Drugs in Psychiatric Disorders Practice Questions

Q: Which drug has a very narrow therapeutic range?

Lithium. **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.

Q: Which of the following is an increased risk associated with Risperidone use?

Cerebrovascular accidents. **Explanation:** **Risperidone** is a second-generation (atypical) antipsychotic. While all atypical antipsychotics carry a "Black Box Warning" regarding increased mortality in elderly patients with dementia-related psychosis, **Risperidone** specifically has a well-documented association with an increased risk of **Cerebrovascular Accidents (CVAs)**, such as strokes and transient ischemic attacks (TIAs), in this vulnerable population. The underlying mechanism is thought to involve a combination of orthostatic hypotension, thromboembolic effects, and altered cardiovascular reflex sensitivity. **Analysis of Incorrect Options:** * **B. Extrapyramidal Symptoms (EPS):** While Risperidone can cause EPS (especially at doses >6mg), it is an *atypical* antipsychotic designed to have a *lower* risk of EPS compared to first-generation drugs like Haloperidol. Therefore, CVA is the more specific "increased risk" highlighted in clinical warnings for this class in the elderly. * **C. Agranulocytosis:** This is a classic, life-threatening side effect specifically associated with **Clozapine**, requiring mandatory WBC monitoring. It is not a characteristic risk of Risperidone. * **D. Diabetes Insipidus:** Nephrogenic Diabetes Insipidus is a hallmark side effect of **Lithium** therapy, not antipsychotics. **High-Yield Clinical Pearls for NEET-PG:** * **Hyperprolactinemia:** Among atypical antipsychotics, Risperidone has the highest propensity to increase prolactin levels (causing gynecomastia/amenorrhea). * **Metabolic Syndrome:** Atypical antipsychotics (especially Clozapine and Olanzapine) are high-risk for weight gain, dyslipidemia, and Type 2 Diabetes. * **Active Metabolite:** The active metabolite of Risperidone is **Paliperidone**, which is available as a long-acting injectable.

Q: Which is a feature of haloperidol toxicity?

Long QT. **Explanation:** Haloperidol is a high-potency, typical (first-generation) antipsychotic that acts primarily as a potent **D2 receptor antagonist**. **Why Option B is Correct:** Haloperidol toxicity is strongly associated with cardiovascular side effects, most notably **QT interval prolongation**. This occurs because haloperidol blocks the delayed rectifier potassium channels ($I_{Kr}$) in the cardiac myocytes. Prolongation of the QT interval increases the risk of life-threatening ventricular arrhythmias, specifically **Torsades de Pointes**. This risk is significantly higher with intravenous administration or high doses. **Why Other Options are Incorrect:** * **A. Weight loss:** Antipsychotics, including haloperidol, are more commonly associated with **weight gain** (though less so than atypical antipsychotics like Olanzapine) due to metabolic changes and H1 receptor blockade. * **C. Diarrhea:** Haloperidol possesses mild anticholinergic properties, which are more likely to cause **constipation** rather than diarrhea. * **D. Tendinitis:** This is a classic side effect associated with **Fluoroquinolones** (e.g., Ciprofloxacin), not antipsychotics. **High-Yield Clinical Pearls for NEET-PG:** * **Extrapyramidal Symptoms (EPS):** Due to high D2 potency, Haloperidol has the highest risk of acute dystonia, akathisia, and parkinsonism. * **Neuroleptic Malignant Syndrome (NMS):** A life-threatening reaction characterized by "lead-pipe" rigidity, hyperthermia, and autonomic instability. * **Hyperprolactinemia:** Haloperidol frequently causes galactorrhea and gynecomastia by blocking dopamine in the tuberoinfundibular pathway. * **Monitoring:** Always perform a baseline ECG before starting high-dose or IV haloperidol to monitor the QTc interval.

Q: 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?

Amitriptyline. ### 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.

Q: Which of the following is not a side effect of lithium?

Blood dyscrasias. **Explanation:** Lithium is the gold-standard mood stabilizer for Bipolar Affective Disorder (BPAD), but it has a narrow therapeutic index and a wide range of systemic side effects. **Why Blood Dyscrasias is the Correct Answer:** Lithium does **not** cause blood dyscrasias (like agranulocytosis or aplastic anemia). In fact, it causes the opposite effect: **Leukocytosis** (specifically neutrophilia). It stimulates granulopoiesis in the bone marrow. This is a benign side effect, though it can sometimes be used therapeutically to treat Felty’s syndrome or chemotherapy-induced neutropenia. **Analysis of Incorrect Options:** * **Polyuria:** Lithium inhibits the action of Antidiuretic Hormone (ADH) on the distal tubules, leading to **Nephrogenic Diabetes Insipidus**. This results in polyuria and compensatory polydipsia. * **Hypothyroidism:** Lithium interferes with iodine organification and thyroid hormone release. It is a common cause of goiter and hypothyroidism, necessitating regular TSH monitoring. * **Weight Gain:** This is a very common metabolic side effect of Lithium, often leading to poor patient compliance. **High-Yield Clinical Pearls for NEET-PG:** * **L-I-T-H-I-U-M Mnemonic for Side Effects:** **L**eukocytosis, **I**nsipidus (Diabetes), **T**remors (Fine)/Teratogenicity (Ebstein's Anomaly), **H**ypothyroidism, **I**ncreased Weight, **U**nder-active heart (Sinus bradycardia), **M**others (Pregnancy contraindication). * **Therapeutic Range:** 0.6–1.2 mEq/L (Prophylaxis: 0.6–0.8; Acute Mania: 0.8–1.2). * **Toxicity:** Occurs >1.5 mEq/L; characterized by **coarse tremors**, ataxia, and seizures. * **Drug Interactions:** Thiazides, NSAIDs, and ACE inhibitors increase Lithium levels (Decreased clearance).

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

Lofepramine. **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.

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

It is not a D2 receptor antagonist.. **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).

Q: Which drug is known to cause agranulocytosis?

Clozapine. **Explanation:** **Clozapine** is an atypical (second-generation) antipsychotic reserved for treatment-resistant schizophrenia. Its most serious and life-threatening side effect is **agranulocytosis** (a severe decrease in the absolute neutrophil count <500/mm³), which occurs in approximately 0.8–1% of patients. The mechanism is thought to be an immune-mediated destruction of granulocytes. Due to this risk, mandatory hematological monitoring (ANC levels) is required—weekly for the first 6 months, biweekly for the next 6 months, and monthly thereafter. **Analysis of Incorrect Options:** * **A. Pimozide:** A typical antipsychotic primarily used for Tourette’s disorder. Its main concern is QT interval prolongation and sudden cardiac death, not agranulocytosis. * **C. Risperidone:** An atypical antipsychotic known for causing significant hyperprolactinemia and extrapyramidal symptoms (EPS) at higher doses, but it does not carry a significant risk of bone marrow suppression. * **D. Olanzapine:** Structurally similar to clozapine but lacks the significant risk of agranulocytosis. Its primary side effects are significant weight gain, sedation, and metabolic syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Clozapine** is the only antipsychotic proven to reduce **suicidal behavior** in schizophrenia. * **Seizures** are a dose-dependent side effect of Clozapine (highest risk at doses >600mg). * **Sialorrhea** (excessive salivation) is a paradoxical but common side effect. * **Myocarditis** is another rare but fatal complication of Clozapine, usually occurring within the first month of treatment.

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

Hypotensive. 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 1

Which drug has a very narrow therapeutic range?

Accepted Answer

Lithium

Answer

Sertraline

Answer

Roxetine

Answer

Dothiepin

Question 2

Which of the following is an increased risk associated with Risperidone use?

Accepted Answer

Cerebrovascular accidents

Answer

Extrapyramidal symptoms

Answer

Agranulocytosis

Answer

Diabetes insipidus

Question 3

Which is a feature of haloperidol toxicity?

Accepted Answer

Long QT

Answer

Weight loss

Answer

Diarrhea

Answer

Tendinitis

Question 4

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?

Accepted Answer

Amitriptyline

Answer

Chlorpromazine

Answer

Haloperidol

Answer

Pimozide

Question 5

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

Accepted Answer

Low oral bioavailability

Answer

Narrow safety margin

Answer

Frequent side effects

Answer

Long latent period for response

Question 6

Which of the following is not a side effect of lithium?

Accepted Answer

Blood dyscrasias

Answer

Polyuria

Answer

Hypothyroidism

Answer

Weight gain

Question 7

Which tricyclic antidepressant has the LEAST autonomic and cardiotoxic effects?

Accepted Answer

Lofepramine

Answer

Amitriptyline

Answer

Desipramine

Answer

Protriptyline

Question 8

Which of the following properties distinguishes Aripiprazole from atypical antipsychotics?

Accepted Answer

It is not a D2 receptor antagonist.

Answer

It is a potent 5-HT2A receptor antagonist.

Answer

Reduced risk of extrapyramidal side effects.

Answer

It can be used in Schizophrenia.

Question 9

Which drug is known to cause agranulocytosis?

Accepted Answer

Clozapine

Answer

Pimozide

Answer

Risperidone

Answer

Olanzapine

Question 10

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

Accepted Answer

Hypotensive

Answer

Antipsychotic

Answer

Hyperprolactinemic

Answer

Antiemetic

Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders — MCQs

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