NAPLEX Quiz: Overdose And Exposure Management

What this quiz covers

This quiz focuses on Overdose And Exposure Management, giving you a quick way to practice the rules, question types, and explanations that matter most for NAPLEX.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

Question 1

1. N-acetylcysteine intravenous per protocol (loading dose followed by maintenance infusions) (correct answer)
2. Naloxone 2 mg intravenous, repeat every 2–3 minutes as needed
3. Atropine 1 mg intravenous every 3–5 minutes until secretions dry
4. Flumazenil 0.2 mg intravenous, repeat to maximum 1 mg

Explanation: This question tests antidote selection for acetaminophen overdose in a patient with risk factors. The patient ingested 20 g of acetaminophen with a toxic level (210 mcg/mL at 6 hours) above the treatment line on the Rumack-Matthew nomogram, with alcohol use disorder as an additional risk factor. N-acetylcysteine (A) is the specific antidote that replenishes glutathione stores depleted by toxic acetaminophen metabolites, preventing hepatotoxicity when given within 8-10 hours of ingestion. Naloxone (B) reverses opioid effects, not acetaminophen toxicity. Atropine (C) treats cholinergic toxicity or symptomatic bradycardia. Flumazenil (D) reverses benzodiazepine effects. The IV N-acetylcysteine protocol includes a loading dose (150 mg/kg over 1 hour), followed by maintenance infusions (50 mg/kg over 4 hours, then 100 mg/kg over 16 hours). Daily alcohol use increases susceptibility to acetaminophen hepatotoxicity through glutathione depletion and CYP2E1 induction.

Question 2

1. Octreotide 50 micrograms subcutaneous (or intravenous) and repeat every 6 hours as needed with dextrose support (correct answer)
2. Protamine sulfate 1 mg per 100 units of heparin administered in the last 2 hours
3. Vitamin K (phytonadione) 5–10 mg intravenous for reversal of anticoagulation
4. Leucovorin 10–25 mg by mouth every 6 hours for folate rescue

Explanation: This question tests antidote selection for sulfonylurea-induced hypoglycemia. The patient has critically low glucose (38 mg/dL) after taking extra glipizide, presenting with confusion and vomiting typical of severe hypoglycemia. Octreotide (A) is the correct antidote as it inhibits insulin secretion from pancreatic beta cells, counteracting sulfonylurea's mechanism and preventing recurrent hypoglycemia that often occurs with dextrose alone. Protamine sulfate (B) reverses heparin anticoagulation, not hypoglycemia. Vitamin K (C) reverses warfarin anticoagulation, which is unrelated to this case. Leucovorin (D) provides folate rescue for methotrexate toxicity, not sulfonylurea overdose. For sulfonylurea overdose, octreotide prevents the hyperinsulinemic response to dextrose administration, reducing the risk of rebound hypoglycemia. The typical dose is 50-100 micrograms subcutaneously every 6-12 hours, with concurrent dextrose support and frequent glucose monitoring.

Question 3

1. Naloxone 0.04–0.4 mg intravenous, titrate and repeat as needed to restore adequate ventilation (correct answer)
2. Naltrexone 50 mg by mouth once daily to reverse acute respiratory depression
3. Fomepizole 15 mg/kg intravenous loading dose for suspected toxic alcohol ingestion
4. Physostigmine 1–2 mg intravenous for suspected anticholinergic poisoning

Explanation: This question tests recognition and treatment of opioid overdose with classic toxidrome. The patient presents with the opioid triad: respiratory depression (RR 6/min), decreased consciousness, and pinpoint pupils, with positive urine toxicology for opioids. Naloxone 0.04-0.4 mg IV (A) is the specific opioid antagonist that competitively reverses respiratory depression, with dosing titrated to restore adequate ventilation without precipitating withdrawal. Naltrexone (B) is an oral long-acting opioid antagonist used for addiction treatment, not acute reversal. Fomepizole (C) treats toxic alcohol ingestions. Physostigmine (D) reverses anticholinergic toxicity, which presents with mydriasis, not miosis. Start with lower naloxone doses (0.04-0.1 mg) and titrate to avoid precipitating severe withdrawal in opioid-dependent patients. The goal is adequate ventilation (RR >12), not full alertness, and repeated doses may be needed due to naloxone's shorter half-life compared to many opioids.

Question 4

1. Mild headache without focal neurologic findings
2. Dark urine with severe myalgias suggesting rhabdomyolysis (correct answer)
3. Intermittent sneezing and nasal congestion
4. Transient nausea after a meal without dehydration

Explanation: This question tests recognition of severe statin-induced rhabdomyolysis from drug interaction. The patient developed severe myalgias and dark urine after starting clarithromycin while on high-dose simvastatin, with markedly elevated CK (18,500 U/L) and acute kidney injury. Dark urine with severe myalgias suggesting rhabdomyolysis (B) indicates severe toxicity, as myoglobin release causes the characteristic dark urine and can lead to acute tubular necrosis. Mild headache (A) is a minor symptom not indicating severe toxicity. Intermittent sneezing (C) is unrelated to statin toxicity. Transient nausea (D) without dehydration is also not indicative of severe toxicity. Clarithromycin is a strong CYP3A4 inhibitor that dramatically increases simvastatin levels, with risk highest at the 80 mg dose. Management includes immediate discontinuation of both drugs, aggressive IV hydration, and monitoring for complications including hyperkalemia and acute kidney injury.

Question 5

1. Administer benzodiazepines to reduce sympathetic outflow and treat agitation and hypertension (correct answer)
2. Administer propranolol as first-line monotherapy for hypertension and tachycardia
3. Give flumazenil to reverse stimulant intoxication
4. Start N-acetylcysteine (NAC) due to possible hepatotoxicity

Explanation: This question tests initial management of cocaine toxicity, prioritizing sympatholysis. The key patient-specific factor is the severe hypertension, tachycardia, and chest pain from catecholamine surge. Benzodiazepines are best to reduce sympathetic outflow, agitation, and cardiovascular stress safely. Propranolol monotherapy risks unopposed alpha stimulation; flumazenil irrelevant; N-acetylcysteine not indicated. A pearl is to avoid beta-blockers in cocaine use due to potential coronary vasospasm worsening. Nitroglycerin or phentolamine can be added for refractory hypertension.

Question 6

1. Administer activated charcoal 1 g/kg by mouth or nasogastric tube if airway is protected (correct answer)
2. Administer N-acetylcysteine 150 mg/kg intravenous loading dose immediately
3. Administer atropine 0.02 mg/kg intravenous for suspected cholinergic toxicity
4. Administer naloxone 0.1 mg/kg intravenous for suspected opioid ingestion

Explanation: This question tests immediate management of calcium channel blocker overdose in a pediatric patient. The 2-year-old presents with hypotension (86/48 mmHg), tachycardia, and hypoglycemia after ingesting extended-release nifedipine within 30 minutes. Activated charcoal (A) is the most important initial action because it can prevent further absorption of the sustained-release formulation if given within 1-2 hours of ingestion, especially critical with extended-release preparations that continue releasing drug. N-acetylcysteine (B) treats acetaminophen overdose, not calcium channel blockers. Atropine (C) is for cholinergic toxicity with bradycardia and excessive secretions, which this patient doesn't exhibit. Naloxone (D) reverses opioid effects, not calcium channel blocker toxicity. For calcium channel blocker overdoses, remember the treatment triad: decontamination (activated charcoal), calcium supplementation, and vasopressor support. Extended-release formulations pose particular danger due to prolonged absorption and delayed peak effects.

Question 7

1. Administer 100% oxygen via nonrebreather mask and remove the patient from the exposure source (correct answer)
2. Administer flumazenil 0.2 mg intravenous for suspected sedative exposure
3. Administer activated charcoal 50 g by mouth to bind inhaled toxins
4. Administer deferoxamine 15 mg/kg/hour intravenous for suspected heavy metal poisoning

Explanation: This question tests initial management of methylene chloride exposure with carbon monoxide formation. The patient has elevated carboxyhemoglobin (18%) from methylene chloride metabolism to carbon monoxide, presenting with headache and dizziness after paint stripper inhalation. Administering 100% oxygen via nonrebreather mask and removing from exposure (A) is the most important initial action, as high-flow oxygen accelerates carbon monoxide elimination and prevents further exposure. Flumazenil (B) is inappropriate as this is an inhalation exposure producing carbon monoxide, not sedative overdose. Activated charcoal (C) doesn't bind inhaled toxins and is useless for gas exposures. Deferoxamine (D) chelates iron, not carbon monoxide. Methylene chloride uniquely continues producing carbon monoxide through hepatic metabolism even after exposure ends, potentially causing delayed or prolonged toxicity. Monitor carboxyhemoglobin levels serially and consider hyperbaric oxygen for severe poisoning, especially with the patient's cardiac history.

Question 8

1. Serum acetaminophen concentration at 4 hours post-ingestion
2. Serial serum salicylate concentrations and acid–base status (arterial or venous blood gas, bicarbonate) (correct answer)
3. International normalized ratio every 6 hours to assess anticoagulation intensity
4. Serum digoxin concentration 6 hours after the last dose

Explanation: This question tests appropriate monitoring parameters for salicylate toxicity. The patient presents with classic salicylate toxicity symptoms: tinnitus, hyperventilation (RR 30/min), and mixed respiratory alkalosis with metabolic acidosis (pH 7.48, low bicarbonate, low PCO2). Serial serum salicylate concentrations and acid-base status (B) are essential for monitoring salicylate toxicity because levels can continue to rise, and acid-base disturbances guide treatment decisions including alkalinization and hemodialysis. Acetaminophen concentration at 4 hours (A) is irrelevant as the patient took aspirin, not acetaminophen. INR monitoring (C) would be appropriate for warfarin overdose, not salicylate toxicity. Serum digoxin concentration (D) is unnecessary without digoxin exposure. In salicylate toxicity, monitor levels every 2-4 hours until declining, along with frequent acid-base assessment, as tissue distribution increases with acidemia. Remember that clinical severity doesn't always correlate with serum levels, especially in chronic toxicity.

Question 9

1. Naloxone 0.04 mg intravenous, repeat every 2 minutes as needed to restore ventilation
2. Flumazenil 0.2 mg intravenous, may repeat in 0.2 mg increments to a maximum of 1 mg (correct answer)
3. N-acetylcysteine 150 mg/kg intravenous loading dose followed by maintenance infusion
4. Fomepizole 15 mg/kg intravenous loading dose followed by 10 mg/kg every 12 hours

Explanation: This question tests the appropriate antidote selection for benzodiazepine overdose with concurrent alcohol intoxication. The patient presents with severe drowsiness, respiratory depression (RR 8/min, O2 sat 90%), and positive urine toxicology for benzodiazepines after alprazolam overdose with alcohol. Flumazenil (B) is the specific benzodiazepine receptor antagonist that competitively reverses benzodiazepine effects, making it the correct choice for this patient with respiratory depression. Naloxone (A) is incorrect as it reverses opioid effects, not benzodiazepines, and the patient has no evidence of opioid exposure. N-acetylcysteine (C) is the antidote for acetaminophen overdose, and fomepizole (D) treats toxic alcohol ingestions, neither of which apply here. When using flumazenil, monitor for seizures, especially in chronic benzodiazepine users or those with seizure history, and be aware that its shorter half-life compared to most benzodiazepines may require repeated dosing.

Question 10

1. Seizures (including delayed-onset seizures) and significant cardiac dysrhythmias (correct answer)
2. Mild headache only
3. Increased appetite and weight gain
4. Runny nose and watery eyes

Explanation: This question tests recognition of severe bupropion toxicity, focusing on neurologic and cardiac effects. The key patient-specific factor is the large ingestion of extended-release bupropion with prolonged QTc indicating high risk. Seizures and cardiac dysrhythmias indicate severe toxicity due to sodium channel blockade and lowered seizure threshold. Mild headache is common but not severe; increased appetite atypical; runny nose irrelevant. A pearl is that seizures can be delayed up to 24 hours with XL formulations. Treat wide QRS with sodium bicarbonate and use benzodiazepines for seizure prophylaxis.

Question 11

1. Frequent blood glucose monitoring for recurrent hypoglycemia and need for dextrose infusion (correct answer)
2. International normalized ratio (INR) every 4 hours to assess bleeding risk
3. Serum acetaminophen concentration at 4 hours post-ingestion
4. Serum lithium concentration every 2 hours

Explanation: This question tests monitoring in sulfonylurea overdose, focusing on prolonged hypoglycemia risk. The key patient-specific factor is the low glucose (34 mg/dL) after taking glyburide without food, indicating insulin release stimulation. Frequent blood glucose monitoring is best to detect and treat recurrent hypoglycemia, often requiring dextrose infusion. INR is incorrect without coagulopathy; acetaminophen level is irrelevant; lithium level is not applicable. A pearl is that long-acting sulfonylureas like glyburide can cause hypoglycemia lasting 24-72 hours. Octreotide may be used as an antidote to suppress insulin release in refractory cases.

Question 12

1. Atropine intravenous with repeated dosing until bronchial secretions and bronchospasm improve, plus pralidoxime as indicated (correct answer)
2. N-acetylcysteine (NAC) oral regimen for 72 hours
3. Naloxone 0.04 mg intravenous, titrate to response
4. Deferoxamine intravenous infusion

Explanation: This question tests the management of organophosphate poisoning, emphasizing anticholinergic and reactivator therapy. The key patient-specific factor is the cholinergic toxidrome (wheezing, pinpoint pupils, fasciculations) post-insecticide exposure. Atropine with pralidoxime is best as atropine dries secretions and counters muscarinic effects, while pralidoxime regenerates acetylcholinesterase. N-acetylcysteine is incorrect without acetaminophen; naloxone is for opioids; deferoxamine is for iron. A pearl is to titrate atropine to resolution of bronchial secretions, not heart rate. Early decontamination and airway protection are critical in severe cases to prevent aspiration.

Question 13

1. Serial anion gap, osmolar gap, and acid–base status (pH/bicarbonate) to guide antidote and dialysis decisions (correct answer)
2. International normalized ratio (INR) every 2 hours to guide therapy
3. Serum acetaminophen concentration at 4 hours post-ingestion only
4. Serum digoxin concentration daily

Explanation: This question tests monitoring in methanol poisoning, guiding therapy based on metabolic parameters. The key patient-specific factor is the acidosis, elevated anion/osmolar gaps, and visual symptoms confirming toxic formic acid accumulation. Serial anion gap, osmolar gap, and acid-base status are best to assess antidote efficacy and need for dialysis. INR irrelevant; single acetaminophen level insufficient; digoxin not applicable. A pearl is that fomepizole or ethanol inhibits metabolism, with hemodialysis for pH <7.3 or high levels. Folate enhances formic acid elimination as adjunct therapy.

Question 14

1. Naloxone 0.04 mg intravenous, titrate every 2–3 minutes to adequate ventilation (correct answer)
2. Flumazenil 0.2 mg intravenous push, repeat as needed
3. N-acetylcysteine (NAC) intravenous loading dose followed by maintenance infusion
4. Atropine 1 mg intravenous every 3–5 minutes as needed for bradycardia

Explanation: This question tests the management of opioid overdose, emphasizing reversal of respiratory depression. The key patient-specific factor is the altered mental status, shallow breathing, pinpoint pupils, and positive urine opioid screen consistent with oxycodone excess. Naloxone is the best choice as it competitively antagonizes mu-opioid receptors, rapidly restoring ventilation when titrated carefully to avoid withdrawal. Flumazenil is incorrect without benzodiazepine involvement; N-acetylcysteine is not indicated absent acetaminophen toxicity; atropine is suboptimal as bradycardia is not the primary issue here. A clinical pearl is to monitor for recurrent respiratory depression due to opioids' longer half-life compared to naloxone. Use lower initial doses in chronic users to minimize precipitation of severe withdrawal.

Question 15

1. Immediate copious water irrigation of the affected area and prompt calcium gluconate topical/intradermal therapy per protocol (correct answer)
2. Apply occlusive petroleum jelly dressing and observe without further treatment
3. Administer activated charcoal 50 g by mouth
4. Induce vomiting to remove toxin

Explanation: This question tests initial management of dermal hydrofluoric acid exposure, focusing on decontamination and chelation. The key patient-specific factor is the severe pain, blanching, and hypokalemia/hypocalcemia from HF binding ions. Copious irrigation and calcium gluconate are best to neutralize fluoride ions and relieve pain, preventing tissue necrosis. Occlusive dressing is ineffective; charcoal is for oral; vomiting irrelevant for dermal. A pearl is that HF penetrates deeply, requiring intradermal or intra-arterial calcium for severe cases. Monitor electrolytes and ECG for systemic effects like QT prolongation.

Question 16

1. Mild nausea without vital sign changes
2. Hyperthermia with neuromuscular rigidity and rapidly rising creatine kinase (correct answer)
3. Occasional yawning and mild insomnia
4. Bradycardia with hypothermia

Explanation: This question tests recognition of severe serotonin syndrome from drug interactions. The key patient-specific factor is the hyperthermia, rigidity, elevated CK, and combination of MAOI, SSRI, and triptan precipitating excess serotonin. Hyperthermia with neuromuscular rigidity and rising CK indicate severe toxicity risking rhabdomyolysis and multiorgan failure. Mild nausea is common but not severe; yawning/insomnia are withdrawal; bradycardia/hypothermia are atypical. A pearl is to avoid serotonergic agents in MAOI users for 2 weeks post-discontinuation. Cyproheptadine may be used as an antidote in moderate-severe cases after benzodiazepines.

Question 17

1. Fomepizole 15 mg/kg intravenous loading dose, then 10 mg/kg every 12 hours (adjust with dialysis as needed) (correct answer)
2. N-acetylcysteine (NAC) intravenous
3. Naloxone 0.04 mg intravenous, titrate
4. Flumazenil 0.2 mg intravenous push

Explanation: This question tests management of ethylene glycol poisoning, focusing on alcohol dehydrogenase inhibition. The key patient-specific factor is the metabolic acidosis, elevated anion/osmolar gaps, and oxalate crystals confirming toxic metabolite formation. Fomepizole is the best choice as it inhibits alcohol dehydrogenase, preventing further toxic acid production, with hemodialysis if severe. N-acetylcysteine is for acetaminophen; naloxone for opioids; flumazenil for benzodiazepines. A pearl is to calculate osmolar gap for suspicion, with anion gap elevation indicating progression. Bicarbonate and thiamine/pyridoxine support therapy in confirmed cases.

Question 18

1. Flumazenil intravenous to reverse benzodiazepine effects
2. Naloxone intravenous titrated to adequate ventilation if opioid co-ingestion is suspected and respiratory depression develops (correct answer)
3. N-acetylcysteine (NAC) per protocol
4. Fomepizole 15 mg/kg intravenous loading dose

Explanation: This question tests antidote selection in benzodiazepine overdose with complicating factors. The key patient-specific factor is the somnolence from alprazolam, opioid maintenance therapy, and seizure history increasing risks. Naloxone is best if opioid co-ingestion is suspected and respiratory depression develops, as it safely reverses opioids without seizure risk. Flumazenil is contraindicated due to seizure history and potential opioid interaction; N-acetylcysteine irrelevant; fomepizole for alcohols. A pearl is to avoid flumazenil in mixed overdoses or chronic benzo users to prevent withdrawal seizures. Supportive care with ventilation is preferred for pure benzo toxicity.

Question 19

1. Use gasoline-powered engines only outdoors or with adequate ventilation and install carbon monoxide detectors in enclosed work areas (correct answer)
2. Take activated charcoal prophylactically before starting work in enclosed spaces
3. Use antibiotics before future work sessions to prevent toxin-related infections
4. Drink milk before work to prevent inhalational toxin absorption

Explanation: This question tests the concept of preventing carbon monoxide (CO) exposure in occupational settings, particularly from combustion sources like gasoline-powered engines. The key patient-specific factor is the history of working in a poorly ventilated basement with a gasoline-powered pressure washer, leading to elevated carboxyhemoglobin levels of 18%, indicative of CO poisoning. The best recommendation is to use gasoline-powered engines only outdoors or with adequate ventilation and install CO detectors in enclosed work areas, as this directly addresses the source of exposure and provides early warning to prevent future incidents. Taking activated charcoal prophylactically is incorrect because it is used for gastrointestinal decontamination of ingested toxins, not for preventing inhalational CO exposure. Using antibiotics before work or drinking milk are suboptimal as they do not mitigate CO inhalation risks and are not evidence-based for this scenario. A key clinical pearl is that CO poisoning often presents with nonspecific symptoms like headache and weakness, emphasizing the importance of exposure history in diagnosis. To prevent CO exposure, always prioritize engineering controls like ventilation and monitoring devices over unproven prophylactic measures.

Question 20

1. Vitamin K (phytonadione) with rapid reversal using 4-factor prothrombin complex concentrate due to major bleeding (correct answer)
2. Protamine sulfate intravenous to reverse warfarin effect
3. Idarucizumab 5 g intravenous for direct thrombin inhibitor reversal
4. Deferoxamine intravenous for chelation

Explanation: This question tests reversal of warfarin toxicity with bleeding, considering drug interactions. The key patient-specific factor is the supratherapeutic INR (7.8) with bleeding, potentiated by trimethoprim-sulfamethoxazole interaction. Vitamin K with 4-factor PCC is best for rapid INR correction and factor replacement in major bleeding. Protamine is for heparin; idarucizumab is for dabigatran; deferoxamine is for iron. A pearl is to use PCC for life-threatening bleeds due to faster onset than FFP. Always review interacting drugs like antibiotics when adjusting warfarin doses.