Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders Indian Medical PG Practice Questions and MCQs

Question 41: Which of the following drugs is associated with the lowest risk of causing extrapyramidal side effects?

A. Chlorpromazine
B. Thioridazine (Correct Answer)
C. Haloperidol
D. Flupenthixol

Explanation: <h3>Explanation</h3>The risk of Extrapyramidal Side Effects (EPS) in antipsychotic therapy is determined by the balance between Dopaminergic (D2) blockade and Muscarinic (M1) blockade in the nigrostriatal pathway [3, 4].1. Why Thioridazine is correct: Thioridazine is a low-potency typical antipsychotic. It possesses strong intrinsic anticholinergic (muscarinic) activity. In the basal ganglia, dopamine and acetylcholine exist in a reciprocal balance. While Thioridazine blocks D2 receptors (which typically causes EPS), its potent anticholinergic effect "re-balances" the system, significantly reducing the manifestation of motor side effects. Therefore, among the typical antipsychotics, it has the lowest risk of EPS [2].2. Analysis of Incorrect Options:<ul><li>Haloperidol & Flupenthixol: These are high-potency antipsychotics. They have high affinity for D2 receptors and very low anticholinergic activity. This results in a profound dopamine-acetylcholine imbalance, making them the drugs with the highest risk of EPS (especially acute dystonia and parkinsonism) [2, 3, 4].</li><li>Chlorpromazine: This is a low-potency antipsychotic with moderate anticholinergic properties. While it has a lower risk of EPS compared to Haloperidol, its anticholinergic profile is not as strong as Thioridazine's [2].</li></ul>3. NEET-PG High-Yield Pearls:<ul><li>The "Thioridazine Trade-off": While it has the lowest EPS risk among typicals, it is notorious for cardiotoxicity (QT prolongation) and Retinitis Pigmentosa (at doses >800mg/day) [2].</li><li>Overall Lowest Risk: If atypical antipsychotics were included, Clozapine and Quetiapine have the lowest risk of EPS overall [1, 2].</li><li>Hyperprolactinemia: Thioridazine and Chlorpromazine cause less prolactin elevation compared to Haloperidol or Risperidone.</li><li>Potency Rule: High potency = High EPS, Low Sedation. Low potency = Low EPS, High Sedation/Autonomic effects [3].</li></ul>

Question 42: Which of the following is NOT a tricyclic, tetracyclic, or MAO antidepressant?

A. Trazodone (Correct Answer)
B. Clomipramine
C. Doxepin
D. Isocarboxazid

Explanation: **Explanation:** The question asks to identify the drug that does not belong to the Tricyclic (TCA), Tetracyclic (TeCA), or Monoamine Oxidase Inhibitor (MAOI) classes. **Why Trazodone is the Correct Answer:** **Trazodone** is classified as a **Serotonin Antagonist and Reuptake Inhibitor (SARI)**. It primarily works by blocking 5-HT₂A receptors and inhibiting the reuptake of serotonin. Unlike TCAs, it lacks significant anticholinergic side effects, though it is highly sedative and carries a specific risk of **priapism** (a high-yield clinical association). **Analysis of Incorrect Options:** * **Clomipramine:** This is a classic **Tricyclic Antidepressant (TCA)**. It is unique among TCAs for being the most potent inhibitor of serotonin reuptake, making it the gold standard for treating **Obsessive-Compulsive Disorder (OCD)**. * **Doxepin:** This is also a **Tricyclic Antidepressant**. It is known for its potent H₁-receptor blocking properties, often used in low doses for insomnia or dermatological conditions involving severe pruritus. * **Isocarboxazid:** This is a **Non-selective, Irreversible MAO Inhibitor**. It belongs to the hydrazine group of MAOIs (along with Phenelzine). **High-Yield Clinical Pearls for NEET-PG:** 1. **Trazodone Side Effect:** Often tested as the "typical cause of priapism" in psychiatry questions. 2. **TCA Overdose:** Characterized by the "3 Cs": Coma, Convulsions, and Cardiotoxicity (arrhythmias due to Na+ channel blockade). Sodium bicarbonate is the antidote. 3. **MAOIs:** Remember the "Cheese Reaction" (hypertensive crisis) when taken with tyramine-rich foods. 4. **Mirtazapine:** Often confused with Trazodone; it is a **NaSSA** (Noradrenergic and Specific Serotonergic Antidepressant) that blocks α₂ receptors.

Question 43: What is the drug of choice for prophylaxis of mania?

A. Diazepam
B. Lithium (Correct Answer)
C. Haloperidol
D. Fluoxetine

Explanation: **Explanation:** **Lithium** is the gold standard and drug of choice for the **prophylaxis of Bipolar Affective Disorder (BPAD)**, specifically for preventing both manic and depressive relapses. Its mechanism involves the inhibition of the Inositol Monophosphatase (IMPase) pathway, leading to the depletion of intracellular phosphoinositides and stabilization of neuronal membranes. It is particularly effective in reducing the risk of suicide in these patients. **Analysis of Incorrect Options:** * **Diazepam (Option A):** A benzodiazepine used for acute anxiety or sedation. It has no mood-stabilizing properties and is not used for long-term prophylaxis of mania. * **Haloperidol (Option C):** A high-potency typical antipsychotic. While it is highly effective for the **acute management** of manic episodes (to control agitation and psychosis), it is not the preferred agent for long-term prophylaxis due to the risk of Extrapyramidal Side Effects (EPS) and Tardive Dyskinesia. * **Fluoxetine (Option D):** An SSRI antidepressant. Using antidepressants alone in bipolar patients is contraindicated as it can trigger a "manic switch." **High-Yield NEET-PG Pearls:** * **Therapeutic Window:** Lithium has a narrow therapeutic index. Prophylactic levels are **0.6–0.8 mEq/L**, while acute mania requires **0.8–1.2 mEq/L**. Toxicity starts >1.5 mEq/L. * **Teratogenicity:** Use in pregnancy is associated with **Ebstein’s Anomaly** (tricuspid valve malformation). * **Alternatives:** If Lithium is contraindicated (e.g., renal failure), **Valproate** or **Lamotrigine** are used as alternative mood stabilizers. * **Monitoring:** Always check Thyroid Function Tests (TFTs) and Renal Function Tests (RFTs) before starting Lithium, as it can cause hypothyroidism and nephrogenic diabetes insipidus.

Question 44: Serotonin syndrome may be precipitated by all of the following medications, except?

A. Chlorpromazine (Correct Answer)
B. Pentazocine
C. Buspirone
D. Meperidine

Explanation: **Explanation:** **Serotonin Syndrome** is a potentially life-threatening condition caused by excessive serotonergic activity in the CNS. It is typically precipitated by drugs that increase serotonin synthesis, release, or activation of receptors, or those that inhibit its reuptake or metabolism. **Why Chlorpromazine is the correct answer:** Chlorpromazine is a **typical antipsychotic** (Phenothiazine) that primarily acts as a **D2 receptor antagonist**. Crucially, it also possesses **5-HT2A receptor blocking** properties. Because it acts as a serotonin antagonist rather than an agonist or enhancer, it does not precipitate serotonin syndrome. In fact, serotonin antagonists (like Cyproheptadine) are used in the management of this condition. **Analysis of Incorrect Options:** * **Meperidine (Pethidine):** An opioid analgesic that acts as a weak Serotonin Reuptake Inhibitor (SRI). It is a notorious trigger for serotonin syndrome, especially when combined with MAO inhibitors. * **Pentazocine:** An opioid with mixed agonist-antagonist properties that also has serotonergic activity; it is documented to precipitate the syndrome. * **Buspirone:** An anxiolytic that acts as a **partial agonist at 5-HT1A receptors**. By directly stimulating serotonin receptors, it can contribute to serotonin toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Triad:** Cognitive effects (delirium, agitation), Autonomic hyperactivity (tachycardia, hyperthermia), and Neuromuscular abnormalities (**Hyperreflexia and Clonus** are hallmark signs). * **Drug of Choice for Management:** **Cyproheptadine** (5-HT2 receptor antagonist). * **Common Culprits:** SSRIs, SNRIs, MAOIs, TCAs, Tramadol, Linezolid (weak MAOI), and St. John's Wort. * **Distinction:** Unlike Neuroleptic Malignant Syndrome (NMS), Serotonin Syndrome has a **rapid onset** (hours) and presents with **hyperreflexia**, whereas NMS presents with "lead-pipe" rigidity and bradyreflexia.

Question 45: Which of the following drugs causes diastolic hypertension as a side effect?

A. Venlafaxine (Correct Answer)
B. Amitriptyline
C. Nefazodone
D. Mianserin

Explanation: **Explanation:** **Venlafaxine** is a Serotonin-Norepinephrine Reuptake Inhibitor (SNRI). At higher doses (>150 mg/day), it significantly inhibits the reuptake of norepinephrine (NE) in addition to serotonin. Increased synaptic NE levels lead to peripheral vasoconstriction and increased peripheral vascular resistance, which clinically manifests as a **dose-dependent increase in blood pressure**, specifically **diastolic hypertension**. Monitoring BP is mandatory for patients on high-dose Venlafaxine. **Analysis of Incorrect Options:** * **Amitriptyline (TCA):** While it also inhibits NE reuptake, its potent **alpha-1 adrenergic blockade** typically causes **orthostatic hypotension** rather than hypertension. * **Nefazodone (SARI):** This drug acts as a 5-HT2 receptor antagonist and weak reuptake inhibitor. It is more commonly associated with sedation and hepatotoxicity; it does not cause hypertension. * **Mianserin (Atypical Antidepressant):** It is an alpha-2 adrenoceptor antagonist. Like TCAs, it is more likely to cause postural hypotension and sedation rather than a sustained rise in diastolic BP. **High-Yield Clinical Pearls for NEET-PG:** * **SNRI Class Effect:** Both Venlafaxine and Desvenlafaxine are notorious for causing hypertension. Duloxetine (another SNRI) has a lesser effect on BP. * **Venlafaxine Withdrawal:** It has a very short half-life; abrupt discontinuation leads to severe "discontinuation syndrome" (flu-like symptoms, electric shock sensations). * **TCA Overdose:** Remember the "3 Cs": Coma, Convulsions, and Cardiotoxicity (arrhythmias due to Na+ channel blockade).

Question 46: Which of the following is not an adverse effect of clomipramine?

A. Dryness of mouth
B. Seizures
C. Bradycardia (Correct Answer)
D. Metabolic acidosis

Explanation: **Explanation:** **Clomipramine** is a Tricyclic Antidepressant (TCA) primarily used in the management of Obsessive-Compulsive Disorder (OCD). Understanding its side effect profile requires knowledge of its multi-receptor blockade. **Why Bradycardia is the correct answer:** TCAs, including clomipramine, are notorious for their **cardiotoxicity**. They exert a "quinidine-like" effect on the heart, blocking fast sodium channels. This leads to slowed conduction, prolonged PR and QRS intervals, and most importantly, **Tachycardia** (due to potent muscarinic blockade and inhibition of norepinephrine reuptake). Therefore, **Bradycardia** is not a feature of TCA action; rather, tachycardia and arrhythmias are expected. **Analysis of Incorrect Options:** * **Dryness of mouth:** This is a classic **anticholinergic (antimuscarinic)** side effect. TCAs block M1 receptors, leading to "red as a beet, dry as a bone" symptoms like xerostomia, blurred vision, and constipation. * **Seizures:** TCAs **lower the seizure threshold**. Clomipramine and Maprotiline are particularly associated with a higher risk of seizures, especially in overdose or in patients with pre-existing epilepsy. * **Metabolic acidosis:** In cases of severe TCA overdose, tissue hypoxia and seizures can lead to **lactic acidosis (metabolic acidosis)**. This is a critical complication managed with Sodium Bicarbonate (which also helps reverse cardiotoxicity). **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Clomipramine is the gold standard for **OCD**, though SSRIs are preferred first-line due to a better safety profile. * **TCA Overdose Triad (3 C’s):** **C**oma, **C**onvulsions, and **C**ardiotoxicity (widened QRS is the most reliable marker). * **Antidote:** Intravenous **Sodium Bicarbonate** is used to treat QRS widening and arrhythmias in TCA poisoning.

Question 47: Propranolol, a non-selective beta-blocker, can be prescribed to decrease anxiety associated with which of the following conditions?

A. Chronic neurotic disorder
B. Schizophrenia
C. Short-term stressful situation (Correct Answer)
D. Endogenous depression

Explanation: ### Explanation **Correct Option: C. Short-term stressful situation** Propranolol is a non-selective beta-adrenergic antagonist. In psychiatry, it is primarily used to manage the **peripheral somatic symptoms of anxiety** (autonomic hyperactivity) rather than the psychological "feeling" of worry. In **short-term stressful situations**—such as public speaking (performance anxiety), stage fright, or examinations—the body undergoes a "fight or flight" response mediated by epinephrine and norepinephrine. This leads to symptoms like palpitations, tremors, tachycardia, and sweating. Propranolol blocks $\beta_1$ and $\beta_2$ receptors, effectively suppressing these physical manifestations, which helps the individual remain calm and perform better. **Why other options are incorrect:** * **A. Chronic neurotic disorder:** Conditions like Generalized Anxiety Disorder (GAD) require treatments that address the psychological component of anxiety, such as SSRIs, SNRIs, or Benzodiazepines. Propranolol does not treat the underlying emotional pathology. * **B. Schizophrenia:** This is a psychotic disorder characterized by dopamine dysregulation. Treatment requires antipsychotics (D2 blockers). While Propranolol is used to treat *Akathisia* (an extrapyramidal side effect of antipsychotics), it is not a treatment for Schizophrenia itself. * **D. Endogenous depression:** Depression is primarily managed with antidepressants (SSRIs, TCAs). Beta-blockers are generally avoided or used with caution in depressed patients as they can occasionally worsen depressive symptoms or cause lethargy. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC) for Akathisia:** Propranolol is the first-line treatment for antipsychotic-induced akathisia (restlessness). * **Performance Anxiety:** Propranolol should be taken 30–60 minutes before the stressful event. * **Essential Tremors:** Propranolol is also the DOC for treating essential tremors. * **Contraindication:** Avoid in patients with **Asthma or COPD** (due to $\beta_2$ blockade causing bronchospasm) and **Diabetes Mellitus** (masks tachycardia, a warning sign of hypoglycemia).

Question 48: Which of the following drugs can cause hyponatremia?

A. Fluoxetine (Correct Answer)
B. Amitriptyline
C. Mianserin
D. Milnacipran

Explanation: **Explanation:** **Fluoxetine** is a Selective Serotonin Reuptake Inhibitor (SSRI). The most common mechanism by which psychotropic drugs cause hyponatremia is the **Syndrome of Inappropriate Antidiuretic Hormone secretion (SIADH)**. SSRIs are the most frequently implicated class of antidepressants in this condition, particularly in elderly patients or those taking diuretics. Serotonin is believed to stimulate the release of ADH (Vasopressin) from the posterior pituitary, leading to water retention and dilutional hyponatremia. **Analysis of Options:** * **Fluoxetine (Option A):** As an SSRI, it carries the highest risk of SIADH among the choices. It is a classic NEET-PG "high-yield" cause of drug-induced hyponatremia. * **Amitriptyline (Option B):** This is a Tricyclic Antidepressant (TCA). While TCAs can rarely cause SIADH, the risk is significantly lower compared to SSRIs. * **Mianserin (Option C):** An atypical tetracyclic antidepressant that acts as an alpha-2 antagonist. It is not typically associated with hyponatremia. * **Milnacipran (Option D):** A Serotonin-Norepinephrine Reuptake Inhibitor (SNRI). While SNRIs can cause SIADH, Fluoxetine (SSRI) is the more established and frequently tested culprit in this context. **Clinical Pearls for NEET-PG:** * **Risk Factors:** Elderly age, female gender, and concomitant use of diuretics (e.g., Thiazides) increase the risk of SSRI-induced hyponatremia. * **Timing:** It usually occurs within the first 2–4 weeks of starting therapy. * **Other drugs causing SIADH:** Carbamazepine (very common), Cyclophosphamide, Vincristine, and Chlorpropamide. * **Management:** Fluid restriction and discontinuation of the offending drug.

Question 49: Which antidepressant drug can cause neuroleptic malignant syndrome and tardive dyskinesia?

A. Amineptin
B. Fluoxetine
C. Amoxapine (Correct Answer)
D. Trazodone

Explanation: **Explanation:** The correct answer is **Amoxapine**. **1. Why Amoxapine is correct:** Amoxapine is a secondary amine tricyclic antidepressant (TCA). Its unique pharmacological profile lies in its metabolism: it is metabolized to **7-hydroxyamoxapine**, which possesses potent **dopamine D2 receptor blocking activity**. This makes it structurally and functionally similar to loxapine (an antipsychotic). Because it blocks dopamine receptors in the nigrostriatal and mesolimbic pathways, it can cause side effects typically associated with antipsychotics, such as **Extrapyramidal Symptoms (EPS)**, **Tardive Dyskinesia**, and the life-threatening **Neuroleptic Malignant Syndrome (NMS)** [1]. **2. Why other options are incorrect:** * **Amineptine:** It is an atypical antidepressant that acts as a dopamine reuptake inhibitor. It does not block D2 receptors and is not associated with NMS or tardive dyskinesia. * **Fluoxetine:** This is a Selective Serotonin Reuptake Inhibitor (SSRI). While it can rarely cause Serotonin Syndrome, it does not have significant D2 blocking activity to cause tardive dyskinesia. * **Trazodone:** A Serotonin Antagonist and Reuptake Inhibitor (SARI). Its most notorious high-yield side effect is **priapism**, not dopamine-related movement disorders. **Clinical Pearls for NEET-PG:** * **Amoxapine** is often the drug of choice for **Psychotic Depression** due to its dual antidepressant and antipsychotic-like properties [1]. * **NMS vs. Serotonin Syndrome:** Remember that NMS presents with "lead-pipe" rigidity and hyporeflexia, whereas Serotonin Syndrome presents with hyperreflexia and myoclonus. * Other antidepressants with unique side effects: **Bupropion** (seizures), **Mirtazapine** (weight gain/sedation), and **Duloxetine** (used for neuropathic pain).

Question 50: Which of the following drugs is associated with the lowest risk of causing extrapyramidal side effects?

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

Explanation: ### Explanation The risk of **Extrapyramidal Side Effects (EPS)** in antipsychotics is primarily determined by the drug's affinity for **D2 receptors** in the nigrostriatal pathway. **Why Clozapine is the Correct Answer:** Clozapine is the prototype **Atypical Antipsychotic (Second Generation)**. It is characterized by a low affinity for D2 receptors and a high affinity for 5-HT2A receptors. It dissociates rapidly from D2 receptors ("loose binding"), which minimizes interference with the nigrostriatal dopamine pathway. Consequently, Clozapine has the **lowest risk of EPS** among all antipsychotics and is virtually devoid of tardive dyskinesia risk. **Analysis of Incorrect Options:** * **Haloperidol (Option C):** A high-potency typical antipsychotic with very strong D2 blockade. It has the **highest risk** of acute dystonia and parkinsonian symptoms. * **Fluphenthixol (Option A):** A high-potency thioxanthene derivative. Like haloperidol, it carries a significant risk of EPS. * **Chlorpromazine (Option D):** A low-potency typical antipsychotic. While it causes fewer EPS than haloperidol due to its inherent anticholinergic activity, the risk is still significantly higher than that of Clozapine. **High-Yield NEET-PG Pearls:** * **Drug of Choice:** Clozapine is the gold standard for **treatment-resistant schizophrenia** and schizophrenia associated with suicidal behavior. * **Adverse Effects:** While EPS risk is low, Clozapine is notorious for **Agranulocytosis** (requires mandatory WBC monitoring), **seizures** (dose-dependent), sialorrhea (drooling), and metabolic syndrome. * **Quetiapine:** Another atypical antipsychotic with a very low EPS risk, often preferred in Parkinson’s disease patients with psychosis.

Practice by Chapter

Antipsychotics: Typical and Atypical

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Antidepressants: SSRIs and SNRIs

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Tricyclic Antidepressants

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MAO Inhibitors

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Mood Stabilizers

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Anxiolytics

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Drugs for ADHD

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Drugs for Sleep Disorders

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Drugs for Dementia

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Drug-Induced Psychiatric Symptoms

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