Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders Indian Medical PG Practice Questions and MCQs

Question 251: All the following statements about clozapine are true except?

A. It is used in schizophrenia.
B. It may precipitate seizures.
C. It may cause agranulocytosis.
D. Extrapyramidal side effects are seen. (Correct Answer)

Explanation: **Explanation:** Clozapine is the prototype **Atypical Antipsychotic** (Second Generation Antipsychotic). The correct answer is **D** because Clozapine is uniquely characterized by its **minimal to no risk of Extrapyramidal Side Effects (EPS)**. **1. Why Option D is the Correct Answer (The "Except"):** Unlike typical antipsychotics (e.g., Haloperidol) which strongly block $D_2$ receptors in the nigrostriatal pathway, Clozapine has a low affinity for $D_2$ receptors and a high affinity for $5-HT_{2A}$ receptors. This specific binding profile prevents the motor side effects like tremors, rigidity, and dystonia, making it the drug of choice for patients who cannot tolerate EPS. **2. Analysis of Other Options:** * **Option A (Used in Schizophrenia):** Clozapine is the "Gold Standard" for **Treatment-Resistant Schizophrenia** (patients failing at least two other antipsychotics) and for reducing suicidal behavior in schizophrenic patients. * **Option B (Precipitate Seizures):** Clozapine significantly lowers the seizure threshold in a dose-dependent manner. Approximately 3–5% of patients on high doses may experience seizures. * **Option C (Agranulocytosis):** This is the most dreaded side effect (occurring in ~1% of patients). It requires mandatory weekly blood monitoring (ANC counts) for the first six months of treatment. **High-Yield Clinical Pearls for NEET-PG:** * **Sialorrhea:** Paradoxically, Clozapine causes excessive salivation (most common side effect), despite having anticholinergic properties. * **Metabolic Syndrome:** It causes significant weight gain, hyperlipidemia, and diabetes mellitus. * **Myocarditis:** A rare but fatal complication; monitor for chest pain or tachycardia in the first month. * **No Prolactin Elevation:** Unlike most antipsychotics, Clozapine does not cause hyperprolactinemia.

Question 252: What is the drug of choice for attention deficit hyperactivity disorder?

A. Haloperidol
B. Imipramine
C. Alprazolam
D. Methylphenidate (Correct Answer)

Explanation: **Explanation:** **Methylphenidate** is the drug of choice (DOC) for Attention Deficit Hyperactivity Disorder (ADHD). The underlying pathophysiology of ADHD involves a deficiency of dopamine and norepinephrine in the prefrontal cortex, which regulates attention and impulse control. Methylphenidate is a **CNS stimulant** that acts by blocking the reuptake of dopamine and norepinephrine (NDRI), thereby increasing their synaptic concentration and improving focus, alertness, and behavioral control. **Analysis of Incorrect Options:** * **A. Haloperidol:** A typical antipsychotic (D2 blocker). It is used in Tourette’s syndrome or acute psychosis but is contraindicated in ADHD as it can worsen cognitive dulling and cause extrapyramidal side effects. * **B. Imipramine:** A Tricyclic Antidepressant (TCA). While it can be used as a second or third-line agent for ADHD (especially if comorbid with nocturnal enuresis), it is not the first-line choice due to its cardiotoxicity and anticholinergic side effects. * **C. Alprazolam:** A benzodiazepine used for anxiety and panic disorders. It causes sedation and cognitive impairment, which would exacerbate the symptoms of ADHD. **High-Yield Clinical Pearls for NEET-PG:** * **Non-stimulant DOC:** **Atomoxetine** (Selective Norepinephrine Reuptake Inhibitor) is the preferred alternative if there is a risk of substance abuse or if stimulants are poorly tolerated. * **Side Effects of Methylphenidate:** Insomnia, anorexia (weight loss), and potential growth suppression in children (requires "drug holidays"). * **Adult ADHD:** While stimulants remain first-line, Atomoxetine is frequently used. * **Other Stimulants:** Amphetamines (e.g., Lisdexamfetamine) are also highly effective first-line agents.

Question 253: Which of the following are extrapyramidal side effects of antipsychotics?

A. Dystonia, Akathisia, and Seizures
B. Akathisia, Seizures, and Diarrhea
C. Dystonia, Akathisia, and Parkinsonism (Correct Answer)
D. Dystonia, Seizures, and Parkinsonism

Explanation: **Explanation:** Extrapyramidal Side Effects (EPS) are movement disorders caused by the blockade of **D2 receptors in the nigrostriatal pathway**. This pathway regulates motor control, and its inhibition by antipsychotics (especially typical ones like Haloperidol) leads to an imbalance between dopamine and acetylcholine. **1. Why Option C is Correct:** The classic triad of early-onset EPS includes: * **Acute Dystonia:** Spasms of muscles (e.g., torticollis, oculogyric crisis). Occurs within hours to days. * **Akathisia:** Subjective feeling of motor restlessness (inability to sit still). This is the most common EPS. * **Parkinsonism:** Tremors, rigidity, and bradykinesia. Occurs within weeks. * *(Note: Tardive Dyskinesia is a late-onset EPS involving choreoathetoid movements.)* **2. Why Other Options are Incorrect:** * **Seizures:** While antipsychotics (especially Clozapine) can lower the seizure threshold, seizures are considered a neurological adverse effect, not an extrapyramidal motor symptom. * **Diarrhea:** Antipsychotics typically have **anticholinergic** properties, which cause constipation, not diarrhea. **NEET-PG High-Yield Pearls:** * **Treatment of Acute Dystonia/Parkinsonism:** Central anticholinergics like **Benztropine** or **Promethazine**. * **Treatment of Akathisia:** Drug of choice is **Propranolol** (Beta-blocker). * **Hyperprolactinemia:** Also caused by D2 blockade, but in the **tuberoinfundibular pathway**, leading to galactorrhea and gynecomastia. * **Lowest EPS Risk:** Quetiapine and Clozapine (Atypical antipsychotics).

Question 254: Valproic acid is used in which of the following disorders?

A. Sydenham's chorea and Mania only
B. Migraine and Obsessive compulsive disorder only
C. Sydenham's chorea, Migraine, and Mania only (Correct Answer)
D. Migraine, Mania, and Obsessive compulsive disorder only

Explanation: **Explanation:** Valproic acid (Sodium Valproate) is a broad-spectrum anticonvulsant with a versatile clinical profile. Its mechanism involves increasing GABA levels, inhibiting T-type calcium channels, and blocking voltage-gated sodium channels. **Why Option C is correct:** 1. **Mania:** Valproate is a first-line mood stabilizer used for the treatment of acute manic episodes in Bipolar Disorder and for maintenance therapy. 2. **Migraine:** It is FDA-approved for the **prophylaxis** of migraine (though not for acute attacks). 3. **Sydenham’s Chorea:** Valproate is considered an effective second-line treatment (after diazepam or haloperidol) to control the involuntary movements associated with this condition, especially in refractory cases. **Why other options are incorrect:** * **Obsessive-Compulsive Disorder (OCD):** The primary treatment for OCD involves SSRIs (e.g., Fluoxetine, Fluvoxamine) and Clomipramine (TCA). Valproate is not a standard treatment for OCD and is only rarely used as an off-label augmentation strategy in treatment-resistant cases, making options B and D incorrect. * **Option A** is incomplete as it misses Migraine, a major clinical indication. **High-Yield Clinical Pearls for NEET-PG:** * **Teratogenicity:** Valproate is highly teratogenic, causing **Neural Tube Defects** (specifically Spina Bifida). It should be avoided in pregnancy. * **Side Effects:** Remember the mnemonic **VALPROATE**: **V**omiting, **A**lopecia (curly hair), **L**iver toxicity (Hepatotoxicity), **P**ancreatitis, **R**etention of weight (Obesity), **O**edema, **A**norexia, **T**remors/Thrombocytopenia, and **E**ncephalopathy (due to hyperammonemia). * **Drug of Choice:** It is the drug of choice for **Myoclonic seizures** and generalized tonic-clonic seizures.

Question 255: Which of the following drugs has a high affinity for 5-HT2 receptors in the brain, does not cause extrapyramidal dysfunction or hematotoxicity, and is reported to increase the risk of significant QT prolongation?

A. Chlorpromazine
B. Clozapine
C. Olanzapine
D. Ziprasidone (Correct Answer)

Explanation: **Explanation:** The question describes the profile of an **Atypical Antipsychotic (Second Generation Antipsychotic)**. These drugs are characterized by a higher affinity for **5-HT2A receptors** compared to D2 receptors, which reduces the risk of Extrapyramidal Side Effects (EPS) [1]. **Why Ziprasidone is the correct answer:** * **Mechanism:** It has a high 5-HT2A/D2 affinity ratio [1]. * **Safety Profile:** Unlike typical antipsychotics, it causes minimal to no EPS. Crucially, it is **not associated with hematotoxicity** (unlike Clozapine) [1]. * **Cardiac Warning:** Ziprasidone is notorious for causing **significant QT interval prolongation**, which can lead to life-threatening arrhythmias like Torsades de Pointes [3]. This makes it contraindicated in patients with a history of arrhythmias or recent MI. **Analysis of Incorrect Options:** * **Chlorpromazine:** A typical (first-generation) antipsychotic. It has a high risk of EPS and significant sedative/anticholinergic effects, but its primary mechanism is D2 blockade, not 5-HT2 dominance. * **Clozapine:** While it has high 5-HT2 affinity and no EPS, it is famously associated with **agranulocytosis (hematotoxicity)**, which the question explicitly excludes [1]. * **Olanzapine:** An atypical antipsychotic with low EPS risk, but its primary metabolic side effect is **significant weight gain** and hyperglycemia, not significant QT prolongation compared to Ziprasidone [2]. **NEET-PG High-Yield Pearls:** * **QT Prolongation:** Remember the mnemonic "Ziprasidone and Thioridazine" as the top antipsychotics causing QT issues [3]. * **Weight Neutrality:** Ziprasidone and Aripiprazole are preferred in patients concerned about weight gain [2]. * **Clozapine Monitoring:** Requires mandatory WBC count monitoring due to the risk of agranulocytosis [1].

Question 256: Amitriptyline is a:

A. Antibiotic
B. Sedative
C. Tricyclic antidepressant (Correct Answer)
D. Diuretic

Explanation: **Explanation:** **Amitriptyline** is a classic prototype of the **Tricyclic Antidepressant (TCA)** class. Its primary mechanism of action involves the non-selective inhibition of the reuptake of norepinephrine (NE) and serotonin (5-HT) at the presynaptic terminals, thereby increasing their concentration in the synaptic cleft. **Analysis of Options:** * **Option C (Correct):** Amitriptyline belongs to the tertiary amine subclass of TCAs. It is widely used for major depressive disorder, though its use is now often limited by its side-effect profile. * **Option A (Incorrect):** Antibiotics are agents used to treat bacterial infections (e.g., Penicillins, Fluoroquinolones). Amitriptyline has no antimicrobial properties. * **Option B (Incorrect):** While Amitriptyline has significant **sedative properties** (due to potent H1-receptor antagonism), it is classified pharmacologically by its primary therapeutic use as an antidepressant, not as a primary sedative-hypnotic like Benzodiazepines. * **Option D (Incorrect):** Diuretics (e.g., Furosemide, Thiazides) act on the kidneys to increase urine output. Amitriptyline actually causes urinary retention as an anticholinergic side effect. **NEET-PG High-Yield Clinical Pearls:** 1. **Other Indications:** Beyond depression, it is a first-line drug for **Neuropathic pain**, **Prophylaxis of Migraine**, and nocturnal enuresis in children (though Imipramine is more common for the latter). 2. **Side Effects:** Mnemonic **"3 Cs" of TCA Toxicity**—**C**oma, **C**onvulsions, and **C**ardiotoxicity (Arrhythmias due to Na+ channel blockade). 3. **Anticholinergic Effects:** Patients often present with dry mouth, blurred vision, constipation, and urinary retention. 4. **Contraindication:** It should be avoided in patients with Angle-closure glaucoma and Benign Prostatic Hyperplasia (BPH).

Question 257: The combination of alcohol and disulfiram results in nausea and hypotension as a result of accumulation of which substance?

A. Acetaldehyde (Correct Answer)
B. Acetate
C. Methanol
D. NADH

Explanation: ### Explanation **Correct Option: A. Acetaldehyde** The metabolism of alcohol (ethanol) primarily occurs in the liver via a two-step oxidative process: 1. **Ethanol** is converted to **Acetaldehyde** by the enzyme *Alcohol Dehydrogenase*. 2. **Acetaldehyde** is then converted to **Acetate** by the enzyme **Aldehyde Dehydrogenase (ALDH)**. **Disulfiram** works by irreversibly inhibiting the enzyme **Aldehyde Dehydrogenase**. When a patient on disulfiram consumes alcohol, the second step of metabolism is blocked, leading to a 5-10 fold accumulation of **Acetaldehyde** in the blood. This toxic buildup triggers the **Disulfiram-Ethanol Reaction (DER)**, characterized by flushing, tachycardia, nausea, vomiting, and potentially fatal hypotension. --- ### Analysis of Incorrect Options: * **B. Acetate:** This is the end-product of normal alcohol metabolism. Disulfiram prevents its formation; therefore, acetate levels decrease rather than accumulate. * **C. Methanol:** This is a different type of alcohol (wood alcohol). While its metabolism also involves similar enzymes, it is not the substance responsible for the disulfiram reaction with ethanol. * **D. NADH:** While the ratio of NADH/NAD+ increases during alcohol metabolism (contributing to lactic acidosis and fatty liver), it is not the specific mediator of the acute physical distress seen in the disulfiram reaction. --- ### High-Yield Clinical Pearls for NEET-PG: * **Disulfiram-like reaction:** Several other drugs can cause a similar reaction when taken with alcohol. Remember the mnemonic **"PMC"**: **P**rocarbazine, **M**etronidazole, **C**ephalosporins (specifically Cefoperazone, Cefotetan). * **Mechanism:** Disulfiram is an example of **Aversion Therapy**. It does not reduce the urge to drink but acts as a psychological deterrent. * **Contraindication:** It should never be administered if the patient has consumed alcohol within the last 12 hours or is in a state of intoxication. * **Fomepizole:** Contrast this with Fomepizole, which inhibits *Alcohol Dehydrogenase* and is used as an antidote for Methanol or Ethylene glycol poisoning.

Question 258: Administration of disulfiram in an alcoholic can cause all these side effects except?

A. Flushing
B. Headache
C. Hypertension (Correct Answer)
D. Nausea

Explanation: The correct answer is **Hypertension**. **Mechanism of Action:** Disulfiram acts by inhibiting the enzyme **Aldehyde Dehydrogenase (ALDH)**. When a patient taking disulfiram consumes alcohol, the metabolism of ethanol is arrested at the stage of **Acetaldehyde**. This leads to a 5-to-10-fold accumulation of acetaldehyde in the blood, resulting in the **Disulfiram-Ethanol Reaction (DER)** [1]. **Why Hypertension is the Correct Answer:** The hallmark of the Disulfiram-Ethanol Reaction is **Hypotension**, not hypertension. The accumulation of acetaldehyde causes intense peripheral vasodilation and releases histamine, leading to a significant drop in blood pressure. In severe cases, this can progress to shock or cardiovascular collapse. **Analysis of Incorrect Options:** * **Flushing (A):** This is the most common and earliest sign of the reaction, caused by acetaldehyde-induced vasodilation of the facial and neck vessels. * **Headache (B):** Often described as a "throbbing" headache, this occurs due to the dilation of intracranial blood vessels. * **Nausea (C):** Acetaldehyde is a potent emetic stimulus; nausea and projectile vomiting are classic components of the DER. **High-Yield Clinical Pearls for NEET-PG:** * **Disulfiram-like reaction:** Several other drugs can cause a similar reaction when taken with alcohol. Mnemonic: **"PM C G"** (**P**rocarbazine, **M**etronidazole, **C**ephalosporins like Cefoperazone/Cefotetan, **G**riseofulvin, and Sulfonylureas). * **Dopamine Beta-Hydroxylase Inhibition:** Disulfiram also inhibits this enzyme, leading to decreased norepinephrine synthesis, which further contributes to hypotension and potential psychosis. * **Contraindication:** It should never be administered to a patient in a state of alcohol intoxication or without their full knowledge.

Question 259: In depression, which neurotransmitter is deficient?

A. 5-Hydroxytryptamine (5-HT) (Correct Answer)
B. Acetylcholine
C. Dopamine
D. Gamma-aminobutyric acid (GABA)

Explanation: ### Explanation The pathophysiology of depression is primarily explained by the **Monoamine Hypothesis**, which suggests that a functional deficiency of monoamine neurotransmitters—specifically **Serotonin (5-HT)** and **Norepinephrine (NE)**—at strategic synapses in the brain leads to depressive symptoms. **1. Why 5-HT is the Correct Answer:** Serotonin (5-Hydroxytryptamine) plays a pivotal role in regulating mood, sleep, and appetite. In clinical depression, there is a documented decrease in 5-HT levels and its metabolite (5-HIAA) in the cerebrospinal fluid. Most first-line antidepressants, such as **SSRIs (Selective Serotonin Reuptake Inhibitors)**, work by increasing the availability of 5-HT in the synaptic cleft. **2. Analysis of Incorrect Options:** * **Acetylcholine:** Excess cholinergic activity is sometimes associated with depression, while deficiencies are linked to cognitive decline and **Alzheimer’s disease**. * **Dopamine:** While dopamine is involved in the brain's reward system (anhedonia), its primary clinical association is with **Schizophrenia** (excess) and **Parkinson’s disease** (deficiency). * **GABA:** This is the primary inhibitory neurotransmitter. Its deficiency is more closely linked to **Anxiety disorders** and **Seizures**, rather than being the primary driver of depression. **Clinical Pearls for NEET-PG:** * **Biogenic Amines:** Depression involves a deficiency of 5-HT and NE; Mania involves an excess. * **Lag Period:** Although antidepressants increase neurotransmitter levels quickly, the clinical antidepressant effect takes **2–4 weeks** due to the time required for receptor down-regulation (e.g., $\beta$-receptors and 5-HT2 receptors). * **Drug of Choice:** SSRIs (e.g., Fluoxetine, Sertraline) are the first-line treatment for most depressive disorders due to their better safety profile compared to TCAs and MAOIs.

Question 260: What is the half-life of lithium?

A. 8 hours
B. 16 hours
C. 24 hours (Correct Answer)
D. 36 hours

Explanation: **Lithium** is the gold-standard mood stabilizer used for Bipolar Affective Disorder (BPAD) [2]. Understanding its pharmacokinetics is crucial for clinical practice and exam preparation.Why 24 hours is correct:The average elimination half-life of lithium in an adult with normal renal function is approximately **24 hours** (ranging typically from 18 to 30 hours). Because it takes roughly 4 to 5 half-lives to reach a steady-state plasma concentration, lithium requires about **5 days** of consistent dosing to achieve stable therapeutic levels. This long half-life allows for once or twice-daily dosing.Analysis of incorrect options:* **8 hours (A):** This is too short. While lithium is rapidly absorbed [1], its elimination is slow because it undergoes extensive renal reabsorption (80% in the proximal tubule) [1].* **16 hours (B):** While some younger patients with high glomerular filtration rates may have shorter half-lives, 24 hours is the standard physiological mean cited in major pharmacology texts (Katzung, KD Tripathi).* **36 hours (D):** This is longer than the average; however, the half-life can extend to 36 hours or more in elderly patients or those with renal impairment, increasing the risk of toxicity.High-Yield Clinical Pearls for NEET-PG:* **Therapeutic Index:** Lithium has a very narrow therapeutic index. Monitoring is essential [1].* **Therapeutic Range:** 0.5–0.8 mEq/L (Maintenance); 0.8–1.2 mEq/L (Acute Mania). Toxicity occurs >1.5 mEq/L.* **Sample Timing:** Blood for Therapeutic Drug Monitoring (TDM) should be drawn **12 hours after the last dose**.* **Drug Interactions:** Thiazides, NSAIDs, and ACE inhibitors decrease lithium clearance, leading to toxicity [3].* **Pregnancy:** Associated with **Ebstein’s Anomaly** (tricuspid valve malformation).

Practice by Chapter

Antipsychotics: Typical and Atypical

Practice Questions

Antidepressants: SSRIs and SNRIs

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Tricyclic Antidepressants

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MAO Inhibitors

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Mood Stabilizers

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Anxiolytics

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Drugs for ADHD

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Drugs for Sleep Disorders

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Drugs for Dementia

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Drug-Induced Psychiatric Symptoms

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