Drugs in Psychiatric Disorders Practice Questions

Q: Which of the following drugs is known to cause hypothyroidism?

Lithium carbonate. **Explanation** **Lithium carbonate** is the correct answer. Lithium is a mood stabilizer primarily used for Bipolar Affective Disorder (BPAD). It is well-known for its endocrine side effects, specifically its ability to cause **hypothyroidism** and goiter. **Mechanism:** Lithium interferes with thyroid function at multiple levels: 1. It inhibits the uptake of iodine into follicular cells. 2. It interferes with the iodination of tyrosine. 3. Most significantly, it **inhibits the release of thyroid hormones (T3 and T4)** from the thyroid gland by interfering with thyroglobulin pinocytosis. This leads to a compensatory rise in TSH, which can cause a goiter. **Analysis of Incorrect Options:** * **Haloperidol (A):** A typical antipsychotic (D2 blocker). Its primary side effects are Extrapyramidal Symptoms (EPS) and hyperprolactinemia, not thyroid dysfunction. * **Clozapine (B):** An atypical antipsychotic. Its "dreaded" side effects include agranulocytosis, seizures, and metabolic syndrome (weight gain, diabetes), but it does not cause hypothyroidism. * **Amoxapine (D):** A tricyclic antidepressant (TCA) with dopamine-blocking properties. It is associated with EPS and anticholinergic effects, but not thyroid suppression. **High-Yield Clinical Pearls for NEET-PG:** * **Monitoring:** Before starting Lithium, baseline **Thyroid Function Tests (TFTs)** and Renal Function Tests (RFTs) are mandatory. * **Management:** If a patient develops hypothyroidism on Lithium, you do **not** necessarily stop the drug. Instead, continue Lithium and add **Levothyroxine** supplementation. * **Other Endocrine Effect:** Lithium can also cause **hyperparathyroidism** (leading to hypercalcemia). * **Renal Effect:** It is a common cause of **Nephrogenic Diabetes Insipidus** (treated with Amiloride).

Q: All are indications of lithium except?

Generalized anxiety disorder. **Explanation:** Lithium is the gold standard mood stabilizer primarily used for Bipolar Affective Disorder (BPAD) [1]. **Generalized Anxiety Disorder (GAD)** is the correct answer because Lithium has no established role in its management. GAD is typically treated with SSRIs, SNRIs, or Benzodiazepines (for short-term relief). **Analysis of Options:** * **Neutropenia:** Lithium induces **leukocytosis** (specifically neutrophilia) by stimulating the production of colony-stimulating factors in the bone marrow. This "side effect" is therapeutically utilized to treat iatrogenic neutropenia (e.g., post-chemotherapy or Clozapine-induced). * **Major Depression:** While not a first-line monotherapy, Lithium is a well-established **augmentation strategy** for treatment-resistant Major Depressive Disorder (MDD) [3]. It is also the only drug proven to reduce the risk of suicide in patients with mood disorders. * **Vasculogenic Headaches:** Lithium is a first-line agent for the prophylaxis of **Cluster Headaches** (a type of trigeminal autonomic cephalalgia/vasculogenic headache). **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Inhibits Inositol Monophosphatase (IP3/DAG pathway) and Glycogen Synthase Kinase-3 (GSK-3). * **Therapeutic Window:** Narrow (0.6–1.2 mEq/L). Toxicity starts >1.5 mEq/L. * **Side Effects (LITHIUM mnemonic):** **L**eukocytosis, **I**nsipidus (Nephrogenic Diabetes Insipidus), **T**remors/Teratogenicity (Ebstein’s Anomaly) [2], **H**ypothyroidism [2], **I**ncreased **U**rine, **M**others (avoid in pregnancy) [2]. * **Drug Interactions:** Thiazides, NSAIDs, and ACE inhibitors increase Lithium levels by decreasing its renal clearance.

Q: Long term use of lithium is known to cause which of the following?

Hypothyroidism. **Explanation:** Lithium is the gold-standard mood stabilizer for Bipolar Affective Disorder (BPAD), but its long-term use is associated with specific endocrine and renal side effects due to its narrow therapeutic index. **Why Hypothyroidism is Correct:** Lithium interferes with thyroid function at multiple levels. It inhibits the uptake of iodine into follicular cells, interferes with the iodination of tyrosine, and—most significantly—**inhibits the release of T3 and T4** from the thyroid gland. Over time, this leads to a compensatory rise in Thyroid Stimulating Hormone (TSH), resulting in **Lithium-induced hypothyroidism** (seen in 5–15% of patients) and occasionally a non-toxic goiter. **Analysis of Incorrect Options:** * **A. Peripheral neuropathy:** This is not a classic side effect of Lithium. Lithium toxicity typically presents with central nervous system symptoms like coarse tremors, ataxia, and dysarthria. * **C. Anaemia:** Lithium does not cause anemia; in fact, it is known to cause **leukocytosis** (increased WBC count) by stimulating granulopoiesis, which is sometimes used therapeutically in Felty’s syndrome. * **D. Jaundice:** Lithium is not metabolized by the liver (it is excreted unchanged by the kidneys); therefore, it is not hepatotoxic and does not cause jaundice. **High-Yield Clinical Pearls for NEET-PG:** * **Renal Side Effects:** Long-term use can cause **Nephrogenic Diabetes Insipidus** (resistance to ADH) and chronic interstitial nephritis. * **Monitoring:** Before starting Lithium, baseline **Thyroid Function Tests (TFTs)** and **Renal Function Tests (RFTs)** are mandatory. * **Teratogenicity:** Use in pregnancy is linked to **Ebstein’s Anomaly** (atrialization of the right ventricle). * **Therapeutic Range:** 0.6–1.2 mEq/L (Prophylaxis: 0.6–0.8; Acute Mania: 0.8–1.2). Toxicity usually starts >1.5 mEq/L.

Q: Which of the following drugs is considered to have dual reuptake inhibition?

All of the above. ### Explanation The term **"Dual Reuptake Inhibition"** refers to the pharmacological action of inhibiting the reuptake of both **Serotonin (5-HT)** and **Norepinephrine (NE)** from the synaptic cleft. This increases the concentration of both neurotransmitters, providing a potent antidepressant effect. **Why "All of the above" is correct:** 1. **Clomipramine:** Although classified as a Tricyclic Antidepressant (TCA), it is unique because it is the most potent serotonin reuptake inhibitor among TCAs, while its active metabolite (desmethylclomipramine) strongly inhibits norepinephrine reuptake. 2. **Amitriptyline:** A classic Tertiary Amine TCA. It non-selectively inhibits the reuptake of both 5-HT and NE. 3. **Venlafaxine:** This drug belongs to the **SNRI (Serotonin-Norepinephrine Reuptake Inhibitor)** class. At lower doses, it primarily inhibits serotonin reuptake, but at medium to higher doses, it significantly inhibits norepinephrine reuptake as well. **Clinical Pearls for NEET-PG:** * **Clomipramine** is the drug of choice (DOC) for **Obsessive-Compulsive Disorder (OCD)**. * **Venlafaxine** is known for causing **dose-dependent hypertension** due to its noradrenergic activity. * **TCAs vs. SNRIs:** While both provide dual reuptake inhibition, SNRIs (like Venlafaxine and Duloxetine) are preferred in modern practice because they lack the "dirty" side-effect profile of TCAs (i.e., they do not significantly block alpha-1, H1-histamine, or muscarinic receptors). * **Duloxetine** (another SNRI) is frequently asked as the DOC for **Diabetic Neuropathy** and Fibromyalgia.

Q: Which antipsychotic drug has the longest elimination half-life?

Aripiprazole. **Explanation:** The correct answer is **Aripiprazole**. **1. Why Aripiprazole is correct:** Aripiprazole is a third-generation atypical antipsychotic characterized by a unique mechanism of action as a **D2 partial agonist**. Among the oral antipsychotics, it possesses an exceptionally long elimination half-life, averaging approximately **75 hours** (extending up to 94 hours in poor metabolizers of CYP2D6). This long half-life allows for once-daily dosing and provides a "buffer" against missed doses, as plasma levels decline slowly. **2. Why the other options are incorrect:** * **Loxapine:** A typical (first-generation) antipsychotic of the dibenzoxazepine class. It has a relatively short half-life of approximately **4 to 8 hours**. * **Quetiapine:** An atypical antipsychotic known for rapid dissociation from D2 receptors. It has one of the shortest half-lives among second-generation drugs, approximately **6 to 7 hours**, often requiring twice-daily dosing or extended-release formulations. * **Ziprasidone:** An atypical antipsychotic with a short half-life of approximately **7 hours**. It must be taken with food (at least 500 calories) to ensure adequate absorption. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Aripiprazole acts as a "Dopamine Stabilizer" (Partial agonist at D2 and 5-HT1A; antagonist at 5-HT2A). * **Side Effect Profile:** It has the lowest risk of weight gain, hyperprolactinemia, and sedation among atypical antipsychotics. However, it is frequently associated with **Akathisia**. * **Long-acting Injectable (LAI):** Aripiprazole is also available as a monthly depot (Aripiprazole Maintena), but even in its **oral form**, it has the longest half-life of the options provided. * **Metabolism:** It is primarily metabolized by **CYP2D6** and **CYP3A4**.

Q: Which of the following medications is known to cause sialorrhea?

Clozapine. **Explanation:** **Clozapine** is the correct answer. While most antipsychotics cause dry mouth (xerostomia) due to potent muscarinic blockade, Clozapine is unique for causing **sialorrhea (excessive salivation)**, particularly at night. **Underlying Mechanism:** The exact mechanism is paradoxical. Although Clozapine has anticholinergic properties, its metabolite acts as a **full agonist at M1 receptors** and an **antagonist at alpha-2 adrenergic receptors**. Alpha-2 blockade prevents the inhibition of salivary secretion, leading to hypersecretion. Additionally, Clozapine impairs the swallowing reflex during sleep, causing "wet pillow syndrome." **Analysis of Incorrect Options:** * **Amisulpride:** A substituted benzamide that primarily blocks D2/D3 receptors. It has minimal affinity for muscarinic receptors and is more likely to cause hyperprolactinemia than salivary changes. * **Olanzapine:** A thienobenzodiazepine derivative. Like most atypical antipsychotics, its side effect profile includes weight gain and metabolic syndrome, but it typically causes dry mouth due to anticholinergic activity. * **Aripiprazole:** A partial D2 agonist. It is generally "weight-neutral" and has a low side-effect profile regarding autonomic symptoms; it does not cause sialorrhea. **High-Yield Clinical Pearls for NEET-PG:** 1. **Management of Clozapine Sialorrhea:** Treat with sublingual **Atropine drops** or oral **Glycopyrrolate** (peripherally acting anticholinergics). 2. **Clozapine Monitoring:** Mandatory WBC count monitoring is required due to the risk of **Agranulocytosis** (most serious side effect). 3. **Seizures:** Clozapine is associated with dose-dependent lowering of the seizure threshold. 4. **Indication:** It is the gold standard for **Treatment-Resistant Schizophrenia**.

Q: What is the common side effect associated with fluoxetine therapy?

Loose stools. **Explanation:** Fluoxetine is a Selective Serotonin Reuptake Inhibitor (SSRI). The mechanism involves increasing synaptic serotonin levels, which not only affects the brain but also acts on peripheral receptors. **Why "Loose Stools" is correct:** Approximately 90% of the body's serotonin is located in the **enterochromaffin cells of the GI tract**. SSRIs like fluoxetine increase serotonergic activity at **5-HT3 and 5-HT4 receptors** in the gut. This stimulates gastrointestinal motility and fluid secretion, leading to common side effects such as nausea, abdominal cramps, and **loose stools/diarrhea**. **Analysis of Incorrect Options:** * **A. Seizure:** While some antidepressants (like Bupropion or Maprotiline) significantly lower the seizure threshold, SSRIs are generally considered safe and have a very low risk of inducing seizures at therapeutic doses. * **B. Anxiety:** Although some patients experience "jitteriness" or transient activation syndrome during the first week of SSRI therapy, it is less common than GI side effects. Fluoxetine is actually used to *treat* chronic anxiety disorders. * **C. Hypotension:** SSRIs do not typically cause orthostatic hypotension. This side effect is more characteristic of Tricyclic Antidepressants (TCAs) due to alpha-1 adrenergic blockade. **High-Yield Clinical Pearls for NEET-PG:** * **Fluoxetine** has the **longest half-life** (4–6 days; its metabolite norfluoxetine lasts up to 16 days) among SSRIs, making it the least likely to cause discontinuation syndrome. * **Most common side effect of SSRIs:** GI upset (Nausea is #1, followed by diarrhea). * **Most common long-term side effect:** Sexual dysfunction (delayed ejaculation/anorgasmia). * **Drug of choice:** SSRIs are the first-line treatment for Depression, OCD, Panic Disorder, and Bulimia Nervosa (specifically Fluoxetine).

Q: Which of the following drugs is not associated with an increase in prolactin levels?

Quetiapine. **Explanation:** The regulation of prolactin secretion is primarily controlled by the **Tuberoinfundibular pathway** in the brain. In this pathway, dopamine acts as a "Prolactin Inhibiting Factor" by stimulating **D2 receptors** on lactotroph cells in the anterior pituitary. Antipsychotic drugs that block these D2 receptors remove this inhibition, leading to **hyperprolactinemia**. **Why Quetiapine is the correct answer:** Quetiapine is a **Second-Generation (Atypical) Antipsychotic**. It is characterized by "loose" binding and rapid dissociation from D2 receptors. Because it does not maintain prolonged blockade of D2 receptors in the pituitary, it is considered **prolactin-sparing**. Along with Aripiprazole and Clozapine, Quetiapine is least likely to cause prolactin elevation. **Analysis of incorrect options:** * **Haloperidol & Chlorpromazine:** These are **First-Generation (Typical) Antipsychotics**. They are potent D2 receptor antagonists with high affinity. They significantly block the tuberoinfundibular pathway, frequently causing side effects like galactorrhea, amenorrhea, and gynecomastia. * **Hydroxysulpiride (and Sulpiride/Amisulpiride):** These are substituted benzamides. Despite being classified as atypical in some contexts, they are notorious for causing the **highest** increases in prolactin levels because they do not cross the blood-brain barrier well and concentrate in the pituitary (which lies outside the BBB). **NEET-PG High-Yield Pearls:** 1. **Highest Prolactin Elevation:** Risperidone, Paliperidone, and Amisulpiride. 2. **Lowest Prolactin Elevation:** Aripiprazole (D2 partial agonist), Quetiapine, and Clozapine. 3. **Clinical Sign:** Hyperprolactinemia can lead to decreased bone mineral density (osteoporosis) due to suppressed GnRH/estrogen.

Q: All are true about Desvenlafaxine except?

It is a D2 receptor antagonist. **Explanation:** **1. Why Option A is the correct answer (The "Except"):** Desvenlafaxine is a **Selective Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)**. It is the active metabolite of Venlafaxine. Its mechanism of action involves inhibiting the reuptake of serotonin (5-HT) and norepinephrine (NE) in the synaptic cleft. It has **no significant affinity** for D2 (Dopamine), cholinergic, histaminergic, or alpha-adrenergic receptors. Therefore, stating it is a D2 receptor antagonist is pharmacologically incorrect. **2. Analysis of other options:** * **Option B (Priapism):** While rare compared to Trazodone, SNRIs and SSRIs have been associated with idiosyncratic cases of priapism due to complex downstream effects on neurotransmitters. * **Option C (Glaucoma):** SNRIs can cause pupillary dilation (mydriasis) due to increased norepinephrine levels. This can trigger an attack of **acute angle-closure glaucoma** in predisposed individuals. * **Option D (Hyperlipidemia):** Desvenlafaxine treatment is clinically associated with dose-related increases in fasting serum total cholesterol, LDL, and triglycerides. Regular lipid monitoring is recommended during therapy. **High-Yield Clinical Pearls for NEET-PG:** * **Active Metabolite:** Desvenlafaxine is the major active metabolite of Venlafaxine (formed via CYP2D6). * **Dose-Response:** Unlike Venlafaxine, which acts like an SSRI at low doses and an SNRI at high doses, Desvenlafaxine shows SNRI activity even at the starting dose (50mg). * **Side Effect Profile:** Common side effects include nausea, insomnia, sweating, and **dose-dependent hypertension** (due to increased NE). * **Discontinuation Syndrome:** SNRIs have a high risk of withdrawal symptoms; tapering is essential.

Question 1

Which of the following drugs is known to cause hypothyroidism?

Accepted Answer

Lithium carbonate

Answer

Haloperidol

Answer

Clozapine

Answer

Amoxapine

Question 2

All are indications of lithium except?

Accepted Answer

Generalized anxiety disorder

Answer

Neutropenia

Answer

Major Depression

Answer

Vasculogenic Headaches

Question 3

Which of the following is true regarding tricyclic antidepressants?

Accepted Answer

Tricyclic antidepressants should not be used in patients with glaucoma.

Answer

Tricyclic antidepressants increase the antihypertensive effect of guanethidine.

Answer

Tricyclic antidepressants have anticonvulsant activity.

Answer

Tricyclic antidepressants may increase oral absorption of levodopa.

Question 4

Long term use of lithium is known to cause which of the following?

Accepted Answer

Hypothyroidism

Answer

Peripheral neuropathy

Answer

Anaemia

Answer

Jaundice

Question 5

Which of the following drugs is considered to have dual reuptake inhibition?

Accepted Answer

All of the above

Answer

Clomipramine

Answer

Amitriptyline

Answer

Venlafaxine

Question 6

Which antipsychotic drug has the longest elimination half-life?

Accepted Answer

Aripiprazole

Answer

Loxapine

Answer

Quetiapine

Answer

Ziprasidone

Question 7

Which of the following medications is known to cause sialorrhea?

Accepted Answer

Clozapine

Answer

Amisulpride

Answer

Olanzapine

Answer

Aripiprazole

Question 8

What is the common side effect associated with fluoxetine therapy?

Accepted Answer

Loose stools

Answer

Seizure

Answer

Anxiety

Answer

Hypotension

Question 9

Which of the following drugs is not associated with an increase in prolactin levels?

Accepted Answer

Quetiapine

Answer

Haloperidol

Answer

Chlorpromazine

Answer

Hydroxysulpiride

Question 10

All are true about Desvenlafaxine except?

Accepted Answer

It is a D2 receptor antagonist

Answer

Can cause priapism

Answer

Can cause glaucoma

Answer

Can cause hyperlipidemia

Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders — MCQs

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