Plant and Food Toxins — MCQs
In strychnos nux vomica poisoning, patient:
Which of the following is not commonly recognized as a hepatotoxic drug?
What is the antidote of choice for Belladonna poisoning?
Abrus precatorius poisoning resembles which poison?
Which of these is not a cardiac poison?
A 60-year-old patient with atrial fibrillation is prescribed digoxin. Which of the following is the MOST common EARLY side effect of digoxin?
Most common digoxin-induced arrhythmia is
Muttering delirium is seen with: NEET 13
A 63-year-old woman with long-standing type 2 diabetes, hypertension, osteoarthritis, and controlled systolic congestive heart failure following a previous anterior myocardial infarction presents for a routine office visit. She denies any significant complaints. The patient faithfully takes her glargine insulin, lisinopril, carvedilol, furosemide, and aspirin. On examination, her blood pressure is 122/82 mmHg, pulse is 85 beats per minute, respiratory rate is 14 breaths per minute, with clear lungs, regular heartbeat, and 1+ bilateral pedal edema. Review of her chart reveals a baseline creatinine of 1.5 mg/dL with an estimated glomerular filtration rate of 42 mL/min. Laboratory studies drawn early in the morning of the visit show: sodium 138 mEq/L, potassium 6.0 mEq/L, bicarbonate 15 mEq/L, chloride 120 mEq/L, blood urea nitrogen 20 mg/dL, creatinine 1.8 mg/dL, and glucose 183 mg/dL. Given these findings, what is the most common pathophysiologic scenario leading to a diagnosis of type 4 renal tubular acidosis?
Sine wave in ECG is seen in?
Plant and Food Toxins Indian Medical PG Practice Questions and MCQs
Question 1: In strychnos nux vomica poisoning, patient:
- A. Remains conscious throughout. (Correct Answer)
- B. Develops respiratory failure at end stage
- C. Develops immediate paralysis
- D. Experiences mild drowsiness in 1 h or so
Explanation: ***Remains conscious throughout.*** - Patients poisoned with **strychnine** (from *Strychnos nux-vomica*) maintain **full consciousness** throughout the entire episode, including during the characteristic **tetanic spasms** and convulsions. - This preservation of consciousness is a **pathognomonic feature** of strychnine poisoning and makes the experience particularly distressing as patients are fully aware of the severe muscle contractions and pain. - This distinguishes strychnine poisoning from many other toxicological emergencies where altered consciousness is common. *Develops respiratory failure at end stage* - While **respiratory failure** does occur in severe strychnine poisoning and is indeed the **usual cause of death**, it is a consequence rather than a distinguishing clinical feature. - Death occurs due to **asphyxia** from sustained tetanic spasm of respiratory muscles or from **exhaustion** following repeated convulsions. - However, maintaining consciousness throughout (Option A) is the more characteristic and diagnostically significant feature. *Develops immediate paralysis* - Strychnine acts as a **competitive antagonist of glycine** at inhibitory receptors in the spinal cord and brainstem, blocking inhibitory neurotransmission. - This leads to **unopposed excitation**, causing **exaggerated reflexes**, **muscle rigidity**, and **tetanic spasms** - the opposite of paralysis. - The primary clinical manifestation is **intense muscle spasms** (especially extensor muscles), resulting in **opisthotonos** and **risus sardonicus**. *Experiences mild drowsiness in 1 h or so* - Strychnine poisoning has a **rapid onset** of severe symptoms, typically within **15-30 minutes** of ingestion. - Mild drowsiness is not characteristic; instead, patients are **hyperalert** and fully conscious, experiencing **intense distress** and pain. - The clinical picture includes **muscle stiffness**, **heightened sensory perception**, and **violent spasms** triggered by minor stimuli (sound, light, touch).
Question 2: Which of the following is not commonly recognized as a hepatotoxic drug?
- A. Chlorpropamide
- B. Allopurinol
- C. Streptomycin (Correct Answer)
- D. Halothane
Explanation: ***Streptomycin*** - Streptomycin is primarily associated with **ototoxicity** (vestibular and cochlear damage) and **nephrotoxicity** (kidney damage), not significant hepatotoxicity. - While most drugs can theoretically cause liver injury, streptomycin is not frequently cited as a major hepatotoxin in clinical practice. *Chlorpropamide* - This **sulfonylurea oral hypoglycemic agent** can cause a range of liver injuries, from asymptomatic enzyme elevations to severe **cholestatic hepatitis** or hepatocellular damage. - Its hepatotoxic potential is well-documented, leading to its decreased use compared to newer antidiabetic agents. *Allopurinol* - Allopurinol, used to treat **gout** and hyperuricemia, is known to cause a variety of adverse effects, including **hypersensitivity reactions** that can involve the liver. - It can lead to **hepatocellular injury**, cholestasis, or mixed liver damage, sometimes as part of a severe drug reaction with eosinophilia and systemic symptoms (**DRESS syndrome**). *Halothane* - Halothane is a potent **halogenated inhalational anesthetic** historically associated with a rare but severe form of idiosyncratic liver injury known as **halothane hepatitis**. - This condition involves **massive hepatic necrosis** and has a high mortality rate, leading to its eventual replacement by newer anesthetics.
Question 3: What is the antidote of choice for Belladonna poisoning?
- A. Flumazenil
- B. Disulfiram
- C. Physostigmine (Correct Answer)
- D. Atropine
Explanation: ***Correct: Physostigmine*** - **Physostigmine** is an **acetylcholinesterase inhibitor** that increases acetylcholine levels in the synaptic cleft, effectively reversing the anticholinergic effects of Belladonna poisoning. - It is particularly useful for central nervous system manifestations such as **delirium**, **hallucinations**, and **seizures** associated with Belladonna toxicity. - Physostigmine is preferred because it **crosses the blood-brain barrier**, making it effective for both peripheral and central anticholinergic symptoms. *Incorrect: Flumazenil* - **Flumazenil** is a **benzodiazepine receptor antagonist** used to reverse the sedative effects of benzodiazepine overdose. - It is inappropriate for Belladonna poisoning, which involves **antimuscarinic** effects, not GABAergic effects. *Incorrect: Disulfiram* - **Disulfiram** is used in the treatment of **chronic alcoholism** to produce an unpleasant reaction when alcohol is consumed by inhibiting aldehyde dehydrogenase. - It has no role or antidote activity in cases of **Belladonna poisoning**. *Incorrect: Atropine* - **Atropine** itself is an **anticholinergic agent** that is chemically similar to Belladonna alkaloids (atropine and scopolamine are the main toxic components). - Administering atropine in Belladonna poisoning would **exacerbate the anticholinergic toxidrome** rather than act as an antidote.
Question 4: Abrus precatorius poisoning resembles which poison?
- A. Arsenic
- B. Ricin (Correct Answer)
- C. Cyanide
- D. Thallium
Explanation: ***Ricin*** - The toxic protein in *Abrus precatorius* seeds, **abrin**, is structurally and functionally similar to **ricin** from *Ricinus communis* seeds. - Both abrin and ricin are **ribosome-inactivating proteins**, leading to similar clinical presentations of multi-organ failure. *Arsenic* - Arsenic poisoning primarily affects the GI tract, cardiovascular system, and nervous system, causing symptoms like **rice-water stools** and **garlic odor** on breath. - It works through enzyme inhibition, specifically targeting **pyruvate dehydrogenase**, unlike the ribosome-inactivating mechanism of abrin. *Cyanide* - Cyanide poisoning rapidly impairs **cellular respiration** by inhibiting cytochrome c oxidase, leading to cellular hypoxia and lactic acidosis. - Clinical features include **rapid onset of symptoms**, bright red venous blood, and **almond odor**, which are distinct from abrin poisoning. *Thallium* - Thallium poisoning is characterized by **neurological symptoms** (e.g., severe peripheral neuropathy), **alopecia**, and gastrointestinal distress. - It interferes with potassium channels and ATPase pumps, a different mechanism of toxicity compared to abrin.
Question 5: Which of these is not a cardiac poison?
- A. Aconite
- B. Atropa belladonna (Correct Answer)
- C. Cerbera thevetia
- D. Nicotiana tabacum
Explanation: ***Atropa belladonna*** - This plant primarily contains **atropine** and other **belladonna alkaloids**, which are **anticholinergic** and cause symptoms like dry mouth, dilated pupils, tachycardia, and hallucinations. - While it can cause *tachycardia*, its primary toxic effects are not directly on the cardiac muscle contractility or rhythmicity leading to a **"cardiac poison"** classification (e.g. arrhythmias or heart failure), but rather through autonomic nervous system modulation. *Aconite* - Aconite, derived from the **monkshood plant**, contains **aconitine**, a potent neurotoxin and cardiotoxin. - It causes severe **arrhythmias**, including ventricular fibrillation, which can be rapidly fatal by directly affecting **sodium channels** in myocardial cells. *Cerbera thevetia* - Commonly known as Yellow Oleander, it contains **cardiac glycosides** similar to digoxin. - These glycosides inhibit the **Na+/K+-ATPase pump** in cardiac myocytes, leading to increased intracellular calcium, enhanced contractility, and dose-dependent **arrhythmias** (bradycardia, heart blocks, ventricular arrhythmias). *Nicotiana tabacum* - Tobacco contains **nicotine**, which primarily acts on **nicotinic acetylcholine receptors**. - Acute poisoning can lead to initial stimulation followed by depression of the autonomic ganglia, causing a range of cardiac effects including **tachycardia**, **hypertension**, and **arrhythmias** due to sympathetic nervous system activation.
Question 6: A 60-year-old patient with atrial fibrillation is prescribed digoxin. Which of the following is the MOST common EARLY side effect of digoxin?
- A. Nausea and vomiting (Correct Answer)
- B. Hypertension
- C. Visual disturbances
- D. Hyperkalemia
Explanation: ***Nausea and vomiting*** - **Gastrointestinal symptoms** such as nausea, vomiting, and anorexia are the **most common early signs** of **digoxin toxicity** due to its effect on the **chemoreceptor trigger zone**. - These symptoms can occur even at therapeutic levels, especially in susceptible individuals or with slight increases in concentration. - GI symptoms typically appear **before** other manifestations of toxicity, making them important early warning signs. *Hypertension* - Digoxin primarily affects **cardiac contractility** and **heart rate**, and it is not typically associated with causing **hypertension**. - In fact, digoxin can somewhat lower blood pressure due to its effects on **cardiac output** and **vasodilation** in some circumstances, though this is not its primary mechanism or side effect. *Visual disturbances* - **Visual disturbances**, including blurred vision, halos around lights, and changes in color perception (e.g., **yellow-green halos**), are a classic and **common symptom of digoxin toxicity**. - However, these typically appear **later** than gastrointestinal symptoms and often occur after or concurrently with GI manifestations. - While significant indicators of toxicity, they are not usually the **earliest** warning sign. *Hyperkalemia* - Digoxin inhibits the **Na+/K+-ATPase pump**, which can lead to **intracellular sodium accumulation** and **extracellular potassium accumulation**. However, **hyperkalemia** is primarily seen in cases of **acute, severe digoxin toxicity** or in patients with **renal impairment**. - More commonly, **hypokalemia** can actually potentiate digoxin's effects and increase the risk of toxicity, rather than digoxin directly causing hyperkalemia at therapeutic or mildly toxic levels.
Question 7: Most common digoxin-induced arrhythmia is
- A. Ventricular bigeminy
- B. Atrial Flutter
- C. Ventricular Premature Beats (Correct Answer)
- D. Ventricular Fibrillation
Explanation: ***Ventricular Premature Beats (VPBs)*** - **Most common** digoxin-induced arrhythmia overall, occurring in up to 50-90% of digoxin toxicity cases. - Digoxin increases intracellular calcium through Na+/K+-ATPase inhibition, leading to **increased automaticity** and **delayed afterdepolarizations** that trigger ventricular ectopy. - **Hypokalemia** (common with concurrent diuretic use) significantly increases the risk by enhancing digoxin binding to Na+/K+-ATPase and further elevating intracellular calcium. - VPBs can manifest in various patterns including isolated beats, couplets, or organized patterns like ventricular bigeminy. *Ventricular bigeminy* - While ventricular bigeminy (every other beat is a VPB) is highly **characteristic** and specific for digoxin toxicity, it is a specific *pattern* of VPBs rather than the most common arrhythmia overall. - Represents severe ventricular irritability and indicates significant digoxin effect, but occurs less frequently than isolated VPBs. - When present, it strongly suggests digoxin toxicity and warrants immediate attention. *Ventricular Fibrillation* - A rare but **life-threatening** complication of severe digoxin toxicity. - Usually preceded by other ventricular arrhythmias (VPBs, ventricular tachycardia) and represents advanced toxicity. - Not common enough to be considered the "most common" digoxin-induced arrhythmia. *Atrial Flutter* - Digoxin can cause various atrial arrhythmias, but atrial flutter is relatively uncommon. - The most characteristic **atrial** arrhythmia in digoxin toxicity is **paroxysmal atrial tachycardia (PAT) with AV block**, not atrial flutter. - Digoxin's primary atrial effect is to slow AV nodal conduction, which may actually help control atrial flutter rather than cause it.
Question 8: Muttering delirium is seen with: NEET 13
- A. Datura (Correct Answer)
- B. Castor oil plant
- C. Cocaine (stimulant)
- D. Monkshood (Aconitum)
Explanation: ***Datura*** - **Datura poisoning** is characterized by an **anticholinergic toxidrome**, which includes central nervous system effects like **muttering delirium, hallucinations**, and disorientation. - The patient exhibits features like **dilated pupils, dry mouth, flushed skin**, and **tachycardia** due to the blockage of muscarinic acetylcholine receptors. *Castor oil plant* - The **castor oil plant** contains **ricin**, a potent toxin that causes **gastrointestinal symptoms** (nausea, vomiting, abdominal pain, bloody diarrhea) and eventually multi-organ failure. - It does not typically cause the central nervous system effects like **muttering delirium** seen with Datura poisoning. *Cocaine (stimulant)* - **Cocaine** is a central nervous system stimulant that causes **euphoria, agitation, paranoia, dilated pupils**, and **tachycardia**. - While it can cause psychosis, the specific **muttering delirium** is not its hallmark presentation; instead, it is associated with a hyperadrenergic state. *Monkshood (Aconitum)* - **Monkshood** contains **aconitine**, a neurotoxin that primarily affects cardiac and neurological function, causing **paresthesias, muscle weakness, bradycardia**, and potentially fatal arrhythmias. - It does not typically cause the **muttering delirium** with features of an anticholinergic syndrome.
Question 9: A 63-year-old woman with long-standing type 2 diabetes, hypertension, osteoarthritis, and controlled systolic congestive heart failure following a previous anterior myocardial infarction presents for a routine office visit. She denies any significant complaints. The patient faithfully takes her glargine insulin, lisinopril, carvedilol, furosemide, and aspirin. On examination, her blood pressure is 122/82 mmHg, pulse is 85 beats per minute, respiratory rate is 14 breaths per minute, with clear lungs, regular heartbeat, and 1+ bilateral pedal edema. Review of her chart reveals a baseline creatinine of 1.5 mg/dL with an estimated glomerular filtration rate of 42 mL/min. Laboratory studies drawn early in the morning of the visit show: sodium 138 mEq/L, potassium 6.0 mEq/L, bicarbonate 15 mEq/L, chloride 120 mEq/L, blood urea nitrogen 20 mg/dL, creatinine 1.8 mg/dL, and glucose 183 mg/dL. Given these findings, what is the most common pathophysiologic scenario leading to a diagnosis of type 4 renal tubular acidosis?
- A. The combination of long-standing diabetes and hypertension has led to distal nephron dysfunction inhibiting both acid and potassium secretion. (Correct Answer)
- B. The patient has been overtreated with diuretics leading to intravascular volume depletion and acidosis.
- C. The patient's aspirin use has led to toxicity in the setting of acute kidney injury and hence the metabolic acidosis.
- D. The patient's heart failure may contribute to renal dysfunction due to decreased renal perfusion, leading to the metabolic abnormalities.
Explanation: ### **The combination of long-standing diabetes and hypertension has led to distal nephron dysfunction inhibiting both acid and potassium secretion.** - This patient's laboratory values show **hyperkalemia (6.0 mEq/L)**, **non-anion gap metabolic acidosis (bicarbonate 15 mEq/L)**, and **impaired renal function (creatinine 1.8 mg/dL, baseline 1.5 mg/dL)**, which are characteristic of **Type 4 renal tubular acidosis (RTA)** [1]. - **Type 4 RTA** is typically caused by **hypoaldosteronism** or **renal tubular unresponsiveness to aldosterone**, often seen in patients with long-standing diabetes and hypertension due to damage to the juxtaglomerular apparatus and distal tubules, leading to impaired potassium and acid secretion. ### *The patient has been overtreated with diuretics leading to intravascular volume depletion and acidosis.* - While **diuretic use** can cause electrolyte imbalances, **furosemide** typically causes **hypokalemia** and **metabolic alkalosis**, not hyperkalemia and non-anion gap metabolic acidosis [2]. - The patient's blood pressure is stable (122/82 mmHg) and she has 1+ pedal edema, making severe **volume depletion** unlikely. ### *The patient's aspirin use has led to toxicity in the setting of acute kidney injury and hence the metabolic acidosis.* - **Aspirin toxicity** can cause metabolic acidosis, but it usually presents with a **high anion gap metabolic acidosis** and possibly respiratory alkalosis (due to stimulation of respiratory drive), which is not evident here given the **normal chloride** and **low bicarbonate** indicating a **non-anion gap acidosis** [1]. - While the creatinine has slightly increased, there are no other clear indicators of acute aspirin toxicity, such as tinnitus or altered mental status. ### *The patient's heart failure may contribute to renal dysfunction due to decreased renal perfusion, leading to the metabolic abnormalities.* - While **heart failure** can lead to **renal dysfunction** (cardiorenal syndrome) due to reduced renal perfusion, this typically causes a general decline in GFR and potentially **high anion gap metabolic acidosis** due to accumulation of metabolic waste products. - It does not specifically account for the combination of **hyperkalemia** and **non-anion gap metabolic acidosis** characteristic of Type 4 RTA.
Question 10: Sine wave in ECG is seen in?
- A. Hypokalemia
- B. Hypercalcemia
- C. Hypocalcemia
- D. Hyperkalemia (Correct Answer)
Explanation: ### Hyperkalemia - A **sine wave pattern** on ECG is a severe and late manifestation of **hyperkalemia**, indicating significant cardiac electrical instability [1]. - It results from the fusion of the widened QRS complexes with the tall, peaked T waves, leading to a smooth, almost sinusoidal waveform [1]. *Hypokalemia* - ECG features of hypokalemia typically include **ST depression**, **T wave flattening** or inversion, prominent U waves, and a prolonged QU interval [1]. - It does not cause a sine wave pattern. *Hypercalcemia* - Hypercalcemia primarily causes a **shortening of the QT interval** and may also lead to ST elevation. - It does not produce a sine wave configuration. *Hypocalcemia* - Hypocalcemia characteristically leads to **prolongation of the QT interval** due to lengthening of the ST segment. - A sine wave pattern is not associated with hypocalcemia.
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