Drugs in Psychiatric Disorders Practice Questions

Q: Which of the following antidepressants is least likely to have sexual side effects?

Mirtazapine. ***Mirtazapine*** - **Mirtazapine** is an atypical antidepressant (NaSSA - Noradrenergic and Specific Serotonergic Antidepressant) that works by blocking alpha-2 adrenergic receptors, enhancing serotonin and norepinephrine release [1]. - It has the **lowest incidence of sexual side effects** among antidepressants because it blocks 5-HT2 and 5-HT3 receptors while avoiding significant 5-HT1A stimulation, which is responsible for sexual dysfunction with SSRIs [1]. - It may even **improve libido** in some cases due to its unique receptor profile and histamine antagonism that can enhance sleep quality. *Amitriptyline* - **Amitriptyline** is a tricyclic antidepressant (TCA) with broad receptor actions, including anticholinergic and antihistaminic effects. - TCAs like amitriptyline can cause **sexual dysfunction** (including erectile dysfunction and decreased libido) due to their anticholinergic properties and effects on multiple neurotransmitter systems, though typically less severe than SSRIs. *Fluoxetine* - **Fluoxetine** is a selective serotonin reuptake inhibitor (SSRI), and while effective for depression, it is associated with a **high incidence of sexual side effects** (30-70% of patients) [2]. - These side effects include **decreased libido**, **anorgasmia**, and **erectile dysfunction**, caused by increased serotonergic activity at 5-HT2 receptors in areas regulating sexual function [2]. *Venlafaxine* - **Venlafaxine** is a serotonin-norepinephrine reuptake inhibitor (SNRI), increasing both serotonin and norepinephrine levels in the brain [1]. - Like SSRIs, SNRIs such as venlafaxine frequently cause **sexual dysfunction**, with common complaints including reduced libido and difficulty achieving orgasm due to enhanced serotonergic neurotransmission [1].

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

lithium. 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

Q: The mechanism of action of haloperidol is the blockade of

Dopamine receptor. ***Dopamine receptor*** - Haloperidol is a **first-generation antipsychotic** that primarily acts as a potent **D2 dopamine receptor antagonist**. - Its therapeutic effects in treating psychosis are largely due to blocking **dopamine D2 receptors** in the mesolimbic pathway, which helps reduce positive symptoms like hallucinations and delusions. *Serotonin receptor* - While some atypical (second-generation) antipsychotics block serotonin receptors (e.g., 5-HT2A), **haloperidol's primary mechanism of action is not serotonin receptor blockade**. - Serotonin receptor antagonism is more associated with the mechanism of action of newer antipsychotics, which also exhibit D2 antagonism but with a different receptor profile. *GABA receptor* - **Haloperidol does not primarily act on GABA receptors**; drugs like benzodiazepines are known for their GABAergic effects. - GABA (gamma-aminobutyric acid) is the main inhibitory neurotransmitter in the brain, and drugs targeting its receptors are typically anxiolytics or sedatives. *Adrenergic receptor* - Although haloperidol can have some weak alpha-1 adrenergic receptor blocking activity, this is a **secondary effect** and not its primary mechanism of action. - Its antipsychotic efficacy is overwhelmingly attributed to its potent **dopamine receptor blockade**.

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

Prevent relapse. ***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.

Q: Which of the following is not an antidepressant?

Pimozide. ***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.

Q: Which of the following drugs causes extrapyramidal symptoms?

Phenothiazines. ***Phenothiazines*** - Phenothiazines are a class of **antipsychotics** that block **dopamine D2 receptors** in the brain. - This blockade, especially in the **nigrostriatal pathway**, can lead to extrapyramidal symptoms such as **dystonia**, **akathisia**, **parkinsonism**, and **tardive dyskinesia**. *Antibiotics* - While some antibiotics (e.g., fluoroquinolones) can cause central nervous system side effects like seizures or confusion, they are **not typically associated** with extrapyramidal symptoms. - Their primary mechanism of action is **antibacterial**, not affecting dopamine pathways in a way that induces these motor side effects. *Salicylates* - Salicylates, such as aspirin, are primarily used for their **anti-inflammatory, analgesic, and antipyretic** effects. - Their side effects mainly involve the **gastrointestinal tract** (e.g., irritation, ulcers) and **bleeding disturbances**, but not extrapyramidal symptoms. *Barbiturates* - Barbiturates are **CNS depressants** that enhance the effects of **GABA**, leading to sedation, hypnosis, and anticonvulsant actions. - Their main side effects include **sedation**, **respiratory depression**, and **tolerance/dependence**, with no direct link to extrapyramidal motor dysfunction.

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

Haloperidol. ***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.

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

Benztropine. ***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.

Q: Which of the following antidepressants causes urine retention?

Imipramine. ***Imipramine*** - Imipramine is a **tricyclic antidepressant (TCA)** with potent **anticholinergic effects** [1] - **Anticholinergic activity** blocks muscarinic receptors in the bladder, causing **urinary retention** by relaxing the detrusor muscle and increasing urethral sphincter tone [1] - TCAs are well-known for causing anticholinergic side effects including dry mouth, constipation, blurred vision, and urinary retention [1] *Fluoxetine (Prozac)* - Fluoxetine is a **selective serotonin reuptake inhibitor (SSRI)** [1] - SSRIs have **minimal anticholinergic activity** and are not typically associated with urinary retention [1] - Side effects are primarily serotonergic (nausea, sexual dysfunction, insomnia) *Bupropion* - Bupropion is a **norepinephrine-dopamine reuptake inhibitor (NDRI)** - Has **minimal anticholinergic effects** and does not typically cause urinary retention - Common side effects include insomnia, agitation, and seizure risk at high doses *Sertraline* - Sertraline is another **selective serotonin reuptake inhibitor (SSRI)** [1] - Like fluoxetine, sertraline has **minimal anticholinergic activity** [1] - Not associated with urinary retention or other anticholinergic side effects

Q: Antipsychotic drug with the least extrapyramidal symptoms?

Clozapine. ***Clozapine***- **Atypical antipsychotics** like clozapine have a **lower affinity for D2 dopamine receptors** and a higher affinity for serotonin 5-HT2A receptors, which contributes to their reduced risk of EPS.- It is known for its effectiveness in **treatment-resistant schizophrenia** and its **low propensity for causing movement disorders** [1, 2].*Pimozide*- **Pimozide** is a **typical antipsychotic** (first-generation) that has a high affinity for D2 dopamine receptors.- This strong D2 antagonism leads to a **higher risk of extrapyramidal symptoms**.*Thioridazine*- **Thioridazine** is a **low-potency typical antipsychotic** that, while having a lower incidence of EPS compared to high-potency typicals, still carries a significant risk [1].- It is associated with other side effects such as **cardiac conduction abnormalities** (e.g., QT prolongation) at higher doses.*Fluphenazine*- **Fluphenazine** is a **high-potency typical antipsychotic** with strong D2 receptor antagonism.- High-potency typical antipsychotics like **Fluphenazine** are known for their **high risk of extrapyramidal symptoms** [1].

Question 1

Which of the following antidepressants is least likely to have sexual side effects?

Accepted Answer

Mirtazapine

Answer

Amitriptyline

Answer

Fluoxetine

Answer

Venlafaxine

Question 2

Which is the mood stabilizer with a narrow therapeutic index?

Accepted Answer

lithium

Answer

valproate

Answer

lamotrigine

Answer

carbamazepine

Question 3

The mechanism of action of haloperidol is the blockade of

Accepted Answer

Dopamine receptor

Answer

Serotonin receptor

Answer

GABA receptor

Answer

Adrenergic receptor

Question 4

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

Accepted Answer

Prevent relapse

Answer

Prevent respiratory depression

Answer

Treatment of opioid overdose

Answer

Treat withdrawal symptoms

Question 5

Which of the following is not an antidepressant?

Accepted Answer

Pimozide

Answer

Fluoxetine

Answer

Trazodone

Answer

Amitriptyline

Question 6

Which of the following drugs causes extrapyramidal symptoms?

Accepted Answer

Phenothiazines

Answer

Antibiotics

Answer

Salicylates

Answer

Barbiturates

Question 7

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

Accepted Answer

Haloperidol

Answer

Metoclopramide

Answer

Phenothiazines

Answer

Clozapine

Question 8

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

Accepted Answer

Benztropine

Answer

Procyclidine

Answer

Biperiden

Answer

Trihexyphenidyl

Question 9

Which of the following antidepressants causes urine retention?

Accepted Answer

Imipramine

Answer

Sertraline

Answer

Bupropion

Answer

Fluoxetine (Prozac)

Question 10

Antipsychotic drug with the least extrapyramidal symptoms?

Accepted Answer

Clozapine

Answer

Pimozide

Answer

Fluphenazine

Answer

Thioridazine

Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders — MCQs

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