Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders Indian Medical PG Practice Questions and MCQs

Question 91: Which of the following is a RIMA?

A. escitalopram
B. selegiline
C. dapoxetine
D. brofaromine (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. brofaromine** **Concept:** **RIMA** stands for **Reversible Inhibitors of MAO-A**. Unlike older, non-selective, irreversible Monoamine Oxidase Inhibitors (MAOIs), RIMAs selectively inhibit the MAO-A enzyme (which metabolizes norepinephrine and serotonin) in a reversible manner [1]. This reversibility significantly reduces the risk of the "Cheese Reaction" (hypertensive crisis), as high levels of dietary tyramine can displace the drug from the enzyme, allowing tyramine metabolism to proceed [1]. The older, irreversible MAOIs include examples like phenelzine and tranylcypromine, which do not distinguish between MAO isozymes [3]. The "Cheese Reaction" involves MAOIs preventing tyramine breakdown, leading to elevated blood pressure and a risk of malignant hypertension with certain foods [2]. **Analysis of Options:** * **Brofaromine (Correct):** Along with **Moclobemide**, it is a classic example of a RIMA [1]. These are primarily used in the treatment of depression and social anxiety. * **Escitalopram (Incorrect):** This is an **SSRI** (Selective Serotonin Reuptake Inhibitor). It is the S-enantiomer of citalopram and is currently one of the most selective SSRIs used for depression and anxiety disorders. * **Selegiline (Incorrect):** This is a **selective, irreversible MAO-B inhibitor**. At low doses, it is used in Parkinson’s disease to increase dopamine levels. At very high doses, it loses selectivity and can inhibit MAO-A. * **Dapoxetine (Incorrect):** This is a short-acting **SSRI** specifically marketed for the treatment of **premature ejaculation** due to its rapid onset and short half-life. **High-Yield Clinical Pearls for NEET-PG:** * **Moclobemide** is the most frequently asked RIMA in exams [1]. * **Cheese Reaction:** Occurs with irreversible MAOIs (e.g., Phenelzine, Tranylcypromine) when taken with tyramine-rich foods (aged cheese, red wine) [2, 3]. RIMAs have a much lower risk [1]. * **Serotonin Syndrome:** Always remember that MAOIs (including RIMAs) should never be combined with SSRIs or TCAs due to the fatal risk of serotonin syndrome. A "washout period" of 2–5 weeks is required when switching between these classes.

Question 92: Which of the following is a selective 5-HT reuptake blocker?

A. Desipramine
B. Amitriptyline
C. Fluoxetine (Correct Answer)
D. Dothiepin

Explanation: ### Explanation **Correct Answer: C. Fluoxetine** **Mechanism of Action:** Fluoxetine is a prototype **Selective Serotonin Reuptake Inhibitor (SSRI)** [1, 3]. It works by specifically inhibiting the serotonin transporter (SERT) at the presynaptic terminal, thereby increasing the concentration of serotonin (5-HT) in the synaptic cleft [2]. Unlike older antidepressants, SSRIs have minimal affinity for adrenergic, histaminergic, or cholinergic receptors, leading to a better side-effect profile [3]. **Analysis of Incorrect Options:** * **A. Desipramine:** This is a secondary amine **Tricyclic Antidepressant (TCA)**. It is highly selective for inhibiting the reuptake of **Norepinephrine (NE)** rather than Serotonin [3]. * **B. Amitriptyline:** A tertiary amine **TCA**. It is a non-selective inhibitor that blocks the reuptake of both **Serotonin and Norepinephrine (SNRI-like action)**. It also possesses significant anticholinergic and sedative properties [1, 3]. * **D. Dothiepin (Dosulepin):** Another **TCA** similar to amitriptyline. It inhibits the reuptake of both NE and 5-HT and is known for its high cardiotoxicity in overdose [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** SSRIs (like Fluoxetine) are the first-line treatment for Depression, OCD, Panic Disorder, Social Phobia, and Post-Traumatic Stress Disorder (PTSD) [3]. * **Longest Half-life:** Fluoxetine has the longest half-life among SSRIs (due to its active metabolite, norfluoxetine), making it the least likely to cause "discontinuation syndrome" [2]. * **Side Effects:** The most common side effects of SSRIs include **GI upset (nausea/diarrhea)** and **sexual dysfunction** (delayed ejaculation) [2]. * **Serotonin Syndrome:** Always monitor for this when SSRIs are combined with MAO inhibitors; a "washout period" of 2–5 weeks is required when switching between them.

Question 93: Vilazodone is a:

A. Selective serotonin reuptake inhibitor (SSRI)
B. Serotonin antagonist and reuptake inhibitor (SARI)
C. Serotonin-norepinephrine reuptake inhibitor (SNRI)
D. Serotonin partial agonist and reuptake inhibitor (SPARI) (Correct Answer)

Explanation: **Explanation:** **Vilazodone** is a unique antidepressant classified as a **Serotonin Partial Agonist and Reuptake Inhibitor (SPARI)**. Its mechanism of action is dual: 1. **Inhibition of Serotonin Reuptake:** It inhibits the serotonin transporter (SERT), similar to SSRIs, increasing synaptic serotonin levels. 2. **5-HT1A Receptor Partial Agonism:** It acts as a partial agonist at the presynaptic and postsynaptic 5-HT1A receptors. This dual action is thought to result in a faster clinical onset and potentially fewer sexual side effects compared to traditional SSRIs. **Analysis of Incorrect Options:** * **Option A (SSRI):** While Vilazodone does inhibit serotonin reuptake, the term SSRI is reserved for drugs like Fluoxetine or Sertraline, which lack direct receptor agonist activity. * **Option B (SARI):** Serotonin Antagonist and Reuptake Inhibitors (e.g., **Trazodone, Nefazodone**) primarily block 5-HT2 receptors rather than acting as 5-HT1A partial agonists. * **Option C (SNRI):** SNRIs (e.g., **Venlafaxine, Duloxetine**) inhibit the reuptake of both Serotonin and Norepinephrine. Vilazodone has no significant effect on norepinephrine reuptake. **High-Yield Clinical Pearls for NEET-PG:** * **Vortioxetine** is another related drug, often called a "Serotonin Modulator and Stimulator" (SMS), which acts as a 5-HT1A agonist and 5-HT3 antagonist. * **Side Effects:** Vilazodone is most commonly associated with GI upset (diarrhea, nausea). * **Key Advantage:** It is noted for having a **lower incidence of sexual dysfunction** and weight gain compared to SSRIs, making it a preferred choice in specific patient profiles.

Question 94: Which antidepressant has no anticholinergic effects?

A. Imipramine
B. Mianserin
C. Fluoxamine (Correct Answer)
D. Amitriptyline

Explanation: **Explanation:** The correct answer is **Fluvoxamine** (Option C). **1. Why Fluvoxamine is correct:** Fluvoxamine belongs to the **Selective Serotonin Reuptake Inhibitors (SSRIs)** class. Unlike older antidepressants, SSRIs specifically inhibit the reuptake of serotonin (5-HT) with minimal to no affinity for muscarinic (cholinergic), alpha-adrenergic, or histaminergic receptors. Consequently, they are devoid of classical anticholinergic side effects such as dry mouth, blurred vision, urinary retention, and constipation. **2. Why other options are incorrect:** * **Imipramine & Amitriptyline (Options A & D):** These are **Tricyclic Antidepressants (TCAs)**. TCAs are notorious for blocking muscarinic receptors. Amitriptyline is, in fact, the most potent anticholinergic among the TCAs. * **Mianserin (Option B):** This is an atypical (tetracyclic) antidepressant. While it has significantly fewer anticholinergic effects compared to TCAs, it still possesses some mild antimuscarinic activity, unlike SSRIs which have none. **3. NEET-PG High-Yield Pearls:** * **Drug of Choice (DOC):** SSRIs (like Fluvoxamine, Fluoxetine, Sertraline) are the first-line treatment for Depression, OCD, Panic Disorder, and Social Phobia due to their superior safety profile. * **Side Effects of SSRIs:** While they lack anticholinergic effects, they commonly cause **GI upset (nausea/diarrhea)** and **sexual dysfunction** (delayed ejaculation). * **TCA Overdose Triad:** Coma, Convulsions, and Cardiotoxicity (due to sodium channel blockade). * **Fluvoxamine Specific:** It is particularly noted for its efficacy in **Obsessive-Compulsive Disorder (OCD)**.

Question 95: Which of the following is a mood-stabilizing drug?

A. Lithium (Correct Answer)
B. Fluoxetine
C. Amitriptyline
D. Haloperidol

Explanation: ### Explanation **Correct Answer: A. Lithium** **Mechanism and Role:** Lithium is the "gold standard" mood stabilizer used primarily in the treatment of **Bipolar Affective Disorder (BPAD)**. It is effective in treating acute mania and is the drug of choice for the long-term prophylaxis of both manic and depressive episodes. Its mechanism involves the inhibition of the **Inositol Monophosphatase (IMPase) pathway**, which depletes intracellular phosphatidylinositol 4,5-bisphosphate (PIP2), thereby dampening overactive neuronal signaling. **Analysis of Incorrect Options:** * **B. Fluoxetine:** This is a **Selective Serotonin Reuptake Inhibitor (SSRI)**. It is an antidepressant used for Major Depressive Disorder and Panic Disorder. In BPAD, using antidepressants alone can potentially trigger a "switch" into mania. * **C. Amitriptyline:** This is a **Tricyclic Antidepressant (TCA)**. It inhibits the reuptake of Norepinephrine and Serotonin. Like Fluoxetine, it is used for depression, not as a primary mood stabilizer. * **D. Haloperidol:** This is a high-potency **First-Generation Antipsychotic (Typical Antipsychotic)**. While it is used to manage acute agitation in manic episodes due to its D2 receptor antagonism, it does not possess the prophylactic mood-stabilizing properties required to prevent future episodes. **High-Yield Clinical Pearls for NEET-PG:** * **Therapeutic Index:** Lithium has a very **narrow therapeutic index** (0.5–1.2 mEq/L). Monitoring is essential. * **Teratogenicity:** Use in pregnancy is associated with **Ebstein’s Anomaly** (atrialization of the right ventricle). * **Side Effects:** Common issues include fine tremors, polyuria (Nephrogenic Diabetes Insipidus), and hypothyroidism. * **Other Mood Stabilizers:** Valproate (often preferred for rapid cycling), Carbamazepine, and Lamotrigine.

Question 96: What is the specific antagonist for benzodiazepines?

A. Flumazenil (Correct Answer)
B. Alprazolam
C. Di-isopropyl phenol
D. Cremophor EL

Explanation: ### Explanation **Correct Option: A. Flumazenil** Flumazenil is a specific **competitive antagonist** at the benzodiazepine (BZD) binding site on the **GABA-A receptor** complex [1], [3]. It effectively reverses the sedative, psychomotor, and anticonvulsant effects of benzodiazepines [1]. It is the drug of choice for managing BZD overdose and for reversing sedation induced during anesthesia or diagnostic procedures [4]. **Analysis of Incorrect Options:** * **B. Alprazolam:** This is a short-to-intermediate acting **benzodiazepine agonist** used primarily for anxiety and panic disorders [2]. It would worsen, rather than antagonize, BZD toxicity. * **C. Di-isopropyl phenol:** This is the chemical name for **Propofol**, a rapid-acting intravenous anesthetic agent. It acts by enhancing GABAergic neurotransmission but at a different site than BZDs. * **D. Cremophor EL:** This is a **polyoxyethylated castor oil** used as a pharmaceutical vehicle (solvent) to solubilize hydrophobic drugs like Diazepam (in older formulations) or Paclitaxel. It is associated with hypersensitivity reactions. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Flumazenil blocks the BZD site but does *not* antagonize the effects of Barbiturates, Ethanol, or General Anesthetics, as they bind to different sites on the GABA receptor [1]. * **Half-life:** Flumazenil has a very short half-life (~1 hour). Because most BZDs have a longer duration of action, **re-sedation** can occur, necessitating repeated doses or an infusion. * **Contraindication:** It should be avoided in patients with a history of seizures or those with mixed tricyclic antidepressant (TCA) overdose, as it can precipitate **refractory seizures** by removing the protective anticonvulsant effect of the BZD [3]. * **Z-drugs:** Flumazenil also reverses the effects of non-benzodiazepine hypnotics like Zolpidem, Zaleplon, and Eszopiclone [1].

Question 97: All of the following are true about Clozapine EXCEPT?

A. It can cause agranulocytosis.
B. It has more affinity to D4 receptors compared to D2 receptors.
C. It has a lesser potency in blocking 5-HT2 than the D2 receptor. (Correct Answer)
D. It is an atypical antipsychotic agent.

Explanation: **Explanation:** Clozapine is the prototype **atypical antipsychotic** (Second Generation Antipsychotic). The core pharmacological distinction of atypical antipsychotics is their receptor binding profile. **Why Option C is the correct answer (The False Statement):** Atypical antipsychotics like Clozapine are characterized by a **higher affinity/potency for 5-HT2A receptors** compared to D2 receptors (5-HT2A > D2). This high 5-HT2 blockade is responsible for their efficacy in treating negative symptoms of schizophrenia and their lower propensity to cause Extrapyramidal Side Effects (EPS). Therefore, stating it has "lesser potency" in blocking 5-HT2 than D2 is factually incorrect. **Analysis of Incorrect Options (True Statements):** * **Option A:** Agranulocytosis is the most serious side effect of Clozapine (occurring in ~1% of patients). It requires mandatory weekly WBC monitoring for the first 6 months. * **Option B:** Clozapine has a unique binding profile with a high affinity for **D4 and 5-HT2** receptors, and relatively weak binding to D2 receptors. * **Option D:** It is the gold-standard atypical antipsychotic, especially used for **treatment-resistant schizophrenia**. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Treatment-resistant schizophrenia and schizophrenia with suicidal behavior. * **Side Effects:** Sialorrhea (excessive salivation), weight gain, myocarditis, and lowering of seizure threshold (dose-dependent). * **EPS:** Clozapine has the **lowest risk** of Extrapyramidal Side Effects and Tardive Dyskinesia among all antipsychotics. * **Metabolism:** It is a substrate of **CYP1A2**; smoking induces this enzyme, leading to decreased clozapine levels.

Question 98: Which of the following SSRIs does NOT affect the blood levels of other drugs?

A. Sertraline (Correct Answer)
B. Fluoxetine
C. Fluvoxamine
D. Paroxetine

Explanation: ### Explanation The primary reason SSRIs (Selective Serotonin Reuptake Inhibitors) affect the blood levels of other drugs is their ability to inhibit **Cytochrome P450 (CYP450)** enzymes in the liver. When these enzymes are inhibited, the metabolism of co-administered drugs (like warfarin, TCAs, or beta-blockers) decreases, leading to increased plasma concentrations and potential toxicity. **1. Why Sertraline is the Correct Answer:** **Sertraline** (along with Citalopram and Escitalopram) is known for having **minimal to no inhibitory effect** on CYP450 isoenzymes. Because it does not significantly interfere with the metabolic pathways of other medications, it has a very low potential for clinically significant drug-drug interactions. This makes it a preferred choice in elderly patients or those on multiple medications (polypharmacy). **2. Why the Other Options are Incorrect:** * **Fluoxetine:** A potent inhibitor of **CYP2D6** and **CYP3A4**. It has a very long half-life and significantly raises the levels of drugs like haloperidol and propranolol. * **Fluvoxamine:** A potent inhibitor of **CYP1A2** and **CYP2C19**. It significantly increases the levels of theophylline and warfarin. * **Paroxetine:** A highly potent inhibitor of **CYP2D6**. It can interfere with its own metabolism and significantly increase the levels of tricyclic antidepressants (TCAs). **Clinical Pearls for NEET-PG:** * **Safest SSRIs (Lowest Drug Interactions):** Sertraline, Citalopram, Escitalopram. * **Most Potent CYP2D6 Inhibitors:** Fluoxetine and Paroxetine. * **Longest Half-life:** Fluoxetine (due to its active metabolite, norfluoxetine), which requires a 5-week washout period before starting an MAOI to avoid **Serotonin Syndrome**. * **Drug of Choice (DOC):** SSRIs are the first-line treatment for Depression, OCD, Panic Disorder, and Social Phobia.

Question 99: All of the following are hallucinogens, except?

A. LSD
B. Phenylcyclidine
C. Mescaline
D. Methylphenidate (Correct Answer)

Explanation: **Explanation:** The correct answer is **Methylphenidate**. **1. Why Methylphenidate is the correct answer:** Methylphenidate is a **CNS stimulant** that primarily acts by increasing the synaptic concentration of dopamine and norepinephrine through the inhibition of their reuptake (similar to cocaine). It is the first-line pharmacological treatment for **Attention Deficit Hyperactivity Disorder (ADHD)** and is also used in Narcolepsy. Unlike hallucinogens, it does not typically induce perceptual distortions or hallucinations at therapeutic doses. **2. Why the other options are incorrect:** * **LSD (Lysergic Acid Diethylamide):** A potent "classic" hallucinogen and a 5-HT2A receptor agonist. It causes profound alterations in sensory perception and "synesthesia" (seeing sounds/hearing colors). * **Phencyclidine (PCP):** Also known as "Angel Dust," it is a **dissociative anesthetic** that acts as an NMDA receptor antagonist. It is notorious for causing hallucinations, agitation, and vertical/horizontal nystagmus. * **Mescaline:** A naturally occurring alkaloid derived from the Peyote cactus. Like LSD, it acts primarily on serotonin receptors to produce hallucinogenic effects. **Clinical Pearls for NEET-PG:** * **Psilocybin** (Magic mushrooms) and **DMT** are other common classic hallucinogens. * **Ketamine** is a "dissociative" hallucinogen similar to PCP (NMDA antagonist). * **Adverse effect of Methylphenidate:** Growth suppression in children (requires "drug holidays") and insomnia. * **Antidote for Hallucinogen Overdose:** Generally supportive care; Benzodiazepines are used for agitation or "bad trips."

Question 100: Which of the following is a monoamine oxidase inhibitor?

A. Phenelzine (Correct Answer)
B. Amitriptyline
C. Benztropine
D. Clonazepam

Explanation: **Explanation:** **Phenelzine** is the correct answer as it is a **non-selective, irreversible Monoamine Oxidase Inhibitor (MAOI)**. It works by inhibiting both MAO-A and MAO-B enzymes, thereby increasing the synaptic concentrations of norepinephrine, serotonin, and dopamine. While effective for atypical depression, it is considered a second-line agent due to its side effect profile and dietary restrictions. **Analysis of Incorrect Options:** * **Amitriptyline:** This is a **Tricyclic Antidepressant (TCA)**. It primarily inhibits the reuptake of serotonin and norepinephrine. It is also known for its significant anticholinergic and sedative properties. * **Benztropine:** This is a **centrally acting anticholinergic** (muscarinic antagonist). In psychiatry, it is primarily used to treat Extrapyramidal Side Effects (EPS) caused by antipsychotics, such as acute dystonia or parkinsonism. * **Clonazepam:** This is a **Benzodiazepine** that acts as a GABA-A receptor modulator. It is used as an anxiolytic, hypnotic, and antiepileptic, but it does not inhibit the MAO enzyme. **High-Yield Clinical Pearls for NEET-PG:** * **Cheese Reaction:** Patients on non-selective MAOIs (like Phenelzine) must avoid tyramine-rich foods (aged cheese, red wine). Tyramine displaces stored norepinephrine, leading to a **hypertensive crisis**. * **Drug Interactions:** MAOIs should never be combined with SSRIs or Pethidine due to the risk of **Serotonin Syndrome**. * **Washout Period:** A 14-day gap is required when switching between MAOIs and other antidepressants to allow for enzyme regeneration. * **Selective MAO-B Inhibitor:** Remember **Selegiline**, used primarily in Parkinson’s disease.

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

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free