Substance Use Disorders — MCQs

Substance Use Disorders Indian Medical PG Practice Questions and MCQs

Question 91: Which of the following drugs is NOT used in the treatment of heroin dependence?

A. Disulfiram (Correct Answer)
B. Buprenorphine
C. Methadone
D. Clonidine

Explanation: ### Explanation The correct answer is **A. Disulfiram**. **Why Disulfiram is the correct answer:** Disulfiram is an aldehyde dehydrogenase inhibitor used exclusively in the treatment of **Alcohol Use Disorder**, not opioid dependence. It works through **aversion therapy**; by preventing the breakdown of acetaldehyde, it causes a highly unpleasant "Disulfiram-ethanol reaction" (flushing, tachycardia, nausea) if the patient consumes alcohol. It has no pharmacological role in managing heroin (opioid) withdrawal or maintenance. **Analysis of incorrect options:** * **B. Buprenorphine:** A **partial mu-opioid agonist**. It is used for both acute detoxification and long-term maintenance therapy in heroin dependence. Its "ceiling effect" makes it safer than full agonists regarding respiratory depression. * **C. Methadone:** A **long-acting full mu-opioid agonist**. It is the gold standard for **Opioid Substitution Therapy (OST)**. It prevents withdrawal symptoms and reduces cravings without producing the intense euphoria associated with heroin. * **D. Clonidine:** An **alpha-2 adrenergic agonist**. It is used to treat the **autonomic symptoms** of opioid withdrawal (e.g., hypertension, tachycardia, sweating, diarrhea). It does not treat cravings but manages the physical distress of "cold turkey" detoxification. **High-Yield Clinical Pearls for NEET-PG:** * **Naltrexone:** An opioid antagonist used for **relapse prevention** in highly motivated patients (must be opioid-free for 7–10 days before starting). * **Lofexidine:** A newer alpha-2 agonist specifically FDA-approved for opioid withdrawal (similar to Clonidine but with less hypotension). * **Drug of Choice for Opioid Overdose:** Intravenous **Naloxone** (pure antagonist). * **Gold Standard for Maintenance:** Methadone (requires specialized clinics due to its long half-life and risk of overdose).

Question 92: Which of the following medications is used to maintain abstinence in alcohol dependence?

A. Naltrexone (Correct Answer)
B. Clonidine
C. Disulfiram
D. Naloxone

Explanation: ### Explanation **Correct Answer: A. Naltrexone** **Why Naltrexone is the Correct Choice:** Naltrexone is an **opioid receptor antagonist** that works by blocking the $\mu$-opioid receptors. In alcohol dependence, it reduces the "reward" or euphoric effects of drinking (the "high") and significantly decreases alcohol cravings. It is considered a first-line agent for **maintaining abstinence** and reducing the frequency of relapse. Unlike Disulfiram, it does not cause a physical reaction if alcohol is consumed, making it better tolerated for long-term use. **Analysis of Incorrect Options:** * **B. Clonidine:** This is an $\alpha_2$-agonist used primarily to manage the **autonomic symptoms of withdrawal** (tachycardia, hypertension, tremors) in opioid or alcohol withdrawal. It does not help in maintaining long-term abstinence. * **C. Disulfiram:** While used in alcohol dependence, it is an **aversive agent** (aldehyde dehydrogenase inhibitor). It causes a severe unpleasant reaction (nausea, flushing, tachycardia) if alcohol is ingested. It does not reduce craving and is generally considered second-line due to poor compliance and safety profile compared to Naltrexone. * **D. Naloxone:** This is a short-acting opioid antagonist used exclusively for the **emergency reversal of acute opioid overdose**. It has no role in the long-term maintenance of alcohol abstinence due to its short half-life and lack of oral bioavailability. **High-Yield NEET-PG Pearls:** * **Acamprosate:** Another first-line drug for abstinence; it is preferred in patients with **liver disease** (Naltrexone is hepatotoxic). * **Disulfiram Reaction:** Caused by the accumulation of **Acetaldehyde**. * **Naltrexone Requirement:** Patients must be opioid-free for 7–10 days before starting Naltrexone to avoid precipitating acute withdrawal. * **Topiramate & Baclofen:** Off-label agents used to reduce alcohol craving.

Question 93: An alcoholic presents with complaints of loss of memory of recent events, impaired insight, confabulation, and dementia of a few months duration. The patient is suffering from:

A. Wernicke's encephalopathy
B. Korsakoff's psychosis (Correct Answer)
C. Delirium tremens
D. Binswanger's disease

Explanation: **Explanation:** The patient is presenting with the classic clinical triad of **Korsakoff’s Psychosis**, a chronic neuropsychiatric condition resulting from severe **Thiamine (Vitamin B1) deficiency**, typically secondary to chronic alcohol use. **Why Korsakoff’s Psychosis is correct:** Korsakoff’s is characterized by **anterograde and retrograde amnesia** (loss of recent memory), **confabulation** (filling memory gaps with fabricated stories), and lack of insight. While often preceded by Wernicke’s Encephalopathy, it is considered the chronic, irreversible stage involving damage to the **mammillary bodies** and dorsomedial nucleus of the thalamus. **Analysis of Incorrect Options:** * **A. Wernicke’s Encephalopathy:** This is the *acute* phase. It is characterized by a different triad: **Ophthalmoplegia/Nystagmus, Ataxia, and Global Confusion**. It is a medical emergency and is reversible with thiamine. * **C. Delirium Tremens:** This is a severe form of **alcohol withdrawal** occurring 48–96 hours after the last drink. It presents with autonomic hyperactivity (tachycardia, hypertension), agitation, and visual hallucinations, rather than chronic memory loss. * **D. Binswanger’s Disease:** Also known as subcortical vascular dementia, it is caused by hypertension and small vessel disease affecting white matter, unrelated to alcohol-induced thiamine deficiency. **High-Yield Clinical Pearls for NEET-PG:** * **Wernicke-Korsakoff Syndrome (WKS):** Wernicke is the acute "neurological" phase; Korsakoff is the chronic "psychiatric" phase. * **Confabulation** is the hallmark sign of Korsakoff’s; the patient is not "lying" but unconsciously compensating for memory loss. * **Management Rule:** Always administer **Thiamine before Glucose** in an alcoholic patient to prevent precipitating Wernicke’s encephalopathy. * **MRI Finding:** Atrophy of the **mammillary bodies** is a pathognomonic sign.

Question 94: What is the mechanism of action of naltrexone in alcohol addiction?

A. Inhibits metabolism of alcohol
B. Blocks opioid receptors (Correct Answer)
C. Affects GABA neurotransmitter system
D. None of the above

Explanation: ### Explanation **Mechanism of Action (The "Why"):** Naltrexone is a long-acting **competitive opioid antagonist**. In alcohol addiction, its efficacy is based on the "endogenous opioid theory." When a person consumes alcohol, it triggers the release of endogenous opioids (endorphins) in the brain. these endorphins bind to **mu-opioid receptors** in the ventral tegmental area, leading to dopamine release in the nucleus accumbens (the reward center). By blocking these opioid receptors, naltrexone prevents the "high" or pleasurable reinforcement associated with drinking, thereby reducing cravings and the likelihood of relapse. **Analysis of Incorrect Options:** * **Option A (Inhibits metabolism):** This describes the mechanism of **Disulfiram**. Disulfiram inhibits the enzyme *aldehyde dehydrogenase*, leading to an accumulation of toxic acetaldehyde, which causes the unpleasant "Disulfiram-ethanol reaction." * **Option C (Affects GABA system):** This primarily describes **Acamprosate**. Acamprosate acts as an NMDA receptor antagonist and a GABA-A receptor agonist, helping to restore the chemical balance in the brain (GABA/Glutamate) that is disrupted by chronic alcohol use. **High-Yield Clinical Pearls for NEET-PG:** * **Indication:** Naltrexone is used for the **maintenance** of abstinence; it is not for acute withdrawal. * **Prerequisite:** Patients must be opioid-free for **7–10 days** before starting naltrexone to avoid precipitating acute opioid withdrawal. * **Contraindication:** It is contraindicated in patients with **acute hepatitis or liver failure** (it is hepatotoxic at high doses). Always check Liver Function Tests (LFTs). * **Vivitrol:** This is the long-acting injectable (monthly) formulation of naltrexone, which improves compliance.

Question 95: What is the primary pharmacological treatment for opioid dependence?

A. Naloxone
B. Naltrexone (Correct Answer)
C. Acamprostate
D. All of the above

Explanation: **Explanation:** The primary pharmacological goal in the long-term management of **Opioid Dependence** is to prevent relapse by blocking the reinforcing effects of opioids. **Why Naltrexone is correct:** Naltrexone is a long-acting **competitive opioid antagonist**. It works by binding to the mu-opioid receptors, effectively blocking the "high" if a patient uses opioids. It is used for **relapse prevention** (maintenance therapy) after the patient has been detoxified and is opioid-free for at least 7–10 days. Its long half-life makes it suitable for daily oral dosing or monthly injectable formulations. **Why other options are incorrect:** * **Naloxone:** While also an opioid antagonist, it has a very short half-life and poor oral bioavailability. It is the drug of choice for **acute opioid overdose** (emergency reversal) but is not used for the long-term treatment of dependence. * **Acamprosate:** This is a NMDA receptor modulator used specifically for the maintenance of abstinence in **Alcohol Dependence**, not opioid dependence. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard for Maintenance:** While Naltrexone is a primary antagonist treatment, **Methadone** (long-acting agonist) and **Buprenorphine** (partial agonist) are also first-line options for Opioid Substitution Therapy (OST). * **Pre-requisite:** Always perform a "Naloxone Challenge Test" before starting Naltrexone; if given while opioids are still in the system, it will precipitate **acute withdrawal syndrome**. * **Clonidine:** Often used to manage the autonomic symptoms of acute opioid withdrawal (e.g., hypertension, tachycardia). * **Pupillary signs:** Opioid overdose presents with **pinpoint pupils** (miosis), whereas withdrawal presents with **mydriasis**.

Question 96: A chronic alcoholic patient, abstinent for two days, presents with nausea, vomiting, dizziness, and generalized tonic-clonic seizures on the third day of abstinence. Which of the following is the most appropriate medication for managing these seizures?

A. Sodium valproate
B. Phenytoin
C. Diazepam (Correct Answer)
D. Carbamazepine

Explanation: ### Explanation **1. Why Diazepam is the Correct Answer:** The patient is experiencing **Alcohol Withdrawal Seizures** (commonly known as "rum fits"). These typically occur 6–48 hours after the last drink, often presenting as generalized tonic-clonic seizures. The underlying pathophysiology involves the sudden removal of alcohol (a GABA agonist and NMDA antagonist), leading to **GABAergic under-activity** and **NMDA over-activity** (glutamate excitability). **Benzodiazepines (BZDs)** like Diazepam or Lorazepam are the drugs of choice because they are cross-tolerant with alcohol; they substitute for alcohol's effect on GABA-A receptors, rapidly increasing the seizure threshold and preventing further episodes or progression to Delirium Tremens. **2. Why Other Options are Incorrect:** * **Phenytoin (Option B):** It is notoriously **ineffective** for alcohol withdrawal seizures. Phenytoin acts on sodium channels, which does not address the GABA/Glutamate imbalance central to withdrawal. * **Sodium Valproate (Option A) & Carbamazepine (Option D):** While these are standard anti-epileptics, they are not indicated for acute withdrawal seizures. Valproate carries a risk of hepatotoxicity (concerning in alcoholics), and Carbamazepine is sometimes used for *maintenance* of abstinence or mild withdrawal, but never for acute seizure management. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** For Alcohol Withdrawal (General/Seizures/Delirium Tremens) = **Benzodiazepines** (Chlordiazepoxide or Diazepam). * **Liver Disease Exception:** If the patient has cirrhosis or liver failure, use **LOT** (Lorazepam, Oxazepam, Temazepam) as they undergo extrahepatic metabolism. * **Seizure Pattern:** Usually occur in clusters; status epilepticus is rare in pure alcohol withdrawal. * **Timeline:** * 6–12 hrs: Insomnia, tremors, anxiety. * 12–24 hrs: Alcoholic Hallucinosis (Visual > Auditory). * **6–48 hrs: Withdrawal Seizures.** * 48–72 hrs: Delirium Tremens (Medical Emergency).

Question 97: In Korsakoff psychosis, which of the following is typically NOT seen?

A. Loss of remote memory (Correct Answer)
B. Loss of recent memory
C. Confabulation
D. The condition is typically irreversible

Explanation: **Explanation:** Korsakoff Psychosis is a chronic neuropsychiatric condition resulting from a deficiency of **Thiamine (Vitamin B1)**, usually following untreated Wernicke’s Encephalopathy. The hallmark of this condition is a profound **anterograde amnesia** (inability to form new memories) and **retrograde amnesia** (loss of memories formed before the onset). **Why Option A is the correct answer:** In Korsakoff Psychosis, memory loss follows **Ribot’s Law**, which states that there is a "time gradient" in memory loss. **Recent memories are lost first**, while **remote (long-term) memories** (e.g., childhood events, basic general knowledge) are typically **preserved**. Therefore, "Loss of remote memory" is NOT a typical feature. **Analysis of Incorrect Options:** * **B. Loss of recent memory:** This is the core feature. Patients have severe impairment in acquiring new information (anterograde amnesia). * **C. Confabulation:** This is a classic compensatory mechanism where the patient fills memory gaps with fabricated, distorted, or misinterpreted stories, believing them to be true. * **D. Irreversibility:** Unlike Wernicke’s Encephalopathy (which is an acute, reversible medical emergency), Korsakoff Psychosis is a chronic stage. Only about 20% of patients show significant recovery; for most, the cognitive deficits are permanent. **NEET-PG High-Yield Pearls:** * **Brain Region Affected:** The **Dorsomedial nucleus of the Thalamus** and the **Mammillary bodies** are the primary sites of lesions. * **Wernicke’s Triad:** Ataxia, Ophthalmoplegia (6th nerve palsy), and Confusion. * **Treatment:** High-dose parenteral Thiamine. **Crucial:** Always administer Thiamine *before* Glucose to prevent precipitating Wernicke’s in a malnourished patient.

Question 98: Which of the following is NOT an anticraving agent for alcohol abuse?

A. Acamprosate
B. Disulfiram (Correct Answer)
C. Topiramate
D. Naltrexone

Explanation: **Explanation:** The distinction between **anticraving agents** and **aversion therapy** is a high-yield concept in alcohol use disorder management. **Why Disulfiram is the correct answer:** Disulfiram is **not** an anticraving agent; it is an **aldehyde dehydrogenase inhibitor** used for **Aversion Therapy**. It works by causing the accumulation of acetaldehyde if alcohol is consumed, leading to the highly unpleasant **Disulfiram-Ethanol Reaction (DER)** (tachycardia, flushing, nausea, and palpitations). It acts as a psychological deterrent rather than reducing the physiological urge (craving) to drink. **Analysis of Incorrect Options:** * **Acamprosate (A):** An NMDA receptor antagonist and GABA-A agonist. It restores the chemical balance in the brain disrupted by chronic alcohol use and is specifically used to maintain abstinence by **reducing cravings**. * **Topiramate (C):** An antiepileptic that modulates glutamate and GABA. Clinical trials have proven its efficacy as an **off-label anticraving agent** that reduces the number of heavy drinking days. * **Naltrexone (D):** An opioid receptor antagonist. It blocks the "reward" or euphoria associated with drinking by inhibiting dopamine release in the nucleus accumbens, thereby **reducing the craving** and the "high." **NEET-PG High-Yield Pearls:** * **Acamprosate** is the drug of choice for patients with **liver disease** (excreted renally). * **Naltrexone** is contraindicated in patients with **acute hepatitis or liver failure**. * **Baclofen** is another emerging anticraving agent, particularly useful in patients with alcoholic liver disease. * **Disulfiram** requires the patient to be highly motivated and must be started only after at least 12–24 hours of abstinence.

Question 99: Neuroadaptation to a drug is the same as which of the following?

A. Physical dependence (Correct Answer)
B. Psychological dependence
C. Addiction
D. Habituation

Explanation: **Explanation:** **Neuroadaptation** refers to the physiological changes that occur in the brain and body in response to the chronic presence of a substance. It is the underlying mechanism of **Physical Dependence**. When the body adapts to a drug, it requires the substance to function "normally." If the drug is abruptly stopped, the body experiences a rebound effect known as **Withdrawal Syndrome**. * **Why Option A is correct:** Physical dependence is defined by the presence of tolerance (needing more drug for the same effect) and withdrawal symptoms. Both are direct results of neuroadaptation at the cellular and receptor levels. * **Why Option B is incorrect:** Psychological dependence (or "craving") refers to the emotional or mental compulsion to use a substance to experience pleasure or avoid discomfort. While it involves the brain's reward system, it is distinct from the physiological neuroadaptation seen in physical dependence. * **Why Option C is incorrect:** Addiction (Substance Use Disorder) is a broader clinical diagnosis characterized by compulsive drug seeking, loss of control, and continued use despite harmful consequences. Physical dependence can exist without addiction (e.g., in patients taking prescribed opioids for chronic pain). * **Why Option D is incorrect:** Habituation is a simpler form of non-associative learning where there is a decrease in response to a repeated stimulus. It does not involve the complex physiological withdrawal seen in neuroadaptation. **High-Yield Clinical Pearls for NEET-PG:** * **Tolerance:** A state where a fixed dose of a drug produces a decreasing effect. * **Cross-tolerance:** When tolerance to one drug (e.g., Alcohol) leads to tolerance to another in the same class (e.g., Benzodiazepines). * **Dual Diagnosis:** The co-occurrence of a substance use disorder and another psychiatric disorder (e.g., Schizophrenia + Alcoholism). * **Key Neurotransmitter:** Dopamine release in the **Nucleus Accumbens** (part of the Mesolimbic pathway) is the final common pathway for the reinforcing properties of most addictive drugs.

Question 100: Which drug is used for smoking cessation?

A. Vareniciline (Correct Answer)
B. Acamprosate
C. Naloxone
D. Sildenafil

Explanation: **Explanation:** **Varenicline** is the correct answer as it is a first-line pharmacological agent for smoking cessation. It acts as a **selective partial agonist at the α4β2 nicotinic acetylcholine receptors** in the brain. Its mechanism is twofold: 1. **Agonist effect:** It provides a low-level release of dopamine, which helps reduce nicotine withdrawal symptoms and cravings. 2. **Antagonist effect:** It blocks nicotine from binding to the receptor, thereby preventing the "reward" or reinforcement associated with smoking if a person relapses. **Analysis of Incorrect Options:** * **B. Acamprosate:** This is used for the maintenance of abstinence in **Alcohol Use Disorder**. It acts as an NMDA receptor antagonist and GABA-A receptor activator to restore the neurochemical balance disrupted by chronic alcohol use. * **C. Naloxone:** An **opioid antagonist** used primarily for the emergency reversal of opioid overdose. It is not used for nicotine addiction. * **D. Sildenafil:** A PDE-5 inhibitor used for the treatment of **Erectile Dysfunction** and Pulmonary Arterial Hypertension. **High-Yield Clinical Pearls for NEET-PG:** * **Varenicline Side Effects:** The most common side effect is **nausea** (minimized by taking it with food). It has also been historically associated with neuropsychiatric symptoms (mood changes, suicidal ideation), though recent studies suggest this risk is lower than previously thought. * **Other Smoking Cessation Drugs:** **Bupropion** (an atypical antidepressant) is another first-line non-nicotine option. It is contraindicated in patients with a history of seizures or eating disorders. * **Nicotine Replacement Therapy (NRT):** Available as gums, patches, lozenges, and inhalers. * **Clonidine and Nortriptyline:** Considered second-line agents for smoking cessation.

Practice by Chapter

Neurobiology of Addiction

Practice Questions

Alcohol Use Disorder

Practice Questions

Opioid Use Disorder

Practice Questions

Cannabis Use Disorder

Practice Questions

Stimulant Use Disorders

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Sedative, Hypnotic, and Anxiolytic Use Disorders

Practice Questions

Tobacco Use Disorder

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Hallucinogen-Related Disorders

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Substance Withdrawal Syndromes

Practice Questions

Pharmacotherapy for Substance Use Disorders

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Psychosocial Interventions

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Dual Diagnosis Management

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