activity from chelation
  2. Increased statin levels and risk of rhabdomyolysis due to CYP3A4 inhibition Correct answer.
  3. Reduced statin efficacy due to enzyme induction
  4. Additive hypoglycemia

Explanation

Clarithromycin is a potent inhibitor of CYP3A4, the enzyme that metabolizes simvastatin. Inhibition raises simvastatin exposure and increases the risk of myopathy and rhabdomyolysis, so the combination should be avoided or the statin temporarily held. Enzyme induction would lower statin levels, the opposite effect.

Question 50Medicine

A patient with major depressive disorder is started on sertraline. Which counseling point is most important regarding onset of therapeutic effect?

  1. The effect is immediate within hours of the first dose
  2. Therapy should be combined with a monoamine oxidase inhibitor for faster response
  3. The drug should be stopped as soon as mood improves
  4. Full antidepressant benefit may take several weeks to emerge Correct answer.

Explanation

Selective serotonin reuptake inhibitors typically require two to six weeks for full antidepressant effect, although adverse effects may appear early. Patients should be counseled to persist and to report worsening symptoms. Combining an SSRI with an MAO inhibitor is contraindicated because of serotonin syndrome risk.