Drugs in Psychiatric Disorders Practice Questions

Q: What is the half-life of lithium?

24 hours. **Explanation:** **Lithium** is the gold standard mood stabilizer used in the treatment of Bipolar Affective Disorder (BPAD). Understanding its pharmacokinetics is crucial for NEET-PG due to its narrow therapeutic index. 1. **Why 24 hours is correct:** The elimination half-life ($t_{1/2}$) of lithium in a healthy adult with normal renal function is approximately **24 hours** (ranging typically from 18 to 30 hours). Because it takes 4 to 5 half-lives to reach a steady-state plasma concentration, lithium requires about 5 days of consistent dosing before therapeutic drug monitoring (TDM) can be accurately performed. 2. **Analysis of Incorrect Options:** * **8 hours:** This is too short for lithium. Drugs with this half-life (like Morphine) require frequent dosing. * **16 hours:** While some sources suggest a range starting at 18 hours, 24 hours is the standard "textbook" value used for clinical calculations and exam purposes. * **36 hours:** This represents the upper limit often seen in elderly patients or those with renal impairment, but it is not the standard physiological half-life. **High-Yield Clinical Pearls for NEET-PG:** * **Excretion:** Lithium is excreted almost entirely by the **kidneys**. It is handled similarly to Sodium; it is reabsorbed in the proximal convoluted tubule (PCT). * **Drug Interactions:** Thiazide diuretics, NSAIDs, and ACE inhibitors increase lithium levels by increasing proximal reabsorption, potentially leading to toxicity. * **Therapeutic Window:** 0.6–1.2 mEq/L (Prophylaxis/Maintenance) and 0.8–1.5 mEq/L (Acute Mania). Toxicity usually occurs above 1.5–2.0 mEq/L. * **Monitoring:** Samples for TDM should be drawn **12 hours post-dose** (trough levels).

Q: Which 5-HT1A agonist drug acts as an anxiolytic agent?

Buspirone. **Explanation:** **Buspirone** is the correct answer as it is a selective **5-HT1A partial agonist** used primarily for the management of Generalized Anxiety Disorder (GAD). Unlike traditional anxiolytics, it does not interact with the GABA-A receptor complex. Its primary mechanism involves stimulating presynaptic 5-HT1A receptors (inhibiting serotonin release) and postsynaptic 5-HT1A receptors in the hippocampus and cortex. **Analysis of Incorrect Options:** * **Diazepam:** A Benzodiazepine (BZD) that acts as a positive allosteric modulator of the **GABA-A receptor**. While it is an anxiolytic, it works via chloride channel opening, not 5-HT receptors. * **Zolpidem:** A "Z-drug" used as a hypnotic. It selectively binds to the **alpha-1 subunit of the GABA-A receptor**. It lacks significant anxiolytic or muscle relaxant properties. * **Cinnarizine:** An **H1-receptor antagonist** and calcium channel blocker used primarily for vertigo and motion sickness; it has no role as a 5-HT1A-mediated anxiolytic. **High-Yield NEET-PG Pearls:** 1. **Delayed Onset:** Buspirone takes **2–4 weeks** to show therapeutic effects, making it unsuitable for acute anxiety or panic attacks. 2. **"3 No’s" of Buspirone:** **No** sedation, **No** muscle relaxation/anticonvulsant activity, and **No** potential for abuse/dependence (unlike BZDs). 3. **No Interaction with Alcohol:** It does not potentiate the effects of CNS depressants. 4. **Metabolism:** It is metabolized by **CYP3A4**; concurrent use with rifampicin (inducer) or erythromycin (inhibitor) requires dose adjustment.

Q: Which of the following typical antipsychotic drugs is not available in depot form?

Chlorpromazine. **Explanation:** The correct answer is **Chlorpromazine**. **1. Why Chlorpromazine is the correct answer:** Chlorpromazine is a low-potency typical antipsychotic. Depot formulations (Long-Acting Injectables or LAIs) are designed for sustained release over weeks to improve compliance in chronic schizophrenia. These are typically created by esterifying high-potency drugs with fatty acids (like decanoate or enanthate) in an oil vehicle. Chlorpromazine is not available in a depot form; it is administered orally or via short-acting intramuscular injection for acute agitation. **2. Analysis of Incorrect Options:** * **Haloperidol (Option A):** This is a high-potency typical antipsychotic available as **Haloperidol Decanoate**. It is one of the most commonly used first-generation depot preparations, administered every 4 weeks. * **Risperidone (Option B):** An atypical antipsychotic available as a long-acting injection (e.g., Risperdal Consta). It uses microsphere technology for sustained release. * **Olanzapine (Option C):** An atypical antipsychotic available as **Olanzapine Pamoate**. Note: It carries a risk of "Post-injection Delirium Sedation Syndrome" (PDSS), requiring mandatory 3-hour observation. **3. High-Yield Clinical Pearls for NEET-PG:** * **Typical Antipsychotics available as Depots:** Haloperidol, Fluphenazine, Flupentixol, and Zuclopenthixol. * **Atypical Antipsychotics available as Depots:** Risperidone, Olanzapine, Paliperidone, and Aripiprazole. * **Mechanism:** Depot forms are usually prodrugs. The ester bond is slowly hydrolyzed by plasma esterases to release the active drug. * **Key Contraindication:** Depot preparations should **never** be given intravenously; they are strictly for deep intramuscular (IM) use.

Q: Which of the following groups of drugs is known to cause neurogenic dislocation?

Antipsychotic drugs. **Explanation:** The correct answer is **Antipsychotic drugs**. **Mechanism and Concept:** Neurogenic dislocation (specifically of the temporomandibular joint or TMJ) is a rare but documented complication of **Acute Dystonia**, which is an Extrapyramidal Side Effect (EPS) caused by antipsychotic medications. Antipsychotics, particularly first-generation (typical) agents like Haloperidol, work by blocking Dopamine (D2) receptors in the nigrostriatal pathway. This blockade leads to a relative excess of cholinergic activity, resulting in involuntary, sustained muscle contractions. When these spasms involve the muscles of mastication (like the lateral pterygoid), the force can be strong enough to pull the condyle out of the glenoid fossa, leading to a "neurogenic" dislocation of the jaw. **Analysis of Incorrect Options:** * **Anxiolytics:** These drugs (e.g., Benzodiazepines) are muscle relaxants and are actually used to *treat* acute dystonic reactions, not cause them. * **Antiparkinsonism drugs:** These agents (e.g., Levodopa or Anticholinergics like Trihexyphenidyl) aim to increase dopamine or decrease acetylcholine. They do not cause acute dystonia; in fact, anticholinergics are the drug of choice to manage antipsychotic-induced dystonia. **NEET-PG High-Yield Pearls:** * **Acute Dystonia** is the earliest EPS to appear (usually within hours to days of starting treatment). * **Risk Factors:** Young males and high-potency antipsychotics. * **Common Presentations:** Torticollis (neck), Oculogyric crisis (eyes), and Trismus/TMJ dislocation (jaw). * **Management:** Immediate treatment involves parenteral **Promethazine** or **Benztropine** (anticholinergics).

Q: Which antipsychotic medication is known to cause cataracts?

Ziprasidone. **Explanation:** The association between antipsychotics and ocular side effects is a high-yield topic in psychopharmacology. Among the atypical (second-generation) antipsychotics, **Ziprasidone** is uniquely associated with an increased risk of lens opacities or **cataracts**. During its early clinical development, preclinical studies in animals suggested a potential for cataract formation, leading to recommendations for periodic slit-lamp examinations (though this is less strictly enforced in current clinical practice compared to Quetiapine). **Analysis of Options:** * **Ziprasidone (Correct):** Beyond cataracts, it is most famous for causing **QTc interval prolongation**, necessitating caution in patients with cardiac arrhythmias. It is weight-neutral but must be taken with food (at least 500 calories) for optimal absorption. * **Aripiprazole:** Known as a "dopamine system stabilizer" (partial agonist). It is least likely to cause metabolic side effects or cataracts but is frequently associated with **akathisia**. * **Olanzapine:** Primarily associated with significant **weight gain**, dyslipidemia, and metabolic syndrome. It does not have a documented specific association with cataracts. * **Risperidone:** Notable for causing **hyperprolactinemia** (leading to gynecomastia or galactorrhea) and extrapyramidal symptoms (EPS) at higher doses. **NEET-PG High-Yield Pearls:** 1. **Quetiapine** is the other major antipsychotic historically linked to cataracts; always check for it if Ziprasidone is not in the options. 2. **Chlorpromazine** (Typical) is famous for causing **lenticular deposits** (star-shaped) and epithelial keratopathy. 3. **Thioridazine** (Typical) is associated with **retinitis pigmentosa** (brownish discoloration of vision) at doses >800mg/day. 4. **Ziprasidone** has the highest risk of QTc prolongation among second-generation antipsychotics.

Q: Which of the following is a known side effect of bupropion?

Seizures. **Explanation:** **Correct Answer: B. Seizures** Bupropion is an atypical antidepressant that acts as a **Norepinephrine-Dopamine Reuptake Inhibitor (NDRI)**. Its most significant and dose-dependent side effect is a **reduction in the seizure threshold**. The risk is particularly high (approx. 0.4%) at doses exceeding 450 mg/day or in patients with pre-existing risk factors. Consequently, bupropion is strictly **contraindicated** in patients with epilepsy and eating disorders (Anorexia or Bulimia nervosa) due to the high incidence of electrolyte imbalances which further increase seizure risk. **Analysis of Incorrect Options:** * **A. Relapse of smoking:** Incorrect. Bupropion is actually FDA-approved for **smoking cessation**. It reduces nicotine cravings and withdrawal symptoms by increasing dopamine levels in the reward pathway. * **C. Impaired attention:** Incorrect. Due to its pro-dopaminergic and pro-noradrenergic effects, bupropion is often used off-label to **improve attention** and focus in ADHD and is considered an "activating" antidepressant. * **D. Decreased sexual desire:** Incorrect. Unlike SSRIs, bupropion does **not** cause sexual dysfunction (it lacks serotonergic activity). It is often used as an add-on or alternative to SSRIs to reverse sexual side effects. **High-Yield Clinical Pearls for NEET-PG:** * **Weight Neutrality:** Bupropion is one of the few antidepressants that causes weight loss rather than weight gain. * **Contraindications:** Always screen for a history of head injury, seizures, or eating disorders before prescribing. * **Mechanism:** It does not inhibit MAO or affect serotonin reuptake, making it unique among common antidepressants.

Q: Vilazodone is a:

Serotonin partial agonist and reuptake inhibitor (SPARI). **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 1

Which drug can act as an antagonist of Haloperidol?

Accepted Answer

Ropinirole

Answer

Clozapine

Answer

Imipramine

Answer

Pimozide

Question 2

Cardiac conduction defects seen with Tricyclic antidepressants are due to which mechanism?

Accepted Answer

Both norepinephrine reuptake inhibition and antimuscarinic action on the heart

Answer

Norepinephrine and serotonin reuptake inhibition

Answer

Antimuscarinic action on the heart

Answer

Only norepinephrine reuptake inhibition

Question 3

What is the half-life of lithium?

Accepted Answer

24 hours

Answer

8 hours

Answer

16 hours

Answer

36 hours

Question 4

Which 5-HT1A agonist drug acts as an anxiolytic agent?

Accepted Answer

Buspirone

Answer

Diazepam

Answer

Zolpidem

Answer

Cinnarizine

Question 5

Which of the following typical antipsychotic drugs is not available in depot form?

Accepted Answer

Chlorpromazine

Answer

Haloperidol

Answer

Risperidone

Answer

Olanzapine

Question 6

Which of the following is a RIMA?

Accepted Answer

brofaromine

Answer

escitalopram

Answer

selegiline

Answer

dapoxetine

Question 7

Which of the following groups of drugs is known to cause neurogenic dislocation?

Accepted Answer

Antipsychotic drugs

Answer

Anxiolytics

Answer

Antiparkinsonism drugs

Answer

None of the above

Question 8

Which antipsychotic medication is known to cause cataracts?

Accepted Answer

Ziprasidone

Answer

Aripiprazole

Answer

Olanzapine

Answer

Risperidone

Question 9

Which of the following is a known side effect of bupropion?

Accepted Answer

Seizures

Answer

Relapse of smoking

Answer

Impaired attention

Answer

Decreased sexual desire

Question 10

Vilazodone is a:

Accepted Answer

Serotonin partial agonist and reuptake inhibitor (SPARI)

Answer

Selective serotonin reuptake inhibitor (SSRI)

Answer

Serotonin antagonist and reuptake inhibitor (SARI)

Answer

Serotonin-norepinephrine reuptake inhibitor (SNRI)

Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders — MCQs

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