Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders Indian Medical PG Practice Questions and MCQs

Question 341: What is the drug of choice for treating delirium tremens?

A. Phenytoin
B. Morphine
C. Lorazepam (Correct Answer)
D. Diazepam

Explanation: ***Lorazepam*** - **Benzodiazepines** are the first-line treatment for **delirium tremens** due to their effectiveness in reducing central nervous system hyperexcitability through GABA-A receptor agonism. - **Lorazepam** is often preferred, especially in patients with liver impairment (common in chronic alcoholics), because it is metabolized by **glucuronidation** rather than hepatic oxidation, making it safer in hepatic dysfunction. - It has an **intermediate half-life (10-20 hours)** with **no active metabolites**, providing predictable pharmacokinetics and easier dose titration. - Can be administered via multiple routes (IV, IM, oral), making it versatile in acute settings. *Diazepam* - Also a **first-line benzodiazepine** for alcohol withdrawal and delirium tremens, particularly effective in patients with normal liver function. - Has a **long half-life (20-100 hours)** with **active metabolites** (desmethyldiazepam), which can accumulate in patients with hepatic impairment, leading to prolonged sedation. - Metabolized by hepatic **oxidation** (CYP450), making it less ideal in liver disease. - The longer duration of action can be advantageous for tapering protocols but may cause excessive sedation in vulnerable patients. *Phenytoin* - **Phenytoin** is an **anticonvulsant** that is **not effective** for treating delirium tremens or alcohol withdrawal seizures as monotherapy. - It does not address the primary pathophysiology of alcohol withdrawal, which involves GABAergic and glutamatergic system imbalance. - May be used as **adjunctive therapy** in patients with concurrent seizure disorders, but benzodiazepines remain the mainstay. *Morphine* - **Morphine** is an **opioid analgesic** with **no role** in the treatment of delirium tremens. - Use of opioids could **worsen respiratory depression**, particularly dangerous in agitated patients with potential for aspiration. - Does not address the neurochemical basis of alcohol withdrawal and may complicate management.

Question 342: Which of the following antipsychotic medications is most commonly used in depot preparation?

A. Haloperidol (Correct Answer)
B. Olanzapine
C. Fluphenazine
D. Risperidone

Explanation: ***Haloperidol*** - **Haloperidol decanoate** is the **most commonly used** depot antipsychotic preparation worldwide - It has been available since the **1970s** and remains the **gold standard** for long-acting injectable antipsychotics - Advantages include **long history of use**, **well-established efficacy**, **wide availability**, and **low cost** - Administered as **intramuscular injection** typically every **2-4 weeks** - Main limitation is higher risk of **extrapyramidal symptoms (EPS)** compared to second-generation depot antipsychotics *Risperidone* - **Risperidone** is available in depot formulations (**Risperdal Consta** - microspheres, **Risperdal Sustenna** - extended-release) - While widely used, it is **not the most common** depot preparation globally - Advantages include being a **second-generation antipsychotic** with lower EPS risk than haloperidol - More expensive than haloperidol decanoate, limiting its use in resource-constrained settings *Olanzapine* - **Olanzapine pamoate** is available as a **long-acting injectable** formulation - Requires mandatory **3-hour post-injection observation** due to risk of **post-injection delirium/sedation syndrome (PDSS)** - This monitoring requirement limits its practical use compared to other depot preparations - Less commonly used than haloperidol or risperidone depot formulations *Fluphenazine* - **Fluphenazine decanoate** is another first-generation antipsychotic available in depot form - Has been used since the 1960s-70s for maintenance therapy in schizophrenia - Similar to haloperidol in terms of EPS risk but less commonly used in current practice

Question 343: Which of the following is an atypical antipsychotic?

A. Clozapine (Correct Answer)
B. Chlorpromazine
C. Thiothixene
D. Haloperidol

Explanation: ***Clozapine*** - **Clozapine** is an **atypical antipsychotic** characterized by its efficacy in treating **refractory schizophrenia** and a lower risk of **extrapyramidal symptoms (EPS)** compared to typical antipsychotics. - Its mechanism involves antagonism of **dopamine D2** and **serotonin 5-HT2A** receptors, as well as several other receptor types. *Chlorpromazine* - **Chlorpromazine** is a **typical (first-generation) antipsychotic**, known for its strong **D2 blockade** and higher incidence of **extrapyramidal side effects**. - It was one of the first antipsychotics developed and is also used for its **antiemetic** properties. *Thiothixene* - **Thiothixene** is a **typical (first-generation) antipsychotic** that primarily acts by blocking **dopamine D2 receptors**. - It is associated with a higher risk of **extrapyramidal symptoms** and other side effects characteristic of typical antipsychotics. *Haloperidol* - **Haloperidol** is a **high-potency typical (first-generation) antipsychotic** with potent **D2 receptor antagonism**. - It is often used for acute psychosis and delirium but carries a significant risk of **extrapyramidal side effects** and **tardive dyskinesia**.

Question 344: Which of the following drugs is not useful in the rehabilitation of alcoholic patients?

A. Acamprosate
B. Rimonabant (Correct Answer)
C. Naltrexone
D. Varenicline

Explanation: Rimonabant - Rimonabant is an inverse agonist of the cannabinoid CB1 receptor that was used as an anti-obesity drug. [1] - It was withdrawn from the market due to significant psychiatric side effects, including depression and suicidal ideation. [1] - Rimonabant has absolutely no role in alcohol rehabilitation and is no longer available for clinical use. Acamprosate - Acamprosate is commonly used in alcohol rehabilitation to reduce alcohol cravings and promote abstinence in detoxified alcohol-dependent individuals. [2] - It is thought to act by restoring the balance between excitation and inhibition in the brain, particularly by modulating glutamate and GABA neurotransmission. - It is FDA-approved for maintenance of alcohol abstinence. Naltrexone - Naltrexone is an opioid receptor antagonist used to reduce alcohol craving and relapse by blocking the pleasurable effects of alcohol. [2], [3] - It is available in both oral and intramuscular long-acting injectable forms and is FDA-approved for alcohol use disorder. [3] - It can also be used for opioid use disorder. [3] Varenicline - Varenicline is a partial agonist of the nicotinic acetylcholine receptor and is primarily FDA-approved for smoking cessation. - Some research has explored its potential for reducing alcohol consumption due to its effects on reward pathways, though it is not FDA-approved for alcohol dependence. - Unlike rimonabant (which is withdrawn and has no role), varenicline has some supporting evidence in alcohol treatment, though it remains off-label use.

Question 345: Which of the following antipsychotics is a partial D2 agonist?

A. Clozapine
B. Quetiapine
C. Ziprasidone
D. Aripiprazole (Correct Answer)

Explanation: Aripiprazole - Aripiprazole is a D2 partial agonist [1][3], meaning it acts as an agonist in areas with low dopamine and an antagonist in areas with high dopamine [3]. - This unique mechanism helps to stabilize dopamine activity, leading to fewer extrapyramidal symptoms and hyperprolactinemia compared to typical antipsychotics. Clozapine - Clozapine is a D2 antagonist with a high affinity for D4 receptors and potent antagonism of 5-HT2A receptors; it is known for its efficacy in treatment-resistant schizophrenia [2]. - It carries a risk of severe side effects such as agranulocytosis [2] and myocarditis, requiring regular blood monitoring. Quetiapine - Quetiapine is primarily a D2 antagonist with significant antagonism at histamine H1 and alpha-1 adrenergic receptors, contributing to its sedative and orthostatic hypotensive effects. - It is known for its relatively low risk of extrapyramidal symptoms due to its rapid dissociation from D2 receptors. Ziprasidone - Ziprasidone is a D2 antagonist and a serotonin 5-HT1A agonist and 5-HT2C antagonist, contributing to its antidepressant and anti-anxiety effects. - It is associated with a risk of QTc prolongation, which necessitates cardiac monitoring in susceptible patients.

Question 346: Which is the mood stabilizer with a narrow therapeutic index?

A. lithium (Correct Answer)
B. valproate
C. lamotrigine
D. carbamazepine

Explanation: Correct Option: Lithium - Lithium has a narrow therapeutic index, meaning there is a small difference between therapeutic and toxic doses (therapeutic range: 0.6-1.2 mEq/L; toxic level: >1.5 mEq/L) [1] - This narrow therapeutic window necessitates frequent monitoring of serum lithium levels and careful dosage adjustments to prevent toxicity while maintaining efficacy in mood stabilization [2] - Common signs of lithium toxicity include tremor, confusion, ataxia, and in severe cases, seizures and renal failure Incorrect Option: Valproate - While valproate is an effective mood stabilizer, its therapeutic index is wider compared to lithium, making it generally safer with less stringent monitoring requirements for toxicity [4] - It's associated with adverse effects like hepatotoxicity and pancreatitis, but acute toxicity from minor dose variations is less common than with lithium Incorrect Option: Carbamazepine - Carbamazepine is an anticonvulsant and mood stabilizer with a wider therapeutic index than lithium, though it requires monitoring for drug interactions and hematologic effects (agranulocytosis, aplastic anemia) [3] - Common side effects include dizziness, ataxia, and hyponatremia, but the risk of severe toxicity from minor dose changes is significantly lower than with lithium [3] Incorrect Option: Lamotrigine - Lamotrigine is a mood stabilizer used for bipolar disorder with a relatively wide therapeutic index, especially when compared to lithium - The most concerning side effect is Stevens-Johnson syndrome, a rare but serious skin rash, which risk is increased by rapid dose escalation; requires slow titration

Question 347: What is the primary use of Naltrexone in the context of opioid dependence?

A. Prevent relapse (Correct Answer)
B. Prevent respiratory depression
C. Treatment of opioid overdose
D. Treat withdrawal symptoms

Explanation: ***Prevent relapse*** - **Naltrexone** is an **opioid antagonist** that blocks opioid receptors, thereby preventing the euphoric and other intoxicating effects of opioids. - This action helps to reduce cravings and deter opioid use, making it a primary medication for **relapse prevention** in individuals with opioid dependence. *Prevent respiratory depression* - Preventing respiratory depression is not the primary use of naltrexone; opioid antagonists like **naloxone** are used to reverse **opioid-induced respiratory depression** in overdose situations. - Naltrexone is used for longer-term management and does not have a direct role in acute respiratory support. *Treatment of opioid overdose* - While both are opioid antagonists, **naloxone** is the drug of choice for immediate **opioid overdose reversal** due to its rapid onset and shorter duration of action. - Naltrexone has a slower onset and longer duration, making it unsuitable for acute overdose treatment. *Treat withdrawal symptoms* - **Naltrexone** is generally *not* used to treat acute opioid withdrawal symptoms because it can precipitate or worsen withdrawal by blocking opioid receptors. - Withdrawal symptoms are typically managed with opioid agonists like **buprenorphine** or other symptomatic treatments.

Question 348: Which of the following is not an antidepressant?

A. Fluoxetine
B. Trazodone
C. Pimozide (Correct Answer)
D. Amitriptyline

Explanation: ***Pimozide*** - **Pimozide** is a **first-generation antipsychotic** medication primarily used to treat **Tourette's syndrome** and chronic severe tics, not depression [1], [2]. - Its mechanism involves blocking **dopamine D2 receptors**, differentiating it from typical antidepressant actions. *Amitriptyline* - **Amitriptyline** is a **tricyclic antidepressant (TCA)** commonly used to treat depression, anxiety, and neuropathic pain [2]. - Its antidepressant effect is due to the **inhibition of serotonin and norepinephrine reuptake** [2]. *Fluoxetine* - **Fluoxetine** is a widely prescribed **selective serotonin reuptake inhibitor (SSRI)**, making it a common antidepressant [2]. - It specifically **blocks the reuptake of serotonin**, leading to increased serotonin levels in the synaptic cleft [2]. *Trazodone* - **Trazodone** is an **antidepressant** with significant sedative properties, often used for depression associated with insomnia. - It acts as a **serotonin antagonist and reuptake inhibitor (SARI)**, with effects on 5-HT2A receptors and serotonin reuptake.

Question 349: Which of the following medications is most commonly associated with causing Neuroleptic Malignant Syndrome (NMS)?

A. Metoclopramide
B. Phenothiazines
C. Haloperidol (Correct Answer)
D. Clozapine

Explanation: ***Haloperidol*** - **Haloperidol** is a potent **first-generation (typical) antipsychotic** (butyrophenone class) that strongly blocks **dopamine D2 receptors**. - This potent D2 antagonism is the primary mechanism underlying the development of **Neuroleptic Malignant Syndrome (NMS)**. - The risk of NMS is **highest** with high-potency typical antipsychotics like haloperidol, especially when initiated at **high doses** or with **rapid dose escalation**. - Haloperidol is the **most commonly cited** individual agent associated with NMS in medical literature. *Phenothiazines* - **Phenothiazines** (e.g., chlorpromazine, fluphenazine) are a class of **first-generation antipsychotics** that also cause NMS due to **dopamine D2 receptor blockade**. - While phenothiazines as a class are associated with NMS, **haloperidol** (a butyrophenone) is considered the **prototypical** and most commonly cited individual drug for NMS. - High-potency phenothiazines (like fluphenazine) carry higher NMS risk than low-potency ones (like chlorpromazine). *Metoclopramide* - Metoclopramide is primarily an **antiemetic** and **prokinetic agent** that has **dopamine-blocking** properties (D2 antagonist). - It has been **rarely** associated with NMS or NMS-like reactions, but this is far less common compared to potent antipsychotics. - Its primary use is for gastrointestinal disorders, not psychiatric conditions. *Clozapine* - **Clozapine** is an **atypical (second-generation) antipsychotic** with relatively **weak D2 receptor affinity** and stronger effects on serotonin receptors. - It has the **lowest risk** of causing NMS among all antipsychotics due to its unique receptor binding profile. - Clozapine is actually sometimes used as an alternative in patients who have experienced NMS with typical antipsychotics.

Question 350: Which drug is the most useful in treating an episode of antipsychotic-induced acute dystonia?

A. Procyclidine
B. Benztropine (Correct Answer)
C. Biperiden
D. Trihexyphenidyl

Explanation: ***Benztropine*** - **Benztropine** is an anticholinergic medication that is the **conventional first-line treatment** for acute dystonic reactions caused by antipsychotics. - It works by blocking muscarinic acetylcholine receptors, thereby restoring the balance between **dopamine** and **acetylcholine** in the basal ganglia. - Can be administered **IV or IM**, providing rapid relief within 15-30 minutes. - Most commonly recommended in standard pharmacology references for Indian medical examinations. *Biperiden* - **Biperiden** is also an effective anticholinergic used for acute dystonia and can be given **IV or IM**. - Has a very rapid onset when given IV (2-5 minutes), making it equally effective for acute episodes. - While both biperiden and benztropine are acceptable first-line agents, **benztropine** is more conventionally cited in standard teaching. *Procyclidine* - **Procyclidine** is another anticholinergic drug used to treat extrapyramidal side effects, including dystonia. - Primarily available as **oral formulation**, making it less suitable for acute emergencies requiring immediate intervention. - More appropriate for maintenance therapy or less severe extrapyramidal symptoms. *Trihexyphenidyl* - **Trihexyphenidyl** is an anticholinergic medication used for drug-induced parkinsonism and dystonia. - Available only in **oral form**, making it unsuitable for acute dystonic crises requiring rapid reversal. - Better suited for chronic management rather than acute emergency treatment.

Practice by Chapter

Antipsychotics: Typical and Atypical

Practice Questions

Antidepressants: SSRIs and SNRIs

Practice Questions

Tricyclic Antidepressants

Practice Questions

MAO Inhibitors

Practice Questions

Mood Stabilizers

Practice Questions

Anxiolytics

Practice Questions

Drugs for ADHD

Practice Questions

Drugs for Sleep Disorders

Practice Questions

Drugs for Dementia

Practice Questions

Drug-Induced Psychiatric Symptoms

Practice Questions

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