Antidotes and Specific Therapies — MCQs
In case of cyanide poisoning, antidote of amyl nitrite is given. This is an example of:
A 3 yrs old child is brought to the emergency room by his parents after they found him having a generalized seizure at home. The child's breath smells of garlic, and he has bloody diarrhea, vomiting, and muscle twitching. Which poison is it likely that this child has encountered?
Antidote for benzodiazepine poisoning: FMGE 10, 13; NEET 14
A child accidentally ingested a fruit from a tree while playing. After the ingestion, he presented with symptoms of restlessness, painful swallowing, photophobia, dry skin, urinary retention, and elevated body temperature. What is the most likely cause of poisoning, and what is the appropriate antidote for it?
Which of these is the best for management of methanol poisoning?
Mees's lines are characteristic of:
The antidote of paracetamol poisoning
A patient presented to the emergency department with an overdose of a drug, exhibiting increased salivation and increased bronchial secretions. On examination, the blood pressure was 88/60 mmHg, and the RBC cholinesterase level was reduced to 50% of normal. What should be the treatment for this individual?
What is the most appropriate initial management for paralysis resulting from organophosphorus poisoning?
A 25-year-old woman is diagnosed with chlamydial cervicitis. Her partner refuses evaluation and treatment. What is the most appropriate approach to partner management?
Antidotes and Specific Therapies Indian Medical PG Practice Questions and MCQs
Question 1: In case of cyanide poisoning, antidote of amyl nitrite is given. This is an example of:
- A. Receptor antagonism
- B. Chemical antagonism (Correct Answer)
- C. Physical antagonism
- D. Physiological antagonism
Explanation: ***Chemical antagonism*** - Amyl nitrite functions by inducing the formation of **methemoglobin**, which has a higher affinity for **cyanide ions** than cytochrome c oxidase. - This effectively sequesters cyanide, rendering it unable to bind to and inhibit the **cytochrome oxidase enzyme**, thus preventing its toxic effects [3]. *Receptor antagonism* - This involves a drug binding to a **receptor** and blocking the action of an **agonist**, without activating the receptor itself [1], [2]. - Amyl nitrite does not exert its effect by binding to a specific receptor and blocking cyanide's action; instead, it directly interacts with cyanide itself. *Physical antagonism* - This type of antagonism involves a drug preventing another drug's action through a **physical property**, such as adsorption or chelation. - While there is an interaction, the formation of methemoglobin and its subsequent binding to cyanide is more precisely described as a chemical reaction rather than a simple physical interaction or adsorption. *Physiological antagonism* - This occurs when two drugs act on **different receptors** or pathways to produce **opposite physiological effects**. - Amyl nitrite does not produce an opposite physiological effect by acting on a different pathway; rather, it directly counteracts the chemical nature of cyanide.
Question 2: A 3 yrs old child is brought to the emergency room by his parents after they found him having a generalized seizure at home. The child's breath smells of garlic, and he has bloody diarrhea, vomiting, and muscle twitching. Which poison is it likely that this child has encountered?
- A. Thallium
- B. Carbon monoxide
- C. Arsenic (Correct Answer)
- D. Lead
Explanation: **Arsenic** - **Arsenic poisoning** in children can present with a combination of **gastrointestinal distress** (bloody diarrhea, vomiting) [1], **neurological symptoms** (seizures, muscle twitching) [1], [3], and a characteristic **garlic-like odor** on the breath [1]. - The rapid onset of severe symptoms, including seizures, is consistent with acute arsenic toxicity [3]. *Thallium* - **Thallium poisoning** typically presents with **hair loss**, painful **neuropathy**, and gastrointestinal upset. - A garlic odor on the breath and acute seizures as prominent initial symptoms are not characteristic of thallium exposure. *Carbon monoxide* - **Carbon monoxide poisoning** would present with symptoms like **headache**, **dizziness**, nausea, and **cherry-red skin** in severe cases, but not a garlic odor or bloody diarrhea. - **Seizures** can occur, but the overall clinical picture, especially the garlic breath and bloody diarrhea, is inconsistent. *Lead* - **Lead poisoning** in children is often chronic, presenting with neurodevelopmental issues, **abdominal pain** (lead colic), **anemia**, and a **"lead line" on the gums** [2]. - While seizures can be a late manifestation of severe lead encephalopathy [2], the acute presentation with garlic breath, bloody diarrhea, and rapid-onset seizures is not typical for lead exposure.
Question 3: Antidote for benzodiazepine poisoning: FMGE 10, 13; NEET 14
- A. Flumazenil (Correct Answer)
- B. Naloxone
- C. Atropine
- D. N-acetyl-cysteine
Explanation: ***Flumazenil*** - **Flumazenil** is a competitive **benzodiazepine receptor antagonist** that can reverse the sedative and other central nervous system effects of benzodiazepines. - It works by blocking benzodiazepines from binding to their receptor sites on the **GABA-A receptor complex**. *Naloxone* - **Naloxone** is a competitive **opioid receptor antagonist** used to reverse opioid overdose. - It has no effect on **benzodiazepine toxicity** as it targets different receptor systems. *Atropine* - **Atropine** is an **anticholinergic drug** used to reverse the effects of **cholinergic poisoning** (e.g., from organophosphates, carbamates) or symptomatic bradycardia. - It works on muscarinic acetylcholine receptors and is not involved in benzodiazepine metabolism or action. *N-acetyl-cysteine* - **N-acetyl-cysteine (NAC)** is primarily used as an antidote for **acetaminophen (paracetamol) poisoning**, where it replenishes glutathione. - It is also used in some cases of mucolysis but has no role in reversing benzodiazepine toxicity.
Question 4: A child accidentally ingested a fruit from a tree while playing. After the ingestion, he presented with symptoms of restlessness, painful swallowing, photophobia, dry skin, urinary retention, and elevated body temperature. What is the most likely cause of poisoning, and what is the appropriate antidote for it?
- A. Datura poisoning & Physostigmine (Correct Answer)
- B. Yellow Oleander poisoning & Atropine
- C. Datura poisoning & Pralidoxime
- D. Organophosphate poisoning & Pralidoxime
- E. Mushroom (Amanita) poisoning & Atropine
Explanation: ***Datura poisoning & Physostigmine*** - The symptoms of **restlessness, painful swallowing, photophobia, dry skin, urinary retention, and elevated body temperature** are classic signs of **anticholinergic toxicity**, which is characteristic of **Datura poisoning**. - **Physostigmine** is an **acetylcholinesterase inhibitor** that increases acetylcholine levels, effectively reversing the anticholinergic effects of Datura. *Yellow Oleander poisoning & Atropine* - **Yellow Oleander poisoning** primarily causes **cardiac effects** (e.g., bradycardia, arrhythmias) due to cardiac glycosides, not the anticholinergic symptoms described. - **Atropine** is an **anticholinergic agent** and would worsen the symptoms of Datura poisoning rather than being an antidote for it. *Datura poisoning & Pralidoxime* - While **Datura poisoning** is correct given the symptoms, **Pralidoxime** is an antidote for **organophosphate poisoning**, acting as a cholinesterase reactivator, and has no efficacy in anticholinergic toxicity. *Organophosphate poisoning & Pralidoxime* - **Organophosphate poisoning** presents with **cholinergic symptoms** (e.g., salivation, lacrimation, urination, defecation, GI upset, emesis, miosis, bronchospasm, bradycardia), which are opposite to the anticholinergic signs seen here. - Although **Pralidoxime** is a correct antidote for organophosphate poisoning, the clinical picture does not support this diagnosis. *Mushroom (Amanita) poisoning & Atropine* - **Certain mushroom poisonings** (e.g., muscarine-containing mushrooms like *Inocybe* and *Clitocybe* species) cause **cholinergic symptoms** (salivation, sweating, miosis, bradycardia), not anticholinergic symptoms. - While **Atropine** would be the correct antidote for muscarinic mushroom poisoning, the clinical presentation here shows anticholinergic toxicity, not cholinergic excess.
Question 5: Which of these is the best for management of methanol poisoning?
- A. Fomepizole (Correct Answer)
- B. Naltrexone
- C. Disulfiram
- D. Acamprosate
Explanation: ***Fomepizole*** - **Fomepizole** is a competitive inhibitor of **alcohol dehydrogenase**, the enzyme responsible for metabolizing methanol into toxic metabolites like formic acid. - By inhibiting this enzyme, it prevents the formation of these toxic metabolites, thereby reducing organ damage and metabolic acidosis in methanol poisoning. *Naltrexone* - **Naltrexone** is an **opioid receptor antagonist** used in the treatment of alcohol and opioid dependence. - It does not have any direct action on the metabolism of methanol or its toxic byproducts. *Disulfiram* - **Disulfiram** inhibits **aldehyde dehydrogenase**, leading to an unpleasant reaction when alcohol is consumed (flushing, nausea, vomiting). - It is used for alcohol cessation and has no role in the management of methanol poisoning. *Acamprosate* - **Acamprosate** is a medication used to reduce alcohol cravings in individuals recovering from alcohol dependence, possibly by modulating **glutamate neurotransmission**. - It does not directly affect the metabolism of methanol or mitigate its toxic effects.
Question 6: Mees's lines are characteristic of:
- A. Lead poisoning
- B. Copper poisoning
- C. Mercury poisoning
- D. Arsenic poisoning (Correct Answer)
Explanation: ***Arsenic poisoning*** - **Mees's lines** are characteristic transverse white bands that appear on the fingernails and toenails, strongly indicative of **arsenic poisoning**. - These lines result from a temporary disruption of nail matrix growth, which occurs during systemic illness or exposure to toxins like arsenic. *Lead poisoning* - **Lead poisoning** is typically associated with **Burton's line** (a blue line on the gums) and neurological symptoms like **foot drop** or **wrist drop**, not Mees's lines. - Other common signs include **abdominal pain** and **anemia**. *Copper poisoning* - **Copper poisoning** can cause **hepatolenticular degeneration** (Wilson's disease if genetic), leading to **Kayser-Fleischer rings** in the eyes, but not Mees's lines. - Acute copper toxicity might present with **nausea, vomiting**, and **diarrhea**. *Mercury poisoning* - **Mercury poisoning** (e.g., Minamata disease) is known for neurological symptoms such as **tremors**, **ataxia**, and **gingivitis**, commonly referred to as **"mad hatter" syndrome**. - It does not specifically manifest **Mees's lines** on the nails.
Question 7: The antidote of paracetamol poisoning
- A. Sodium bicarbonate
- B. Flumazenil
- C. N-acetyl cysteine (Correct Answer)
- D. Naloxone
Explanation: ***N-acetyl cysteine*** - **N-acetyl cysteine (NAC)** is the specific antidote for **paracetamol (acetaminophen)** overdose. - NAC works by replenishing **glutathione stores** in the liver, which are crucial for detoxifying the toxic metabolite **N-acetyl-p-benzoquinone imine (NAPQI)**. *Sodium bicarbonate* - **Sodium bicarbonate** is used to treat **metabolic acidosis** and certain drug overdoses that cause cardiac toxicity, such as tricyclic antidepressants. - It does not have a direct role in detoxifying paracetamol or its metabolites. *Flumazenil* - **Flumazenil** is an antagonist at the **benzodiazepine receptor** and is used to reverse the sedative effects of benzodiazepine overdose. - It has no effect on paracetamol toxicity. *Naloxone* - **Naloxone** is an **opioid receptor antagonist** used to reverse the effects of opioid overdose. - It does not interact with the metabolic pathways or toxic effects of paracetamol.
Question 8: A patient presented to the emergency department with an overdose of a drug, exhibiting increased salivation and increased bronchial secretions. On examination, the blood pressure was 88/60 mmHg, and the RBC cholinesterase level was reduced to 50% of normal. What should be the treatment for this individual?
- A. Atropine (Correct Answer)
- B. Physostigmine
- C. Flumazenil
- D. Neostigmine
Explanation: ***Atropine*** - The patient exhibits symptoms of **cholinergic crisis** (increased salivation, bronchial secretions, hypotension) and reduced RBC esterase, strongly indicative of **organophosphate poisoning**. - **Atropine** is the primary antidote, as it competitively blocks muscarinic acetylcholine receptors, reversing the parasympathetic effects. *Neostigmine* - **Neostigmine** is an **acetylcholinesterase inhibitor**, meaning it would worsen the cholinergic crisis by increasing acetylcholine levels further. - It is used in conditions like **myasthenia gravis** to improve muscle strength, not in organophosphate poisoning. *Flumazenil* - **Flumazenil** is an **antagonist of benzodiazepine receptors** and is used to reverse benzodiazepine overdose. - It has no role in treating organophosphate poisoning or cholinergic symptoms. *Physostigmine* - **Physostigmine** is also an **acetylcholinesterase inhibitor** that can cross the blood-brain barrier. - While it has some ophthalmic uses, it would exacerbate the cholinergic symptoms of organophosphate poisoning due to increased acetylcholine.
Question 9: What is the most appropriate initial management for paralysis resulting from organophosphorus poisoning?
- A. Supportive care, including respiratory support (Correct Answer)
- B. Atropine to counteract muscarinic symptoms
- C. Oximes to reactivate acetylcholinesterase
- D. No specific antidote
Explanation: **Supportive care, including respiratory support** * **Paralysis** in organophosphorus poisoning (OPP) is often due to **nicotinic effects** at the neuromuscular junction, leading to respiratory muscle weakness and failure [2]. * **Respiratory support** through mechanical ventilation is crucial to maintain oxygenation and prevent complications while awaiting the effects of antidotal therapy [1], [2]. * *Atropine to counteract muscarinic symptoms* * **Atropine** primarily blocks **muscarinic receptors**, effectively treating symptoms like bradycardia, bronchorrhea, and miosis [2]. * It does **not reverse the nicotinic effects** responsible for muscle paralysis and respiratory failure. * *Oximes to reactivate acetylcholinesterase* * **Oximes (e.g., pralidoxime)** reactivate **acetylcholinesterase**, thereby addressing the underlying cause of acetylcholine accumulation [2]. * They are most effective if given **early** before irreversible aging of the enzyme occurs, but their effect on established paralysis can be limited without concurrent respiratory support [2]. * *No specific antidote* * This statement is incorrect; **atropine** and **oximes** are specific antidotes for organophosphorus poisoning [2]. * While these antidotes are vital, initial management prioritizing **airway and breathing support** is paramount due to the life-threatening respiratory paralysis [1].
Question 10: A 25-year-old woman is diagnosed with chlamydial cervicitis. Her partner refuses evaluation and treatment. What is the most appropriate approach to partner management?
- A. Counsel patient on condom use only
- B. Withhold treatment until partner presents
- C. Provider referral through health department
- D. Expedited partner therapy (Correct Answer)
Explanation: ***Expedited partner therapy*** - **Expedited Partner Therapy (EPT)** is the evidence-based, internationally recommended approach for partner management when partners refuse evaluation and treatment for **chlamydia** and **gonorrhea**. - EPT involves providing **antibiotic medication** directly to the partner without clinical examination, ensuring immediate treatment and preventing **reinfection** of the index patient and reducing community transmission. *Provider referral through health department* - While **contact tracing** through health departments is valuable for STI control, it may be **time-consuming** and less effective when partners actively refuse treatment. - This approach relies on **persuasion** rather than direct treatment provision, potentially allowing continued transmission during the delay period. *Counsel patient on condom use only* - **Condom counseling** alone does not address the **current chlamydial infection** in the partner, leaving them untreated. - The infected partner can **reinfect** the patient even with condom use due to potential inconsistent usage or condom failure. *Withhold treatment until partner presents* - Withholding treatment is **medically inappropriate** and can lead to serious complications including **pelvic inflammatory disease (PID)**, chronic pelvic pain, and **infertility**. - The index patient requires **immediate antibiotic treatment** regardless of partner cooperation, as delaying treatment puts the patient at risk for ascending infection.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free