1
Pharmacology NBME Exam 2025/2026
– Comprehensive Questions with
Verified Solutions
General Pharmacology (10 Questions)
Question 1
Which pharmacokinetic parameter describes the time it takes for a drug’s plasma concentration
to decrease by 50%?
A) Volume of distribution
B) Half-life
C) Clearance
D) Bioavailability
Answer: B) Half-life
Rationale: The half-life (t½) is the time required for the plasma concentration of a drug to
decrease by 50%, reflecting the drug’s elimination rate.
Question 2
What is the primary route of drug excretion for most medications?
A) Hepatic metabolism
B) Renal excretion
C) Biliary excretion
D) Pulmonary excretion
Answer: B) Renal excretion
Rationale: The kidneys are the primary route of excretion for most drugs, either as
unchanged drug or metabolites, via glomerular filtration, tubular secretion, or reabsorption.
Question 3
Which factor most significantly affects a drug’s bioavailability?
A) First-pass metabolism
B) Plasma protein binding
C) Volume of distribution
D) Elimination half-life
, 2
Answer: A) First-pass metabolism
Rationale: First-pass metabolism in the liver reduces the amount of orally administered drug
reaching systemic circulation, significantly impacting bioavailability.
Question 4
A drug with a high volume of distribution is most likely to:
A) Be confined to plasma
B) Distribute extensively into tissues
C) Be excreted unchanged by the kidneys
D) Have a short half-life
Answer: B) Distribute extensively into tissues
Rationale: A high volume of distribution indicates that a drug distributes widely into body
tissues, rather than remaining in the plasma.
Question 5
Which enzyme system is primarily responsible for phase I drug metabolism?
A) Cytochrome P450
B) Glucuronyl transferase
C) Sulfotransferase
D) N-acetyltransferase
Answer: A) Cytochrome P450
Rationale: The cytochrome P450 enzyme system in the liver is responsible for phase I
metabolism, involving oxidation, reduction, or hydrolysis reactions to modify drugs.
Question 6
What is the primary effect of a competitive antagonist at a receptor?
A) Irreversibly blocks the receptor
B) Binds to the receptor and activates it
C) Reversibly binds to the receptor, preventing agonist binding
D) Increases the receptor’s affinity for the agonist
Answer: C) Reversibly binds to the receptor, preventing agonist binding
Rationale: A competitive antagonist reversibly binds to the same receptor site as the agonist,
preventing its action but can be overcome by increasing agonist concentration.
, 3
Question 7
Which type of drug interaction occurs when two drugs compete for plasma protein binding?
A) Pharmacodynamic
B) Pharmacokinetic
C) Additive
D) Synergistic
Answer: B) Pharmacokinetic
Rationale: Competition for plasma protein binding affects the free fraction of a drug,
altering its distribution and is classified as a pharmacokinetic interaction.
Question 8
A patient is prescribed a drug with a narrow therapeutic index. What is the clinical implication?
A) The drug is safe at any dose
B) The drug requires careful monitoring to avoid toxicity
C) The drug has a long half-life
D) The drug has minimal side effects
Answer: B) The drug requires careful monitoring to avoid toxicity
Rationale: A narrow therapeutic index means the therapeutic dose is close to the toxic dose,
necessitating close monitoring to ensure safety.
Question 9
Which parameter best predicts a drug’s steady-state concentration during continuous
administration?
A) Bioavailability
B) Clearance
C) Volume of distribution
D) Half-life
Answer: B) Clearance
Rationale: Clearance determines the rate at which a drug is removed from the body, directly
influencing the steady-state concentration during continuous dosing.
Question 10
What is the primary purpose of phase II drug metabolism?
A) To activate prodrugs
B) To increase water solubility
, 4
C) To reduce drug toxicity
D) To enhance receptor binding
Answer: B) To increase water solubility
Rationale: Phase II metabolism involves conjugation reactions (e.g., glucuronidation) that
increase a drug’s water solubility, facilitating renal excretion.
Cardiovascular Pharmacology (20 Questions)
Question 11
What is the mechanism of action of lisinopril?
A) Beta-adrenergic receptor blockade
B) Angiotensin-converting enzyme inhibition
C) Calcium channel blockade
D) Sodium-potassium ATPase inhibition
Answer: B) Angiotensin-converting enzyme inhibition
Rationale: Lisinopril inhibits ACE, reducing angiotensin II formation, which lowers blood
pressure by decreasing vasoconstriction and aldosterone release.
Question 12
A patient on losartan develops hyperkalemia. What is the most likely cause?
A) Increased potassium excretion
B) Reduced aldosterone production
C) Increased sodium retention
D) Enhanced potassium reabsorption
Answer: B) Reduced aldosterone production
Rationale: Losartan, an ARB, blocks angiotensin II receptors, reducing aldosterone
production, which decreases potassium excretion and can lead to hyperkalemia.
Question 13
What is a common side effect of amlodipine?
A) Dry cough
B) Peripheral edema
C) Hyperkalemia
D) Bradycardia
Answer: B) Peripheral edema
Pharmacology NBME Exam 2025/2026
– Comprehensive Questions with
Verified Solutions
General Pharmacology (10 Questions)
Question 1
Which pharmacokinetic parameter describes the time it takes for a drug’s plasma concentration
to decrease by 50%?
A) Volume of distribution
B) Half-life
C) Clearance
D) Bioavailability
Answer: B) Half-life
Rationale: The half-life (t½) is the time required for the plasma concentration of a drug to
decrease by 50%, reflecting the drug’s elimination rate.
Question 2
What is the primary route of drug excretion for most medications?
A) Hepatic metabolism
B) Renal excretion
C) Biliary excretion
D) Pulmonary excretion
Answer: B) Renal excretion
Rationale: The kidneys are the primary route of excretion for most drugs, either as
unchanged drug or metabolites, via glomerular filtration, tubular secretion, or reabsorption.
Question 3
Which factor most significantly affects a drug’s bioavailability?
A) First-pass metabolism
B) Plasma protein binding
C) Volume of distribution
D) Elimination half-life
, 2
Answer: A) First-pass metabolism
Rationale: First-pass metabolism in the liver reduces the amount of orally administered drug
reaching systemic circulation, significantly impacting bioavailability.
Question 4
A drug with a high volume of distribution is most likely to:
A) Be confined to plasma
B) Distribute extensively into tissues
C) Be excreted unchanged by the kidneys
D) Have a short half-life
Answer: B) Distribute extensively into tissues
Rationale: A high volume of distribution indicates that a drug distributes widely into body
tissues, rather than remaining in the plasma.
Question 5
Which enzyme system is primarily responsible for phase I drug metabolism?
A) Cytochrome P450
B) Glucuronyl transferase
C) Sulfotransferase
D) N-acetyltransferase
Answer: A) Cytochrome P450
Rationale: The cytochrome P450 enzyme system in the liver is responsible for phase I
metabolism, involving oxidation, reduction, or hydrolysis reactions to modify drugs.
Question 6
What is the primary effect of a competitive antagonist at a receptor?
A) Irreversibly blocks the receptor
B) Binds to the receptor and activates it
C) Reversibly binds to the receptor, preventing agonist binding
D) Increases the receptor’s affinity for the agonist
Answer: C) Reversibly binds to the receptor, preventing agonist binding
Rationale: A competitive antagonist reversibly binds to the same receptor site as the agonist,
preventing its action but can be overcome by increasing agonist concentration.
, 3
Question 7
Which type of drug interaction occurs when two drugs compete for plasma protein binding?
A) Pharmacodynamic
B) Pharmacokinetic
C) Additive
D) Synergistic
Answer: B) Pharmacokinetic
Rationale: Competition for plasma protein binding affects the free fraction of a drug,
altering its distribution and is classified as a pharmacokinetic interaction.
Question 8
A patient is prescribed a drug with a narrow therapeutic index. What is the clinical implication?
A) The drug is safe at any dose
B) The drug requires careful monitoring to avoid toxicity
C) The drug has a long half-life
D) The drug has minimal side effects
Answer: B) The drug requires careful monitoring to avoid toxicity
Rationale: A narrow therapeutic index means the therapeutic dose is close to the toxic dose,
necessitating close monitoring to ensure safety.
Question 9
Which parameter best predicts a drug’s steady-state concentration during continuous
administration?
A) Bioavailability
B) Clearance
C) Volume of distribution
D) Half-life
Answer: B) Clearance
Rationale: Clearance determines the rate at which a drug is removed from the body, directly
influencing the steady-state concentration during continuous dosing.
Question 10
What is the primary purpose of phase II drug metabolism?
A) To activate prodrugs
B) To increase water solubility
, 4
C) To reduce drug toxicity
D) To enhance receptor binding
Answer: B) To increase water solubility
Rationale: Phase II metabolism involves conjugation reactions (e.g., glucuronidation) that
increase a drug’s water solubility, facilitating renal excretion.
Cardiovascular Pharmacology (20 Questions)
Question 11
What is the mechanism of action of lisinopril?
A) Beta-adrenergic receptor blockade
B) Angiotensin-converting enzyme inhibition
C) Calcium channel blockade
D) Sodium-potassium ATPase inhibition
Answer: B) Angiotensin-converting enzyme inhibition
Rationale: Lisinopril inhibits ACE, reducing angiotensin II formation, which lowers blood
pressure by decreasing vasoconstriction and aldosterone release.
Question 12
A patient on losartan develops hyperkalemia. What is the most likely cause?
A) Increased potassium excretion
B) Reduced aldosterone production
C) Increased sodium retention
D) Enhanced potassium reabsorption
Answer: B) Reduced aldosterone production
Rationale: Losartan, an ARB, blocks angiotensin II receptors, reducing aldosterone
production, which decreases potassium excretion and can lead to hyperkalemia.
Question 13
What is a common side effect of amlodipine?
A) Dry cough
B) Peripheral edema
C) Hyperkalemia
D) Bradycardia
Answer: B) Peripheral edema
