Drugs in Psychiatric Disorders Practice Questions

Q: Tardive dyskinesia is least commonly associated with which of the following drugs?

Clozapine. **Explanation:** **Tardive Dyskinesia (TD)** is a late-onset extrapyramidal side effect (EPS) characterized by involuntary, choreoathetoid movements, typically involving the tongue, face, and jaw. It is caused by the **upregulation and supersensitivity of Dopamine D2 receptors** in the nigrostriatal pathway following chronic blockade. **Why Clozapine is the correct answer:** Clozapine is an atypical (second-generation) antipsychotic with a unique pharmacological profile. It has a **very low affinity for D2 receptors** and a high affinity for D4 and Serotonin (5-HT2A) receptors. It dissociates rapidly from D2 receptors ("loose binding"), which significantly minimizes the risk of nigrostriatal side effects. Clozapine is the only antipsychotic with a **near-zero risk** of causing TD and is, in fact, the drug of choice for managing patients who have already developed TD. **Analysis of Incorrect Options:** * **Thioridazine (A):** A low-potency typical antipsychotic. While it has some intrinsic anticholinergic activity that lowers acute EPS, it still carries a significant risk of TD with long-term use. * **Metoclopramide (B):** A prokinetic antiemetic that acts as a potent D2 receptor antagonist. It is a notorious non-psychiatric cause of TD, especially in elderly patients. * **Thiothixene (C):** A high-potency typical antipsychotic (thioxanthene class) with strong D2 blockade, making it highly associated with the development of TD. **High-Yield Clinical Pearls for NEET-PG:** * **Treatment of choice for TD:** Valbenazine or Deutetrabenazine (VMAT2 inhibitors). * **Drug of choice for TD in a psychotic patient:** Clozapine. * **Risk Factor:** Long-term use of typical antipsychotics and advancing age. * **Note:** Anticholinergics (like Trihexyphenidyl) **worsen** TD, unlike other EPS.

Q: Coarse tremors, dysarthria, and ataxia are side effects of which medication?

Lithium. **Explanation:** The correct answer is **Lithium**. The symptoms described—**coarse tremors, dysarthria (slurred speech), and ataxia (stumbling gait)**—are classic neurological hallmarks of **Lithium Toxicity**. 1. **Why Lithium is correct:** Lithium has a very narrow therapeutic index (0.6–1.2 mEq/L). While *fine* tremors are a common side effect at therapeutic levels, the progression to *coarse* tremors, along with cerebellar signs like ataxia and dysarthria, indicates toxicity (usually levels >1.5–2.0 mEq/L). These symptoms occur because lithium interferes with neurotransmission and can cause reversible or, in severe cases, permanent cerebellar damage (SILENT syndrome). 2. **Why other options are incorrect:** * **Haloperidol:** A typical antipsychotic primarily associated with **Extrapyramidal Side Effects (EPS)** such as acute dystonia, parkinsonism (resting tremors, not coarse), and akathisia. * **Imipramine:** A Tricyclic Antidepressant (TCA) characterized by **anticholinergic side effects** (dry mouth, blurred vision, constipation) and cardiotoxicity (prolonged QTc) in overdose, rather than ataxia and coarse tremors. **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). * **Early signs of toxicity:** Nausea, vomiting, and coarse tremors. * **Severe toxicity (>2.5 mEq/L):** Seizures, coma, and death. **Hemodialysis** is the treatment of choice for severe toxicity. * **Drug Interactions:** Thiazides, NSAIDs, and ACE inhibitors increase Lithium levels (decreasing clearance), potentially precipitating toxicity.

Q: Which of the following medicines is associated with the side effect of sexual dysfunction?

Fluoxetine. **Explanation:** **Fluoxetine** is a Selective Serotonin Reuptake Inhibitor (SSRI). Sexual dysfunction is one of the most common and distressing side effects of SSRIs, occurring in approximately 30% to 60% of patients. The underlying mechanism involves the stimulation of **5-HT2 receptors** in the spinal cord and brain, which inhibits the spinal reflexes associated with orgasm and ejaculation, and decreases dopamine release in the reward centers, leading to reduced libido. **Analysis of Incorrect Options:** * **Mianserin:** This is a tetracyclic antidepressant (TeCA) that acts as an antagonist at H1, α1, α2, and 5-HT2 receptors. Because it blocks 5-HT2 receptors rather than increasing serotonin at those sites, it is generally associated with a much lower risk of sexual dysfunction compared to SSRIs. * **Bupropion:** This is a Norepinephrine-Dopamine Reuptake Inhibitor (NDRI). It does not affect the serotonergic system. In fact, it is often used as an "add-on" or alternative treatment to alleviate SSRI-induced sexual dysfunction because it enhances dopaminergic neurotransmission. **Clinical Pearls for NEET-PG:** * **Most common sexual side effects:** Delayed ejaculation and anorgasmia. * **Management:** If sexual dysfunction occurs, the clinician may consider a "drug holiday" (briefly stopping the drug over the weekend), switching to **Bupropion, Mirtazapine, or Nefazodone**, or adding **Sildenafil**. * **High-Yield Fact:** Among SSRIs, **Paroxetine** is often cited as having the highest incidence of sexual side effects.

Q: All of the following are predictable adverse effects of treatment with phenothiazines such as chlorpromazine, EXCEPT?

Excessive salivation. **Explanation:** Chlorpromazine is a low-potency typical antipsychotic (phenothiazine) that acts by blocking multiple receptors, including Dopamine ($D_2$), Alpha-1 ($\alpha_1$), Muscarinic ($M_1$), and Histamine ($H_1$). **Why "Excessive Salivation" is the correct answer:** Phenothiazines like chlorpromazine have significant **anticholinergic (antimuscarinic) properties**. Blockade of $M_1$ receptors leads to decreased secretions, resulting in **Dry Mouth (Xerostomia)**, not excessive salivation. *(Note: Clozapine is a unique exception among antipsychotics as it causes sialorrhea/excessive salivation).* **Analysis of Incorrect Options:** * **A. Orthostatic Hypotension:** This is a predictable effect caused by the blockade of **$\alpha_1$-adrenergic receptors** in the peripheral vasculature, leading to vasodilation. * **B. Parkinson’s Syndrome:** By blocking **$D_2$ receptors** in the **Nigrostriatal pathway**, phenothiazines cause Extrapyramidal Symptoms (EPS), including drug-induced Parkinsonism (tremors, rigidity, bradykinesia). * **D. Hyperprolactinemia:** $D_2$ blockade in the **Tuberoinfundibular pathway** removes the inhibitory effect of dopamine on prolactin release. This leads to elevated prolactin levels, potentially causing galactorrhea and gynecomastia. **NEET-PG High-Yield Pearls:** 1. **Low Potency (Chlorpromazine/Thioridazine):** High sedation, high anticholinergic effects, high alpha-blockade, but lower risk of EPS. 2. **High Potency (Haloperidol/Fluphenazine):** Low sedation, low anticholinergic effects, but very high risk of EPS. 3. **Thioridazine Warning:** Associated with Retinitis Pigmentosa and QTc prolongation. 4. **Clozapine:** The "rule breaker"—it is the only antipsychotic that commonly causes **excessive salivation** (likely due to $M_4$ receptor agonism or inhibition of the swallowing reflex).

Q: Lithium is used in a pregnant woman. Which of the following congenital anomalies occurs in the fetus?

Ebstein anomaly. **Explanation:** **Lithium** is a mood stabilizer primarily used for Bipolar Affective Disorder. It is a known **teratogen** (Category D), and its use during the first trimester of pregnancy is classically associated with **Ebstein anomaly**. **Why Ebstein Anomaly is the correct answer:** Ebstein anomaly is a rare congenital heart defect characterized by the **downward displacement of the tricuspid valve leaflets** into the right ventricle. This "atrializes" the right ventricle, leading to severe tricuspid regurgitation and right-sided heart failure. While the absolute risk of this anomaly in lithium-exposed pregnancies is low (approx. 1 in 1,000), it represents a 10–20 fold increase compared to the general population, making it the most specific association for the exam. **Why other options are incorrect:** * **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 syndromes (like Down syndrome or DiGeorge syndrome) or other environmental factors. **High-Yield Clinical Pearls for NEET-PG:** * **Timing:** The risk is highest during the **first trimester** (organogenesis). * **Management:** If a pregnant woman must take Lithium, fetal echocardiography is recommended at 18–20 weeks. * **Other Lithium Side Effects:** In neonates, Lithium can cause **"Floppy Infant Syndrome"** (hypotonia, cyanosis, and lethargy) and neonatal goiter. * **Excretion:** Lithium is excreted in breast milk; hence, breastfeeding is generally discouraged while on high-dose therapy.

Q: Which of the following antidepressants is a reversible inhibitor of monoamine oxidase A (RIMA)?

Moclobemide. **Explanation:** **Moclobemide** is the correct answer because it belongs to the class of **Reversible Inhibitors of Monoamine Oxidase A (RIMA)**. Unlike older, irreversible MAOIs, Moclobemide selectively inhibits the MAO-A enzyme (which metabolizes serotonin, norepinephrine, and dopamine) in a reversible manner. This reversibility is clinically significant because if systemic tyramine levels rise (e.g., from consuming aged cheese), the tyramine can displace Moclobemide from the enzyme, allowing for tyramine metabolism and significantly reducing the risk of a hypertensive crisis ("cheese reaction"). **Analysis of Incorrect Options:** * **Phenelzine:** This is a **non-selective, irreversible MAO inhibitor**. It binds permanently to both MAO-A and MAO-B, requiring strict dietary restrictions to avoid life-threatening hypertensive crises. * **Sertraline & Fluoxetine:** These are **Selective Serotonin Reuptake Inhibitors (SSRIs)**. They work by inhibiting the serotonin transporter (SERT) rather than the MAO enzyme. Fluoxetine is notable for its very long half-life due to its active metabolite, norfluoxetine. **High-Yield Clinical Pearls for NEET-PG:** * **The "Cheese Reaction":** Occurs when tyramine displaces stored norepinephrine; RIMAs like Moclobemide have a much lower risk compared to Phenelzine or Tranylcypromine. * **MAO-B Inhibitor:** **Selegiline** (used in Parkinson’s) is a selective MAO-B inhibitor at low doses but loses selectivity at higher antidepressant doses. * **Washout Period:** When switching from an MAOI to an SSRI, a 2-week washout period is required (5 weeks for Fluoxetine) to prevent **Serotonin Syndrome**. * **Drug of Choice:** SSRIs (like Sertraline) remain the first-line treatment for depression due to their superior safety profile.

Q: Which of the following drugs does not activate opioid receptors, has been proposed as a drug in the management of opioid addiction, and with just a single dose blocks the action of injected heroin for up to 48 hours?

Naltrexone. ### Explanation **Correct Option: D. Naltrexone** **Mechanism and Rationale:** Naltrexone is a potent, long-acting **pure opioid antagonist** [1], [3]. Unlike methadone or buprenorphine, it has **zero agonist activity** (it does not activate opioid receptors) [3], [4]. It works by competitively binding to $\mu$-opioid receptors, thereby blocking the effects of exogenous opioids like heroin. * **Pharmacokinetics:** It has a significantly longer half-life than naloxone [4]. A single oral dose of 50 mg can effectively block the "high" and physical effects of injected heroin for **up to 48–72 hours**. This makes it an ideal agent for **relapse prevention** in highly motivated patients who have already undergone detoxification [5]. **Analysis of Incorrect Options:** * **A. Amphetamine:** A CNS stimulant that increases synaptic dopamine and norepinephrine. It has no role in opioid addiction management and is itself a drug of abuse. * **B. Buspirone:** A 5-HT$_{1A}$ partial agonist used as an anxiolytic. It does not interact with opioid receptors. * **C. Methadone:** While used in opioid addiction (maintenance therapy), it is a **full $\mu$-opioid agonist** [5]. It activates the receptors to prevent withdrawal symptoms, which contradicts the question's criteria. **High-Yield Clinical Pearls for NEET-PG:** * **Naltrexone vs. Naloxone:** Naltrexone is orally active and long-acting (used for maintenance/alcoholism); Naloxone is given parenterally and is short-acting (used for acute opioid overdose) [5]. * **Alcoholism:** Naltrexone is also FDA-approved for alcohol dependence as it reduces "craving" by blocking endogenous opioid-mediated reward pathways [2], [4]. * **Pre-requisite:** Naltrexone must **never** be started until a patient is opioid-free for at least 7–10 days; otherwise, it will precipitate severe, acute withdrawal.

Q: Which of the following medications is most associated with extrapyramidal side effects?

Haloperidol. **Explanation:** The correct answer is **Haloperidol**. This question tests your understanding of the side effect profiles of typical antipsychotics based on their receptor potency. **1. Why Haloperidol is correct:** Haloperidol is a **High-Potency Typical Antipsychotic**. It acts as a potent antagonist at **D2 receptors** in the mesolimbic and nigrostriatal pathways. Because it has a very high affinity for D2 receptors and low anticholinergic activity, it is the drug most frequently associated with **Extrapyramidal Side Effects (EPS)**, such as acute dystonia, akathisia, and parkinsonism. **2. Why the other options are incorrect:** * **Chlorpromazine:** This is a **Low-Potency Typical Antipsychotic**. While it can cause EPS, it has significant **anticholinergic (M1) activity**. Since acetylcholine and dopamine exist in a reciprocal balance in the basal ganglia, the inherent anticholinergic effect of chlorpromazine partially "buffers" against EPS. It is more commonly associated with sedation and orthostatic hypotension. * **Imipramine & Clomipramine:** These are **Tricyclic Antidepressants (TCAs)**. Their primary side effects are related to muscarinic, alpha-1, and histaminic blockade (dry mouth, blurred vision, sedation). They do not primarily block D2 receptors and thus do not typically cause EPS. **High-Yield NEET-PG Pearls:** * **EPS Hierarchy:** High potency (Haloperidol, Fluphenazine) > Low potency (Chlorpromazine, Thioridazine) > Atypicals (Clozapine, Quetiapine). * **Treatment of Acute Dystonia:** Centrally acting anticholinergics like **Promethazine** or **Benztropine**. * **Neuroleptic Malignant Syndrome (NMS):** A severe side effect of Haloperidol; treated with **Dantrolene** or Bromocriptine. * **Rule of Thumb:** High potency = High EPS; Low potency = High Sedation/Autonomic effects.

Question 1

Tardive dyskinesia is least commonly associated with which of the following drugs?

Accepted Answer

Clozapine

Answer

Thioridazine

Answer

Metoclopramide

Answer

Thiothixene

Question 2

Coarse tremors, dysarthria, and ataxia are side effects of which medication?

Accepted Answer

Lithium

Answer

Haloperidol

Answer

Imipramine

Answer

None of the above

Question 3

Which of the following medicines is associated with the side effect of sexual dysfunction?

Accepted Answer

Fluoxetine

Answer

Mianserin

Answer

Bupropion

Answer

None of the above

Question 4

All of the following statements are true, except?

Accepted Answer

Agranulocytosis is the most common side effect of clozapine.

Answer

Dipyridamole shows coronary steal phenomena.

Answer

Omeprazole inhibits CYP 2C19.

Answer

SNRIs are the drug of choice for severe depression.

Question 5

All of the following are predictable adverse effects of treatment with phenothiazines such as chlorpromazine, EXCEPT?

Accepted Answer

Excessive salivation

Answer

Orthostatic hypotension

Answer

Parkinson's syndrome

Answer

Hyperprolactinemia

Question 6

Discontinuation of which of the following drugs can result in anxiety and insomnia?

Accepted Answer

Venlafaxine

Answer

Imipramine

Answer

Valproate

Answer

Olanzapine

Question 7

Lithium is used in a pregnant woman. Which of the following congenital anomalies occurs in the fetus?

Accepted Answer

Ebstein anomaly

Answer

Tetralogy of Fallot's

Answer

Tricuspid atresia

Answer

Pulmonary stenosis

Question 8

Which of the following antidepressants is a reversible inhibitor of monoamine oxidase A (RIMA)?

Accepted Answer

Moclobemide

Answer

Phenelzine

Answer

Sertraline

Answer

Fluoxetine

Question 9

Which of the following drugs does not activate opioid receptors, has been proposed as a drug in the management of opioid addiction, and with just a single dose blocks the action of injected heroin for up to 48 hours?

Accepted Answer

Naltrexone

Answer

Amphetamine

Answer

Buspirone

Answer

Methadone

Question 10

Which of the following medications is most associated with extrapyramidal side effects?

Accepted Answer

Haloperidol

Answer

Chlorpromazine

Answer

Imipramine

Answer

Clomipramine

Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders — MCQs

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