Drugs in Psychiatric Disorders Practice Questions

Q: Which of the following substances is hallucinogenic?

Cocaine. **Explanation:** **Cocaine** is a potent central nervous system (CNS) stimulant that acts by inhibiting the reuptake of dopamine, norepinephrine, and serotonin [2]. While primarily classified as a stimulant, high doses or chronic use can lead to **"Cocaine Psychosis,"** characterized by vivid visual, auditory, and tactile hallucinations (e.g., **Formication** or "Cocaine bugs"—the sensation of insects crawling under the skin). **Analysis of Options:** * **Codeine (Option A):** An opioid analgesic and antitussive. Its primary side effects are sedation, constipation, and respiratory depression, not hallucinations. * **Papaverine (Option B):** A non-opioid benzylisoquinoline alkaloid used as a vasodilator and smooth muscle relaxant. It has no significant CNS activity related to psychosis. * **Steroids (Option D):** While corticosteroids can cause "Steroid Psychosis" (mood swings, mania, or depression), they are not classified as primary hallucinogens. In the context of classic drugs of abuse, Cocaine is the more definitive answer for hallucinogenic potential. **High-Yield NEET-PG Pearls:** * **Formication (Magnan’s Symptom):** A classic tactile hallucination pathognomonic for cocaine toxicity. * **Mechanism:** Cocaine blocks the **DAT (Dopamine Transporter)**, leading to increased dopamine in the nucleus accumbens, causing euphoria and psychosis [2]. * **Other Hallucinogens to remember:** LSD (most potent), Psilocybin, Mescaline, and Phencyclidine (PCP) [1]. * **Management:** Acute cocaine toxicity is managed with **Benzodiazepines**; Beta-blockers are generally avoided due to the risk of unopposed alpha-adrenergic stimulation.

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.

Q: Which of the following is NOT a side effect of clozapine?

Hyperprolactinemia. **Explanation:** Clozapine is a prototype **Atypical Antipsychotic** (Second Generation). The correct answer is **Hyperprolactinemia** because clozapine is unique among antipsychotics for its minimal effect on prolactin levels. 1. **Why Hyperprolactinemia is NOT a side effect:** Most typical antipsychotics block $D_2$ receptors in the **tuberoinfundibular pathway**, leading to increased prolactin. However, Clozapine has low affinity for $D_2$ receptors and rapidly dissociates from them. Consequently, it does not cause significant hyperprolactinemia, making it a preferred drug in patients experiencing galactorrhea or gynecomastia from other agents. 2. **Analysis of Incorrect Options:** * **Agranulocytosis:** This is the most dreaded side effect (1% of patients). It requires mandatory weekly WBC monitoring for the first 6 months. * **Hypersalivation (Sialorrhea):** Paradoxically, despite having anticholinergic properties, clozapine causes significant nighttime drooling, likely due to $M_4$ receptor agonism or impairment of the swallowing reflex. * **Myocarditis:** A rare but potentially fatal idiosyncratic reaction, usually occurring within the first 2 months of treatment. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Clozapine is the gold standard for **Treatment-Resistant Schizophrenia** and schizophrenia associated with suicidality. * **Seizures:** It carries a dose-dependent risk of seizures (highest among antipsychotics). * **Metabolic Syndrome:** It causes significant weight gain, dyslipidemia, and Type 2 Diabetes. * **No EPS:** It has the lowest risk of Extrapyramidal Side-effects (EPS) and Tardive Dyskinesia.

Q: Which of the following antipsychotic drugs is available as a depot injection?

Fluphenazine. **Explanation:** **1. Why Fluphenazine is Correct:** Fluphenazine is a high-potency typical antipsychotic. It is available as **Fluphenazine decanoate**, an esterified formulation in a sesame oil vehicle. When administered intramuscularly, it is released slowly into the bloodstream, providing a therapeutic effect for 2–4 weeks. This "depot" preparation is primarily used to improve treatment adherence in patients with chronic schizophrenia who are non-compliant with oral medications. **2. Analysis of Incorrect Options:** * **Ziprasidone:** An atypical antipsychotic available in oral and **short-acting** IM forms (used for acute agitation), but it does not have a long-acting depot formulation. * **Trifluoperazine:** A high-potency typical antipsychotic used orally for schizophrenia and anxiety; however, it is not available as a depot injection. * **Aripiprazole:** While Aripiprazole *does* have a depot form (Aripiprazole Maintena), in the context of standard medical examinations like NEET-PG, **Fluphenazine** and **Haloperidol** are the classic, high-yield examples of depot injections. In this specific MCQ, Fluphenazine is the established traditional answer. **3. High-Yield Clinical Pearls for NEET-PG:** * **Common Depot Drugs:** The most frequently tested depot antipsychotics are **Fluphenazine decanoate** and **Haloperidol decanoate**. * **Atypical Depots:** Newer long-acting injectables (LAIs) include Risperidone, Paliperidone, and Olanzapine (though Olanzapine carries a risk of Post-injection Delirium Sedation Syndrome). * **Mechanism:** Esterification with long-chain fatty acids (like decanoate) increases lipophilicity, allowing slow release from the muscle site. * **Side Effects:** Depot injections of typical antipsychotics carry a high risk of **Extrapyramidal Side Effects (EPS)** due to their high potency and long duration of action.

Q: Dry mouth during antidepressant therapy is caused by blockade of which receptors?

Muscarinic acetylcholine receptors. **Explanation:** Dry mouth (xerostomia) is a classic side effect of several antidepressant classes, most notably **Tricyclic Antidepressants (TCAs)** like Amitriptyline and certain SSRIs/SNRIs. **1. Why Muscarinic Acetylcholine Receptors are correct:** The salivary glands are primarily under the control of the parasympathetic nervous system. Stimulation of **M3 muscarinic receptors** by acetylcholine normally triggers watery salivation. Many antidepressants possess potent **anticholinergic (antimuscarinic)** properties. By blocking these receptors, the drugs inhibit parasympathetic signaling, leading to decreased secretions, resulting in dry mouth, blurred vision, urinary retention, and constipation. **2. Analysis of Incorrect Options:** * **Serotonergic receptors:** Blockade or stimulation of these receptors (e.g., 5-HT2) is associated with side effects like sexual dysfunction, GI upset, or serotonin syndrome, but not typically dry mouth. * **Dopaminergic receptors:** Blockade of D2 receptors (common in antipsychotics) leads to Extrapyramidal Symptoms (EPS) and hyperprolactinemia. * **GABA receptors:** These are inhibitory receptors in the CNS. Drugs acting here (like Benzodiazepines) cause sedation and anxiolysis, not peripheral autonomic side effects like xerostomia. **High-Yield Clinical Pearls for NEET-PG:** * **TCAs** are the biggest culprits of "Anti-SLUDGE" effects (Salivation, Lacrimation, Urination, Defecation, GI upset, Emesis—all of which are decreased). * **Amitriptyline** has the highest anticholinergic potency among TCAs. * **Management:** Patients are often advised to use sugarless gum or frequent sips of water. * **Contraindication:** Due to their muscarinic blockade, these drugs should be used with caution in patients with **narrow-angle glaucoma** and **benign prostatic hyperplasia (BPH)**.

Q: Which of the following drugs has the least anticholinergic side effects?

Desipramine. **Explanation:** The question tests your knowledge of the side effect profiles of **Tricyclic Antidepressants (TCAs)**. All options listed belong to the TCA class, which typically block muscarinic (M1), histamine (H1), and alpha-1 adrenergic receptors, leading to their characteristic side effect profile. **Why Desipramine is Correct:** TCAs are broadly divided into **Tertiary Amines** and **Secondary Amines**. * **Secondary Amines** (e.g., Desipramine, Nortriptyline) are metabolites of tertiary amines. * They are more selective for inhibiting Norepinephrine reuptake and, crucially, have a **significantly lower affinity** for muscarinic, histaminic, and alpha-adrenergic receptors compared to their parent compounds. * **Desipramine** is the most potent norepinephrine reuptake inhibitor among TCAs and possesses the **least anticholinergic and sedative activity** in this group. **Why Other Options are Incorrect:** * **A, C, and D (Clomipramine, Imipramine, Trimipramine):** These are all **Tertiary Amines**. Tertiary amines are potent inhibitors of both Serotonin and Norepinephrine reuptake but also have a high affinity for muscarinic receptors. This results in significant anticholinergic effects such as dry mouth, blurred vision, urinary retention, and constipation. Among these, **Amitriptyline** (not listed) and **Clomipramine** are often cited as having the highest anticholinergic potency. **High-Yield NEET-PG Pearls:** 1. **Most Anticholinergic TCA:** Amitriptyline. 2. **Least Anticholinergic/Least Sedating TCA:** Desipramine. 3. **Least Arrhythmogenic/Safest in Elderly:** Nortriptyline (a secondary amine with a better safety profile). 4. **Drug of Choice for OCD:** Clomipramine (due to high serotonin selectivity). 5. **TCA Overdose Triad:** Coma, Convulsions, and Cardiac arrhythmias (prolonged QRS/QT intervals). The antidote for cardiotoxicity is Sodium Bicarbonate.

Q: Which of the following drugs belongs to the NaSSA group?

Mirtazapine. **Explanation:** **Mirtazapine** is the correct answer as it is the prototype drug of the **NaSSA** (Noradrenergic and Specific Serotonergic Antidepressant) class. ### Why Mirtazapine is correct: Mirtazapine works through a unique dual mechanism: 1. **Alpha-2 ($\alpha_2$) Antagonism:** It blocks presynaptic $\alpha_2$ autoreceptors (on noradrenergic neurons) and heteroreceptors (on serotonergic neurons). This "disinhibits" the neurons, leading to increased release of both Norepinephrine and Serotonin. 2. **Specific Serotonergic Action:** It blocks **$5-HT_2$** and **$5-HT_3$** receptors. By blocking these, it directs serotonin to specifically stimulate the **$5-HT_1A$** receptor, which mediates antidepressant effects while avoiding side effects like anxiety ($5-HT_2$) or nausea ($5-HT_3$). ### Why other options are incorrect: * **Amoxetine (Atomoxetine):** A selective **NRI** (Norepinephrine Reuptake Inhibitor) primarily used in ADHD. * **Duloxetine & Venlafaxine:** These belong to the **SNRI** (Serotonin-Norepinephrine Reuptake Inhibitor) class. They work by inhibiting the reuptake transporters (SERT and NET) rather than blocking $\alpha_2$ receptors. ### High-Yield Clinical Pearls for NEET-PG: * **Side Effect Profile:** Mirtazapine is a potent **$H_1$ blocker**, leading to significant **sedation** and **weight gain**. * **Clinical Utility:** It is the drug of choice for depressed patients suffering from **insomnia** and **underweight/anorexia**. * **Sexual Dysfunction:** Unlike SSRIs, Mirtazapine has a very low incidence of sexual dysfunction due to its $5-HT_2$ blockade. * **The "California Rocket Fuel":** A high-yield combination of Venlafaxine + Mirtazapine used for treatment-resistant depression.

Question 1

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

Accepted Answer

Venlafaxine

Answer

Imipramine

Answer

Valproate

Answer

Olanzapine

Question 2

Which of the following substances is hallucinogenic?

Accepted Answer

Cocaine

Answer

Codeine

Answer

Papaverine

Answer

Steroid

Question 3

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 4

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

Accepted Answer

Haloperidol

Answer

Chlorpromazine

Answer

Imipramine

Answer

Clomipramine

Question 5

Which of the following is NOT a side effect of clozapine?

Accepted Answer

Hyperprolactinemia

Answer

Agranulocytosis

Answer

Hypersalivation

Answer

Myocarditis

Question 6

Which of the following antipsychotic drugs is available as a depot injection?

Accepted Answer

Fluphenazine

Answer

Ziprasidone

Answer

Trifluoperazine

Answer

Aripiprazole

Question 7

Dry mouth during antidepressant therapy is caused by blockade of which receptors?

Accepted Answer

Muscarinic acetylcholine receptors

Answer

Serotonergic receptors

Answer

Dopaminergic receptors

Answer

GABA receptors

Question 8

Which of the following drugs has the least anticholinergic side effects?

Accepted Answer

Desipramine

Answer

Clomipramine

Answer

Imipramine

Answer

Trimipramine

Question 9

Which of the following drugs belongs to the NaSSA group?

Accepted Answer

Mirtazapine

Answer

Amoxetine

Answer

Duloxetine

Answer

Venlafaxine

Question 10

Which of the following statements is NOT true for the therapy with lithium?

Accepted Answer

Sodium ion is a specific antidote for lithium clearance.

Answer

It is used in bipolar disorder.

Answer

Amiloride is useful in treating lithium-induced diabetes insipidus.

Answer

Regular measurements of blood concentration of lithium are necessary.

Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders — MCQs

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