Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders Indian Medical PG Practice Questions and MCQs

Question 201: A 60-year-old male presents with acute urinary retention for 12 hours. Examination reveals a distended bladder. His son reports that the patient has been taking a drug for depression for the past two days. What is the most likely drug?

A. Chlorpromazine
B. Amitriptyline (Correct Answer)
C. Haloperidol
D. Pimozide

Explanation: ### Explanation **Correct Answer: B. Amitriptyline** **Mechanism and Clinical Correlation:** Amitriptyline is a **Tricyclic Antidepressant (TCA)**. TCAs are notorious for their potent **antimuscarinic (anticholinergic) side effects**. By blocking $M_3$ receptors on the detrusor muscle of the bladder, these drugs prevent bladder contraction, leading to **acute urinary retention**. This is particularly common in elderly males who may have underlying (often subclinical) Benign Prostatic Hyperplasia (BPH). The timeline of two days matches the acute onset of side effects following the initiation of therapy. **Analysis of Incorrect Options:** * **A. Chlorpromazine:** While this is a typical antipsychotic with significant anticholinergic properties, it is primarily used for schizophrenia or psychosis, not as a first-line treatment for depression. * **C. Haloperidol:** A high-potency typical antipsychotic. It has very low affinity for muscarinic receptors; its primary side effects are Extrapyramidal Symptoms (EPS) rather than urinary retention. * **D. Pimozide:** Another typical antipsychotic used mainly for Tourette’s syndrome or resistant psychosis. Like haloperidol, it lacks significant anticholinergic activity compared to TCAs. **NEET-PG High-Yield Pearls:** * **TCA Side Effect Profile:** Remember the "3 Cs" of TCA overdose: **C**oma, **C**onvulsions, and **C**ardiotoxicity (Arrhythmias due to Na+ channel blockade). * **Anticholinergic Toxidrome:** "Dry as a bone (dry mouth), Red as a beet (flushing), Hot as a hare (hyperthermia), Blind as a bat (mydriasis), and Mad as a hatter (delirium)." * **Contraindications:** TCAs should be avoided in patients with BPH, Narrow-angle glaucoma, and recent Myocardial Infarction. * **Drug of Choice:** For nocturnal enuresis in children, Imipramine (a TCA) was traditionally used, though Desmopressin is now preferred.

Question 202: Which antidepressant is used in the prophylaxis of migraine?

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

Explanation: **Explanation:** **Amitriptyline** is a Tricyclic Antidepressant (TCA) and is considered the **first-line antidepressant** for the prophylaxis of migraine. Its efficacy stems from its multi-modal mechanism: it inhibits the reuptake of serotonin and norepinephrine and possesses anticholinergic and antihistaminic properties. In migraine prevention, it is believed to downregulate 5-HT₂ receptors and modulate NMDA receptor-mediated transmission, thereby increasing the threshold for migraine triggers. It is particularly useful in patients who also suffer from tension-type headaches, insomnia, or depression. **Why other options are incorrect:** * **Fluoxetine & Citalopram:** These are Selective Serotonin Reuptake Inhibitors (SSRIs). While they are excellent for depression and anxiety, clinical trials have shown they are generally **ineffective** for migraine prophylaxis compared to TCAs. * **Trazodone:** This is a SARI (Serotonin Antagonist and Reuptake Inhibitor) primarily used for insomnia due to its highly sedative nature. It does not have a proven role in migraine prevention. **High-Yield Clinical Pearls for NEET-PG:** * **DOC for Migraine Prophylaxis:** Propranolol (Beta-blocker) is generally the first choice, but Amitriptyline is the preferred TCA. * **Side Effects of Amitriptyline:** Sedation, weight gain, and anticholinergic effects (dry mouth, blurred vision, urinary retention). It is contraindicated in patients with glaucoma or prostatic hypertrophy. * **Other Prophylactic Agents:** Anticonvulsants (Topiramate, Valproate), Calcium Channel Blockers (Flunarizine), and CGRP antagonists (Erenumab). * **Acute Attack Treatment:** Triptans (5-HT$_{1B/1D}$ agonists) are the drugs of choice for acute migraine relief.

Question 203: Which of the following is NOT an anxiolytic agent?

A. Buspirone
B. Fluoxetine (Correct Answer)
C. Diazepam
D. Nitrazepam

Explanation: ### Explanation The correct answer is **Fluoxetine**. **1. Why Fluoxetine is the correct answer:** Fluoxetine is a **Selective Serotonin Reuptake Inhibitor (SSRI)**. While SSRIs are the first-line treatment for chronic anxiety disorders (like GAD, Panic Disorder, and OCD), they are pharmacologically classified as **Antidepressants**, not anxiolytics. Unlike true anxiolytics, they have a delayed onset of action (2–4 weeks) and may initially worsen anxiety symptoms. **2. Analysis of Incorrect Options:** * **Buspirone (Option A):** A selective **5-HT1A partial agonist**. It is a pure anxiolytic that does not cause sedation, muscle relaxation, or anticonvulsant effects. It is ideal for Generalized Anxiety Disorder (GAD) but ineffective for acute panic attacks due to its slow onset. * **Diazepam (Option B):** A long-acting **Benzodiazepine (BZD)**. It acts by enhancing GABAergic transmission (increasing the frequency of Cl⁻ channel opening). It is a classic anxiolytic used for rapid relief of acute anxiety. * **Nitrazepam (Option D):** Another Benzodiazepine primarily used for its hypnotic properties, but it possesses significant anxiolytic, muscle relaxant, and anticonvulsant activities. **3. NEET-PG High-Yield Clinical Pearls:** * **Drug of Choice (DOC) for Acute Anxiety/Panic Attack:** Benzodiazepines (e.g., Alprazolam, Diazepam). * **DOC for Performance Anxiety:** Propranolol (Beta-blocker), taken 30–60 minutes before the event. * **Buspirone Advantage:** No risk of dependence or withdrawal, making it safer for long-term use compared to BZDs. * **SSRI Paradox:** In the first week of treating anxiety with Fluoxetine, "jitteriness syndrome" may occur; hence, BZDs are often co-prescribed for the first 2 weeks.

Question 204: All of the following are limitations of typical tricyclic antidepressants EXCEPT:

A. Narrow safety margin
B. Low oral bioavailability (Correct Answer)
C. Frequent side effects
D. Long latent period for response

Explanation: **Explanation:** Tricyclic Antidepressants (TCAs) like Amitriptyline and Imipramine have been largely replaced by SSRIs due to several clinical limitations. However, **low oral bioavailability is NOT a characteristic limitation** of this class. **1. Why "Low oral bioavailability" is the correct answer:** TCAs are generally **well-absorbed** from the gastrointestinal tract. While they undergo significant first-pass metabolism in the liver, their systemic bioavailability is typically moderate to high (e.g., Amitriptyline is ~40-60%), and they are highly lipophilic, allowing them to distribute widely into tissues. This is not considered a primary clinical "limitation" compared to their side effect profile. **2. Analysis of incorrect options (Limitations of TCAs):** * **Narrow safety margin (Option A):** TCAs are cardiotoxic in overdose. They block sodium channels in the heart, leading to arrhythmias and QRS prolongation. A 10-day supply can be fatal, making them dangerous for suicidal patients. * **Frequent side effects (Option C):** TCAs are "dirty drugs" that block multiple receptors: * **Muscarinic:** Dry mouth, blurred vision, constipation, urinary retention. * **Alpha-1:** Orthostatic hypotension. * **H1 Histamine:** Sedation and weight gain. * **Long latent period (Option D):** Like most antidepressants, TCAs require **2–4 weeks** of continuous therapy to show significant clinical improvement in mood, despite immediate neurotransmitter effects. **High-Yield Clinical Pearls for NEET-PG:** * **The 3 C’s of TCA Toxicity:** **C**oma, **C**onvulsions, and **C**ardiotoxicity (Arrhythmias). * **Antidote:** Sodium Bicarbonate is used to treat TCA-induced cardiotoxicity (it reverses sodium channel blockade). * **Drug of Choice:** Clomipramine (a TCA) is the gold standard for Obsessive-Compulsive Disorder (OCD), though SSRIs are first-line due to safety. * **Enuresis:** Imipramine is used for nocturnal enuresis in children.

Question 205: Which tricyclic antidepressant has the LEAST autonomic and cardiotoxic effects?

A. Amitriptyline
B. Desipramine
C. Lofepramine (Correct Answer)
D. Protriptyline

Explanation: **Explanation:** **Lofepramine** is a second-generation tricyclic antidepressant (TCA) and a prodrug of desipramine. It is unique among TCAs because it possesses a bulky side chain that significantly reduces its affinity for cholinergic (muscarinic), alpha-adrenergic, and histaminergic receptors. 1. **Why Lofepramine is correct:** * **Low Cardiotoxicity:** It has a much lower risk of causing arrhythmias or QTc prolongation compared to older TCAs, making it safer in overdose. * **Low Autonomic Effects:** Due to its low anticholinergic activity, it causes minimal dry mouth, blurred vision, and urinary retention. It also causes less orthostatic hypotension. 2. **Why other options are incorrect:** * **Amitriptyline (Option A):** This is a tertiary amine and is considered the **most** anticholinergic and sedative TCA. It has significant cardiotoxicity and is often used as the "prototype" for TCA side effects. * **Desipramine (Option B):** While it is a metabolite of lofepramine and has less sedative effect than amitriptyline, it still carries a higher risk of cardiotoxicity and sudden cardiac death in vulnerable patients compared to lofepramine. * **Protriptyline (Option D):** This is a potent stimulant-like TCA. While less sedative, it still possesses significant anticholinergic properties and can cause tachycardia and arrhythmias. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** TCAs primarily inhibit the reuptake of Norepinephrine (NE) and Serotonin (5-HT). * **TCA Overdose Triad (The 3 C's):** **C**oma, **C**onvulsions, and **C**ardiotoxicity (widened QRS complex). * **Antidote for Cardiotoxicity:** Intravenous **Sodium Bicarbonate** is the drug of choice to manage QRS widening and arrhythmias. * **Most Cardiotoxic TCA:** Amitriptyline. * **Least Cardiotoxic TCA:** Lofepramine.

Question 206: Which of the following properties distinguishes Aripiprazole from atypical antipsychotics?

A. It is a potent 5-HT2A receptor antagonist.
B. Reduced risk of extrapyramidal side effects.
C. It can be used in Schizophrenia.
D. It is not a D2 receptor antagonist. (Correct Answer)

Explanation: **Explanation:** The defining pharmacological feature of **Aripiprazole** that distinguishes it from both typical and other atypical antipsychotics is its mechanism of action at the dopamine D2 receptor. **1. Why Option D is Correct:** Unlike traditional atypical antipsychotics (e.g., Risperidone, Olanzapine), which act as **D2 receptor antagonists**, Aripiprazole is a **Partial D2 Receptor Agonist**. It acts as a "dopamine stabilizer": in areas of high dopamine activity (mesolimbic pathway), it acts as a functional antagonist to reduce positive symptoms; in areas of low dopamine activity (mesocortical pathway), it provides enough agonism to improve negative symptoms. Because it does not fully block the receptor, it is technically not a pure antagonist. **2. Why the other options are incorrect:** * **Option A:** Most atypical antipsychotics (SDA – Serotonin-Dopamine Antagonists) are potent **5-HT2A antagonists**. Aripiprazole also possesses this property, so it does not distinguish it from the group. * **Option B:** A reduced risk of extrapyramidal side effects (EPS) is a **shared characteristic** of almost all atypical antipsychotics compared to typical ones (like Haloperidol). * **Option C:** Schizophrenia is the **primary clinical indication** for all antipsychotics, including Aripiprazole and other atypicals. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Partial agonist at D2 and 5-HT1A receptors; Antagonist at 5-HT2A. * **Side Effect Profile:** It has the **lowest risk of weight gain, hyperprolactinemia, and QT prolongation** among atypicals. * **Common Side Effect:** Akathisia is the most frequently reported EPS. * **Other Partial Agonists:** Brexpiprazole and Cariprazine (newer agents with similar mechanisms).

Question 207: Which of the following serum concentrations of lithium indicates lithium toxicity?

A. 2 mEq/L (Correct Answer)
B. 4 mEq/L
C. 6 mEq/L
D. 8 mEq/L

Explanation: **Explanation:** Lithium is a drug with a **narrow therapeutic index**, meaning the margin between its therapeutic effect and toxicity is very slim. Monitoring serum lithium levels is mandatory for patient safety. * **Why Option A is Correct:** The therapeutic range for lithium is generally **0.6 to 1.2 mEq/L**. Levels between 1.2 and 1.5 mEq/L are considered the "warning zone." Clinical toxicity typically manifests when serum levels exceed **1.5 mEq/L**. Therefore, **2 mEq/L** is the first point among the options that clearly indicates established lithium toxicity, often presenting with symptoms like coarse tremors, vomiting, diarrhea, and ataxia. * **Why Options B, C, and D are Incorrect:** While 4, 6, and 8 mEq/L are indeed toxic levels, they represent **severe to life-threatening toxicity**. In the context of medical exams, when asked to identify "toxicity," the lowest value that exceeds the therapeutic threshold is chosen as the definitive indicator of the onset of toxicity. Levels above 4 mEq/L are often fatal and require emergency hemodialysis. **High-Yield NEET-PG Pearls:** 1. **Therapeutic Range:** 0.6–1.2 mEq/L (Prophylaxis: 0.6–0.8; Acute Mania: 0.8–1.2). 2. **Sampling Time:** Serum levels should be measured **12 hours after the last dose** (Steady-state). 3. **Drug Interactions:** Thiazides, NSAIDs, and ACE inhibitors increase lithium levels (by decreasing renal clearance). 4. **Side Effects:** L-I-T-H: **L**eukocytosis, **I**nsipidus (Diabetes Insipidus), **T**remors/Teratogenicity (Ebstein's Anomaly), **H**ypothyroidism. 5. **Management of Toxicity:** Gastric lavage and **Hemodialysis** (Treatment of choice for severe toxicity >3.5 mEq/L).

Question 208: All actions of chlorpromazine are based on its antidopaminergic property EXCEPT:

A. Antipsychotic
B. Hyperprolactinemic
C. Antiemetic
D. Hypotensive (Correct Answer)

Explanation: Chlorpromazine (CPZ) is a prototype low-potency typical antipsychotic. Its pharmacological effects are mediated by blocking multiple receptors, including Dopamine ($D_2$), Alpha-adrenergic ($\alpha_1$), Muscarinic ($M_1$), and Histaminergic ($H_1$) receptors [1], [2]. **1. Why Hypotension is the Correct Answer:** The **hypotensive** effect of chlorpromazine is primarily due to the **blockade of $\alpha_1$-adrenergic receptors**, leading to peripheral vasodilation [1], [2]. It is not related to dopamine antagonism. This often manifests as orthostatic (postural) hypotension, a common side effect of low-potency antipsychotics [1]. **2. Why the other options are incorrect (Antidopaminergic actions):** * **Antipsychotic:** This effect is due to the blockade of $D_2$ receptors in the **mesolimbic and mesocortical pathways**. * **Hyperprolactinemic:** Dopamine normally inhibits prolactin release via the tuberoinfundibular pathway. $D_2$ blockade here removes this inhibition, leading to increased prolactin levels (galactorrhea, gynecomastia) [1], [2]. * **Antiemetic:** CPZ exerts its antiemetic effect by blocking $D_2$ receptors in the **Chemoreceptor Trigger Zone (CTZ)** of the medulla. **High-Yield Clinical Pearls for NEET-PG:** * **Low Potency vs. High Potency:** Low-potency drugs like Chlorpromazine have high $\alpha_1$ and $M_1$ blocking activity (more sedation/hypotension) but lower risk of Extrapyramidal Symptoms (EPS) [1]. High-potency drugs like Haloperidol have high $D_2$ affinity and a higher risk of EPS. * **Other non-dopaminergic effects of CPZ:** Sedation ($H_1$ blockade) and dry mouth/constipation ($M_1$ blockade) [1]. * **Specific Indication:** Chlorpromazine is also a drug of choice for **intractable hiccups**.

Question 209: Which one of the following drugs is NOT used in the management of glaucoma?

A. Timolol
B. Physostigmine
C. Donepezil (Correct Answer)
D. Dipivefrine

Explanation: **Explanation:** The correct answer is **Donepezil**. **1. Why Donepezil is the correct answer:** Donepezil is a centrally acting, reversible acetylcholinesterase inhibitor. Its primary clinical indication is the symptomatic treatment of **Alzheimer’s disease**, as it increases acetylcholine levels in the brain to improve cognitive function. Unlike other cholinesterase inhibitors, it has high selectivity for the central nervous system and is not used topically or systemically for the management of glaucoma. **2. Analysis of incorrect options:** * **Timolol (Option A):** A non-selective beta-blocker and the traditional first-line agent for glaucoma. It works by reducing the production of aqueous humor from the ciliary body. * **Physostigmine (Option B):** A tertiary amine anticholinesterase. When applied topically to the eye, it causes miosis and contraction of the ciliary muscle, which facilitates the drainage of aqueous humor through the trabecular meshwork. * **Dipivefrine (Option C):** A prodrug of epinephrine. It is more lipophilic, allowing better ocular penetration. It reduces intraocular pressure by increasing uveoscleral outflow. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** Currently, **Latanoprost** (Prostaglandin analogue) is the DOC for Open-Angle Glaucoma due to high efficacy and once-daily dosing. * **Avoid in Glaucoma:** Mydriatics (like Atropine) are strictly contraindicated in closed-angle glaucoma as they can precipitate an acute attack. * **Donepezil Side Effects:** Common side effects are cholinergic in nature, such as bradycardia, nausea, and diarrhea (SLUDGE syndrome).

Question 210: Which drug possesses antidepressant and antipsychotic properties?

A. Buspirone
B. Amoxapine (Correct Answer)
C. Trazodone
D. Mianserine

Explanation: **Explanation:** **Amoxapine** is a tetracyclic antidepressant (TeCA) and a metabolite of the antipsychotic drug loxapine. It is unique because it exhibits a dual pharmacological profile: 1. **Antidepressant Action:** It inhibits the reuptake of Norepinephrine (and to a lesser extent, Serotonin), similar to Tricyclic Antidepressants (TCAs). 2. **Antipsychotic Action:** Unlike other antidepressants, Amoxapine possesses significant **Postsynaptic Dopamine (D2) receptor blockade** activity. This makes it the drug of choice for **Psychotic Depression** (Major Depressive Disorder with psychotic features). **Analysis of Incorrect Options:** * **A. Buspirone:** An azapirone derivative used as a non-benzodiazepine anxiolytic. It acts as a selective 5-HT1A partial agonist. It does not have antipsychotic properties. * **C. Trazodone:** A SARI (Serotonin Antagonist and Reuptake Inhibitor). It is primarily used for depression with insomnia due to its highly sedative nature, but it lacks D2 blocking (antipsychotic) activity. * **D. Mianserine:** A tetracyclic compound that acts as an alpha-2 blocker. While it is an antidepressant, it does not possess significant D2 receptor antagonism. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects:** Because of its D2 blocking property, Amoxapine can cause **Extrapyramidal Side Effects (EPS)**, such as parkinsonism or tardive dyskinesia, and hyperprolactinemia—side effects typically associated with antipsychotics rather than antidepressants. * **Drug of Choice:** Always consider Amoxapine for "Psychotic Depression." * **Seizure Risk:** Like other tetracyclics, Amoxapine carries a risk of seizures in overdose.

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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