Drugs in Psychiatric Disorders Practice Questions

Q: Dryness of mouth caused by antipsychotic drugs is primarily due to the blockade of which type of receptors?

Muscarinic acetylcholine receptors. **Explanation:** The dryness of mouth (xerostomia) associated with antipsychotic drugs is a classic **anticholinergic side effect**. Many antipsychotics, particularly low-potency typical antipsychotics (e.g., Chlorpromazine) and certain atypicals (e.g., Clozapine, Olanzapine), have a high affinity for **Muscarinic (M1) receptors**. Blockade of these receptors in the salivary glands inhibits parasympathetic stimulation, leading to reduced salivary secretion. **Analysis of Options:** * **Option A (Correct):** Muscarinic blockade prevents the action of acetylcholine on salivary glands. This "atropine-like" effect also causes blurred vision, constipation, and urinary retention. * **Option B (Incorrect):** GABA is the primary inhibitory neurotransmitter. Drugs affecting GABA (like benzodiazepines) cause sedation and anxiolysis, not dry mouth. * **Option C (Incorrect):** Serotonergic (5-HT2A) blockade is a hallmark of atypical antipsychotics and helps reduce extrapyramidal symptoms (EPS), but it does not cause xerostomia. * **Option D (Incorrect):** Dopaminergic (D2) blockade in the mesolimbic pathway is the primary mechanism for the *antipsychotic* effect. Blockade in the nigrostriatal pathway leads to EPS (Parkinsonism), not dry mouth. **High-Yield NEET-PG Pearls:** * **Mnemonic for Anticholinergic Toxicity:** "Dry as a bone (dry mouth/skin), Red as a beet (flushing), Hot as a hare (hyperthermia), Blind as a bat (mydriasis), Mad as a hatter (delirium)." * **Thioridazine and Chlorpromazine** are the typical antipsychotics with the strongest anticholinergic profiles. * **Clozapine Paradox:** Despite being a potent muscarinic antagonist, Clozapine often causes **sialorrhea** (excessive salivation) instead of dry mouth, likely due to its agonist activity at M4 receptors or inhibition of the swallowing reflex.

Q: Tianeptine acts by which of the following mechanisms?

Serotonin uptake enhancer. **Explanation:** **Tianeptine** is a unique antidepressant that defies the traditional "monoamine hypothesis" of depression. While most conventional antidepressants (like SSRIs) work by inhibiting the reuptake of serotonin to increase its synaptic concentration, Tianeptine acts as a **Selective Serotonin Reuptake Enhancer (SSRE)**. It increases the presynaptic uptake of serotonin (5-HT), thereby decreasing 5-HT levels in the synaptic cleft. Despite this paradoxical mechanism, it effectively exerts antidepressant and anxiolytic effects, likely through its downstream modulation of glutamate receptors (NMDA and AMPA) and its role in neuroplasticity. **Analysis of Options:** * **Option A (MAO Inhibitor):** MAOIs (e.g., Phenelzine, Selegiline) prevent the breakdown of monoamines. Tianeptine does not inhibit the Monoamine Oxidase enzyme. * **Option B (Serotonin uptake inhibitor):** This is the mechanism of **SSRIs** (e.g., Fluoxetine, Sertraline). Tianeptine acts in the exact opposite manner by *enhancing* uptake. * **Option D (5-HT agonist):** Drugs like Buspirone (5-HT1A partial agonist) act here. Tianeptine does not have significant direct affinity for serotonin receptors. **High-Yield Clinical Pearls for NEET-PG:** * **Neuroprotection:** Tianeptine is known to prevent stress-induced atrophy of dendrites in the hippocampus. * **Opioid Link:** Recent studies show Tianeptine also acts as a **full agonist at μ-opioid receptors**, which may contribute to its mood-elevating effects. * **Pharmacokinetics:** It is primarily metabolized by the liver (beta-oxidation) rather than the Cytochrome P450 system, leading to fewer drug-drug interactions. * **Side Effects:** Unlike SSRIs, it typically **does not cause sexual dysfunction** or significant sedation.

Q: A patient presents with complaints of diminished vision. Ophthalmological examination revealed corneal and lenticular opacities. The patient had been prescribed an antipsychotic drug during a previous visit. Which of the following drugs could have caused these symptoms?

Thioridazine. ### Explanation **Correct Option: A. Thioridazine** Thioridazine is a low-potency typical antipsychotic known for specific ocular side effects. The key to this question lies in the anatomical location of the opacities. * **Corneal and Lenticular (Lens) Opacities:** These are classic side effects of **Chlorpromazine** and **Thioridazine**. They typically present as "star-shaped" opacities that are usually asymptomatic but can diminish vision if extensive. * **Retinal Pigmentation:** Thioridazine is uniquely associated with **Retinitis Pigmentosa** (pigmentary retinopathy) when used in high doses (usually >800 mg/day). This can lead to permanent visual loss and "brownish" vision. **Why Incorrect Options are Wrong:** * **B. Haloperidol:** A high-potency typical antipsychotic. It is more commonly associated with Extrapyramidal Side Effects (EPS) rather than ocular opacities. * **C. Flupenthixol:** A thioxanthene derivative used for psychosis and depression. While it can cause blurred vision due to anticholinergic effects, it does not typically cause structural corneal or lenticular opacities. * **D. Pimozide:** Used primarily for Tourette’s syndrome and delusional parasitosis. Its main side effect concern is QTc prolongation rather than ocular toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Chlorpromazine:** Associated with **blue-grey skin discoloration** and corneal/lens opacities (the "C" in Chlorpromazine for Corneal). * **Thioridazine:** Associated with **Retinal deposits** (the "R" in Thioridazine for Retinal) and has the highest risk of QTc prolongation among typical antipsychotics. * **Mnemonic:** **C**hlorpromazine = **C**orneal/Lens; **T**hioridazine = **T**errible **R**etinopathy. * **Monitoring:** Patients on long-term Thioridazine require periodic fundus examinations.

Q: Which drug is associated with a blue-grey skin discoloration?

Chlorpromazine. **Explanation:** **Chlorpromazine (Option A)** is a low-potency typical antipsychotic known for causing specific dermatological and ocular side effects. Long-term use at high doses can lead to a characteristic **blue-grey skin discoloration** in sun-exposed areas. This occurs due to the accumulation of drug metabolites and melanin in the dermis. Additionally, chlorpromazine is classically associated with **benign whitish-brown granular deposits** in the anterior lens and posterior cornea (often described as "star-shaped cataracts"). **Why other options are incorrect:** * **Risperidone (Option B):** An atypical antipsychotic primarily associated with hyperprolactinemia (leading to galactorrhea/amenorrhea) and extrapyramidal symptoms at higher doses, but not skin pigmentation. * **Memantine (Option C):** An NMDA receptor antagonist used in Alzheimer’s disease; its side effects are generally neurological (dizziness, confusion) or gastrointestinal. * **Clozapine (Option D):** An atypical antipsychotic famous for **agranulocytosis** (requiring mandatory WBC monitoring), seizures, and hypersalivation, but it does not cause blue-grey skin changes. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Chlorpromazine (CPZ):** **C**orneal/Lens deposits, **P**igmentation (blue-grey), and **Z**-level (low) potency. * **Thioridazine** (another typical antipsychotic) is associated with **retinitis pigmentosa** (brownish vision), unlike the corneal changes in chlorpromazine. * Other drugs causing blue-grey skin: **Amiodarone** (anti-arrhythmic) and **Silver** (Argyria). * Chlorpromazine is also a first-line pharmacological treatment for **intractable hiccups**.

Q: Which of the following statements regarding Lithium is false?

There is no individual variation in the rate of excretion.. ### Explanation **1. Why Option C is the Correct (False) Statement:** Lithium excretion is almost entirely renal, and there is **significant individual variation** in its rate of excretion. The elimination half-life of Lithium varies widely (approximately 18–36 hours) depending on the patient’s age, renal function, and sodium balance. Because of this variability and its narrow therapeutic index, **Therapeutic Drug Monitoring (TDM)** is mandatory to tailor the dose for each individual. **2. Analysis of Other Options:** * **Option A (True):** Lithium has a very **low therapeutic index** (0.6–1.2 mEq/L). High peak plasma concentrations (Cmax) are avoided to prevent acute toxicity; hence, sustained-release formulations or divided doses are often used. * **Option B (True):** Lithium is generally contraindicated in pregnancy, especially during the first trimester, due to its teratogenic potential. It is associated with **Ebstein’s anomaly** (atrialization of the right ventricle). * **Option D (True):** Lithium is handled by the kidneys similarly to sodium. Approximately **80% of the filtered load is reabsorbed in the proximal convoluted tubule (PCT)**. This is clinically significant because conditions causing sodium depletion (e.g., diuretics, dehydration) lead to increased proximal reabsorption of Lithium, potentially causing toxicity. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drug Interactions:** Thiazides, NSAIDs, and ACE inhibitors increase Lithium levels by decreasing its clearance. * **Side Effects:** L-I-T-H: **L**eukocytosis, **I**nsipidus (Nephrogenic Diabetes Insipidus), **T**remors/Teratogenicity, **H**ypothyroidism. * **Monitoring:** Check Serum Creatinine, TSH, and ECG before starting therapy. * **Drug of Choice:** Lithium remains the gold standard for the prophylaxis of Bipolar Affective Disorder (BPAD).

Q: Which of the following is a side effect of SNRIs?

Delayed orgasm. **Explanation:** **SNRIs (Serotonin-Norepinephrine Reuptake Inhibitors)**, such as Venlafaxine and Duloxetine, increase the synaptic concentration of serotonin. Elevated serotonin levels in the CNS stimulate **5-HT2 receptors**, which inhibits the spinal cord reflexes required for ejaculation and orgasm. Consequently, **delayed orgasm** (anorgasmia) and delayed ejaculation are common side effects of both SSRIs and SNRIs. **Analysis of Options:** * **Option A (Premature ejaculation):** This is incorrect. Because SNRIs delay ejaculation, they are actually used **off-label to treat** premature ejaculation (Dapoxetine, an SSRI, is specifically approved for this). * **Option C (Cancer):** There is no clinical evidence linking SNRIs to an increased risk of malignancy. * **Option D (Hypotension):** This is incorrect. While some antidepressants (like TCAs) cause orthostatic hypotension, SNRIs are associated with **Hypertension**. The "N" in SNRI stands for Norepinephrine; increased noradrenergic activity can lead to dose-dependent increases in blood pressure. **High-Yield Clinical Pearls for NEET-PG:** * **Sexual Dysfunction:** This is the most common reason for long-term non-compliance with SSRIs/SNRIs. To manage this, clinicians may switch the patient to **Bupropion** or **Mirtazapine**, which have minimal sexual side effects. * **Discontinuation Syndrome:** Abrupt withdrawal of SNRIs (especially Venlafaxine) causes "flu-like" symptoms and "electric shock" sensations. * **Duloxetine:** Specifically indicated for painful physical symptoms (diabetic neuropathy, fibromyalgia) alongside depression.

Q: Obstructive jaundice may be seen as a side effect of therapy with which of the following medications?

Chlorpromazine. **Explanation:** The correct answer is **Chlorpromazine**. **Mechanism of Toxicity:** Chlorpromazine, a typical antipsychotic of the phenothiazine class, is a classic cause of **intrahepatic cholestatic jaundice**. This is an idiosyncratic (Type B) hypersensitivity reaction rather than a dose-dependent effect. It typically occurs within the first 1–4 weeks of therapy. The drug causes interference with bile canalicular transport and leads to the inflammation of the portal tracts, resulting in "obstructive" features (elevated alkaline phosphatase and conjugated bilirubin) despite no physical blockage in the large bile ducts. **Analysis of Incorrect Options:** * **A. Isoniazid:** While highly hepatotoxic, Isoniazid typically causes **hepatocellular necrosis** (elevated ALT/AST) rather than obstructive jaundice. Its toxicity is mediated by its metabolite, acetylhydrazine. * **B. Reserpine:** This older antihypertensive/antipsychotic is associated with side effects like depression, parkinsonism, and gastric ulcers, but it is not known for causing cholestatic jaundice. * **C. Furosemide:** This loop diuretic is primarily associated with ototoxicity, hypokalemia, and hyperuricemia. It does not have a significant association with obstructive jaundice. **High-Yield Clinical Pearls for NEET-PG:** * **Cholestatic Jaundice Triad:** Other drugs frequently causing this pattern include **Erythromycin estolate**, **Oral Contraceptive Pills (OCPs)**, and **Anabolic Steroids**. * **Chlorpromazine Side Effects:** Remember the "3 Cs" – **C**holestatic jaundice, **C**orneal deposits, and **C**onvulsions (lowers seizure threshold). * **Management:** The jaundice is usually reversible upon discontinuation of the drug.

Q: Which of the following tricyclic antidepressants is used in the management of nocturnal enuresis?

imipramine. **Explanation:** **Imipramine** is a tertiary amine Tricyclic Antidepressant (TCA) that has been traditionally used in the management of nocturnal enuresis (bedwetting) in children aged 6 years and older. Its efficacy is attributed to a dual mechanism: 1. **Anticholinergic effect:** It increases the bladder capacity by relaxing the detrusor muscle. 2. **Noradrenergic effect:** It increases the tone of the internal urethral sphincter. 3. **Sleep architecture:** It alters the sleep-wake pattern, making the child more easily arousable by a full bladder. **Analysis of Incorrect Options:** * **Fluoxetine and Sertraline (Options B & D):** These are Selective Serotonin Reuptake Inhibitors (SSRIs). While they are first-line for depression and anxiety, they do not possess the potent anticholinergic properties required to treat enuresis. * **Bupropion (Option C):** This is an Atypical Antidepressant (NDRI) used primarily for smoking cessation and depression. It lacks anticholinergic activity and is contraindicated in patients with seizure disorders. **Clinical Pearls for NEET-PG:** * **First-line treatment** for nocturnal enuresis is **Behavioral Therapy** (e.g., Bed-alarm/Enuresis alarm). * **Desmopressin (ADH analogue)** is the first-line pharmacological agent due to a better safety profile. * **Imipramine** is considered second-line or third-line due to its narrow therapeutic index and risk of **cardiotoxicity** (QT prolongation) in overdose. * **Other TCAs:** Clomipramine is the drug of choice for OCD; Amitriptyline is commonly used for neuropathic pain and migraine prophylaxis.

Q: Which drug, when given to a patient with alcohol dependence, can cause an adverse drug reaction if the patient consumes alcohol due to a drug interaction?

Disulfiram. **Explanation:** The correct answer is **Disulfiram**. This drug is used as **Aversion Therapy** in alcohol dependence. **1. Why Disulfiram is correct:** Disulfiram inhibits the enzyme **Aldehyde Dehydrogenase (ALDH)**. Normally, alcohol is metabolized into Acetaldehyde, which ALDH then converts into Acetic Acid. By blocking ALDH, Disulfiram causes a toxic accumulation of **Acetaldehyde** in the blood if alcohol is consumed. This leads to the **Disulfiram-Ethanol Reaction (DER)**, characterized by flushing, throbbing headache, nausea, vomiting, tachycardia, and hypotension. The fear of this unpleasant reaction deters the patient from drinking. **2. Why other options are incorrect:** * **Acamprosate:** It is an NMDA receptor antagonist used to maintain abstinence by reducing "protracted withdrawal" symptoms (craving). It does not cause a reaction with alcohol. * **Naltrexone:** An opioid antagonist that reduces the "reward" or euphoria associated with drinking by blocking mu-opioid receptors. It is the drug of choice for reducing cravings but has no interaction reaction. * **Naloxone:** An intravenous opioid antagonist used primarily for acute opioid overdose, not for the long-term management of alcohol dependence. **Clinical Pearls for NEET-PG:** * **Drug of Choice for Alcohol Withdrawal:** Benzodiazepines (e.g., Chlordiazepoxide, Diazepam). * **Drug of Choice to Reduce Craving:** Naltrexone. * **Other drugs causing Disulfiram-like reactions:** Metronidazole (most common), Cefotetan, Cefoperazone, Chlorpropamide, and Griseofulvin. * **Contraindication:** Disulfiram should never be administered if the patient has consumed alcohol within the last 12 hours or is in a state of intoxication.

Question 1

Dryness of mouth caused by antipsychotic drugs is primarily due to the blockade of which type of receptors?

Accepted Answer

Muscarinic acetylcholine receptors

Answer

GABA receptors

Answer

Serotonergic receptors

Answer

Dopaminergic receptors

Question 2

Tianeptine acts by which of the following mechanisms?

Accepted Answer

Serotonin uptake enhancer

Answer

MAO inhibitor

Answer

Serotonin uptake inhibitor

Answer

5-HT agonist

Question 3

A patient presents with complaints of diminished vision. Ophthalmological examination revealed corneal and lenticular opacities. The patient had been prescribed an antipsychotic drug during a previous visit. Which of the following drugs could have caused these symptoms?

Accepted Answer

Thioridazine

Answer

Haloperidol

Answer

Flupenthixol

Answer

Pimozide

Question 4

Which drug is associated with a blue-grey skin discoloration?

Accepted Answer

Chlorpromazine

Answer

Risperidone

Answer

Memantine

Answer

Clozapine

Question 5

Which of the following statements regarding Lithium is false?

Accepted Answer

There is no individual variation in the rate of excretion.

Answer

Maximum plasma concentration is avoided due to a low therapeutic index.

Answer

It is contraindicated in pregnancy.

Answer

80% is reabsorbed in the proximal convoluted tubule.

Question 6

Which of the following drugs should not be given in a patient with acute angle-closure glaucoma?

Accepted Answer

Clozapine

Answer

Pilocarpine

Answer

Fluphenazine

Answer

Paroxetine

Question 7

Which of the following is a side effect of SNRIs?

Accepted Answer

Delayed orgasm

Answer

Premature ejaculation

Answer

Cancer

Answer

Hypotension

Question 8

Obstructive jaundice may be seen as a side effect of therapy with which of the following medications?

Accepted Answer

Chlorpromazine

Answer

Isoniazid

Answer

Reserpine

Answer

Furosemide

Question 9

Which of the following tricyclic antidepressants is used in the management of nocturnal enuresis?

Accepted Answer

imipramine

Answer

fluoxetine

Answer

bupropion

Answer

sertraline

Question 10

Which drug, when given to a patient with alcohol dependence, can cause an adverse drug reaction if the patient consumes alcohol due to a drug interaction?

Accepted Answer

Disulfiram

Answer

Acamprosate

Answer

Naloxone

Answer

Naltrexone

Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders — MCQs

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