Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders Indian Medical PG Practice Questions and MCQs

Question 161: Which group of drugs is considered first-line in the management of schizophrenia?

A. Opioids
B. Antiepileptics
C. Serotonergic drugs
D. Dopamine antagonists (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Dopamine Antagonists** The management of schizophrenia is primarily based on the **Dopamine Hypothesis**, which suggests that the positive symptoms of the disorder (hallucinations, delusions) are caused by overactivity of dopamine in the **mesolimbic pathway**. All standard antipsychotics (both Typical and Atypical) exert their primary therapeutic effect by blocking **D2 receptors**. * **Typical Antipsychotics** (e.g., Haloperidol) are potent D2 antagonists. * **Atypical Antipsychotics** (e.g., Risperidone, Olanzapine) block both D2 and 5-HT2A receptors, and are currently the preferred first-line agents due to a lower risk of Extrapyramidal Side Effects (EPS). **Why other options are incorrect:** * **A. Opioids:** These are primarily used for analgesia and anesthesia. They have no role in treating psychosis and can actually induce delirium or worsen mental status. * **B. Antiepileptics:** While drugs like Valproate or Carbamazepine are used as **mood stabilizers** in Bipolar Disorder or as adjuncts for aggression, they do not treat the core psychotic symptoms of schizophrenia. * **C. Serotonergic drugs:** While Atypical antipsychotics do have serotonin-blocking properties, "serotonergic drugs" usually refers to SSRIs/SNRIs used for depression and anxiety. Pure serotonergic stimulation can sometimes exacerbate psychotic symptoms. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice for Resistant Schizophrenia:** Clozapine (requires mandatory WBC monitoring for agranulocytosis). * **Most Potent D2 Blocker:** Haloperidol (highest risk of EPS). * **Hyperprolactinemia:** A common side effect of D2 blockade in the tuberoinfundibular pathway (most common with Risperidone). * **Negative Symptoms:** Atypical antipsychotics are generally better than typical ones for treating negative symptoms (apathy, social withdrawal).

Question 162: Which among the following selective serotonin reuptake inhibitors is longest acting?

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

Explanation: **Explanation:** The correct answer is **Fluoxetine**. **1. Why Fluoxetine is correct:** Fluoxetine is unique among Selective Serotonin Reuptake Inhibitors (SSRIs) due to its exceptionally long half-life. The parent drug has a half-life of approximately **2 to 3 days**, but it is metabolized into an active metabolite, **Norfluoxetine**, which has a half-life of **7 to 9 days**. This prolonged duration of action means that the drug remains in the system for several weeks even after discontinuation. This property makes it the safest SSRI to discontinue abruptly, as it essentially "self-tapers," resulting in the lowest risk of **SSRI Discontinuation Syndrome**. **2. Why the other options are incorrect:** * **Fluvoxamine:** It has the shortest half-life (approx. 15 hours) among the SSRIs and often requires twice-daily dosing. * **Sertraline:** It has an intermediate half-life (approx. 26 hours). While it also has an active metabolite (Desmethylsertraline), it is significantly less potent than Norfluoxetine. * **Paroxetine:** It has a half-life of about 21 hours. Notably, it is associated with the highest risk of Discontinuation Syndrome because it lacks active metabolites and has a relatively short half-life. **3. High-Yield Clinical Pearls for NEET-PG:** * **Washout Period:** Due to its long half-life, a **5-week washout period** is required when switching from Fluoxetine to a Monoamine Oxidase Inhibitor (MAOI) to avoid **Serotonin Syndrome** (other SSRIs usually require only 2 weeks). * **Drug of Choice:** Fluoxetine is the preferred SSRI for treating depression in **children and adolescents**. * **Side Effects:** Paroxetine is the most "sedating" and has the most significant anticholinergic effects, whereas Fluoxetine is often considered "activating" (can cause insomnia/anxiety initially).

Question 163: What is the first-line drug preferred for the treatment of akathisia?

A. Benzhexol
B. Trihexyphenidyl hydrochloride
C. Promethazine
D. Propranolol (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Propranolol** **Medical Concept:** Akathisia is an Extrapyramidal Side Effect (EPS) characterized by a subjective feeling of inner restlessness and an inability to sit still. Unlike other EPS (like dystonia or parkinsonism) which are primarily mediated by dopamine-acetylcholine imbalance in the nigrostriatal pathway, akathisia involves complex adrenergic mechanisms. **Propranolol**, a non-selective beta-blocker, is the **drug of choice** because it effectively crosses the blood-brain barrier and antagonizes beta-receptors, thereby reducing the physiological and psychological manifestations of restlessness. **Analysis of Incorrect Options:** * **A & B (Benzhexol / Trihexyphenidyl):** These are the same drug (anticholinergics). While they are first-line for **Acute Dystonia** and **Drug-Induced Parkinsonism**, they are significantly less effective for akathisia and are considered second-line options. * **C (Promethazine):** This is an antihistamine with sedative and anticholinergic properties. While it may be used for acute dystonia, it is not the preferred treatment for akathisia and may even worsen the condition due to its sedative profile. **High-Yield Clinical Pearls for NEET-PG:** * **Acute Dystonia:** Earliest EPS to appear (hours to days). Treatment: Central anticholinergics (e.g., Benztropine, Promethazine). * **Akathisia:** Most common EPS. Treatment: **Propranolol** (1st line), Benzodiazepines (2nd line). * **Drug-Induced Parkinsonism:** Treatment: Central anticholinergics (Trihexyphenidyl). *Note: Levodopa is contraindicated.* * **Tardive Dyskinesia:** Occurs after long-term use (months to years). Treatment: Switch to Clozapine; use VMAT-2 inhibitors (Valbenazine/Deutetrabenazine). Anticholinergics **worsen** Tardive Dyskinesia.

Question 164: A patient was treated with amitriptyline for depression and developed urinary retention, constipation, and blurring of vision. What is the most likely cause of these symptoms?

A. Symptoms of depression persisting
B. Anticholinergic side effects (Correct Answer)
C. Depression medicamentosa
D. Any of the above

Explanation: ### Explanation **Correct Option: B. Anticholinergic side effects** Amitriptyline is a **Tricyclic Antidepressant (TCA)**. While its primary therapeutic action is the inhibition of norepinephrine and serotonin reuptake, it also possesses significant antagonist activity at several other receptors, most notably **Muscarinic (M1) receptors**. The symptoms described—**urinary retention, constipation, and blurring of vision** (due to cycloplegia/mydriasis)—are classic manifestations of **anticholinergic toxicity**. By blocking muscarinic receptors, TCAs inhibit the parasympathetic nervous system ("rest and digest"), leading to "drying" effects: * **Mydriasis/Cycloplegia:** Blurred vision. * **Decreased Secretions:** Dry mouth (xerostomia). * **Smooth Muscle Relaxation:** Constipation and urinary retention. --- **Why other options are incorrect:** * **Option A:** Persistent depression typically presents with mood symptoms (anhedonia, low energy) rather than acute autonomic physical signs like urinary retention. * **Option C:** "Depression medicamentosa" refers to depression induced by drugs (e.g., Reserpine or Propranolol). It does not describe the physical side effects of antidepressants themselves. --- ### High-Yield NEET-PG Pearls: * **TCA Receptor Profile:** Remember the "Side Effect Profile" of TCAs: 1. **Anti-Muscarinic:** Dry mouth, blurred vision, constipation, urinary retention. 2. **Anti-Alpha 1:** Orthostatic hypotension. 3. **Anti-Histaminic (H1):** Sedation and weight gain. * **Cardiac Toxicity:** In TCA overdose, the most dangerous effect is **Sodium channel blockade**, leading to QRS prolongation and arrhythmias. **Sodium Bicarbonate** is the antidote for TCA-induced cardiac toxicity. * **Contraindication:** Due to anticholinergic effects, TCAs should be avoided in patients with **Benign Prostatic Hyperplasia (BPH)** and **Narrow-angle Glaucoma**.

Question 165: Which of the following is NOT a common side effect of chlorpromazine?

A. Osteoporosis (Correct Answer)
B. Parkinsonism
C. Skin rash
D. Amenorrhea

Explanation: **Explanation:** Chlorpromazine is a **typical (first-generation) antipsychotic** belonging to the phenothiazine class. It acts primarily by blocking dopamine ($D_2$) receptors in various brain pathways. **Why Osteoporosis is the correct answer:** While long-term use of antipsychotics can theoretically lead to decreased bone mineral density due to hyperprolactinemia (which suppresses estrogen/testosterone), **osteoporosis is not considered a "common" or classic side effect** of chlorpromazine. In the context of NEET-PG, the other three options represent well-documented, hallmark side effects of this drug class. **Analysis of Incorrect Options:** * **Parkinsonism (B):** Chlorpromazine blocks $D_2$ receptors in the **nigrostriatal pathway**, leading to Extrapyramidal Side Effects (EPS), including pseudoparkinsonism (rigidity, tremors, and bradykinesia). * **Skin Rash (C):** Chlorpromazine is notorious for dermatological side effects, including **photosensitivity** and a unique "blue-grey" skin discoloration in sun-exposed areas. * **Amenorrhea (D):** By blocking $D_2$ receptors in the **tuberoinfundibular pathway**, chlorpromazine removes the inhibitory effect of dopamine on prolactin. The resulting **hyperprolactinemia** causes galactorrhea, amenorrhea, and infertility. **High-Yield Clinical Pearls for NEET-PG:** 1. **Low Potency:** Chlorpromazine is a low-potency antipsychotic; it has a high affinity for $H_1$, $\alpha_1$, and $M_1$ receptors, leading to significant sedation, hypotension, and anticholinergic effects. 2. **Ocular Deposits:** A classic exam fact is that chlorpromazine causes **stellate corneal and lenticular opacities**, whereas Thioridazine causes retinitis pigmentosa. 3. **Weight Gain:** It is associated with significant metabolic side effects and weight gain compared to high-potency drugs like Haloperidol.

Question 166: Fluoxetine causes all of the following side effects, except:

A. Diarrhoea
B. Insomnia
C. Sedation (Correct Answer)
D. Anxiety

Explanation: **Explanation:** Fluoxetine is a prototype **Selective Serotonin Reuptake Inhibitor (SSRI)**. Unlike older tricyclic antidepressants (TCAs), SSRIs lack significant antihistaminic and anticholinergic properties, which are the primary drivers of sedation. **Why Sedation is the Correct Answer:** Fluoxetine is unique among SSRIs because it is **activating** rather than sedating. It has a stimulant-like effect on the CNS, which is why it is typically administered in the morning. Sedation is a characteristic side effect of TCAs (like Amitriptyline) or certain atypical antidepressants (like Mirtazapine), but not Fluoxetine. **Analysis of Incorrect Options:** * **Diarrhoea:** SSRIs increase serotonin levels in the gut, stimulating 5-HT3 receptors. This leads to gastrointestinal side effects, including nausea, vomiting, and diarrhoea. * **Insomnia:** Due to its activating nature and increased serotonergic neurotransmission in the brainstem, Fluoxetine frequently causes sleep disturbances and difficulty falling asleep. * **Anxiety:** In the initial stages of therapy, the stimulant effect of Fluoxetine can paradoxically worsen anxiety, agitation, or restlessness (akathisia-like symptoms). **High-Yield Clinical Pearls for NEET-PG:** 1. **Longest Half-life:** Fluoxetine has the longest half-life (2–4 days) among SSRIs, and its active metabolite, **norfluoxetine**, lasts 7–15 days. 2. **Washout Period:** Due to its long half-life, a 5-week washout period is required before starting an MAO inhibitor to avoid **Serotonin Syndrome**. 3. **Drug of Choice:** Fluoxetine is the preferred SSRI for treating depression in children and adolescents and is also used in Bulimia Nervosa.

Question 167: Methylphenidate is used for which condition?

A. Attention deficit disorder (Correct Answer)
B. Alzheimer's disease
C. Seizure disorder
D. Obsessive compulsive disorder

Explanation: **Explanation:** **Methylphenidate** is a central nervous system (CNS) stimulant that acts primarily by blocking the reuptake of **dopamine and norepinephrine** into presynaptic neurons. This increases the concentration of these neurotransmitters in the synaptic cleft, particularly in the prefrontal cortex, which enhances focus, attention, and impulse control. 1. **Why Option A is correct:** **Attention Deficit Hyperactivity Disorder (ADHD)** is the primary clinical indication for Methylphenidate. In patients with ADHD, there is an underlying catecholamine dysfunction; by increasing synaptic dopamine and norepinephrine, Methylphenidate improves the "signal-to-noise ratio" in brain circuits responsible for executive function. 2. **Why other options are incorrect:** * **Alzheimer’s Disease:** Managed with Cholinesterase inhibitors (Donepezil, Rivastigmine) or NMDA antagonists (Memantine). * **Seizure Disorder:** Stimulants like Methylphenidate can actually lower the seizure threshold and are generally contraindicated or used with extreme caution in patients with epilepsy. * **Obsessive Compulsive Disorder (OCD):** The first-line treatment involves SSRIs (e.g., Fluoxetine) or the TCA Clomipramine. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Inhibits the transporters DAT (Dopamine Transporter) and NET (Norepinephrine Transporter). * **Other Indications:** It is also used as a second-line treatment for **Narcolepsy**. * **Side Effects:** Insomnia, anorexia (weight loss), growth suppression in children (requires "drug holidays"), and tachycardia. * **Contraindications:** Glaucoma, motor tics (Tourette’s syndrome), and concomitant use of MAO inhibitors (risk of hypertensive crisis).

Question 168: Which of the following is NOT a serotonin-norepinephrine reuptake inhibitor?

A. Paroxetine (Correct Answer)
B. Mianserin
C. None of the above
D. Venlafaxine

Explanation: **Explanation:** The core of this question lies in distinguishing between different classes of antidepressants based on their mechanism of action. **1. Why Paroxetine is the correct answer:** **Paroxetine** is a potent and selective **Selective Serotonin Reuptake Inhibitor (SSRI)**. It works by specifically inhibiting the reuptake of serotonin (5-HT) at the presynaptic terminal, increasing its availability in the synaptic cleft. It does not significantly inhibit the reuptake of norepinephrine, which is why it is **not** classified as an SNRI. **2. Analysis of other options:** * **Venlafaxine:** This is the prototype **Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)**. At lower doses, it primarily affects serotonin, but at higher doses, it significantly inhibits norepinephrine reuptake. * **Mianserin:** This is an **Atypical Antidepressant** (specifically a tetracyclic antidepressant). While its primary mechanism is blocking presynaptic $\alpha_2$-adrenoceptors (increasing NE release), it also inhibits the reuptake of norepinephrine. In many pharmacological classifications used for competitive exams, it is grouped with drugs that enhance noradrenergic transmission, distinct from pure SSRIs. * **None of the above:** Incorrect, as Paroxetine clearly fits the criteria for an SSRI. **Clinical Pearls for NEET-PG:** * **SNRIs:** Include Venlafaxine, Desvenlafaxine, Duloxetine, and Milnacipran. * **Duloxetine** is the drug of choice for diabetic neuropathy and fibromyalgia. * **Paroxetine** has the shortest half-life among SSRIs and is most associated with **Discontinuation Syndrome**. It is also notably associated with weight gain and anticholinergic side effects compared to other SSRIs. * **Fluoxetine** has the longest half-life and is the SSRI of choice in children and adolescents.

Question 169: All of the following are Selective Serotonin Reuptake Inhibitors (SSRIs) except?

A. Paroxetine
B. Escitalopram
C. Fluvoxamine
D. Mirtazapine (Correct Answer)

Explanation: **Explanation:** The correct answer is **Mirtazapine**. **1. Why Mirtazapine is the correct answer:** Mirtazapine is not an SSRI; it is classified as a **Noradrenergic and Specific Serotonergic Antidepressant (NaSSA)** [2]. Its mechanism of action involves blocking **presynaptic $\alpha_2$-autoreceptors**, which increases the release of both norepinephrine and serotonin. It also blocks 5-$HT_2$ and 5-$HT_3$ receptors, which helps reduce the common side effects associated with SSRIs, such as anxiety and nausea [1]. **2. Why the other options are incorrect:** * **Paroxetine (A):** A potent SSRI often used for panic disorders and OCD [2], [3]. It has a relatively short half-life and is known for having the highest risk of "discontinuation syndrome" among SSRIs. * **Escitalopram (B):** The S-enantiomer of citalopram [1]. It is considered the most selective SSRI with the fewest drug-drug interactions, making it a first-line choice for depression [3]. * **Fluvoxamine (C):** An SSRI primarily indicated for Obsessive-Compulsive Disorder (OCD) [2], [3]. It is unique for its potent inhibition of CYP enzymes. **3. NEET-PG High-Yield Clinical Pearls:** * **SSRIs** are the first-line treatment for Depression, OCD, Panic Disorder, and Social Phobia. * **Mirtazapine** is a "weight-positive" antidepressant. It is a preferred choice for depressed patients suffering from **insomnia and significant weight loss** due to its side effects of sedation (H1 blockade) and increased appetite [2]. * **Sexual dysfunction** is a common side effect of SSRIs (Options A, B, C) [1], but **Mirtazapine** is "serotonin-sparing" in this regard and is often used when patients cannot tolerate the sexual side effects of SSRIs. * **Drug of choice for OCD:** Fluoxetine/Fluvoxamine. * **Drug of choice for Depression:** SSRIs (Escitalopram is frequently preferred).

Question 170: Which of the following is NOT a side effect of amitriptyline?

A. Constipation
B. Fine tremors
C. Weight loss (Correct Answer)
D. Dry mouth

Explanation: **Explanation:** Amitriptyline is a **Tricyclic Antidepressant (TCA)**. The side effect profile of TCAs is determined by their multi-receptor antagonism, specifically blocking Muscarinic (M1), Histaminic (H1), and Alpha-1 (α1) receptors. **Why Weight Loss is the Correct Answer:** Amitriptyline is notorious for causing **weight gain**, not weight loss. This occurs primarily due to its potent **H1-receptor antagonism**, which increases appetite and slows metabolism. In clinical practice, weight gain is a common reason for patient non-compliance with TCAs. **Analysis of Incorrect Options:** * **Constipation & Dry Mouth (Options A & D):** These are classic **Anticholinergic (Antimuscarinic)** side effects. TCAs block M1 receptors, leading to the "dry" symptoms: dry mouth (xerostomia), constipation, urinary retention, and blurred vision. * **Fine Tremors (Option B):** TCAs inhibit the reuptake of Norepinephrine (NE). Increased synaptic NE levels can lead to sympathetic overactivity, manifesting as fine tremors, tachycardia, or sweating. **NEET-PG High-Yield Pearls:** 1. **Mechanism:** TCAs inhibit the reuptake of both Serotonin (5-HT) and Norepinephrine (NE). 2. **Cardiac Toxicity:** The most serious side effect in overdose is **cardiotoxicity** (arrhythmias and QRS prolongation) due to Sodium (Na+) channel blockade. The antidote is **Sodium Bicarbonate**. 3. **The 3 C’s of TCA Overdose:** **C**oma, **C**onvulsions, and **C**ardiotoxicity. 4. **Contraindication:** Avoid in patients with Glaucoma (due to mydriasis) and Benign Prostatic Hyperplasia (due to urinary retention).

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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