Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders Indian Medical PG Practice Questions and MCQs

Question 191: All of the following drugs are monoamine oxidase inhibitors except?

A. Moclobemide
B. Tranylcypromine
C. Selegiline
D. Duloxetine (Correct Answer)

Explanation: **Explanation:** The correct answer is **Duloxetine** because it belongs to the class of **Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs)**, not Monoamine Oxidase Inhibitors (MAOIs). It works by inhibiting the reuptake of both serotonin and norepinephrine in the synaptic cleft. **Breakdown of Options:** * **Moclobemide:** It is a **RIMA** (Reversible Inhibitor of MAO-A). Unlike older MAOIs, it has a lower risk of the "cheese reaction" because it can be displaced from the enzyme by tyramine. * **Tranylcypromine:** It is a **Non-selective, Irreversible MAOI** (inhibits both MAO-A and MAO-B). It is one of the older, "classical" antidepressants. * **Selegiline:** It is a **Selective Irreversible MAO-B Inhibitor**. At low doses, it is used primarily in Parkinson’s disease to increase dopamine levels. At higher doses, it loses selectivity and can act as an antidepressant. **High-Yield Clinical Pearls for NEET-PG:** 1. **Cheese Reaction:** Occurs when patients on non-selective MAOIs consume tyramine-rich food (aged cheese, wine). Tyramine displaces stored NE, leading to a **hypertensive crisis**. Treatment of choice: **Phentolamine** (Alpha-blocker). 2. **Serotonin Syndrome:** A dangerous interaction occurring when MAOIs are combined with SSRIs or SNRIs (like Duloxetine). Always maintain a **washout period** of at least 14 days when switching between these classes. 3. **Duloxetine Indications:** Apart from MDD and GAD, it is a first-line drug for **Diabetic Neuropathy**, Fibromyalgia, and Stress Urinary Incontinence.

Question 192: Which of the following drugs should not be used with rivastigmine in patients with Alzheimer's disease?

A. SSRI
B. Tricyclic antidepressant (Correct Answer)
C. RIMA
D. Atypical antidepressants

Explanation: **Explanation:** The core pharmacological principle here is **pharmacodynamic antagonism**. Rivastigmine is a centrally acting **acetylcholinesterase inhibitor (AChEI)** used to increase synaptic acetylcholine levels in Alzheimer’s disease to improve cognitive function. **Why Tricyclic Antidepressants (TCAs) are contraindicated:** TCAs (e.g., Amitriptyline, Imipramine) possess significant **potent anticholinergic (antimuscarinic) properties**. When co-administered with rivastigmine, TCAs directly oppose the therapeutic action of the AChEI. This "pharmacological tug-of-war" results in reduced efficacy of the Alzheimer’s treatment and can worsen cognitive decline, confusion, and sedation in elderly patients. **Analysis of Incorrect Options:** * **A. SSRIs (e.g., Sertraline):** These are the preferred antidepressants in Alzheimer’s patients because they lack significant anticholinergic activity and are generally well-tolerated. * **C. RIMA (e.g., Moclobemide):** Reversible Inhibitors of MAO-A do not possess anticholinergic properties and do not directly interfere with the cholinergic pathway. * **D. Atypical Antidepressants (e.g., Mirtazapine, Trazodone):** While some may be sedating, they do not have the potent muscarinic blockade seen with TCAs and are often used to manage insomnia or agitation in dementia. **High-Yield Clinical Pearls for NEET-PG:** * **Avoid "The Anticholinergic Burden":** In elderly patients with dementia, always avoid drugs with anticholinergic side effects (e.g., TCAs, first-generation antihistamines, oxybutynin, and antipsychotics like chlorpromazine). * **Rivastigmine Unique Feature:** It inhibits both **Acetylcholinesterase (AChE)** and **Butyrylcholinesterase (BuChE)** and is available as a transdermal patch to reduce GI side effects. * **Drug of Choice:** Donepezil is often the first-line AChEI due to its once-daily dosing.

Question 193: Which of the following drugs is classified under FDA teratogenic risk category B for pregnancy?

A. Phenytoin
B. Risperidone
C. Olanzapine
D. Clozapine (Correct Answer)

Explanation: **Explanation:** The classification of drugs in pregnancy is a high-yield topic for NEET-PG. While the FDA has transitioned away from the old A-B-C-D-X lettering system, these categories remain frequently tested in competitive exams. **1. Why Clozapine is Correct:** **Clozapine** is the only atypical antipsychotic traditionally classified under **FDA Category B**. This means animal reproduction studies have failed to demonstrate a risk to the fetus, and there are no adequate and well-controlled studies in pregnant women. While it is the "gold standard" for treatment-resistant schizophrenia, its use in pregnancy requires careful monitoring for maternal agranulocytosis and gestational diabetes. **2. Analysis of Incorrect Options:** * **Phenytoin (Option A):** Classified as **Category D**. It is a known teratogen associated with **Fetal Hydantoin Syndrome** (craniofacial anomalies, hypoplastic phalanges, and growth retardation). * **Risperidone (Option B):** Classified as **Category C**. Animal studies have shown adverse effects on the fetus, and there are no adequate human studies. Most atypical antipsychotics (like Quetiapine and Aripiprazole) fall into this category. * **Olanzapine (Option C):** Also classified as **Category C**. While commonly used, it carries a higher risk of significant maternal weight gain and gestational metabolic complications compared to other agents. **3. NEET-PG Clinical Pearls:** * **Lithium:** Category D; specifically associated with **Ebstein’s Anomaly** (tricuspid valve displacement). * **Valproate:** Category X/D; highest risk for **Neural Tube Defects** (Spina Bifida). * **SSRIs:** Most are Category C, except **Paroxetine**, which is Category D (risk of fetal cardiac malformations). * **Drug of Choice:** For psychosis in pregnancy, **Haloperidol** (typical) has the most extensive safety data, though Clozapine remains the Category B outlier among atypicals.

Question 194: Which of the following is the newest antidepressant?

A. Buspirone
B. Fluoxetine (Correct Answer)
C. Penfluridol
D. Clozapine

Explanation: **Explanation:** The correct answer is **Fluoxetine**. This question tests the classification and historical context of psychotropic medications, which is a high-yield area for NEET-PG. **Why Fluoxetine is correct:** Fluoxetine is the prototype of the **Selective Serotonin Reuptake Inhibitors (SSRIs)**. While "newest" is a relative term in pharmacology textbooks, among the options provided, Fluoxetine represents the most modern class of antidepressants. It revolutionized depression treatment by providing efficacy similar to older Tricyclic Antidepressants (TCAs) but with a significantly better safety profile and fewer anticholinergic side effects. **Why the other options are incorrect:** * **Buspirone (Option A):** This is an **Anxiolytic** (specifically a 5-HT1A partial agonist). It is used for Generalized Anxiety Disorder (GAD), not primarily as an antidepressant. * **Penfluridol (Option C):** This is a long-acting **Typical Antipsychotic** (Diphenylbutylpiperidine class) used in the treatment of schizophrenia. * **Clozapine (Option D):** This is an **Atypical Antipsychotic**. It is the gold standard for "Treatment-Resistant Schizophrenia" but is not classified as an antidepressant. **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. * **Drug of Choice (DOC):** SSRIs are currently the first-line treatment for Depression, Panic Disorder, OCD, Social Phobia, and PTSD. * **Side Effects:** Watch for sexual dysfunction (most common long-term side effect) and "Serotonin Syndrome" if combined with MAO inhibitors. * **Clozapine Alert:** Always remember the risk of **Agranulocytosis**; mandatory WBC monitoring is required.

Question 195: Which of the following is not a MAO-B inhibitor?

A. Safinamide
B. Selegiline
C. Rasagiline
D. Cariprazine (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Cariprazine** **1. Why Cariprazine is the correct answer:** Cariprazine is an **atypical antipsychotic** (second-generation). Its unique mechanism of action involves being a **D3-preferring D2/D3 receptor partial agonist**. Unlike the other options, it has no inhibitory effect on the Monoamine Oxidase (MAO) enzymes. It is primarily used in the treatment of Schizophrenia and Bipolar I disorder (manic or mixed episodes). **2. Why the other options are incorrect:** * **A. Safinamide:** A highly selective and reversible **MAO-B inhibitor** used as an add-on treatment to Levodopa/Carbidopa in Parkinson’s disease to manage "off" episodes. * **B. Selegiline:** A classic irreversible **MAO-B inhibitor**. At low doses, it is selective for MAO-B (found predominantly in the striatum), making it useful for Parkinson’s disease. At high doses, it loses selectivity and inhibits MAO-A. * **C. Rasagiline:** A potent, irreversible, and selective **MAO-B inhibitor**. It is more potent than Selegiline and is used as monotherapy in early Parkinson’s or as an adjunct in advanced stages. **3. High-Yield Clinical Pearls for NEET-PG:** * **MAO-A vs. MAO-B:** MAO-A degrades Serotonin, NE, and Melatonin (Target for Antidepressants like Moclobemide). MAO-B degrades **Dopamine** (Target for Antiparkinsonian drugs). * **Cheese Reaction:** This is associated with non-selective MAO inhibitors or high-dose MAO-B inhibitors due to the accumulation of **Tyramine**, leading to a hypertensive crisis. * **Cariprazine Specialty:** It is often highlighted in exams for its high affinity for **D3 receptors**, which is thought to improve negative symptoms of schizophrenia and cognitive function. * **Mnemonic for MAO-B Inhibitors:** "**S**afe **R**ats **S**electively" (**S**afinamide, **R**asagiline, **S**elegiline).

Question 196: Which of the following is an atypical antidepressant?

A. Citalopram
B. Sertraline
C. Venlafaxine (Correct Answer)
D. Reboxetine

Explanation: ### Explanation **Correct Option: C. Venlafaxine** Venlafaxine is classified as a **Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)** [1]. In the context of pharmacology classifications often tested in NEET-PG, SNRIs, NDRIs (Bupropion), and NaSSAs (Mirtazapine) are grouped under **"Atypical Antidepressants"** to distinguish them from the older Tricyclic Antidepressants (TCAs) and the classic Selective Serotonin Reuptake Inhibitors (SSRIs). Venlafaxine works by inhibiting the reuptake of both serotonin and norepinephrine, making it effective for major depression, generalized anxiety disorder, and certain neuropathic pain conditions [1], [2]. **Analysis of Incorrect Options:** * **A. Citalopram & B. Sertraline:** These are **SSRIs** (Selective Serotonin Reuptake Inhibitors) [1]. They are the first-line treatment for depression but are categorized in their own distinct class, not as "atypical." * **D. Reboxetine:** This is a **Selective Norepinephrine Reuptake Inhibitor (NRI)** [3]. While it has a specific mechanism, it is generally categorized separately or as a specific NRI rather than the broader "atypical" label often associated with SNRIs like Venlafaxine. **High-Yield Clinical Pearls for NEET-PG:** * **Dose-Dependent Action:** At low doses (<150 mg), Venlafaxine acts primarily as an SSRI. At higher doses, its norepinephrine reuptake inhibition becomes significant [2]. * **Side Effect Profile:** A unique and high-yield side effect of Venlafaxine (especially at high doses) is **dose-dependent hypertension**. Monitoring blood pressure is mandatory. * **Discontinuation Syndrome:** Venlafaxine has a short half-life; abrupt withdrawal can lead to severe "electric shock" sensations and flu-like symptoms. * **Duloxetine:** Another common SNRI, often preferred if the patient has comorbid chronic pain or diabetic neuropathy [2].

Question 197: Which drug has a very narrow therapeutic range?

A. Lithium (Correct Answer)
B. Sertraline
C. Roxetine
D. Dothiepin

Explanation: **Explanation:** **Lithium** is the correct answer because it is the classic example of a drug with a **narrow therapeutic index (NTI)**. Its therapeutic serum levels (0.6–1.2 mEq/L) are very close to its toxic levels (>1.5 mEq/L). Because the margin of safety is so slim, even minor changes in dosage or renal clearance can lead to life-threatening toxicity. Consequently, patients on Lithium require mandatory **Therapeutic Drug Monitoring (TDM)**. **Analysis of Incorrect Options:** * **Sertraline (B) and Paroxetine (C):** These are Selective Serotonin Reuptake Inhibitors (SSRIs). SSRIs have a wide therapeutic window, meaning the dose required for efficacy is significantly lower than the dose that causes severe toxicity. They are generally safe in overdose. * **Dothiepin (D):** This is a Tricyclic Antidepressant (TCA). While TCAs are more toxic in overdose than SSRIs (primarily due to cardiotoxicity), they still possess a wider therapeutic range than Lithium and do not require routine TDM. **High-Yield Clinical Pearls for NEET-PG:** * **Therapeutic Range:** 0.6–1.2 mEq/L (Prophylaxis: 0.6–0.8; Acute Mania: 0.8–1.2). * **Toxicity:** Levels >1.5 mEq/L cause coarse tremors, ataxia, and seizures. Levels >2.0 mEq/L are a medical emergency often requiring hemodialysis. * **Drug Interactions:** Thiazides, NSAIDs, and ACE inhibitors increase Lithium levels by decreasing renal excretion (High-yield: "The **TAN** mnemonic – **T**hiazides, **A**CEi, **N**SAIDs"). * **Monitoring:** Before starting Lithium, always check Renal Function Tests (RFT) and Thyroid Function Tests (TFT), as it can cause nephrogenic diabetes insipidus and hypothyroidism.

Question 198: A patient started on imipramine presents with a heart rate of 120/min and blurred vision. These effects can be explained by the fact that imipramine:

A. Is a muscarinic antagonist (Correct Answer)
B. Potentiates epinephrine
C. Is a ganglionic blocker
D. Is a potent alpha-adrenergic blocker

Explanation: **Explanation:** Imipramine is a **Tricyclic Antidepressant (TCA)**. While its primary therapeutic mechanism involves inhibiting the reuptake of Norepinephrine (NE) and Serotonin (5-HT), it also possesses significant antagonistic activity at various receptors, most notably **muscarinic (M1) receptors**. **1. Why Option A is Correct:** The clinical presentation of tachycardia (HR 120/min) and blurred vision is a classic manifestation of **anticholinergic (antimuscarinic) toxicity**. By blocking muscarinic receptors: * **Heart:** It inhibits the vagal (parasympathetic) tone, leading to tachycardia. * **Eyes:** It causes paralysis of the ciliary muscle (cycloplegia) and pupillary dilation (mydriasis), resulting in blurred vision. * *Other effects include dry mouth, urinary retention, and constipation.* **2. Why Other Options are Incorrect:** * **Option B:** While TCAs increase synaptic NE, "potentiating epinephrine" is not the primary mechanism for the specific anticholinergic symptoms (blurred vision) described. * **Option C:** TCAs do not block nicotinic receptors at autonomic ganglia; they act directly on the effector organ receptors. * **Option D:** TCAs do have alpha-1 blocking properties, but this typically causes **orthostatic hypotension** and reflex tachycardia, not the constellation of anticholinergic symptoms like blurred vision. **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). * **ECG Findings:** Widening of the QRS complex (>100ms) is a critical marker of TCA toxicity. * **Antidote:** Sodium bicarbonate is used to treat TCA-induced cardiotoxicity. * **Contraindication:** TCAs should be avoided in patients with Narrow-Angle Glaucoma and Benign Prostatic Hyperplasia (BPH) due to their potent anticholinergic effects.

Question 199: Methadone is used in the management of opioid addiction because:

A. Its analgesic activity is less than that of morphine
B. It is an opioid receptor antagonist
C. It is not addictive
D. It is longer acting and causes milder withdrawal symptoms (Correct Answer)

Explanation: **Explanation:** Methadone is a synthetic, long-acting **full μ-opioid receptor agonist**. Its utility in opioid de-addiction (Maintenance Therapy) stems from its unique pharmacokinetic profile. **Why Option D is Correct:** Methadone has a significantly longer half-life (24–36 hours) compared to morphine or heroin. Because of this slow elimination, the decline in plasma concentration is gradual, leading to **milder, though more prolonged, withdrawal symptoms**. Furthermore, its slow onset of action when taken orally prevents the "rush" or euphoria associated with intravenous heroin, helping to stabilize the patient and reduce drug-seeking behavior. **Why Other Options are Incorrect:** * **Option A:** Methadone is a potent analgesic. Its analgesic potency is roughly equal to or greater than morphine; this is not the reason it is used for addiction. * **Option B:** Methadone is a full **agonist**, not an antagonist. Naloxone and Naltrexone are examples of opioid antagonists. * **Option C:** Methadone is an opioid and has significant **addictive potential**. However, it is used to replace a "dangerous" addiction (heroin) with a "controlled" addiction under medical supervision. **High-Yield Clinical Pearls for NEET-PG:** * **NMDA Antagonism:** Besides μ-receptors, Methadone also antagonizes NMDA receptors, which may help in treating neuropathic pain and reducing opioid tolerance. * **ECG Monitoring:** A critical side effect of Methadone is **QT interval prolongation**, which can lead to *Torsades de Pointes*. * **Levomethadyl acetate (LAAM):** A related drug with an even longer half-life (72–96 hours), allowing for dosing every 2–3 days. * **Buprenorphine:** Often preferred over methadone for office-based treatment as it is a **partial agonist** with a lower risk of fatal overdose (ceiling effect).

Question 200: Lithium is used in a pregnant woman. Which of the following congenital anomalies may occur in the fetus?

A. Tetralogy of Fallot
B. Tricuspid atresia
C. Ebstein anomaly (Correct Answer)
D. Pulmonary stenosis

Explanation: **Explanation:** **Lithium** is a mood stabilizer primarily used for Bipolar Affective Disorder (BPAD). It is a known teratogen, and its administration during the first trimester of pregnancy is specifically associated with **Ebstein’s Anomaly** [1]. **1. Why Ebstein Anomaly is the Correct Answer:** Ebstein anomaly is a rare congenital cardiac defect characterized by the **downward displacement of the tricuspid valve leaflets** into the right ventricle [1]. This results in "atrialization" of the right ventricle, leading to severe tricuspid regurgitation and right-sided heart failure. While the absolute risk remains low (approx. 1 in 1,000 to 2,000 exposures), the relative risk is significantly higher in infants exposed to Lithium in utero compared to the general population [1]. **2. Analysis of Incorrect Options:** * **Tetralogy of Fallot (A), Tricuspid Atresia (B), and Pulmonary Stenosis (D):** While these are common congenital cyanotic heart diseases, they are not specifically linked to Lithium exposure. They are more commonly associated with genetic factors (e.g., Down syndrome, DiGeorge syndrome) or other maternal factors like diabetes. **3. NEET-PG High-Yield Clinical Pearls:** * **Monitoring:** Lithium has a narrow therapeutic index (0.6–1.2 mEq/L). Toxicity occurs >1.5 mEq/L. * **Pregnancy Management:** If a woman on Lithium plans to conceive, the drug should ideally be tapered. If she is already pregnant, fetal echocardiography is recommended at 18–20 weeks to screen for cardiac defects. In balancing the risk versus benefit of using lithium in pregnancy, it is important to evaluate the risk of inadequate prophylaxis for bipolar disorder [2]. Lithium freely crosses the placenta, and fetal or neonatal lithium toxicity may develop even when maternal blood levels are within the therapeutic range [2]. * **Breastfeeding:** Lithium is contraindicated during breastfeeding as it is excreted in milk and can cause toxicity in the infant [1]. * **Renal Side Effects:** Long-term use can cause Nephrogenic Diabetes Insipidus (treated with Amiloride).

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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