Forensic Toxicology Practice Questions

Q: All of the following effects are seen with cocaine except?

Sympatholytic effect. **Explanation:** The correct answer is **D. Sympatholytic effect**. Cocaine is a potent **indirect-acting sympathomimetic** agent. It works by blocking the reuptake of catecholamines (dopamine, norepinephrine, and serotonin) at the synaptic cleft. This leads to an excess of norepinephrine, causing a "sympathomimetic toxidrome" characterized by tachycardia, hypertension, mydriasis, and diaphoresis. Therefore, it has a **sympathomimetic** effect, not a sympatholytic (blocking) one. **Analysis of other options:** * **A. Black pigmentation of the tongue:** Chronic cocaine smokers may develop a characteristic black coating on the dorsum of the tongue, often referred to as "cocaine tongue," likely due to the direct effects of the smoke or contaminants. * **B. Nasal septal perforation:** Cocaine is a powerful vasoconstrictor. When snorted (insufflation), it causes intense local ischemia in the nasal mucosa. Chronic use leads to necrosis of the cartilaginous septum, resulting in perforation. * **C. Freebasing:** This refers to the process of converting cocaine hydrochloride (powder) into a purified, smokable "freebase" form (like crack cocaine) to achieve a more rapid and intense high. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Inhibits reuptake of biogenic amines (Dopamine > NE > 5-HT). * **Cardiac Risk:** Cocaine-induced vasospasm can lead to Myocardial Infarction. **Beta-blockers are contraindicated** in management due to the risk of unopposed alpha-adrenergic stimulation. * **Formication:** A tactile hallucination known as "Cocaine bugs" (Magnan’s sign) where the patient feels insects crawling under the skin. * **Pupils:** Causes **Mydriasis** (dilated pupils), unlike opioids which cause Miosis.

Q: What is the active substance in Hashish?

TetraHydrocannabinol. **Explanation** **Correct Answer: D. TetraHydrocannabinol (THC)** Hashish (Charas) is a resinous extract obtained from the flowering tops of the plant *Cannabis sativa*. The primary psychoactive constituent responsible for the "high" and medicinal effects of all cannabis products is **Delta-9-TetraHydrocannabinol (THC)**. It acts predominantly on CB1 and CB2 receptors in the central nervous system. **Analysis of Incorrect Options:** * **A. Morphine:** This is the principal alkaloid derived from the Opium poppy (*Papaver somniferum*). It is a potent opioid analgesic, not a cannabinoid. * **B. LSD (Lysergic Acid Diethylamide):** A potent semisynthetic psychedelic drug derived from Ergot fungus (*Claviceps purpurea*). It acts primarily on serotonin receptors. * **C. Mescaline:** A naturally occurring hallucinogenic alkaloid found in the Peyote cactus (*Lophophora williamsii*). **High-Yield Clinical Pearls for NEET-PG:** * **Cannabis Products:** Ranked by potency (THC content): **Bhang** (leaves/lowest) < **Ganja** (flower tops) < **Charas/Hashish** (resin/highest). * **Hashish Oil:** The most concentrated form of cannabis. * **Clinical Signs:** Characterized by "Red eyes" (conjunctival injection), increased appetite (munchies), and tachycardia. * **Psychological Effects:** Can cause "Run Amok" (a state of homicidal mania) and "Amotivational Syndrome" (chronic use). * **Test:** The **Duquenois-Levine test** is the chemical screening test used to identify cannabis (shows a violet color in the chloroform layer).

Q: Rhabdomyolysis can be caused by which of the following?

Sea snake venom. **Explanation:** The correct answer is **Sea snake venom (Option A)**. **1. Why Sea Snake Venom is Correct:** Sea snake venom is primarily **myotoxic**. It contains phospholipase A2 and small-molecule toxins that directly damage skeletal muscle fibers, leading to extensive **rhabdomyolysis**. This process releases massive amounts of myoglobin into the bloodstream (myoglobinemia), which is then excreted in the urine (myoglobinuria), often causing acute kidney injury (AKI) due to tubular necrosis. Clinically, patients present with generalized muscle pain, stiffness, and "cola-colored" urine. **2. Why the Other Options are Incorrect:** * **Cobra (Option B) and Krait (Option D):** These are **elapids** whose venom is primarily **neurotoxic**. They act on the neuromuscular junction (Cobra: post-synaptic; Krait: pre-synaptic), leading to muscle paralysis and respiratory failure, but they do not typically cause direct muscle fiber breakdown (rhabdomyolysis). * **Viper (Option C):** Viper venom is primarily **vasculotoxic** and **hemotoxic**. It causes local tissue necrosis, coagulopathy (DIC), and hemorrhages. While severe swelling can occasionally lead to compartment syndrome, the primary mechanism of systemic toxicity is not rhabdomyolysis. **3. High-Yield Clinical Pearls for NEET-PG:** * **Sea Snake Bite:** Characterized by a "painless" bite with a latent period (30 mins to several hours) before the onset of muscle aches and myoglobinuria. * **Diagnosis:** Elevated Serum Creatine Phosphokinase (CPK) levels are the most sensitive indicator of myotoxicity. * **Treatment:** Polyvalent Antisnake Venom (ASV) in India does **not** cover sea snake bites. Specific monovalent antivenom is required. * **Rule of Thumb:** * Elapids (Cobra/Krait) = Neurotoxic * Vipers = Vasculotoxic * Sea Snakes = Myotoxic

Q: Which of the following is true for kraits?

4th infralabial scale is large. To identify venomous snakes in forensic toxicology, specific morphological features of the scales are high-yield diagnostic markers. ### **Explanation of the Correct Answer** **Option C (4th infralabial scale is large)** is the characteristic feature of a **Krait** (*Bungarus* species). In Kraits, the 4th infralabial (lower lip) scale is significantly larger than the others. Additionally, Kraits are identified by a row of enlarged **hexagonal scales** along the mid-dorsal spine and undivided sub-caudal scales. ### **Analysis of Incorrect Options** * **Option A (Pit present near the nostrils):** This is a characteristic of **Vipers** (specifically Pit Vipers like the Crotalinae subfamily). The loreal pit is a thermo-receptive organ located between the eye and the nostril. Kraits are elapids and lack this pit. * **Option B (3rd supralabial scale is large):** This is the classic identification mark for a **Cobra** (*Naja naja*). In Cobras, the 3rd supralabial (upper lip) scale touches both the eye and the nostril. ### **Clinical Pearls for NEET-PG** * **Neurotoxicity:** Kraits are primarily **pre-synaptically neurotoxic**. They prevent the release of Acetylcholine, making their bite often unresponsive to Neostigmine (unlike Cobras, which are post-synaptic). * **The "Silent" Bite:** Krait bites often occur at night while the victim is sleeping. The bite is relatively painless with minimal local swelling, often leading to a "silent" death due to respiratory paralysis. * **Abdominal Pain:** A unique clinical presentation of Krait poisoning is severe abdominal pain, which can mimic an acute abdomen. * **Management:** Polyvalent Anti-Snake Venom (ASV) is the mainstay of treatment. In India, ASV covers the "Big Four": Cobra, Krait, Russell’s Viper, and Saw-scaled Viper.

Q: Acrodynia is also known as:

Both of the above.. **Explanation:** **Acrodynia**, also known as **Pink disease** or **Swift disease**, is a clinical syndrome resulting from chronic exposure to **mercury** (elemental or inorganic). It was historically common in infants exposed to mercurous chloride in teething powders and calomel lotions. 1. **Why the correct answer is right:** * **Pink disease:** This name is derived from the characteristic clinical presentation where the patient’s hands and feet become bright pink, swollen, and painful (erythromelalgia). * **Swift disease:** It is named after Dr. H. Swift, who first described the condition in detail in 1914. * Since both terms are synonymous with Acrodynia, **Option C** is the correct choice. 2. **Analysis of Options:** * **Option A & B:** While both are correct, selecting only one would be incomplete. * **Option D:** Incorrect, as the terminology is well-established in pediatric toxicology. 3. **High-Yield Clinical Pearls for NEET-PG:** * **Pathophysiology:** Mercury inhibits the enzyme *catechol-O-methyltransferase* (COMT), leading to an accumulation of epinephrine and norepinephrine. This causes the characteristic "sympathetic storm." * **Clinical Features (The 6 P’s):** **P**ink skin, **P**aresthesia, **P**uffiness (edema), **P**erspiration (profuse sweating), **P**hotophobia, and **P**ersonality changes (irritability). * **Other features:** Hypertension, hypotonia, and loss of teeth/nails. * **Diagnosis:** Elevated 24-hour urinary mercury levels. * **Treatment:** Removal of the source and chelation therapy using **Succimer (DMSA)** or **Dimercaprol (BAL)**.

Q: Borax is classified as which of the following?

Gastrointestinal irritant. **Explanation:** **Borax (Sodium Borate)** is a white, crystalline powder commonly used in industrial processes and as a household cleaning agent. In forensic toxicology, it is classified as a **Gastrointestinal (GI) Irritant**. 1. **Why the Correct Answer is Right:** When ingested, Borax acts as a local irritant to the mucosal lining of the stomach and intestines. Acute poisoning manifests primarily through GI symptoms, including metallic taste, vomiting, diarrhea (sometimes greenish-blue), and abdominal pain. It is also a systemic toxin that can cause a characteristic "boiled lobster" appearance (erythematous rash) and renal damage. 2. **Why the Other Options are Wrong:** * **Genitourinary irritant:** While Borax is excreted via the kidneys and can cause oliguria or albuminuria, it is not primarily classified as a GU irritant. This category typically refers to substances like Cantharides. * **Ecbolic:** These are agents that stimulate uterine contractions to expel its contents (e.g., Ergot). While Borax has a historical reputation in folk medicine as an abortifacient, it does not possess specific ecbolic properties. * **Emmenagogue:** These are substances that stimulate or increase menstrual flow. Borax is not pharmacologically classified as an emmenagogue. **High-Yield Clinical Pearls for NEET-PG:** * **Boiled Lobster Appearance:** A pathognomonic sign of chronic or severe acute borate poisoning characterized by intense desquamative erythroderma. * **Fatal Dose:** Approximately 15–20 grams in adults; 3–6 grams in infants. * **Uses in Crime:** Occasionally used as an **abortifacient** (by local application to the cervix via "abortion sticks") or as a weak antiseptic. * **Post-mortem finding:** Hemorrhagic gastro-enteritis and fatty changes in the liver and kidneys.

Q: Bright red color on postmortem staining is found in poisoning by which of the following?

Hydrogen cyanide (HCN). **Explanation:** The color of postmortem staining (livor mortis) is determined by the state of hemoglobin in the dermal capillaries after death. **Why Hydrogen Cyanide (HCN) is correct:** In cyanide poisoning, the toxin inhibits the enzyme **cytochrome oxidase**, preventing cells from utilizing oxygen (histotoxic hypoxia). Consequently, the venous blood remains highly oxygenated. The presence of high levels of **oxyhemoglobin** in the tissues gives the postmortem staining a characteristic **bright cherry-red** or pinkish appearance. **Analysis of Incorrect Options:** * **Carbon Monoxide (CO):** While CO also produces a "cherry-red" discoloration, it is due to the formation of **carboxyhemoglobin**. In many exams, if both are present, HCN is specifically associated with a "bright red" or "pink" hue, whereas CO is the classic "cherry-red." However, in this specific question context, HCN is the designated answer. * **Hydrogen Sulfide (H2S):** This typically produces a **bluish-green** or dark discoloration due to the formation of sulfhemoglobin. * **Phosphorus (P):** Acute phosphorus poisoning usually results in **dark brown** staining, often associated with jaundice and "luminous" vomitus. **High-Yield Clinical Pearls for NEET-PG:** * **Cherry Red:** CO poisoning (Carboxyhemoglobin). * **Bright Red/Pink:** Cyanide (Oxyhemoglobin). * **Chocolate Brown:** Nitrates, Aniline, Nitrobenzene (Methemoglobinemia). * **Blue-Green:** Hydrogen Sulfide. * **Deep Blue/Violet:** Asphyxial deaths. * **Yellow:** Phosphorus, Copper sulfate (due to jaundice/hemolysis). **Key Concept:** Always differentiate between CO and Cyanide by the mechanism—CO binds to hemoglobin (displacing O2), while Cyanide prevents O2 utilization at the cellular level (leaving O2 bound to hemoglobin).

Q: What is the characteristic postmortem finding of carbolic acid poisoning?

Brown leathery stomach. **Explanation:** **Carbolic acid (Phenol)** is a corrosive organic acid. Unlike mineral acids that cause liquefactive or coagulative necrosis with significant tissue destruction, phenol has a unique **hygroscopic and anesthetic effect**. 1. **Why "Brown leathery stomach" is correct:** Phenol acts as a local anesthetic and a powerful dehydrating agent. When ingested, it fixes the gastric mucosa, turning it **tough, corrugated, and leathery**. The color typically ranges from grayish-white to **dark brown** due to the formation of acid hematin and the chemical fixing of proteins. This "leathery" texture is a hallmark diagnostic feature in forensic autopsies. 2. **Why other options are incorrect:** * **Greenish stomach:** This is characteristic of **Ferrous Sulfate** or certain copper salts (Blue-green). * **Yellow charred stomach:** This is the classic finding in **Nitric Acid** poisoning due to the *xanthoproteic reaction* with tissue proteins. * **Black charred stomach:** This is seen in **Sulfuric Acid** poisoning, where intense dehydration and carbonization of tissues occur. **High-Yield Clinical Pearls for NEET-PG:** * **Odor:** A characteristic **"phenolic" or "carbolic" odor** (like hospital disinfectant) is present at the mouth and in the internal organs. * **Urine:** **Carboluria** – the urine turns **greenish-black** on standing due to the oxidation of metabolites (hydroquinone and pyrocatechol). * **Skin:** It causes **painless white corrosive burns** (due to its local anesthetic property). * **Antidote:** No specific antidote; gastric lavage is done cautiously with lukewarm water or olive oil (which dissolves phenol). Avoid alcohol as it hastens absorption.

Q: Increasing doses of alcohol depress brain function in which of the following orders?

Frontal lobe, Occipital lobe, Cerebellum. **Explanation:** Alcohol (Ethanol) is a CNS depressant that follows a **descending pattern of depression**, affecting the brain from the highest evolutionary functions (cortical) to the most primitive (medullary). The order of depression is determined by the sensitivity of specific brain regions to increasing Blood Alcohol Concentrations (BAC). 1. **Frontal Lobe (First):** This area is most sensitive. Depression leads to the loss of "inhibitory control," resulting in euphoria, talkativeness, and loss of social judgment. 2. **Occipital Lobe (Second):** As doses increase, the visual cortex is affected, leading to blurred vision, diplopia (double vision), and altered depth perception. 3. **Cerebellum (Third):** Higher concentrations affect motor coordination, resulting in the classic signs of ataxia, slurred speech, and loss of equilibrium. 4. **Medulla (Last):** At toxic levels, the vital centers (respiratory and vasomotor) are depressed, which can lead to coma and death. **Analysis of Incorrect Options:** * **Options A & D:** Incorrect because the cerebellum is affected much later than the frontal cortex. Ataxia usually occurs after the initial stage of disinhibition. * **Option B:** Incorrect because visual disturbances (Occipital) typically precede the gross motor incoordination (Cerebellar) seen in severe intoxication. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Alcohol enhances **GABA-A** receptors (increasing Cl- conductance) and inhibits **NMDA** (Glutamate) receptors. * **Metabolism:** Follows **Zero-order kinetics** (constant amount metabolized per unit time). * **Wernicke-Korsakoff Syndrome:** Caused by Thiamine (B1) deficiency; characterized by the triad of Ataxia, Ophthalmoplegia, and Confusion. * **Legal Limit:** In India, the legal limit for driving is **30 mg/100 ml** of blood.

Question 1

All of the following effects are seen with cocaine except?

Accepted Answer

Sympatholytic effect

Answer

Black pigmentation of the tongue

Answer

Nasal septal perforation

Answer

Freebasing

Question 2

What is the active substance in Hashish?

Accepted Answer

TetraHydrocannabinol

Answer

Morphine

Answer

LSD

Answer

Mescaline

Question 3

Rhabdomyolysis can be caused by which of the following?

Accepted Answer

Sea snake venom

Answer

Cobra venom

Answer

Viper venom

Answer

Krait venom

Question 4

Which of the following is true for kraits?

Accepted Answer

4th infralabial scale is large

Answer

Pit present near the nostrils

Answer

3rd supralabial scale is large

Answer

All of the above

Question 5

Acrodynia is also known as:

Accepted Answer

Both of the above.

Answer

Pink disease.

Answer

Swift disease.

Answer

None.

Question 6

A young child ingests silver polish by accident, which contains cyanide. For a patient with toxic cyanide ingestion, what is the most likely clinical effect?

Accepted Answer

Combines with cytochromes and catalase to block hydrogen and electron transport, thus producing tissue asphyxia.

Answer

Methemoglobinemia.

Answer

Vertigo, hyperventilation, tinnitus, and deafness.

Answer

Bone marrow depression.

Question 7

Borax is classified as which of the following?

Accepted Answer

Gastrointestinal irritant

Answer

Genitourinary irritant

Answer

Ecbolic

Answer

Emmenagogue

Question 8

Bright red color on postmortem staining is found in poisoning by which of the following?

Accepted Answer

Hydrogen cyanide (HCN)

Answer

Carbon monoxide (CO)

Answer

Hydrogen sulfide (H2S)

Answer

Phosphorus (P)

Question 9

What is the characteristic postmortem finding of carbolic acid poisoning?

Accepted Answer

Brown leathery stomach

Answer

Greenish stomach

Answer

Yellow charred stomach

Answer

Black charred stomach

Question 10

Increasing doses of alcohol depress brain function in which of the following orders?

Accepted Answer

Frontal lobe, Occipital lobe, Cerebellum

Answer

Cerebellum, Frontal lobe, Occipital lobe

Answer

Frontal lobe, Cerebellum, Occipital lobe

Answer

Cerebellum, Occipital lobe, Frontal lobe

Forensic Toxicology — MCQs

Forensic Toxicology — MCQs

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