Antidotal therapy is a critical and high-stakes area of toxicology where the right drug, given at the right time, can be life-saving. As medication experts, pharmacists are essential members of the team managing poisonings and overdoses, responsible for identifying the need for an antidote, ensuring its correct preparation and administration, and monitoring the patient’s response. This quiz for PharmD students will test your knowledge of specific antidotes, their mechanisms of action, and the toxic syndromes they are used to treat.
1. A patient presents to the emergency department with classic signs of opioid overdose, including respiratory depression and pinpoint pupils. What is the first-line antidote?
- Flumazenil
- N-acetylcysteine
- Naloxone
- Atropine
Answer: Naloxone
2. Naloxone exerts its therapeutic effect by acting as a(n):
- Agonist at the mu-opioid receptor.
- Competitive antagonist at the mu-opioid receptor.
- Partial agonist at the kappa-opioid receptor.
- Irreversible inhibitor of opioid metabolism.
Answer: Competitive antagonist at the mu-opioid receptor.
3. The primary antidote for an acute acetaminophen overdose is:
- Vitamin K
- Methylene blue
- N-acetylcysteine (NAC)
- Sodium bicarbonate
Answer: N-acetylcysteine (NAC)
4. N-acetylcysteine works primarily by:
- Binding directly to the acetaminophen molecule.
- Increasing the speed of acetaminophen’s renal clearance.
- Repleting glutathione stores in the liver to detoxify the toxic metabolite, NAPQI.
- Preventing the absorption of acetaminophen from the gut.
Answer: Repleting glutathione stores in the liver to detoxify the toxic metabolite, NAPQI.
5. A patient who overdosed on a benzodiazepine like lorazepam presents with severe sedation and respiratory depression. The specific reversal agent for this is:
- Naloxone
- Flumazenil
- Physostigmine
- Pralidoxime
Answer: Flumazenil
6. The use of flumazenil is often cautioned or contraindicated in patients on chronic benzodiazepine therapy due to the risk of precipitating:
- A hypertensive crisis.
- Severe seizures.
- Serotonin syndrome.
- A cardiac arrhythmia.
Answer: Severe seizures.
7. A patient with a severe bleed who is on warfarin would be treated with which of the following as an antidote?
- Protamine sulfate
- Idarucizumab
- Vitamin K and/or Four-Factor Prothrombin Complex Concentrate (4F-PCC).
- Andexanet alfa
Answer: Vitamin K and/or Four-Factor Prothrombin Complex Concentrate (4F-PCC).
8. Protamine sulfate is the specific reversal agent for an overdose of which anticoagulant?
- Warfarin
- Dabigatran
- Apixaban
- Heparin
Answer: Heparin
9. A patient taking dabigatran (Pradaxa®) presents with a life-threatening bleed. The specific monoclonal antibody antidote for this agent is:
- Andexanet alfa
- Idarucizumab
- Vitamin K
- Kcentra®
Answer: Idarucizumab
10. A patient presents with severe bradycardia and hypotension after an overdose of a beta-blocker. In addition to supportive care, what is considered a first-line antidote?
- Sodium bicarbonate
- High-dose insulin euglycemia therapy (HIET)
- Glucagon
- Both B and C are used
Answer: Both B and C are used
11. A patient with severe digoxin toxicity, characterized by life-threatening arrhythmias and hyperkalemia, should be treated with:
- Intravenous calcium gluconate.
- Digoxin immune Fab (DigiFab®).
- Sodium polystyrene sulfonate.
- A beta-blocker.
Answer: Digoxin immune Fab (DigiFab®).
12. Hydroxocobalamin is a key antidote for poisoning with which chemical warfare agent and product of combustion?
- Sarin gas
- Mustard gas
- Cyanide
- Ricin
Answer: Cyanide
13. A patient who ingested a toxic amount of ethylene glycol (antifreeze) is at risk for severe metabolic acidosis and kidney failure. The antidote, fomepizole, works by:
- Chelating the ethylene glycol.
- Inhibiting the enzyme alcohol dehydrogenase, preventing the formation of toxic metabolites.
- Increasing the renal clearance of ethylene glycol.
- Correcting the metabolic acidosis directly.
Answer: Inhibiting the enzyme alcohol dehydrogenase, preventing the formation of toxic metabolites.
14. A patient has developed methemoglobinemia after exposure to a topical anesthetic. The antidote of choice for this condition is:
- Methylene blue.
- Sodium thiosulfate.
- Pralidoxime.
- Deferoxamine.
Answer: Methylene blue.
15. A farm worker is exposed to an organophosphate insecticide and presents with classic cholinergic toxicity (SLUDGE symptoms). In addition to atropine, which agent is given to reactivate cholinesterase?
- Physostigmine
- Pralidoxime (2-PAM)
- Fomepizole
- Hydroxocobalamin
Answer: Pralidoxime (2-PAM)
16. Atropine is a functional antagonist used in organophosphate poisoning to:
- Regenerate the cholinesterase enzyme.
- Block the effects of excess acetylcholine at muscarinic receptors.
- Bind the organophosphate molecule directly.
- Sedate the patient.
Answer: Block the effects of excess acetylcholine at muscarinic receptors.
17. The use of intravenous lipid emulsion (ILE) therapy is an emerging treatment for toxicity caused by:
- Water-soluble drugs.
- Lipophilic drugs, such as local anesthetics and certain psychotropic medications.
- Heavy metals.
- Acetaminophen.
Answer: Lipophilic drugs, such as local anesthetics and certain psychotropic medications.
18. A child has ingested a toxic number of iron tablets. This requires treatment with a chelating agent such as:
- Succimer
- Dimercaprol
- Deferoxamine
- Penicillamine
Answer: Deferoxamine
19. Sodium bicarbonate is used as an antidote in a tricyclic antidepressant (TCA) overdose primarily to:
- Increase the excretion of the drug in the urine.
- Treat the QRS widening and cardiac toxicity by increasing the extracellular sodium concentration.
- Reverse the CNS sedation.
- Both A and B are correct.
Answer: Both A and B are correct.
20. A patient overdoses on a sulfonylurea and develops severe, persistent hypoglycemia. In addition to dextrose, which medication may be given as an antidote to decrease insulin secretion?
- Metformin
- Octreotide
- Glucagon
- Diazoxide
Answer: Octreotide
21. The role of a Poison Control Center in managing toxic exposures is to:
- Provide expert, real-time consultation to the public and healthcare providers.
- Only collect data for research purposes.
- Dispatch emergency medical services.
- Regulate the sale of poisons.
Answer: Provide expert, real-time consultation to the public and healthcare providers.
22. A key leadership role for a hospital pharmacist in toxicology is to:
- Ensure that critical antidotes are stocked and accessible in the pharmacy and/or emergency department.
- Personally administer all antidotes.
- Make all final treatment decisions.
- Manage the hospital’s legal response to an overdose.
Answer: Ensure that critical antidotes are stocked and accessible in the pharmacy and/or emergency department.
23. Physostigmine is a cholinesterase inhibitor that can be used to reverse the central effects of a pure ________ overdose.
- Anticholinergic
- Cholinergic
- Opioid
- Benzodiazepine
Answer: Anticholinergic
24. Chelation therapy is the primary treatment for toxicity from:
- Beta-blockers
- Heavy metals
- Salicylates
- Carbon monoxide
Answer: Heavy metals
25. A pharmacist’s role in a “first response” to a poisoning or overdose at home, before EMS arrives, is to:
- Advise the caller to immediately contact the Poison Control Center and/or 911.
- Recommend a universal home remedy.
- Tell the caller to drive the person to the hospital.
- Ask for the person’s insurance information.
Answer: Advise the caller to immediately contact the Poison Control Center and/or 911.
26. The “toxidrome” approach to a poisoned patient involves:
- Identifying the specific poison based on a lab test.
- Grouping a patient’s signs and symptoms into a recognizable pattern to narrow down the potential toxin.
- A type of antidote.
- A method for gastric decontamination.
Answer: Grouping a patient’s signs and symptoms into a recognizable pattern to narrow down the potential toxin.
27. A patient with methanol poisoning is treated with fomepizole. This is an example of which antidotal mechanism?
- Chemical inactivation
- Receptor antagonism
- Metabolic inhibition
- Chelation
Answer: Metabolic inhibition
28. High-dose insulin euglycemia therapy (HIET) is a treatment for severe calcium channel blocker or beta-blocker overdose. The “euglycemia” part requires the co-administration of:
- Dextrose, to prevent hypoglycemia.
- Glucagon.
- Sodium bicarbonate.
- Potassium.
Answer: Dextrose, to prevent hypoglycemia.
29. A key part of the “forging ahead” mindset for a pharmacist in emergency medicine is:
- Staying up-to-date on new and emerging toxicities and antidotal therapies.
- Relying only on knowledge gained in pharmacy school.
- Avoiding all toxicology-related cases.
- Focusing only on the dispensing of antidotes.
Answer: Staying up-to-date on new and emerging toxicities and antidotal therapies.
30. The ultimate goal of antidotal therapy is to:
- Punish the patient for the overdose.
- Use the most expensive treatment available.
- Reduce morbidity and mortality from a poisoning.
- Test a new and experimental drug.
Answer: Reduce morbidity and mortality from a poisoning.
31. The administration of 100% oxygen is the primary antidote for poisoning with:
- Carbon monoxide
- Cyanide
- Methane
- Sulfur dioxide
Answer: Carbon monoxide
32. The “therapeutic index” is a key toxicological concept. A drug with a narrow therapeutic index is one that:
- Has a high risk of accidental overdose.
- Is very safe at any dose.
- Rarely requires monitoring.
- Has a wide margin of safety.
Answer: Has a high risk of accidental overdose.
33. The pharmacist’s knowledge of __________ is critical for calculating the correct dose of an antidote, especially in pediatric patients.
- Pharmacokinetics and pharmaceutical calculations
- Medicinal chemistry
- Pharmacy history
- Marketing
Answer: Pharmacokinetics and pharmaceutical calculations
34. The use of urine alkalinization with sodium bicarbonate can enhance the elimination of which acidic drug in overdose?
- Opioids
- Benzodiazepines
- Salicylates (aspirin)
- Digoxin
Answer: Salicylates (aspirin)
35. A “disulfiram-like reaction” can be considered a form of toxicity caused by a drug-alcohol interaction. A pharmacist would counsel a patient on which antibiotic to avoid alcohol?
- Amoxicillin
- Metronidazole
- Azithromycin
- Doxycycline
Answer: Metronidazole
36. A pharmacist’s role in the hospital’s disaster preparedness plan includes ensuring the formulary contains antidotes for:
- Common household poisonings only.
- Potential chemical or biological terrorism agents (CBRNE).
- Only medication overdoses.
- Animal bites and stings.
Answer: Potential chemical or biological terrorism agents (CBRNE).
37. Which of the following is an example of a “functional” or “physiologic” antidote?
- Using epinephrine to counteract the bronchoconstriction and hypotension of anaphylaxis.
- Using an antibody to bind a toxin.
- Using a chelator to bind a heavy metal.
- Using a receptor antagonist.
Answer: Using epinephrine to counteract the bronchoconstriction and hypotension of anaphylaxis.
38. The effective use of an “antidote cart” in an emergency department is an application of which principle?
- Human factors engineering, to make critical medications readily accessible and easy to find in an emergency.
- Financial management.
- Marketing.
- Basic dispensing.
Answer: Human factors engineering, to make critical medications readily accessible and easy to find in an emergency.
39. A key skill for a pharmacist on a toxicology rotation or service is the ability to:
- Quickly and efficiently retrieve and evaluate evidence from drug information resources.
- Manually compound all antidotes.
- Diagnose the patient.
- Perform a physical exam.
Answer: Quickly and efficiently retrieve and evaluate evidence from drug information resources.
40. The concept of “toxidrome,” such as the cholinergic toxidrome, is a key part of which step of the patient care process?
- Collect and Assess
- Plan
- Implement
- Follow-up
Answer: Collect and Assess
41. The administration of __________ is the antidote for methotrexate toxicity.
- Folic acid
- Leucovorin (folinic acid)
- Methylene blue
- Cyanocobalamin
Answer: Leucovorin (folinic acid)
42. A pharmacist’s role as a patient advocate in toxicology involves:
- Ensuring a patient who has overdosed receives compassionate, non-judgmental care.
- Reporting the patient to the police.
- Refusing to provide an antidote.
- Blaming the patient for their condition.
Answer: Ensuring a patient who has overdosed receives compassionate, non-judgmental care.
43. The use of a “body packer” case (a person who has ingested packets of illicit drugs) is a toxicological emergency that may require:
- An antidote only.
- Whole bowel irrigation.
- A surgical intervention.
- Both B and C are potential interventions.
Answer: Both B and C are potential interventions.
44. A key leadership role for an emergency medicine pharmacist is to:
- Provide education on toxicology and antidotal therapy to other healthcare professionals.
- Manage the hospital’s budget.
- Hire and fire emergency department staff.
- Set the schedule for the physicians.
Answer: Provide education on toxicology and antidotal therapy to other healthcare professionals.
45. Which of the following is NOT a general mechanism of action for an antidote?
- Receptor antagonism
- Chelation
- Metabolic inhibition
- Potentiation of the toxin’s effect
Answer: Potentiation of the toxin’s effect
46. A pharmacist’s understanding of __________ is crucial for recognizing that a patient’s symptoms may be an adverse drug reaction rather than a new disease.
- Pharmacology and toxicology
- Health economics
- Pharmacy law
- Human resources
Answer: Pharmacology and toxicology
47. Andexanet alfa is a novel reversal agent for which class of anticoagulants?
- Vitamin K antagonists (warfarin)
- Unfractionated heparin
- Direct Factor Xa inhibitors (e.g., apixaban, rivaroxaban)
- Direct thrombin inhibitors (e.g., dabigatran)
Answer: Direct Factor Xa inhibitors (e.g., apixaban, rivaroxaban)
48. Why is it important for a pharmacist to know the formulation and concentration of an antidote?
- To ensure the correct and safe dose is prepared and administered.
- It is not important.
- To be able to bill for the highest possible amount.
- To help the manufacturer with marketing.
Answer: To ensure the correct and safe dose is prepared and administered.
49. An interprofessional team approach is critical in managing a poisoned patient because:
- It requires the coordinated expertise of physicians, nurses, and pharmacists.
- Each profession should work independently.
- The pharmacist is the only team member needed.
- It is a requirement for insurance reimbursement.
Answer: It requires the coordinated expertise of physicians, nurses, and pharmacists.
50. The ultimate reason pharmacists must be experts in antidotal therapy is to:
- Improve patient safety and save lives.
- Increase the use of expensive medications.
- Fulfill a continuing education requirement.
- Make their job more interesting.
Answer: Improve patient safety and save lives.

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
Mail- Sachin@pharmacyfreak.com