Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders Indian Medical PG Practice Questions and MCQs

Question 11: Which of the following drugs causes sedation but no extrapyramidal side effects?

A. Clozapine (Correct Answer)
B. Pimozide
C. Fluphenazine
D. Haloperidol

Explanation: **Explanation:** The question tests the distinction between **Typical (First-generation)** and **Atypical (Second-generation)** antipsychotics regarding their side-effect profiles. **1. Why Clozapine is correct:** Clozapine is the prototype **Atypical Antipsychotic**. Its mechanism involves weak D2 receptor blockade and potent 5-HT2A antagonism. Because it has low affinity for D2 receptors in the nigrostriatal pathway and dissociates rapidly from them, it is unique for causing **virtually no Extrapyramidal Side Effects (EPS)**. However, it possesses strong H1-histaminergic and alpha-adrenergic blocking properties, leading to significant **sedation**. **2. Why the other options are incorrect:** * **Haloperidol & Fluphenazine:** These are high-potency Typical Antipsychotics. They cause strong D2 blockade in the nigrostriatal pathway, leading to a very high incidence of EPS (dystonia, akathisia, parkinsonism). While they can cause some sedation, their hallmark is motor side effects. * **Pimozide:** This is another Typical Antipsychotic (diphenylbutylpiperidine class) primarily used for Tourette’s syndrome. Like Haloperidol, it carries a significant risk of EPS and is associated with QTc prolongation. **3. High-Yield NEET-PG Pearls:** * **Clozapine Gold Standards:** It is the drug of choice for **treatment-resistant schizophrenia** and schizophrenia associated with suicidal behavior. * **Adverse Effects:** While it lacks EPS, it is notorious for **Agranulocytosis** (requires mandatory WBC monitoring), seizures (dose-dependent), myocarditis, and significant weight gain/metabolic syndrome. * **Sialorrhea:** Paradoxically, Clozapine causes excessive salivation (wet pillow sign) despite having anticholinergic properties at other sites.

Question 12: Which of the following is NOT an anxiolytic drug?

A. Melatonin (Correct Answer)
B. Haloperidol
C. Alprazolam
D. Sertraline

Explanation: The correct answer is **A. Melatonin**. Melatonin is a hormone produced by the pineal gland that regulates the sleep-wake cycle (circadian rhythm). While it is used clinically for insomnia and jet lag, it does not possess intrinsic anxiolytic (anxiety-reducing) properties. **Analysis of Options:** * **Alprazolam (Option C):** A Benzodiazepine (BZD) that acts as a positive allosteric modulator of the $GABA_A$ receptor. It is a first-line agent for the acute management of generalized anxiety disorder (GAD) and panic disorder [1]. * **Sertraline (Option D):** A Selective Serotonin Reuptake Inhibitor (SSRI). SSRIs are considered the gold standard for long-term pharmacological management of various anxiety disorders, including Social Anxiety and OCD [1, 2]. * **Haloperidol (Option B):** A typical antipsychotic (D2 blocker). While primarily used for schizophrenia, it is frequently used "off-label" in acute clinical settings to manage severe agitation and anxiety associated with psychosis or delirium. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** For **Performance Anxiety** (e.g., stage fright), the DOC is **Propranolol** (Beta-blocker), taken 30-60 minutes before the event. * **Acute vs. Chronic:** Benzodiazepines (like Alprazolam) are used for immediate relief, while SSRIs (like Sertraline) are preferred for maintenance due to the lack of dependence potential [1]. * **Buspirone:** A selective $5-HT_{1A}$ partial agonist used for GAD; it is unique because it lacks sedative, hypnotic, or muscle relaxant properties and has no abuse potential [2, 3]. * **Melatonin Agonists:** Drugs like **Ramelteon** and **Tasimelteon** are used for insomnia but, like melatonin, are not classified as anxiolytics.

Question 13: Buspirone as compared to benzodiazepines:

A. Is a more potent anticonvulsant
B. Does not interfere with GABAergic transmission (Correct Answer)
C. Is more effective in severe anxiety with panic attacks
D. Produces significantly more sedation

Explanation: **Explanation:** **Mechanism of Action (The Core Concept):** Buspirone is a non-benzodiazepine anxiolytic that acts as a **selective partial agonist at 5-HT1A receptors** [1], [2]. Unlike Benzodiazepines (BZDs), which act as positive allosteric modulators of the GABA-A receptor complex to enhance GABAergic inhibition [2], Buspirone has **no affinity for GABA receptors** [1]. Therefore, it does not interfere with GABAergic transmission, making Option B the correct answer. **Analysis of Incorrect Options:** * **Option A:** Buspirone lacks anticonvulsant and muscle relaxant properties [1]. BZDs are the drugs of choice for acute seizures (e.g., Diazepam, Lorazepam). * **Option C:** Buspirone has a slow onset of action (taking 2–4 weeks for effect) [1], [2]. It is ineffective in acute anxiety or panic attacks [1], where BZDs or SSRIs are preferred [3]. It is primarily used for Generalized Anxiety Disorder (GAD) [1], [2]. * **Option D:** One of the primary clinical advantages of Buspirone is that it **lacks sedative, hypnotic, and cognitive-impairing effects** [1], [2]. It does not cause psychomotor impairment or "hangover" effects common with BZDs [1], [2]. **High-Yield Clinical Pearls for NEET-PG:** * **No Interaction with Alcohol:** Unlike BZDs, Buspirone does not potentiate the effects of CNS depressants like alcohol [2]. * **No Dependence:** It has no abuse potential and does not cause withdrawal symptoms or rebound anxiety upon discontinuation [1]. * **Driving Safety:** It is preferred for patients whose occupations require high mental alertness (e.g., pilots, drivers). * **Metabolism:** It is metabolized by **CYP3A4**; its levels can increase significantly if taken with grapefruit juice or erythromycin.

Question 14: Which of the following is a Selective Serotonin Reuptake Inhibitor (SSRI)?

A. clomipramine
B. fluoxetine (Correct Answer)
C. milnacipran
D. trazadone

Explanation: **Explanation:** **Fluoxetine** is the correct answer as it is a prototypical **Selective Serotonin Reuptake Inhibitor (SSRI)**. SSRIs work by selectively inhibiting the presynaptic reuptake transporter (SERT), thereby increasing the concentration of serotonin in the synaptic cleft. They are currently the first-line treatment for Depression, Panic Disorder, OCD, and Social Phobia due to their favorable side-effect profile compared to older antidepressants. **Analysis of Incorrect Options:** * **A. Clomipramine:** This is a **Tricyclic Antidepressant (TCA)**. While it is highly potent in inhibiting serotonin reuptake (often used for OCD), it also affects norepinephrine reuptake and blocks muscarinic, histaminic, and alpha-adrenergic receptors, leading to more side effects than SSRIs. * **C. Milnacipran:** This belongs to the **SNRI (Serotonin-Norepinephrine Reuptake Inhibitor)** class. It inhibits the reuptake of both serotonin and norepinephrine. * **D. Trazodone:** This is a **SARI (Serotonin Antagonist and Reuptake Inhibitor)**. It primarily blocks 5-HT2A receptors and has significant sedative properties. **High-Yield Clinical Pearls for NEET-PG:** * **Fluoxetine** has the longest half-life among SSRIs (due to its active metabolite, norfluoxetine), making it the drug of choice for patients with poor compliance as it has the lowest risk of discontinuation syndrome. * **Drug of choice (DOC):** SSRIs are the DOC for most anxiety disorders and OCD. * **Side Effects:** Common side effects include GI upset and sexual dysfunction. A rare but life-threatening complication is **Serotonin Syndrome** (hyperthermia, rigidity, myoclonus) when combined with MAO inhibitors. * **Fluvoxamine** is specifically preferred for OCD.

Question 15: What is a common side effect of SSRIs?

A. Nausea
B. Diarrhea
C. Weight gain (Correct Answer)
D. Rash

Explanation: **Explanation:** Selective Serotonin Reuptake Inhibitors (SSRIs) are first-line agents for depression and anxiety. While they have a better safety profile than TCAs, they are associated with specific metabolic and gastrointestinal side effects. **Why Weight Gain is Correct:** While SSRIs may cause initial weight loss due to nausea and anorexia, **long-term use** (especially beyond 6 months) is frequently associated with significant **weight gain**. This is attributed to increased appetite, changes in metabolic rate, and improved mood leading to better food intake. Among SSRIs, **Paroxetine** is most notorious for weight gain, whereas Fluoxetine is the least likely. **Analysis of Incorrect Options:** * **A & B (Nausea and Diarrhea):** These are very common **early/acute** side effects of SSRIs due to the stimulation of 5-HT3 receptors in the GI tract. However, they are usually transient and resolve within 1–2 weeks as receptors downregulate. In the context of chronic therapy and NEET-PG patterns, weight gain is a more persistent clinical concern. * **D (Rash):** While any drug can cause a hypersensitivity reaction, a rash is not a characteristic or "common" side effect specific to the mechanism of SSRIs. **High-Yield Clinical Pearls for NEET-PG:** * **Sexual Dysfunction:** The most common *long-term* reason for non-compliance (presents as decreased libido or delayed ejaculation). * **Drug of Choice:** SSRIs are the DOC for OCD, Panic Disorder, GAD, and PTSD. * **Discontinuation Syndrome:** Abrupt withdrawal (especially with Paroxetine) causes "flu-like" symptoms and "electric shock" sensations. * **Serotonin Syndrome:** Characterized by the triad of cognitive changes, autonomic hyperactivity, and neuromuscular hyperactivity (clonus/hyperreflexia).

Question 16: Which of the following is a selective serotonin and norepinephrine reuptake inhibitor?

A. Fluoxetine
B. Venlafaxine (Correct Answer)
C. Selegiline
D. Aripiprazole

Explanation: **Explanation:** **Venlafaxine** is the correct answer because it belongs to the class of **Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs)** [1], [2]. These drugs work by inhibiting the transporters for both serotonin (5-HT) and norepinephrine (NE), thereby increasing the synaptic concentration of both neurotransmitters [1], [3]. At lower doses, venlafaxine primarily inhibits serotonin reuptake, while at higher doses, its effect on norepinephrine becomes more pronounced [2], [3]. **Analysis of Incorrect Options:** * **A. Fluoxetine:** This is a **Selective Serotonin Reuptake Inhibitor (SSRI)** [1], [3]. It selectively inhibits the reuptake of serotonin with minimal effect on norepinephrine or dopamine. * **C. Selegiline:** This is a **MAO-B inhibitor** (Monoamine Oxidase-B inhibitor). It is primarily used in Parkinson’s disease to prevent the breakdown of dopamine. At higher doses, it can act as a non-selective MAO inhibitor used for depression. * **D. Aripiprazole:** This is an **Atypical Antipsychotic**. It acts as a partial agonist at $D_2$ and $5-HT_{1A}$ receptors and an antagonist at $5-HT_{2A}$ receptors. **High-Yield Clinical Pearls for NEET-PG:** * **SNRIs include:** Venlafaxine, Desvenlafaxine, Duloxetine, and Milnacipran [1], [2]. * **Duloxetine** is specifically preferred in patients with comorbid **neuropathic pain** or fibromyalgia [3]. * **Side Effect Profile:** Because SNRIs increase norepinephrine, they can cause a dose-dependent **increase in blood pressure** (hypertension) and heart rate. * **Venlafaxine** has a short half-life; abrupt discontinuation often leads to a significant **withdrawal syndrome** (dizziness, electric shock-like sensations).

Question 17: Which of the following is a tricyclic antidepressant (TCA)?

A. Amoxapine (Correct Answer)
B. Citalopram
C. Venlafaxine
D. Bupropion

Explanation: ### Explanation **Correct Option: A. Amoxapine** Amoxapine is a **Tricyclic Antidepressant (TCA)** belonging to the dibenzoxazepine subclass. While it acts by inhibiting the reuptake of norepinephrine and serotonin, it is unique among TCAs because its metabolite (7-hydroxyamoxapine) possesses **dopamine (D2) receptor blocking activity**. This gives it mild antipsychotic properties but also increases the risk of extrapyramidal side effects (EPS). **Incorrect Options:** * **B. Citalopram:** This is a **Selective Serotonin Reuptake Inhibitor (SSRI)**. SSRIs are currently the first-line treatment for depression due to their better safety profile and lower side-effect burden compared to TCAs. * **C. Venlafaxine:** This is a **Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)**. It inhibits the reuptake of both neurotransmitters but lacks the significant antihistaminic and anticholinergic effects seen with TCAs. * **D. Bupropion:** This is an **Atypical Antidepressant** that acts as a Norepinephrine-Dopamine Reuptake Inhibitor (NDRI). It is notably used for smoking cessation and has a lower risk of causing sexual dysfunction or weight gain. **High-Yield Clinical Pearls for NEET-PG:** * **Classification Tip:** TCAs are divided into Tertiary amines (Amitriptyline, Imipramine, Clomipramine) and Secondary amines (Nortriptyline, Desipramine). * **Amoxapine Unique Fact:** It is the TCA most likely to cause **Extrapyramidal Symptoms (EPS)** and tardive dyskinesia due to D2 blockade. * **TCA Toxicity:** The "3 Cs" of TCA overdose are **C**oma, **C**onvulsions, and **C**ardiotoxicity (arrhythmias due to Na+ channel blockade). The antidote for cardiotoxicity is Sodium Bicarbonate. * **Clomipramine:** The most serotonin-selective TCA; it is the drug of choice for Obsessive-Compulsive Disorder (OCD) among TCAs.

Question 18: 5-HT1A partial agonists are used as which class of drugs?

A. Anti-anxiety drugs (Correct Answer)
B. Antipsychotic drugs
C. Anti-reflux medications
D. Anti-emetic drugs

Explanation: **Explanation:** The correct answer is **Anti-anxiety drugs**. **Buspirone**, along with its derivatives Gepirone and Ipsapirone, acts as a **selective 5-HT1A receptor partial agonist**. By binding to these presynaptic and postsynaptic receptors in the raphe nuclei and hippocampus, these drugs modulate serotonin neurotransmission to produce anxiolytic effects. Unlike benzodiazepines, they do not interact with GABA receptors, meaning they lack sedative, hypnotic, anticonvulsant, or muscle-relaxant properties. **Why other options are incorrect:** * **Antipsychotic drugs:** These primarily target Dopamine (D2) receptors and 5-HT2A receptors (in the case of atypicals). While some atypicals have 5-HT1A activity, it is not their defining mechanism. * **Anti-reflux medications:** These typically involve Proton Pump Inhibitors (PPIs) or H2 blockers. However, **Mosapride** (a prokinetic) is a 5-HT4 agonist, not a 5-HT1A agonist. * **Anti-emetic drugs:** These are typically **5-HT3 antagonists** (e.g., Ondansetron) or D2 antagonists (e.g., Metoclopramide). **High-Yield Clinical Pearls for NEET-PG:** * **Latency of Action:** Buspirone has a slow onset of action (taking **1–2 weeks**) and is therefore not useful for acute anxiety or panic attacks. * **Safety Profile:** It has **no potential for abuse or addiction**, does not cause rebound anxiety upon withdrawal, and does not potentiate the effects of alcohol. * **DOC:** It is a preferred choice for Generalized Anxiety Disorder (GAD) in patients where sedation must be avoided (e.g., elderly or heavy machinery operators).

Question 19: Which of the following adverse effects of neuroleptic drugs is directly and positively correlated with the antipsychotic potency of different compounds?

A. Sedation
B. Extrapyramidal motor disturbances (Correct Answer)
C. Postural hypotension
D. Lowering of seizure threshold

Explanation: ### Explanation **Concept: The Dopamine Hypothesis and Potency** The antipsychotic potency of neuroleptic drugs (Typical Antipsychotics) is directly proportional to their affinity for **D2 receptors** in the brain. * **Therapeutic Effect:** Occurs due to D2 blockade in the **mesolimbic pathway**. * **Extrapyramidal Symptoms (EPS):** Occur due to D2 blockade in the **nigrostriatal pathway**. Because both the desired antipsychotic effect and the motor side effects are mediated by the same mechanism (D2 blockade), drugs with high antipsychotic potency (e.g., Haloperidol, Fluphenazine) inevitably carry a higher risk of EPS. This is known as a **positive correlation**. **Analysis of Incorrect Options:** * **A. Sedation:** This is primarily due to **H1 (histamine)** receptor blockade. Low-potency drugs (e.g., Chlorpromazine) are more sedating than high-potency ones. * **C. Postural Hypotension:** This results from **alpha-1 adrenergic** blockade. It is more common with low-potency neuroleptics. * **D. Lowering of Seizure Threshold:** While most antipsychotics lower the seizure threshold, this effect is most pronounced with low-potency drugs and certain atypicals (e.g., Clozapine), rather than being correlated with D2-potency. **High-Yield Clinical Pearls for NEET-PG:** 1. **High Potency = High EPS, Low Sedation/Autonomic effects** (e.g., Haloperidol). 2. **Low Potency = Low EPS, High Sedation/Autonomic effects** (e.g., Chlorpromazine, Thioridazine). 3. **Hyperprolactinemia** is another side effect that correlates positively with D2 blockade (tuberoinfundibular pathway). 4. **Atypical Antipsychotics** (e.g., Quetiapine, Clozapine) have lower EPS risk because they dissociate rapidly from D2 receptors or have higher 5-HT2A affinity.

Question 20: Which of the following drugs is a Selective Serotonin Reuptake Inhibitor (SSRI)?

A. Desipramine
B. Clomipramine
C. Fluvoxamine (Correct Answer)
D. Imipramine

Explanation: **Explanation:** **Fluvoxamine** is a Selective Serotonin Reuptake Inhibitor (SSRI). The mechanism of action involves the potent and selective inhibition of the neuronal reuptake of serotonin (5-HT) into the presynaptic terminal, thereby increasing serotonin levels in the synaptic cleft. Unlike older antidepressants, SSRIs have minimal affinity for adrenergic, histaminergic, or cholinergic receptors, leading to a more favorable side-effect profile. **Analysis of Options:** * **Fluvoxamine (Correct):** A classic SSRI frequently used in the management of Obsessive-Compulsive Disorder (OCD) and Social Anxiety Disorder. * **Desipramine (Incorrect):** A secondary amine Tricyclic Antidepressant (TCA). It is a metabolite of imipramine and is highly selective for inhibiting **Norepinephrine (NE)** reuptake. * **Clomipramine (Incorrect):** A TCA that is unique because it is highly selective for **Serotonin** reuptake. However, it is structurally classified as a TCA, not an SSRI, and possesses the typical TCA side effects (anticholinergic, sedative). * **Imipramine (Incorrect):** A prototype tertiary amine TCA that inhibits the reuptake of both **Norepinephrine and Serotonin**. **High-Yield Clinical Pearls for NEET-PG:** * **SSRI Mnemonic:** **F**lashbacks **P**aralyze **S**enior **C**itizens **F**or **S**ure (**F**luoxetine, **P**aroxetine, **S**ertraline, **C**italopram, **F**luvoxamine, **E**scitalopram). * **Drug of Choice:** SSRIs are the first-line treatment for Depression, OCD, Panic Disorder, Social Phobia, and PTSD. * **Side Effects:** Sexual dysfunction (most common long-term), GI upset, and **Serotonin Syndrome** (if combined with MAO inhibitors). * **Specific Fact:** **Fluoxetine** has the longest half-life (due to its active metabolite norfluoxetine), making it the safest choice if a patient occasionally misses a dose.

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

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Drugs for Dementia

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Drug-Induced Psychiatric Symptoms

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