Drugs in Psychiatric Disorders Practice Questions

Q: Administration of disulfiram in an alcoholic can cause all these side effects except?

Hypertension. The correct answer is **Hypertension**. **Mechanism of Action:** Disulfiram acts by inhibiting the enzyme **Aldehyde Dehydrogenase (ALDH)**. When a patient taking disulfiram consumes alcohol, the metabolism of ethanol is arrested at the stage of **Acetaldehyde**. This leads to a 5-to-10-fold accumulation of acetaldehyde in the blood, resulting in the **Disulfiram-Ethanol Reaction (DER)** [1]. **Why Hypertension is the Correct Answer:** The hallmark of the Disulfiram-Ethanol Reaction is **Hypotension**, not hypertension. The accumulation of acetaldehyde causes intense peripheral vasodilation and releases histamine, leading to a significant drop in blood pressure. In severe cases, this can progress to shock or cardiovascular collapse. **Analysis of Incorrect Options:** * **Flushing (A):** This is the most common and earliest sign of the reaction, caused by acetaldehyde-induced vasodilation of the facial and neck vessels. * **Headache (B):** Often described as a "throbbing" headache, this occurs due to the dilation of intracranial blood vessels. * **Nausea (C):** Acetaldehyde is a potent emetic stimulus; nausea and projectile vomiting are classic components of the DER. **High-Yield Clinical Pearls for NEET-PG:** * **Disulfiram-like reaction:** Several other drugs can cause a similar reaction when taken with alcohol. Mnemonic: **"PM C G"** (**P**rocarbazine, **M**etronidazole, **C**ephalosporins like Cefoperazone/Cefotetan, **G**riseofulvin, and Sulfonylureas). * **Dopamine Beta-Hydroxylase Inhibition:** Disulfiram also inhibits this enzyme, leading to decreased norepinephrine synthesis, which further contributes to hypotension and potential psychosis. * **Contraindication:** It should never be administered to a patient in a state of alcohol intoxication or without their full knowledge.

Q: Which of the following antidepressants causes hypertensive crisis?

Phenelzine. **Explanation** The correct answer is **Phenelzine**. Phenelzine is a non-selective, irreversible **Monoamine Oxidase Inhibitor (MAOI)**. **Why Phenelzine causes Hypertensive Crisis:** MAOIs inhibit the enzyme monoamine oxidase, which is responsible for breaking down tyramine in the gastrointestinal tract and liver. When a patient taking an MAOI consumes **tyramine-rich foods** (e.g., aged cheese, red wine, cured meats), tyramine enters the systemic circulation and acts as an indirect sympathomimetic. It displaces large amounts of stored norepinephrine from presynaptic vesicles into the synaptic cleft, leading to severe vasoconstriction and a potentially fatal **hypertensive crisis** (the "Cheese Reaction"). **Analysis of Incorrect Options:** * **A. Dapoxetine:** A short-acting Selective Serotonin Reuptake Inhibitor (SSRI) used primarily for premature ejaculation. It does not significantly affect norepinephrine levels. * **B. Duloxetine:** A Serotonin-Norepinephrine Reuptake Inhibitor (SNRI). While it can cause a modest increase in blood pressure, it does not trigger a sudden hypertensive crisis via the tyramine pathway. * **C. Clomipramine:** A Tricyclic Antidepressant (TCA) that primarily inhibits serotonin reuptake. Its main side effects are anticholinergic and cardiac arrhythmias, not hypertensive crisis. **NEET-PG High-Yield Pearls:** * **Antidote:** The treatment of choice for an MAOI-induced hypertensive crisis is **Phentolamine** (an alpha-blocker). * **Washout Period:** When switching from an MAOI to an SSRI, a **2-week washout period** is required (5 weeks for Fluoxetine) to prevent **Serotonin Syndrome**. * **Other MAOIs:** Isocarboxazid and Tranylcypromine are also non-selective MAOIs associated with this risk.

Q: Which of the following is NOT a side effect of depression?

Flupenthixol. **Explanation:** The question asks to identify the drug that does **not** cause depression as a side effect. The correct answer is **Flupenthixol**. **1. Why Flupenthixol is the correct answer:** Flupenthixol is a thioxanthene derivative (typical antipsychotic). While high doses are used to treat psychosis, **low doses (0.5–1.5 mg)** have a unique **activating and antidepressant effect**. It is often used clinically to treat mild-to-moderate depression with anxiety or psychosomatic symptoms. Therefore, it is a treatment for depression rather than a cause. **2. Why the other options are incorrect (Drugs causing depression):** * **Propranolol:** Beta-blockers, particularly lipophilic ones like Propranolol, cross the blood-brain barrier and are well-documented to cause CNS side effects, including fatigue, lethargy, and clinical depression. * **Oral Contraceptives (OCPs):** Estrogen and progesterone can influence neurotransmitter levels (like serotonin). Chronic use of OCPs is a known risk factor for mood swings and depressive symptoms in susceptible women. * **Reserpine:** This is a classic pharmacological example. Reserpine inhibits the Vesicular Monoamine Transporter (VMAT), leading to the depletion of norepinephrine, dopamine, and serotonin. This depletion directly led to the "Monoamine Hypothesis" of depression. **Clinical Pearls for NEET-PG:** * **Reserpine-induced depression** is a high-yield fact; it is contraindicated in patients with a history of mental illness. * Other drugs causing depression: **Corticosteroids, Interferon-alpha, Methyldopa, and Isotretinoin.** * **Flupenthixol** is often combined with Melitracen (a TCA) in clinical practice for its rapid onset of mood-elevating effects.

Q: What is the half-life of lithium?

24 hours. **Lithium** is the gold-standard mood stabilizer used for Bipolar Affective Disorder (BPAD) [2]. Understanding its pharmacokinetics is crucial for clinical practice and exam preparation.Why 24 hours is correct:The average elimination half-life of lithium in an adult with normal renal function is approximately **24 hours** (ranging typically from 18 to 30 hours). Because it takes roughly 4 to 5 half-lives to reach a steady-state plasma concentration, lithium requires about **5 days** of consistent dosing to achieve stable therapeutic levels. This long half-life allows for once or twice-daily dosing.Analysis of incorrect options:* **8 hours (A):** This is too short. While lithium is rapidly absorbed [1], its elimination is slow because it undergoes extensive renal reabsorption (80% in the proximal tubule) [1].* **16 hours (B):** While some younger patients with high glomerular filtration rates may have shorter half-lives, 24 hours is the standard physiological mean cited in major pharmacology texts (Katzung, KD Tripathi).* **36 hours (D):** This is longer than the average; however, the half-life can extend to 36 hours or more in elderly patients or those with renal impairment, increasing the risk of toxicity.High-Yield Clinical Pearls for NEET-PG:* **Therapeutic Index:** Lithium has a very narrow therapeutic index. Monitoring is essential [1].* **Therapeutic Range:** 0.5–0.8 mEq/L (Maintenance); 0.8–1.2 mEq/L (Acute Mania). Toxicity occurs >1.5 mEq/L.* **Sample Timing:** Blood for Therapeutic Drug Monitoring (TDM) should be drawn **12 hours after the last dose**.* **Drug Interactions:** Thiazides, NSAIDs, and ACE inhibitors decrease lithium clearance, leading to toxicity [3].* **Pregnancy:** Associated with **Ebstein’s Anomaly** (tricuspid valve malformation).

Q: Which of the following is NOT an adverse effect of Selective Serotonin Reuptake Inhibitors (SSRIs)?

Galactorrhea. **Explanation:** The correct answer is **D. Galactorrhea**. **1. Why Galactorrhea is the correct choice:** Galactorrhea (inappropriate milk production) is primarily caused by **hyperprolactinemia**. Prolactin secretion is inhibited by **Dopamine** (acting as Prolactin Inhibiting Factor). Drugs that block D2 receptors (like typical antipsychotics) or deplete dopamine (like Reserpine) lead to increased prolactin levels. **SSRIs primarily affect the serotonergic system**, not the dopaminergic pathway, and therefore do not typically cause galactorrhea. **2. Analysis of Incorrect Options:** * **A. Weight changes:** SSRIs can cause initial weight loss, but long-term use (especially with Paroxetine) is frequently associated with **weight gain**. * **B. Diarrhoea:** Serotonin (5-HT) is abundant in the GI tract. By increasing synaptic 5-HT, SSRIs stimulate 5-HT3 and 5-HT4 receptors, leading to nausea, vomiting, and **diarrhoea** (the most common acute side effects). * **C. Delayed ejaculation:** Sexual dysfunction is the most common long-term side effect of SSRIs. It includes decreased libido and **delayed ejaculation/anorgasmia**. This property is actually utilized therapeutically in treating premature ejaculation (e.g., Dapoxetine). **3. NEET-PG High-Yield Pearls:** * **Drug of Choice:** SSRIs are the first-line treatment for Depression, OCD, Panic Disorder, Social Phobia, and PTSD. * **Fluoxetine:** Has the longest half-life (due to its active metabolite norfluoxetine); least likely to cause withdrawal symptoms. * **Serotonin Syndrome:** A dangerous interaction when SSRIs are combined with MAO inhibitors, characterized by hyperthermia, muscle rigidity, and cardiovascular collapse. * **Discontinuation Syndrome:** Characterized by "FINISH" symptoms (Flu-like symptoms, Insomnia, Nausea, Imbalance, Sensory disturbances, Hyperarousal).

Q: Pimozide belongs to which class of drugs?

Diphenyl butyl piperidine. **Explanation:** **Pimozide** is a potent first-generation (typical) antipsychotic. Chemically, it is classified as a **Diphenyl butyl piperidine** derivative. This class is structurally related to butyrophenones but is characterized by a longer duration of action. **Why the correct option is right:** * **Diphenyl butyl piperidine:** Pimozide is the prototype of this class. Its primary mechanism of action involves the potent blockade of postsynaptic **D2 receptors**. Due to its high potency and long half-life, it is frequently used in the management of chronic schizophrenia and is the drug of choice for **Tourette’s syndrome** and **Delusional Parasitosis** (Ekbom syndrome). **Why the other options are incorrect:** * **Thiothixanthene:** This class includes drugs like **Thiothixene** and Flupentixol. They are structurally similar to phenothiazines but contain a carbon atom instead of nitrogen in the central ring. * **Phenothiazine:** This is the largest class of typical antipsychotics, further divided into Aliphatic (Chlorpromazine), Piperidine (Thioridazine), and Piperazine (Fluphenazine) subgroups. * **Butyrophenone:** This class includes **Haloperidol** and Droperidol. While diphenyl butyl piperidines are chemical derivatives of butyrophenones, they are categorized separately in pharmacological classification. **High-Yield Clinical Pearls for NEET-PG:** 1. **Specific Indication:** Pimozide is highly effective for **monosymptomatic hypochondriacal psychosis** (e.g., Delusional Parasitosis). 2. **ECG Changes:** A critical side effect of Pimozide is **QT interval prolongation**, which can lead to Torsades de Pointes; thus, baseline ECG monitoring is recommended. 3. **Potency:** It has a high extrapyramidal side effect (EPS) profile similar to Haloperidol due to its potent D2 antagonism.

Q: Which of the following is an atypical antipsychotic with the least metabolic side effects?

Ziprasidone. ***Ziprasidone*** - Among the atypical (second-generation) antipsychotics, **Ziprasidone** has the lowest risk regarding adverse **metabolic side effects**, including **weight gain**, dyslipidemia, and insulin resistance. - Due to its minimal impact on metabolic parameters, it is a preferred choice for patients with pre-existing **cardiovascular risk factors** or obesity. *Haloperidol* - Haloperidol is a **first-generation (typical)** antipsychotic, which primarily risks **extrapyramidal symptoms (EPS)** and elevated prolactin, rather than being an atypical agent. - While its metabolic risk is generally lower than high-risk atypicals (e.g., Olanzapine), it is not the correct classification for answering a question focusing on *atypical* drugs. *Risperidone* - Risperidone is an atypical antipsychotic but carries a **moderate to high risk** of causing significant **weight gain** and **hyperprolactinemia**. - Its metabolic profile is considerably worse than that of Ziprasidone or Aripiprazole. *Quetiapine* - Quetiapine carries a substantial risk profile regarding metabolic adverse effects, specifically high rates of **sedation** and clinically significant **weight gain**. - It is frequently linked to the development of **dyslipidemia** and **Type 2 diabetes mellitus**.

Q: A psychiatrist prescribes lithium for a patient who is diagnosed with bipolar disorder. Which of the following statements is incorrect regarding lithium?

Hemodialysis is not useful in lithium overdose. ***Correct Answer: Hemodialysis is not useful in lithium overdose*** - This statement is **INCORRECT** (making it the right answer to this negation question) - **Hemodialysis IS actually very useful** in severe lithium toxicity - Lithium has low molecular weight (~7 Da), minimal protein binding, and small volume of distribution, making it effectively removed by hemodialysis - **Indications for hemodialysis in lithium toxicity:** Lithium levels >4 mEq/L, severe clinical toxicity (seizures, altered consciousness), or renal failure *Incorrect Option: Lithium is teratogenic if given to pregnant females* - This statement is TRUE, so it's not the answer - Lithium causes **Ebstein's anomaly** (downward displacement of tricuspid valve) when given in first trimester - Risk is 1-2% (20x higher than general population) - FDA pregnancy category D *Incorrect Option: Lithium toxicity is exacerbated with thiazide* - This statement is TRUE, so it's not the answer - Thiazide diuretics decrease renal lithium clearance by promoting sodium depletion - This leads to **compensatory increase in proximal tubular reabsorption** of both sodium and lithium - NSAIDs and ACE inhibitors also increase lithium levels similarly *Incorrect Option: Lithium can decrease thyroid hormone levels* - This statement is TRUE, so it's not the answer - Lithium inhibits thyroid hormone synthesis and release, causing **hypothyroidism in 5-35%** of patients - Mechanism: Inhibits iodine uptake and blocks thyroid hormone release - Requires regular thyroid function monitoring (TSH, T3, T4) during lithium therapy

Q: A 35-year-old male patient presents to surgery emergency with painful erection for past 7 hours. He has a history of mood disorder and was recently prescribed a medication by treating psychiatrist. Which is the likely offending drug?

Trazodone. ***Trazodone*** - **Trazodone** is a commonly known antidepressant that can cause **priapism** as a side effect, especially at higher doses, due to its alpha-adrenergic blocking activity. [1] - The patient's presentation of a **painful erection lasting 7 hours** after starting a new psychiatric medication strongly points towards a drug-induced cause, for which trazodone is a well-established culprit. [1] *Venlafaxine* - **Venlafaxine** is an SNRI antidepressant that generally does not cause priapism as a recognized side effect. - Its adverse effect profile primarily includes nausea, insomnia, and sexual dysfunction (e.g., erectile dysfunction, anorgasmia), rather than prolonged erections. *Tianeptine* - **Tianeptine** is an atypical antidepressant that is not known to cause priapism. - It works by enhancing serotonin reuptake and is more commonly associated with side effects such as nausea, constipation, and dizziness. *Mirtazapine* - **Mirtazapine** is a tetracyclic antidepressant that works by blocking alpha-2 adrenergic receptors and certain serotonin receptors. - While it can cause sedation and weight gain, priapism is not a typical or recognized side effect of mirtazapine.

Q: Choose the correctly matched pairs regarding the drugs used in schizophrenia: 1. D2 antagonism: Reduces positive symptoms 2. 5HT2A antagonism: Reduces negative symptoms 3. 5HT1A agonism: Weight loss 4. Muscarinic antagonism: Reduces extrapyramidal symptoms

1,2. ***1,2*** - **D2 antagonism** is the primary mechanism by which antipsychotics reduce **positive symptoms** of schizophrenia, such as hallucinations and delusions. - **5HT2A antagonism** is a key mechanism of atypical antipsychotics contributing to the reduction of **negative symptoms** (e.g., apathy, anhedonia, flat affect) and cognitive deficits, while also reducing the risk of extrapyramidal symptoms. *1,2,3,4* - This option is incorrect because **5HT1A agonism** is not associated with **weight loss**. While 5HT1A partial agonism (as seen with aripiprazole and brexpiprazole) may improve negative symptoms, anxiety, and cognitive function, it does not directly cause weight loss. - Additionally, **muscarinic antagonism** does not reduce extrapyramidal symptoms as a primary mechanism. Rather, anticholinergic (muscarinic antagonist) drugs like benztropine are used to **treat** EPS after it occurs. The reduction of EPS in atypical antipsychotics primarily comes from 5HT2A antagonism and lower D2 binding affinity. *1,2,4* - This option is incorrect because **muscarinic antagonism** is not a mechanism that reduces EPS. Anticholinergic agents are used therapeutically to counteract EPS caused by dopamine blockade, but anticholinergic effects themselves do not prevent or reduce EPS. - The reduction of EPS with atypical antipsychotics is mainly due to **5HT2A antagonism** balancing dopaminergic blockade, selective limbic over striatal binding, and fast D2 dissociation kinetics. *1,4* - This option is incorrect because it omits **5HT2A antagonism**, which is crucial for reducing **negative symptoms** in schizophrenia. - It also incorrectly includes muscarinic antagonism as a mechanism that reduces EPS, when in reality anticholinergics are used to treat EPS rather than prevent it.

Question 1

Administration of disulfiram in an alcoholic can cause all these side effects except?

Accepted Answer

Hypertension

Answer

Flushing

Answer

Headache

Answer

Nausea

Question 2

Which of the following antidepressants causes hypertensive crisis?

Accepted Answer

Phenelzine

Answer

Dapoxetine

Answer

Duloxetine

Answer

Clomipramine

Question 3

Which of the following is NOT a side effect of depression?

Accepted Answer

Flupenthixol

Answer

Propranolol

Answer

Oral contraceptives

Answer

Reserpine

Question 4

What is the half-life of lithium?

Accepted Answer

24 hours

Answer

8 hours

Answer

16 hours

Answer

36 hours

Question 5

Which of the following is NOT an adverse effect of Selective Serotonin Reuptake Inhibitors (SSRIs)?

Accepted Answer

Galactorrhea

Answer

Weight changes

Answer

Diarrhoea

Answer

Delayed ejaculation

Question 6

Pimozide belongs to which class of drugs?

Accepted Answer

Diphenyl butyl piperidine

Answer

Thiothixanthene

Answer

Phenothiazine

Answer

Butyrophenone

Question 7

Which of the following is an atypical antipsychotic with the least metabolic side effects?

Accepted Answer

Ziprasidone

Answer

Risperidone

Answer

Haloperidol

Answer

Quetiapine

Question 8

A psychiatrist prescribes lithium for a patient who is diagnosed with bipolar disorder. Which of the following statements is incorrect regarding lithium?

Accepted Answer

Hemodialysis is not useful in lithium overdose

Answer

Lithium is teratogenic if given to pregnant females

Answer

Lithium toxicity is exacerbated with thiazide

Answer

Lithium can decrease thyroid hormone levels

Question 9

A 35-year-old male patient presents to surgery emergency with painful erection for past 7 hours. He has a history of mood disorder and was recently prescribed a medication by treating psychiatrist. Which is the likely offending drug?

Accepted Answer

Trazodone

Answer

Venlafaxine

Answer

Tianeptine

Answer

Mirtazapine

Question 10

Choose the correctly matched pairs regarding the drugs used in schizophrenia:

1. D2 antagonism: Reduces positive symptoms
2. 5HT2A antagonism: Reduces negative symptoms
3. 5HT1A agonism: Weight loss
4. Muscarinic antagonism: Reduces extrapyramidal symptoms

Accepted Answer

1,2

Answer

1,4

Answer

1,2,4

Answer

1,2,3,4

Drugs in Psychiatric Disorders — MCQs

Drugs in Psychiatric Disorders — MCQs

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