Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders Indian Medical PG Practice Questions and MCQs

Question 131: Which drug effect mimics schizophrenia?

A. Barbiturates
B. Cocaine
C. Phencyclidine (Correct Answer)
D. Levodopa

Explanation: **Explanation:** The correct answer is **Phencyclidine (PCP)**. **1. Why Phencyclidine is correct:** Phencyclidine (PCP), also known as "angel dust," is a non-competitive antagonist at the **NMDA (N-methyl-D-aspartate) glutamate receptor**. Unlike other psychotomimetic drugs (like LSD), PCP is unique because it mimics **both the positive symptoms** (hallucinations, delusions, thought disorder) and **negative symptoms** (social withdrawal, flattened affect, cognitive impairment) of schizophrenia. This observation led to the "Glutamate Hypothesis" of schizophrenia, suggesting that NMDA receptor hypofunction plays a central role in the pathogenesis of the disorder. **2. Why the other options are incorrect:** * **Barbiturates:** These are CNS depressants that act as GABA-A receptor mimetics. Overdose leads to sedation, respiratory depression, and coma, rather than a schizophrenic-like state. * **Cocaine:** Cocaine increases synaptic dopamine by inhibiting reuptake. While it can induce "Cocaine Psychosis" (characterized by paranoid delusions and tactile hallucinations like formication), it primarily mimics the **positive symptoms** only and lacks the negative/cognitive symptom profile of schizophrenia. * **Levodopa:** A dopamine precursor used in Parkinson’s disease. While it can cause drug-induced psychosis (visual hallucinations) due to increased dopamine in the mesolimbic pathway, it does not replicate the full clinical spectrum of schizophrenia as closely as PCP. **3. NEET-PG High-Yield Pearls:** * **Ketamine:** Like PCP, it is an NMDA antagonist and can also induce dissociative anesthesia and schizophrenic-like symptoms. * **Dopamine Hypothesis:** Traditional antipsychotics work by blocking D2 receptors, primarily targeting positive symptoms. * **Glutamate Hypothesis:** Explains why NMDA antagonists (PCP/Ketamine) produce a more "complete" model of schizophrenia than dopaminergic agents.

Question 132: What is the drug of choice in phenothiazine-induced dystonia?

A. Diphenhydramine
B. Metoclopramide
C. Trifluperamide
D. Benztropine (Correct Answer)

Explanation: **Explanation:** Phenothiazines (like Chlorpromazine) are typical antipsychotics that block dopamine ($D_2$) receptors in the nigrostriatal pathway. This creates a chemical imbalance where **cholinergic (acetylcholine) activity becomes relatively overactive** compared to dopamine, leading to Extrapyramidal Side Effects (EPS), such as acute dystonia. **1. Why Benztropine is Correct:** To treat acute dystonia, the goal is to restore the dopamine-acetylcholine balance. **Benztropine** is a potent **centrally-acting anticholinergic** drug. By blocking muscarinic receptors in the basal ganglia, it rapidly suppresses the cholinergic overactivity, providing quick relief from muscle spasms. It is considered the gold standard for drug-induced EPS. **2. Analysis of Incorrect Options:** * **Diphenhydramine:** While this is an antihistamine with significant anticholinergic properties and *can* be used as an alternative, Benztropine is more specific and preferred in clinical guidelines for dystonia. * **Metoclopramide:** This is a $D_2$ receptor antagonist used as an antiemetic. It actually **causes** dystonia rather than treating it. * **Trifluperamide:** This is an antipsychotic itself. Adding more antipsychotics would worsen the dopamine blockade and exacerbate the dystonia. **High-Yield Clinical Pearls for NEET-PG:** * **Acute Dystonia:** Usually occurs within hours to days of starting antipsychotics (e.g., torticollis, grimacing). * **Drug of Choice (DOC):** Central anticholinergics like **Benztropine** or **Trihexyphenidyl (PACANE)**. * **Route:** For acute crises, parenteral (IV/IM) administration is preferred for rapid onset. * **Prophylaxis:** If a patient is prone to EPS, oral anticholinergics are often co-prescribed with high-potency neuroleptics.

Question 133: Which of the following is true about mianserin?

A. It is a type of NaSSA. (Correct Answer)
B. It is a type of SSRI.
C. It is a type of SARI.
D. It is a type of SNRI.

Explanation: **Explanation:** **Mianserin** is a tetracyclic antidepressant that belongs to the **NaSSA (Noradrenergic and Specific Serotonergic Antidepressant)** class. Its primary mechanism of action involves blocking **presynaptic $\alpha_2$-autoreceptors**, which leads to an increased release of norepinephrine. It also antagonizes 5-HT$_2$ and 5-HT$_3$ receptors, thereby directing serotonin to the 5-HT$_1$ receptor (hence "specific serotonergic"). **Analysis of Options:** * **Option A (Correct):** Mianserin, along with its newer analogue **Mirtazapine**, are the prototypical NaSSAs. They enhance neurotransmission without inhibiting reuptake. * **Option B (Incorrect):** SSRIs (e.g., Fluoxetine, Sertraline) work by inhibiting the serotonin transporter (SERT). Mianserin does not significantly inhibit serotonin reuptake. * **Option C (Incorrect):** SARIs (Serotonin Antagonist and Reuptake Inhibitors) include drugs like **Trazodone** and Nefazodone. While Mianserin antagonizes 5-HT receptors, it lacks the reuptake inhibition characteristic of this class. * **Option D (Incorrect):** SNRIs (e.g., Venlafaxine, Duloxetine) inhibit the reuptake of both serotonin and norepinephrine. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects:** Unlike Mirtazapine, Mianserin is associated with a risk of **agranulocytosis** and **aplastic anemia**, necessitating regular blood counts in some protocols. * **Sedation:** It has potent H$_1$-receptor blocking activity, making it highly sedative (useful for depressed patients with insomnia). * **Safety:** It lacks the significant anticholinergic and cardiotoxic side effects typical of Tricyclic Antidepressants (TCAs), making it safer in overdose. * **Mnemonic:** Remember **"M&M"** (Mianserin and Mirtazapine) for **NaSSA**.

Question 134: Lithium is used in the prophylaxis of which of the following conditions?

A. Recurrent phobia
B. Alcohol dependence
C. Paranoid schizophrenia
D. Recurrent manic depressive attacks (Correct Answer)

Explanation: **Explanation:** **1. Why Option D is Correct:** Lithium is the **gold standard mood stabilizer** and the drug of choice for the prophylaxis of **Bipolar Affective Disorder (BPAD)**, historically known as manic-depressive illness. It is uniquely effective in preventing both manic and depressive relapses. Its mechanism involves inhibiting the **Inositol Monophosphatase (IMPase)** pathway (the "Inositol Depletion Hypothesis") and modulating G-proteins and protein kinase C, which stabilizes neuronal overactivity. **2. Why Other Options are Incorrect:** * **A. Recurrent Phobia:** Phobias are anxiety disorders primarily treated with Cognitive Behavioral Therapy (CBT), SSRIs, or Benzodiazepines (for acute symptoms). Lithium has no role in treating phobias. * **B. Alcohol Dependence:** Management involves detoxification (Benzodiazepines) and relapse prevention (Naltrexone, Acamprosate, or Disulfiram). Lithium is not used unless the patient has a comorbid bipolar disorder. * **C. Paranoid Schizophrenia:** This requires antipsychotics (e.g., Risperidone, Olanzapine) to block dopamine D2 receptors. Lithium is not an antipsychotic and does not treat primary delusions or hallucinations. **3. High-Yield Clinical Pearls for NEET-PG:** * **Therapeutic Index:** Lithium has a very **narrow therapeutic index**. * Prophylaxis range: **0.6 – 0.8 mEq/L**. * Acute Mania range: **0.8 – 1.2 mEq/L**. * Toxicity: >1.5 mEq/L. * **Side Effects (LITHIUM Mnemonic):** **L**eukocytosis, **I**nsipidus (Nephrogenic Diabetes Insipidus), **T**remors (Fine)/ **T**eratogenicity (Ebstein’s Anomaly), **H**ypothyroidism, **I**ncreased **U**rine, **M**others (avoid in pregnancy). * **Drug Interactions:** Thiazides, NSAIDs, and ACE inhibitors increase Lithium levels (decreased clearance), leading to toxicity.

Question 135: Which of the following is a use of NDRI?

A. Hypoactive sexual desire
B. Smoking cessation
C. ADHD
D. All of the above (Correct Answer)

Explanation: The correct answer is **D. All of the above**. **Mechanism of Action:** NDRIs (**Norepinephrine-Dopamine Reuptake Inhibitors**), primarily represented by **Bupropion**, work by inhibiting the neuronal reuptake of dopamine and norepinephrine [1], [2]. Unlike SSRIs, they have no significant effect on serotonin, which accounts for their unique clinical profile and lack of sexual side effects. **Breakdown of Uses:** 1. **Hypoactive Sexual Desire Disorder (HSDD):** Bupropion is frequently used off-label (and as a component in newer formulations) to treat HSDD. Because it increases dopamine levels in the reward pathway and lacks serotonergic activity (which usually inhibits sexual desire), it can actually improve libido and arousal. 2. **Smoking Cessation:** Bupropion is an FDA-approved non-nicotine aid for smoking cessation [1]. It mimics the effect of nicotine by increasing dopamine in the nucleus accumbens, thereby reducing withdrawal symptoms and the "craving" associated with quitting [1]. 3. **ADHD:** By increasing norepinephrine and dopamine in the prefrontal cortex, NDRIs help improve focus and impulse control. Bupropion is considered a second-line, non-stimulant treatment for ADHD, especially in adults or patients with comorbid depression. **Clinical Pearls for NEET-PG:** * **Seizure Risk:** The most significant side effect of Bupropion is a dose-dependent increase in seizure risk. It is strictly **contraindicated** in patients with epilepsy, eating disorders (bulimia/anorexia), or those undergoing alcohol withdrawal [1]. * **Weight Neutrality:** Unlike many antidepressants, Bupropion is associated with weight loss rather than weight gain [1]. * **The "Happy-Horny-Skinny" Pill:** A common mnemonic to remember that Bupropion treats depression without causing sexual dysfunction or weight gain.

Question 136: All of the following are typical autonomic side effects of antipsychotic drugs EXCEPT:

A. Constipation
B. Dry mouth and throat
C. Postural hypotension (Correct Answer)
D. Urinary retention

Explanation: ### Explanation The question asks to identify the side effect that is **not** a typical autonomic side effect of antipsychotic drugs among the choices provided. **1. Why "Postural Hypotension" is the Correct Answer (Concept):** While antipsychotics do cause postural hypotension, the question is a classic "except" style question focusing on the **mechanism of action**. Antipsychotics block several receptors: Muscarinic (M1), Alpha-1 adrenergic ($\alpha_1$), and Histamine (H1). * **Constipation, Dry mouth, and Urinary retention** are all **Anticholinergic (Antimuscarinic)** side effects. * **Postural hypotension** is an **Antiadrenergic ($\alpha_1$ blockade)** side effect. In many pharmacological classifications, "autonomic side effects" is often used as a synonym for "anticholinergic side effects" in the context of typical antipsychotics (like Chlorpromazine). However, more accurately, postural hypotension is caused by peripheral vasodilation (alpha-blockade), whereas the others are results of parasympathetic inhibition. **2. Analysis of Incorrect Options:** * **A, B, and D (Constipation, Dry mouth, Urinary retention):** These are classic manifestations of **Muscarinic (M1) receptor blockade**. They occur because antipsychotics (especially low-potency ones like Chlorpromazine and Thioridazine) inhibit the parasympathetic nervous system. Other effects include blurred vision (cycloplegia) and tachycardia. **3. NEET-PG High-Yield Clinical Pearls:** * **Low Potency vs. High Potency:** Low-potency antipsychotics (Chlorpromazine, Thioridazine) have **higher** autonomic (anticholinergic/alpha-blocking) side effects but **lower** Extrapyramidal Symptoms (EPS). * **High Potency:** Drugs like Haloperidol have **lower** autonomic side effects but **higher** risk of EPS. * **Thioridazine Warning:** It is the antipsychotic most associated with QTc prolongation and retinal pigmentation. * **Clozapine:** The most anticholinergic atypical antipsychotic; paradoxically, it often causes **sialorrhea** (excessive salivation) instead of dry mouth.

Question 137: Which antidepressant drug can be safely used in children?

A. Imipramine
B. Fluoxetine (Correct Answer)
C. Dothiepin
D. Risperidone

Explanation: **Explanation:** **Fluoxetine** is the correct answer because it is the only antidepressant consistently approved by major regulatory bodies (like the US-FDA) for the treatment of Major Depressive Disorder (MDD) in children and adolescents (ages 8 and older). **Why Fluoxetine?** Fluoxetine is a Selective Serotonin Reuptake Inhibitor (SSRI). It is preferred in the pediatric population due to its long half-life (reducing withdrawal symptoms if a dose is missed) and a superior safety profile compared to older antidepressants. While SSRIs carry a "black box warning" regarding increased suicidal ideation in young patients, Fluoxetine remains the first-line pharmacological choice when therapy is indicated. **Analysis of Incorrect Options:** * **A. Imipramine:** This is a Tricyclic Antidepressant (TCA). While it is used for nocturnal enuresis in children, it is **not** recommended for pediatric depression due to significant cardiotoxicity and lack of proven efficacy in this age group. * **C. Dothiepin (Dosulepin):** Another TCA with a high risk of toxicity in overdose and significant sedative/anticholinergic side effects, making it unsuitable for children. * **D. Risperidone:** This is an **atypical antipsychotic**, not an antidepressant. While used in children for irritability associated with autism or conduct disorders, it is not a primary treatment for depression. **High-Yield NEET-PG Pearls:** * **First-line for Pediatric MDD:** Fluoxetine. * **Second-line for Pediatric MDD:** Sertraline or Escitalopram (often used off-label or for OCD). * **OCD in Children:** Fluvoxamine and Sertraline are also FDA-approved. * **Black Box Warning:** All antidepressants carry a warning for increased risk of suicidal thoughts/behavior in patients under 24 years of age.

Question 138: Which of the following drugs is NOT used for anxiety?

A. Propranolol
B. Alprazolam
C. Buspirone
D. Haloperidol (Correct Answer)

Explanation: **Explanation:** The correct answer is **Haloperidol**. Haloperidol is a high-potency **typical antipsychotic** that acts primarily by blocking dopamine D2 receptors in the mesolimbic pathway. It is indicated for schizophrenia, acute psychosis, and Tourette syndrome, but it has no inherent anxiolytic properties. In fact, it can cause akathisia (motor restlessness), which may be mistaken for or worsen agitation. **Analysis of other options:** * **Propranolol (Option A):** A non-selective beta-blocker used to treat the **peripheral autonomic symptoms** of anxiety (tachycardia, tremors, sweating). It is specifically high-yield for **performance anxiety** (stage fright). * **Alprazolam (Option B):** A Benzodiazepine (BZD) that enhances GABAergic inhibition. It is a first-line agent for the acute management of **Panic Disorder** and Generalized Anxiety Disorder (GAD) due to its rapid onset. * **Buspirone (Option C):** A selective **5-HT1A partial agonist**. It is used for chronic GAD. Unlike BZDs, it lacks sedative, hypnotic, or muscle relaxant properties and has no abuse potential, though it takes 2-4 weeks to show effects. **NEET-PG High-Yield Pearls:** 1. **Drug of choice (DOC) for GAD:** SSRIs (e.g., Escitalopram) are preferred for long-term management; BZDs are used for short-term relief. 2. **Buspirone vs. BZDs:** Buspirone does not cause "rebound anxiety" upon discontinuation and does not potentiate the effects of alcohol. 3. **Performance Anxiety:** Propranolol should be taken 30-60 minutes before the event. 4. **Haloperidol Side Effects:** Watch for Extrapyramidal Symptoms (EPS) like acute dystonia and Neuroleptic Malignant Syndrome (NMS).

Question 139: Which of the following drugs is a Selective Serotonin Reuptake Inhibitor (SSRI)?

A. Citalopram
B. Fluoxetine
C. Sertraline
D. All of the above (Correct Answer)

Explanation: **Explanation:** Selective Serotonin Reuptake Inhibitors (SSRIs) are the first-line pharmacotherapy for various psychiatric conditions, including Major Depressive Disorder, Panic Disorder, and OCD. Their primary mechanism of action involves the potent inhibition of the presynaptic serotonin transporter (SERT), leading to increased serotonin levels in the synaptic cleft. **Analysis of Options:** * **Fluoxetine:** The first SSRI to be marketed. It has the longest half-life (due to its active metabolite, norfluoxetine), making it the drug of choice for patients with poor compliance as it carries a lower risk of discontinuation syndrome. * **Sertraline:** A widely used SSRI known for its safety profile in patients with cardiovascular disease (post-MI). It is also frequently used for Premenstrual Dysphoric Disorder (PMDD). * **Citalopram:** An SSRI known for its high selectivity. Its S-enantiomer, **Escitalopram**, is considered the most potent and selective SSRI available. Since all three drugs belong to the SSRI class, the correct answer is **D. All of the above.** **NEET-PG High-Yield Pearls:** 1. **Side Effects:** The most common side effects include GI upset (nausea/diarrhea), sexual dysfunction (delayed ejaculation), and sleep disturbances. 2. **Serotonin Syndrome:** A life-threatening condition (hyperthermia, muscle rigidity, myoclonus) that can occur if SSRIs are combined with MAO inhibitors. A washout period of 2–5 weeks is required when switching between them. 3. **Drug of Choice (DOC):** SSRIs are the DOC for OCD, Social Phobia, and PTSD. 4. **Fluvoxamine** and **Paroxetine** are other important members of this class.

Question 140: Which of the following is NOT a clinical indication for tricyclic antidepressants?

A. Enuresis in elderly patients
B. Neuropathic pain
C. Panic disorder
D. Uncontrolled seizures (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. Uncontrolled seizures**. **1. Why "Uncontrolled Seizures" is the correct answer:** Tricyclic Antidepressants (TCAs), such as Amitriptyline and Imipramine, are known to **lower the seizure threshold**. They interfere with GABAergic transmission and alter ion channel activity in the CNS. In patients with pre-existing epilepsy or uncontrolled seizures, TCAs can precipitate status epilepticus or increase the frequency of fits. Therefore, uncontrolled seizures are a major **contraindication**, not an indication, for TCA use. **2. Analysis of Incorrect Options:** * **A. Enuresis in elderly patients:** While more commonly used for nocturnal enuresis in children (Imipramine), TCAs have strong anticholinergic properties that increase bladder neck resistance and decrease detrusor contraction, making them a clinical option for certain types of urinary incontinence. * **B. Neuropathic pain:** This is a high-yield "off-label" use. TCAs (especially Amitriptyline) are first-line agents for neuropathic pain (e.g., Diabetic Neuropathy, Post-herpetic neuralgia) because they enhance descending inhibitory pain pathways by blocking the reuptake of Serotonin and Norepinephrine. * **C. Panic disorder:** TCAs like Imipramine and Clomipramine are effective in treating panic disorder and various phobias, though SSRIs are now preferred due to a better side-effect profile. **3. NEET-PG High-Yield Pearls:** * **Mechanism of Action:** Block reuptake of NE and 5-HT. * **The "3 Cs" of Toxicity:** Coma, Convulsions, and Cardiotoxicity (Arrhythmias due to Na+ channel blockade). * **Antidote for Cardiotoxicity:** Sodium Bicarbonate (to overcome Na+ channel blockade). * **Specific Drug:** Clomipramine is the most selective for 5-HT reuptake and is a gold standard for Obsessive-Compulsive Disorder (OCD).

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

Practice Questions

Drugs for Dementia

Practice Questions

Drug-Induced Psychiatric Symptoms

Practice Questions

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