Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders Indian Medical PG Practice Questions and MCQs

Question 231: All are true about Desvenlafaxine except?

A. It is a D2 receptor antagonist (Correct Answer)
B. Can cause priapism
C. Can cause glaucoma
D. Can cause hyperlipidemia

Explanation: **Explanation:** **1. Why Option A is the correct answer (The "Except"):** Desvenlafaxine is a **Selective Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)**. It is the active metabolite of Venlafaxine. Its mechanism of action involves inhibiting the reuptake of serotonin (5-HT) and norepinephrine (NE) in the synaptic cleft. It has **no significant affinity** for D2 (Dopamine), cholinergic, histaminergic, or alpha-adrenergic receptors. Therefore, stating it is a D2 receptor antagonist is pharmacologically incorrect. **2. Analysis of other options:** * **Option B (Priapism):** While rare compared to Trazodone, SNRIs and SSRIs have been associated with idiosyncratic cases of priapism due to complex downstream effects on neurotransmitters. * **Option C (Glaucoma):** SNRIs can cause pupillary dilation (mydriasis) due to increased norepinephrine levels. This can trigger an attack of **acute angle-closure glaucoma** in predisposed individuals. * **Option D (Hyperlipidemia):** Desvenlafaxine treatment is clinically associated with dose-related increases in fasting serum total cholesterol, LDL, and triglycerides. Regular lipid monitoring is recommended during therapy. **High-Yield Clinical Pearls for NEET-PG:** * **Active Metabolite:** Desvenlafaxine is the major active metabolite of Venlafaxine (formed via CYP2D6). * **Dose-Response:** Unlike Venlafaxine, which acts like an SSRI at low doses and an SNRI at high doses, Desvenlafaxine shows SNRI activity even at the starting dose (50mg). * **Side Effect Profile:** Common side effects include nausea, insomnia, sweating, and **dose-dependent hypertension** (due to increased NE). * **Discontinuation Syndrome:** SNRIs have a high risk of withdrawal symptoms; tapering is essential.

Question 232: All of the following are used for the treatment of morphine dependence except?

A. Methadone
B. Clonidine
C. Naltrexone
D. Disulfiram (Correct Answer)

Explanation: **Explanation:** The treatment of morphine (opioid) dependence involves managing acute withdrawal symptoms and long-term maintenance therapy to prevent relapse. **Why Disulfiram is the correct answer:** **Disulfiram** is an aldehyde dehydrogenase inhibitor used exclusively in the treatment of **Alcohol Dependence**. It creates an aversive reaction (Disulfiram-like reaction) by causing acetaldehyde accumulation if alcohol is consumed. It has no pharmacological role in the management of opioid withdrawal or dependence. **Analysis of Incorrect Options:** * **Methadone (Option A):** A long-acting μ-opioid agonist used for **opioid substitution therapy (OST)**. It prevents withdrawal symptoms and reduces "drug-seeking" behavior due to its long half-life and cross-tolerance with morphine. * **Clonidine (Option B):** An $\alpha_2$ agonist used to manage the **autonomic symptoms** of opioid withdrawal (e.g., hypertension, tachycardia, sweating, and tremors). It reduces the sympathetic overactivity caused by the locus coeruleus during detoxification. * **Naltrexone (Option C):** A long-acting **opioid antagonist** used for relapse prevention. It blocks the reinforcing effects (euphoria) of opioids. It is only started after the patient is completely detoxified to avoid precipitating acute withdrawal. **High-Yield Clinical Pearls for NEET-PG:** * **Buprenorphine:** A partial μ-agonist and κ-antagonist; it is the preferred drug for office-based opioid substitution due to its "ceiling effect" on respiratory depression. * **Naloxone:** The drug of choice for **acute opioid poisoning** (short-acting antagonist). * **Lofexidine:** An $\alpha_{2A}$ agonist recently approved specifically for managing opioid withdrawal symptoms, often preferred over clonidine due to less hypotension.

Question 233: Which of the following is a Selective Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)?

A. Venlafaxine (Correct Answer)
B. Reboxetine
C. Moclobemide
D. Bupropion

Explanation: ### Explanation **Correct Option: A. Venlafaxine** Venlafaxine is a prototype **Selective Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)**. It works by inhibiting the reuptake of both serotonin (5-HT) and norepinephrine (NE) into the presynaptic neuron, thereby increasing their concentration in the synaptic cleft. At lower doses, it primarily acts on serotonin, while at higher doses, its effect on norepinephrine becomes significant. It is commonly used for Major Depressive Disorder (MDD), Generalized Anxiety Disorder (GAD), and neuropathic pain. **Analysis of Incorrect Options:** * **B. Reboxetine:** This is a **Selective Norepinephrine Reuptake Inhibitor (NARI)**. It selectively increases norepinephrine levels without significantly affecting serotonin. * **C. Moclobemide:** This is a **Reversible Inhibitor of MAO-A (RIMA)**. It prevents the breakdown of monoamines (primarily serotonin and NE) but does not inhibit their reuptake. * **D. Bupropion:** This is an **Atypical Antidepressant** that acts as a **Norepinephrine-Dopamine Reuptake Inhibitor (NDRI)**. It is notable for having no serotonergic activity, making it a preferred choice to avoid sexual dysfunction. **High-Yield Clinical Pearls for NEET-PG:** * **SNRI Examples:** Venlafaxine, Desvenlafaxine, Duloxetine, and Milnacipran. * **Duloxetine** is the drug of choice for **diabetic neuropathy** and fibromyalgia. * **Venlafaxine Side Effect:** Can cause a dose-dependent **increase in blood pressure** (hypertension); monitoring is essential. * **Bupropion** is used for **smoking cessation** but is contraindicated in patients with seizure disorders (lowers seizure threshold).

Question 234: Agranulocytosis is a known side effect of which of the following medications?

A. Risperidone
B. Clonazepam
C. Olanzapine
D. Carbamazepine (Correct Answer)

Explanation: **Explanation:** **Correct Answer: D. Carbamazepine** **Mechanism and Rationale:** Carbamazepine is an iminostilbene derivative used as an antiepileptic and a mood stabilizer in Bipolar Disorder. One of its most serious, albeit rare, idiosyncratic adverse effects is **bone marrow suppression**, leading to **agranulocytosis**, aplastic anemia, and leucopenia. This occurs due to the direct toxic effect of its metabolites on the bone marrow or an immune-mediated reaction. Because of this risk, baseline and periodic Complete Blood Count (CBC) monitoring is recommended during treatment. **Analysis of Incorrect Options:** * **A. Risperidone:** An atypical antipsychotic primarily associated with extrapyramidal symptoms (at high doses), hyperprolactinemia, and weight gain. It does not typically cause agranulocytosis. * **B. Clonazepam:** A benzodiazepine used for anxiety and seizures. Its primary side effects are sedation, ataxia, and cognitive impairment; it is not associated with hematological toxicity. * **C. Olanzapine:** An atypical antipsychotic notorious for causing significant metabolic side effects (weight gain, dyslipidemia, and Type 2 Diabetes). While it is chemically related to Clozapine, it does **not** carry the same high risk of agranulocytosis. **High-Yield Clinical Pearls for NEET-PG:** * **Clozapine vs. Carbamazepine:** Both cause agranulocytosis. Clozapine is the *most common* psychiatric drug associated with this (requires mandatory WBC monitoring), but among the options provided, Carbamazepine is the correct answer. * **HLA-B*1502:** In patients of Asian descent, Carbamazepine is strongly linked to Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN). * **Enzyme Induction:** Carbamazepine is a potent **cytochrome P450 inducer**, leading to numerous drug-drug interactions (e.g., decreasing the efficacy of oral contraceptives). * **Other Side Effects:** SIADH (hyponatremia) and teratogenicity (neural tube defects).

Question 235: What adverse effect can sodium valproate cause in a patient with bipolar mood disorder?

A. Peripheral neuropathy
B. Hepatotoxicity (Correct Answer)
C. Renal failure
D. Cystitis

Explanation: **Explanation:** **Sodium Valproate** is a broad-spectrum antiepileptic drug also used as a first-line mood stabilizer in Bipolar Mood Disorder. **Why Hepatotoxicity is the Correct Answer:** Valproate is metabolized in the liver. Its most serious and potentially fatal adverse effect is **idiosyncratic hepatotoxicity**. This typically occurs within the first six months of therapy. It is caused by the formation of toxic metabolites (like 4-pentenoic acid) that interfere with mitochondrial beta-oxidation. Risk is highest in children under two years old and those on polytherapy, but it remains a critical monitoring parameter for all psychiatric patients on long-term valproate. **Analysis of Incorrect Options:** * **A. Peripheral neuropathy:** This is more commonly associated with drugs like **Phenytoin** or **Isoniazid**, not Valproate. * **B. Renal failure:** Valproate is not nephrotoxic. In contrast, **Lithium** (another mood stabilizer) is known for causing nephrogenic diabetes insipidus and chronic interstitial nephritis. * **D. Cystitis:** Specifically **Hemorrhagic Cystitis** is a classic side effect of **Cyclophosphamide** (due to acrolein), not valproate. **High-Yield NEET-PG Pearls:** * **Teratogenicity:** Valproate is highly teratogenic, causing **Neural Tube Defects** (specifically Spina Bifida) due to interference with folate metabolism. * **Other Side Effects:** Remember the mnemonic **VALPROATE**: **V**omiting, **A**lopecia (transient), **L**iver toxicity, **P**ancreatitis (acute), **R**etention of weight (Weight gain), **O**edema, **A**ppetite increase, **T**hrombocytopenia, and **E**ncephalopathy (due to hyperammonemia). * **Monitoring:** Baseline and periodic **Liver Function Tests (LFTs)** are mandatory.

Question 236: Which antipsychotic drug has the maximum hypotensive side effect?

A. Fluphenazine
B. Trifluoperazine
C. Thioridazine (Correct Answer)
D. Haloperidol

Explanation: **Explanation:** The hypotensive effect of antipsychotic drugs is primarily mediated by the blockade of **alpha-1 (̑1) adrenergic receptors** in the peripheral vasculature [2]. **Why Thioridazine is correct:** Antipsychotics are broadly classified into high-potency and low-potency groups. **Thioridazine** is a **low-potency** typical antipsychotic [3]. Low-potency drugs generally have a lower affinity for D2 receptors but a much higher affinity for alpha-adrenergic, muscarinic, and histaminergic receptors. Among the options provided, Thioridazine has the most potent ̑1-blocking activity, leading to significant peripheral vasodilation and **orthostatic (postural) hypotension** [2]. **Why other options are incorrect:** * **Fluphenazine, Trifluoperazine, and Haloperidol** are all **high-potency** typical antipsychotics [3]. * High-potency drugs have a very high affinity for D2 receptors (leading to more Extrapyramidal Side Effects/EPS) but a **low affinity** for alpha-1 receptors [2]. * Consequently, these drugs are much less likely to cause hypotension compared to low-potency agents like Thioridazine or Chlorpromazine. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic:** "Low potency = Low BP, High Sedation, High Anticholinergic." * **Cardiotoxicity:** Thioridazine is also notorious for causing **QT interval prolongation** and *Torsades de Pointes*, often limiting its clinical use [3]. * **Ocular Side Effect:** Thioridazine is uniquely associated with **retinitis pigmentosa** (brownish discoloration of vision) at high doses. * **Potency vs. Efficacy:** All antipsychotics have similar efficacy for positive symptoms; they differ only in their potency and side-effect profiles [1].

Question 237: Which of the following antipsychotics is not available as a depot preparation for the treatment of psychosis?

A. Aripiprazole
B. Olanzapine
C. Clozapine (Correct Answer)
D. Haloperidol

Explanation: **Explanation:** The correct answer is **Clozapine**. Depot preparations (Long-Acting Injectables or LAIs) are designed to improve compliance in patients with chronic schizophrenia by providing sustained drug release over weeks or months. **Why Clozapine is not available as a depot:** Clozapine is reserved for **treatment-resistant schizophrenia**. Its use is strictly regulated due to the risk of **agranulocytosis** (severe leucopenia). Patients on Clozapine require mandatory, regular blood monitoring (ANC counts). If Clozapine were administered as a long-acting depot, it would be impossible to rapidly "withdraw" the drug from the system if a patient developed life-threatening bone marrow suppression. Therefore, it is only available in oral formulations to allow for immediate cessation if toxicity occurs. **Analysis of Incorrect Options:** * **Haloperidol:** A typical (first-generation) antipsychotic available as **Haloperidol Decanoate**, usually administered every 4 weeks. * **Aripiprazole:** An atypical (second-generation) antipsychotic available as **Aripiprazole Maintena** (monthly) and **Lauroxil**. * **Olanzapine:** Available as **Olanzapine Pamoate**. Note: It carries a risk of "Post-injection Delirium Sedation Syndrome," requiring 3 hours of clinical observation after administration. **High-Yield Clinical Pearls for NEET-PG:** * **Other Depot Drugs:** Fluphenazine decanoate, Risperidone microspheres, and Paliperidone palmitate. * **Clozapine Side Effects:** Agranulocytosis (most serious), seizures (dose-dependent), myocarditis, and significant weight gain/sialorrhea. * **Monitoring:** Clozapine is the only antipsychotic proven to reduce **suicidal behavior** in schizophrenia.

Question 238: Which of the following is a reversible monoamine oxidase inhibitor (MAOI)?

A. Nicorandil
B. Selegiline
C. Moclobemide (Correct Answer)
D. Fluphenazine

Explanation: **Explanation:** **Moclobemide** is the correct answer because it is a **Reversible Inhibitor of MAO-A (RIMA)**. Unlike older, irreversible MAOIs (like Phenelzine), Moclobemide binds non-covalently to the MAO-A enzyme. This reversibility is clinically significant because if dietary tyramine levels rise, the tyramine can displace Moclobemide from the enzyme, allowing for its metabolism. This significantly reduces the risk of the "Cheese Reaction" (hypertensive crisis). **Analysis of Incorrect Options:** * **A. Nicorandil:** This is a potassium channel opener with a nitrate-like action used in the management of angina pectoris, not a psychiatric medication. * **B. Selegiline:** While it is an MAOI, it is an **irreversible** inhibitor. At low doses, it is selective for MAO-B (used in Parkinson’s disease); at higher doses, it loses selectivity and inhibits both MAO-A and MAO-B. * **C. Fluphenazine:** This is a high-potency **typical antipsychotic** (Phenothiazine class) that acts primarily by blocking D2 receptors. **NEET-PG High-Yield Pearls:** * **MAO-A** primarily metabolizes Norepinephrine, Serotonin, and Tyramine. **MAO-B** primarily metabolizes Dopamine. * **RIMA (Moclobemide):** Preferred in atypical depression due to the lack of stringent dietary restrictions. * **Cheese Reaction:** Occurs when irreversible MAOIs prevent the breakdown of tyramine (found in aged cheese/wine), leading to massive NE release and hypertensive crisis. **Phentolamine** (alpha-blocker) is the drug of choice for treatment. * **Serotonin Syndrome:** A dangerous interaction when MAOIs are combined with SSRIs; a "washout period" of 2–5 weeks is required when switching between these classes.

Question 239: Which of the following is an antidepressant?

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

Explanation: **Explanation:** The question asks to identify an antidepressant from the given list. While all options listed are technically used in the management of depression, this question likely focuses on the primary classification of **Selective Serotonin Reuptake Inhibitors (SSRIs)**, which are the first-line agents for depression in modern clinical practice. **1. Why Citalopram is the Correct Answer:** **Citalopram** is a prototypical SSRI. It works by specifically inhibiting the reuptake of serotonin (5-HT) at the presynaptic terminal, increasing its availability in the synaptic cleft. It is preferred due to its high selectivity, better side-effect profile, and lower toxicity in overdose compared to older classes. **2. Analysis of Other Options:** * **Amitriptyline:** This is a **Tricyclic Antidepressant (TCA)**. It inhibits the reuptake of both Norepinephrine and Serotonin but also blocks muscarinic, histaminic, and alpha-adrenergic receptors, leading to significant side effects (sedation, dry mouth, arrhythmias). * **Trazodone & Nefazodone:** These belong to the **SARI (Serotonin Antagonist and Reuptake Inhibitor)** class. They are "atypical" antidepressants. Trazodone is more commonly used today as a hypnotic for insomnia rather than a primary antidepressant due to its highly sedative nature. **Clinical Pearls for NEET-PG:** * **SSRIs (Drug of Choice):** Escitalopram is the most specific SSRI; Fluoxetine has the longest half-life (safe from withdrawal syndrome). * **Side Effects:** SSRIs commonly cause sexual dysfunction and GI upset. TCAs are notorious for the "3 Cs": Coma, Convulsions, and Cardiotoxicity (arrhythmias due to Na+ channel blockade). * **Nefazodone Warning:** It is rarely used now due to the risk of **hepatotoxicity**. * **Trazodone:** Associated with the rare but high-yield side effect of **priapism**.

Question 240: Which of the following is a tricyclic antidepressant?

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

Explanation: **Explanation:** **Amitriptyline** is the correct answer as it belongs to the **Tricyclic Antidepressant (TCA)** class. TCAs are characterized by a three-ring chemical structure and work primarily by inhibiting the reuptake of both Serotonin (5-HT) and Norepinephrine (NE) from the synaptic cleft. Amitriptyline is a tertiary amine, meaning it has a more pronounced effect on serotonin reuptake compared to secondary amines like Nortriptyline. **Analysis of Incorrect Options:** * **Fluoxetine (Option B):** This is a prototype **Selective Serotonin Reuptake Inhibitor (SSRI)**. It is the first-line treatment for depression due to its better safety profile and fewer side effects compared to TCAs. * **Trazodone (Option C):** This is a **Serotonin Antagonist and Reuptake Inhibitor (SARI)**. It is frequently used off-label as a hypnotic due to its significant sedative properties (H1 blockade). * **Bupropion (Option D):** This is an **Atypical Antidepressant** that acts as a Norepinephrine-Dopamine Reuptake Inhibitor (NDRI). It is notable for lacking sexual side effects and is also used for smoking cessation. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects of TCAs:** They cause "3 Cs"—**C**oma, **C**onvulsions, and **C**ardiotoxicity (due to sodium channel blockade leading to QRS prolongation). They also have strong anticholinergic (dry mouth, blurred vision) and antihistaminic (sedation) effects. * **Antidote:** Sodium bicarbonate is used to treat TCA-induced cardiotoxicity. * **Drug of Choice:** While SSRIs are first-line for depression, TCAs like Amitriptyline are often used for **neuropathic pain** and **migraine prophylaxis**. Imipramine (another TCA) is a classic drug for **nocturnal enuresis** in children.

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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