NSG 526 PRACTICE EXAM
1. Which cytochrome P450 isoenzyme is responsible for metabolizing the
largest proportion of commonly prescribed drugs?
A. CYP2D6
B. CYP3A4
C. CYP1A2
D. CYP2E1
Correct answer: B. CYP3A4
Rationale: CYP3A4 metabolizes roughly half of all drugs, which is why CYP3A4
inhibitors and inducers cause so many clinically significant interactions.
2. A patient taking simvastatin is told to avoid large amounts of grapefruit
juice. What is the reason?
A. Grapefruit induces CYP3A4, lowering simvastatin effectiveness
B. Grapefruit binds simvastatin in the gut and prevents absorption
C. Grapefruit increases renal excretion of simvastatin
D. Grapefruit inhibits intestinal CYP3A4, raising simvastatin levels and the risk of
myopathy
Correct answer: D. Grapefruit inhibits intestinal CYP3A4, raising simvastatin levels
and the risk of myopathy
Rationale: Grapefruit juice inhibits gut-wall CYP3A4, decreasing first-pass
metabolism and increasing systemic drug exposure, which raises the risk of
myopathy and rhabdomyolysis.
3. Which route of administration avoids hepatic first-pass metabolism?
A. Sublingual
B. Oral
C. Rectal (upper rectum, via superior rectal vein)
D. Enteral via nasogastric tube
Correct answer: A. Sublingual
Rationale: Sublingual drugs are absorbed into the systemic venous circulation
through the oral mucosa and bypass the portal circulation and liver on the first pass.
,4. Approximately how many half-lives are required for a drug given at regular
intervals to reach steady state?
A. 1 to 2
B. 10 to 12
C. 4 to 5
D. 20 or more
Correct answer: C. 4 to 5
Rationale: Steady state is reached after about 4 to 5 half-lives, regardless of the
dose, because elimination and input balance at that point.
5. Which pharmacokinetic parameter is the primary determinant of a loading
dose?
A. Clearance
B. Half-life
C. Volume of distribution
D. Protein binding of metabolites only
Correct answer: C. Volume of distribution
Rationale: Loading dose = target concentration x volume of distribution (adjusted for
bioavailability). Clearance determines the maintenance dose.
6. Which equation is most commonly used by prescribers to estimate renal
function when adjusting drug doses in adults?
A. Cockcroft-Gault creatinine clearance
B. Body surface area formula
C. Henderson-Hasselbalch equation
D. Mean arterial pressure formula
Correct answer: A. Cockcroft-Gault creatinine clearance
Rationale: Cockcroft-Gault, based on age, weight, sex and serum creatinine, is the
estimate used in most drug labeling for renal dose adjustment.
,7. According to the Beers Criteria, which medication should generally be
avoided in older adults because of strong anticholinergic effects?
A. Acetaminophen
B. Lisinopril
C. Metformin
D. Diphenhydramine
Correct answer: D. Diphenhydramine
Rationale: First-generation antihistamines such as diphenhydramine cause
confusion, urinary retention, constipation and falls in older adults, so they are listed
as potentially inappropriate.
8. Which antibiotic is most likely to significantly increase the INR in a patient
taking warfarin?
A. Cephalexin
B. Trimethoprim-sulfamethoxazole
C. Nitrofurantoin
D. Azithromycin at standard 5-day dosing
Correct answer: B. Trimethoprim-sulfamethoxazole
Rationale: TMP-SMX inhibits CYP2C9 (the main metabolizer of S-warfarin) and can
displace warfarin from protein binding, causing a marked rise in INR and bleeding
risk.
9. A patient taking an SSRI is given linezolid and develops agitation,
hyperthermia, tremor and inducible clonus. Which medication can be used to
treat this condition?
A. Dantrolene
B. Haloperidol
C. Benztropine
D. Cyproheptadine
Correct answer: D. Cyproheptadine
Rationale: These findings indicate serotonin syndrome. After stopping the offending
drugs and giving supportive care and benzodiazepines, cyproheptadine, a 5-HT2A
antagonist, is the antidote.
, 10. Which medication increases serum lithium levels and raises the risk of
lithium toxicity?
A. Amlodipine
B. Hydrochlorothiazide
C. Omeprazole
D. Acetaminophen
Correct answer: B. Hydrochlorothiazide
Rationale: Thiazide diuretics increase proximal tubular lithium reabsorption.
NSAIDs and ACE inhibitors have the same effect, so levels must be monitored
closely.
11. What is the mechanism of ACE inhibitor-induced cough?
A. Histamine release from mast cells
B. Increased angiotensin II levels
C. Accumulation of bradykinin
D. Hyperkalemia
Correct answer: C. Accumulation of bradykinin
Rationale: ACE also degrades bradykinin. Inhibiting the enzyme allows bradykinin
to accumulate in the airways. Switching to an ARB resolves the cough.
12. Why are ACE inhibitors and ARBs contraindicated in pregnancy?
A. They can cause fetal renal injury, oligohydramnios and fetal death
B. They cause neural tube defects only in the first week
C. They cause maternal hyperglycemia
D. They reduce uterine blood flow causing preterm labor only
Correct answer: A. They can cause fetal renal injury, oligohydramnios and fetal
death
Rationale: Drugs that block the renin-angiotensin system, especially in the second
and third trimesters, cause fetal renal dysfunction, oligohydramnios, skull hypoplasia
and fetal death.
1. Which cytochrome P450 isoenzyme is responsible for metabolizing the
largest proportion of commonly prescribed drugs?
A. CYP2D6
B. CYP3A4
C. CYP1A2
D. CYP2E1
Correct answer: B. CYP3A4
Rationale: CYP3A4 metabolizes roughly half of all drugs, which is why CYP3A4
inhibitors and inducers cause so many clinically significant interactions.
2. A patient taking simvastatin is told to avoid large amounts of grapefruit
juice. What is the reason?
A. Grapefruit induces CYP3A4, lowering simvastatin effectiveness
B. Grapefruit binds simvastatin in the gut and prevents absorption
C. Grapefruit increases renal excretion of simvastatin
D. Grapefruit inhibits intestinal CYP3A4, raising simvastatin levels and the risk of
myopathy
Correct answer: D. Grapefruit inhibits intestinal CYP3A4, raising simvastatin levels
and the risk of myopathy
Rationale: Grapefruit juice inhibits gut-wall CYP3A4, decreasing first-pass
metabolism and increasing systemic drug exposure, which raises the risk of
myopathy and rhabdomyolysis.
3. Which route of administration avoids hepatic first-pass metabolism?
A. Sublingual
B. Oral
C. Rectal (upper rectum, via superior rectal vein)
D. Enteral via nasogastric tube
Correct answer: A. Sublingual
Rationale: Sublingual drugs are absorbed into the systemic venous circulation
through the oral mucosa and bypass the portal circulation and liver on the first pass.
,4. Approximately how many half-lives are required for a drug given at regular
intervals to reach steady state?
A. 1 to 2
B. 10 to 12
C. 4 to 5
D. 20 or more
Correct answer: C. 4 to 5
Rationale: Steady state is reached after about 4 to 5 half-lives, regardless of the
dose, because elimination and input balance at that point.
5. Which pharmacokinetic parameter is the primary determinant of a loading
dose?
A. Clearance
B. Half-life
C. Volume of distribution
D. Protein binding of metabolites only
Correct answer: C. Volume of distribution
Rationale: Loading dose = target concentration x volume of distribution (adjusted for
bioavailability). Clearance determines the maintenance dose.
6. Which equation is most commonly used by prescribers to estimate renal
function when adjusting drug doses in adults?
A. Cockcroft-Gault creatinine clearance
B. Body surface area formula
C. Henderson-Hasselbalch equation
D. Mean arterial pressure formula
Correct answer: A. Cockcroft-Gault creatinine clearance
Rationale: Cockcroft-Gault, based on age, weight, sex and serum creatinine, is the
estimate used in most drug labeling for renal dose adjustment.
,7. According to the Beers Criteria, which medication should generally be
avoided in older adults because of strong anticholinergic effects?
A. Acetaminophen
B. Lisinopril
C. Metformin
D. Diphenhydramine
Correct answer: D. Diphenhydramine
Rationale: First-generation antihistamines such as diphenhydramine cause
confusion, urinary retention, constipation and falls in older adults, so they are listed
as potentially inappropriate.
8. Which antibiotic is most likely to significantly increase the INR in a patient
taking warfarin?
A. Cephalexin
B. Trimethoprim-sulfamethoxazole
C. Nitrofurantoin
D. Azithromycin at standard 5-day dosing
Correct answer: B. Trimethoprim-sulfamethoxazole
Rationale: TMP-SMX inhibits CYP2C9 (the main metabolizer of S-warfarin) and can
displace warfarin from protein binding, causing a marked rise in INR and bleeding
risk.
9. A patient taking an SSRI is given linezolid and develops agitation,
hyperthermia, tremor and inducible clonus. Which medication can be used to
treat this condition?
A. Dantrolene
B. Haloperidol
C. Benztropine
D. Cyproheptadine
Correct answer: D. Cyproheptadine
Rationale: These findings indicate serotonin syndrome. After stopping the offending
drugs and giving supportive care and benzodiazepines, cyproheptadine, a 5-HT2A
antagonist, is the antidote.
, 10. Which medication increases serum lithium levels and raises the risk of
lithium toxicity?
A. Amlodipine
B. Hydrochlorothiazide
C. Omeprazole
D. Acetaminophen
Correct answer: B. Hydrochlorothiazide
Rationale: Thiazide diuretics increase proximal tubular lithium reabsorption.
NSAIDs and ACE inhibitors have the same effect, so levels must be monitored
closely.
11. What is the mechanism of ACE inhibitor-induced cough?
A. Histamine release from mast cells
B. Increased angiotensin II levels
C. Accumulation of bradykinin
D. Hyperkalemia
Correct answer: C. Accumulation of bradykinin
Rationale: ACE also degrades bradykinin. Inhibiting the enzyme allows bradykinin
to accumulate in the airways. Switching to an ARB resolves the cough.
12. Why are ACE inhibitors and ARBs contraindicated in pregnancy?
A. They can cause fetal renal injury, oligohydramnios and fetal death
B. They cause neural tube defects only in the first week
C. They cause maternal hyperglycemia
D. They reduce uterine blood flow causing preterm labor only
Correct answer: A. They can cause fetal renal injury, oligohydramnios and fetal
death
Rationale: Drugs that block the renin-angiotensin system, especially in the second
and third trimesters, cause fetal renal dysfunction, oligohydramnios, skull hypoplasia
and fetal death.
