MAO Inhibitors — MCQs
Systemic desensitization therapy is used for
A patient stabilized on a selective serotonin reuptake inhibitor (SSRI) for depression may experience withdrawal symptoms when stopped. Which of the following drugs has the minimum risk of causing drug discontinuation symptoms?
Which of the following actions is NOT associated with tricyclic antidepressants?
Which of the following medications in the treatment of Parkinson's disease is an NMDA antagonist?
A mother reports that her daughter ingested a substance in an unknown dose. The girl presents with hypertension, tachycardia, mydriasis, and hyperthermia. What is the most likely substance?
The cardiovascular side effects of Dexmedetomidine are as follows:
Which of the following drugs used for obsessive-compulsive disorder has maximum anticholinergic effect?
Which of the following is a selective serotonin and norepinephrine reuptake inhibitor?
A 72 year old lady is severely depressed. For the past 2 days she has suicidal thoughts with an actual intent to die. Which of the following is best suitable to alleviate the symptoms?
Venlafaxine comes under which class of drugs?
MAO Inhibitors Indian Medical PG Practice Questions and MCQs
Question 1: Systemic desensitization therapy is used for
- A. Phobia (Correct Answer)
- B. Depression/Mania
- C. Organic brain syndrome
- D. Schizophrenia
Explanation: ***Phobia*** - **Systemic desensitization** is a highly effective behavioral therapy specifically designed to treat **phobias** and other **anxiety disorders**. - It involves gradually exposing the individual to the feared object or situation while teaching them **relaxation techniques** to replace the anxiety response. *Depression/Mania* - These conditions are primarily treated with a combination of **pharmacotherapy** (e.g., antidepressants, mood stabilizers) and other forms of psychotherapy like **cognitive behavioral therapy (CBT)** or **interpersonal therapy**. - Systemic desensitization is not a primary or effective treatment for the core symptoms of **mood disorders**. *Organic brain syndrome* - This is a broad term referring to mental impairment caused by a **physical disease or injury affecting the brain**, such as dementia or delirium. - Treatment focuses on addressing the **underlying medical cause** and managing cognitive or behavioral symptoms, not desensitization. *Schizophrenia* - Schizophrenia is a severe mental illness characterized by **psychosis**, **disorganized thinking**, and significant functional impairment. - Treatment primarily involves **antipsychotic medications** and psychosocial interventions, rather than exposure-based therapies like systemic desensitization.
Question 2: A patient stabilized on a selective serotonin reuptake inhibitor (SSRI) for depression may experience withdrawal symptoms when stopped. Which of the following drugs has the minimum risk of causing drug discontinuation symptoms?
- A. Paroxetine
- B. Fluoxetine (Correct Answer)
- C. Fluvoxamine
- D. Sertraline
Explanation: ***Fluoxetine*** - **Fluoxetine** (Prozac) has the **longest half-life** among the SSRIs, leading to a much slower decrease in plasma concentration upon discontinuation. - This gradual reduction in drug levels lessens the severity and incidence of **discontinuation syndrome** symptoms. *Paroxetine* - **Paroxetine** (Paxil) has one of the **shortest half-lives** among the SSRIs, making it associated with a higher risk of severe discontinuation symptoms. - Its rapid elimination from the body leads to a quicker onset of withdrawal effects if stopped abruptly. *Sertraline* - **Sertraline** (Zoloft) has an intermediate half-life among SSRIs. - While generally better tolerated than paroxetine during discontinuation, it still carries a higher risk of withdrawal symptoms compared to fluoxetine. *Fluvoxamine* - **Fluvoxamine** (Luvox) has a relatively short half-life, similar to paroxetine, contributing to a higher risk of **discontinuation syndrome**. - It is particularly known for its potential for significant interactions due to potent **CYP450 inhibition**.
Question 3: Which of the following actions is NOT associated with tricyclic antidepressants?
- A. Block 5-HT or NE reuptake
- B. Anticholinergic action
- C. MAO inhibition (Correct Answer)
- D. Causes sedation
Explanation: ***MAO inhibition*** - Tricyclic antidepressants (TCAs) primarily exert their effects by inhibiting the reuptake of **norepinephrine** and **serotonin**, not by inhibiting monoamine oxidase (MAO). - **MAO inhibitors** are a distinct class of antidepressants with a different mechanism of action and side effect profile. *Anticholinergic action* - Many TCAs have significant **anticholinergic effects**, blocking muscarinic receptors and leading to side effects like dry mouth, constipation, and blurred vision. - These effects contribute to the **adverse event profile** of TCAs, especially in elderly patients. *Block 5-HT or NE reuptake* - The primary mechanism of action of TCAs involves the **inhibition of serotonin (5-HT)** and **norepinephrine (NE) reuptake** into presynaptic neurons. - This action increases the concentration of these neurotransmitters in the **synaptic cleft**, thereby potentiating their effects. *Causes sedation* - TCAs frequently cause **sedation**, particularly the more histaminergic ones (e.g., amitriptyline, doxepin), due to their **histamine H1 receptor antagonism**. - This side effect can be beneficial for patients with insomnia but can be problematic for daytime functioning.
Question 4: Which of the following medications in the treatment of Parkinson's disease is an NMDA antagonist?
- A. Amantadine (Correct Answer)
- B. Selegiline
- C. Entacapone
- D. Ropinirole
Explanation: ***Amantadine*** - **Amantadine** is an **NMDA receptor antagonist**, which contributes to its antiparkinsonian effects by modulating glutamatergic neurotransmission. - It works by reducing the **excitatory effects of glutamate**, potentially improving motor fluctuations and dyskinesia in Parkinson's disease. *Selegiline* - **Selegiline** is a **selective irreversible inhibitor of monoamine oxidase B (MAO-B)**, which prevents the breakdown of dopamine. - It enhances the availability of dopamine in the brain but does not act as an NMDA antagonist. *Entacapone* - **Entacapone** is a **catechol-O-methyltransferase (COMT) inhibitor** that prevents the peripheral breakdown of levodopa. - This action increases the bioavailability of levodopa to the brain, but it is not an NMDA antagonist. *Ropinirole* - **Ropinirole** is a **dopamine agonist** that directly stimulates dopamine receptors in the brain. - It mimics the effects of dopamine but does not interact with NMDA receptors.
Question 5: A mother reports that her daughter ingested a substance in an unknown dose. The girl presents with hypertension, tachycardia, mydriasis, and hyperthermia. What is the most likely substance?
- A. Heroin
- B. Morphine
- C. Cocaine (Correct Answer)
- D. Chlorpheniramine
- E. Organophosphate
Explanation: ***Cocaine*** - The presented symptoms of **hypertension, tachycardia, mydriasis, and hyperthermia** are characteristic of a **sympathomimetic toxidrome**, frequently caused by cocaine overdose. - Cocaine acts as a **norepinephrine-dopamine-serotonin reuptake inhibitor**, leading to excessive stimulation of the central and peripheral nervous systems. *Heroin* - Heroin is an **opioid**, and overdose generally presents with **respiratory depression, bradycardia, miosis (pinpoint pupils)**, and hypotension, which are contrary to the patient's symptoms. - Patients typically exhibit central nervous system **depression**, rather than the hyperactive state seen here. *Morphine* - Similar to heroin, morphine is an **opioid** and causes symptoms like **respiratory depression, bradycardia, miosis**, and hypotension. - These effects are the opposite of the **sympathomimetic** signs observed in the patient. *Chlorpheniramine* - Chlorpheniramine is an **antihistamine** with significant **anticholinergic effects**. An overdose might cause **mydriasis and tachycardia**, but not typically severe hypertension or hyperthermia as the primary features. - Other anticholinergic signs such as **dry mucous membranes, urinary retention, and altered mental status (delirium)** would also be expected. *Organophosphate* - Organophosphate poisoning causes a **cholinergic toxidrome** due to **acetylcholinesterase inhibition**, resulting in excessive cholinergic stimulation. - Classic presentation includes **SLUDGE syndrome** (Salivation, Lacrimation, Urination, Defecation, GI upset, Emesis) along with **miosis (pinpoint pupils), bradycardia, bronchospasm**, and muscle fasciculations. - These findings are the **opposite** of the sympathomimetic signs seen in this patient.
Question 6: The cardiovascular side effects of Dexmedetomidine are as follows:
- A. Hypertension and Tachycardia
- B. Hypertension and Bradycardia
- C. Hypotension and Bradycardia (Correct Answer)
- D. Hypotension and Tachycardia
Explanation: ***Hypotension and Bradycardia*** - **Dexmedetomidine** is an **alpha-2 adrenergic agonist** that causes a dose-dependent decrease in heart rate (bradycardia) and blood pressure (hypotension) due to reduced sympathetic outflow. - The initial hypertensive effect seen with rapid IV administration is usually transient and followed by sustained hypotension. *Hypertension and Tachycardia* - This combination is not typical for **dexmedetomidine**, which primarily exerts its effects by centrally reducing sympathetic tone, leading to lowered heart rate and blood pressure. - **Tachycardia** is a rare and usually reflex-mediated response if severe hypotension occurs, but it's not a primary effect. *Hypertension and Bradycardia* - While an initial, transient **hypertension** can occur with rapid **dexmedetomidine** infusion due to peripheral alpha-2 stimulation, this is not its predominant long-term cardiovascular effect. - The sustained effect is usually **hypotension**, not hypertension, making this option incorrect as a primary side effect. *Hypotension and Tachycardia* - Although **hypotension** is a common side effect of **dexmedetomidine**, **tachycardia** is generally not. - The drug mainly causes a reduction in heart rate (**bradycardia**) as part of its central sympatholytic action.
Question 7: Which of the following drugs used for obsessive-compulsive disorder has maximum anticholinergic effect?
- A. Fluvoxamine
- B. Buspirone
- C. Sertraline
- D. Clomipramine (Correct Answer)
Explanation: ***Clomipramine*** - **Clomipramine** is a **tricyclic antidepressant (TCA)** with potent efficacy in OCD treatment. - It has **strong anticholinergic effects** including dry mouth, blurred vision, constipation, urinary retention, and cognitive impairment. - Among all medications used for OCD, clomipramine has the **maximum anticholinergic burden** due to its action on muscarinic receptors. - While effective for OCD, its significant side effect profile often limits its use to refractory cases. *Fluvoxamine* - **Fluvoxamine** is a **selective serotonin reuptake inhibitor (SSRI)** with FDA approval for OCD. - SSRIs have **minimal anticholinergic effects** compared to TCAs. - It selectively targets serotonin reuptake with little affinity for muscarinic cholinergic receptors. *Buspirone* - **Buspirone** is a **5-HT1A partial agonist** used primarily for **generalized anxiety disorder**. - It is **not a standard or approved treatment for OCD** - this makes it an inappropriate choice regardless of side effect profile. - It has negligible anticholinergic effects but lacks efficacy in OCD. *Sertraline* - **Sertraline** is an **SSRI** with FDA approval for OCD treatment. - Like other SSRIs, it has **very low affinity for muscarinic receptors** and minimal anticholinergic effects. - It is a first-line agent for OCD with a favorable side effect profile.
Question 8: Which of the following is a selective serotonin and norepinephrine reuptake inhibitor?
- A. Fluoxetine
- B. Venlafaxine (Correct Answer)
- C. Sertraline
- D. Aripiprazole
Explanation: ***Venlafaxine*** - **Venlafaxine** is a commonly used antidepressant that inhibits the reuptake of both **serotonin** and **norepinephrine**, making it an SNRI. - Its dual mechanism of action can be effective for a broad range of depressive and anxiety disorders. *Fluoxetine* - **Fluoxetine** is a **selective serotonin reuptake inhibitor (SSRI)**, primarily affecting serotonin levels in the brain. - It does not significantly inhibit norepinephrine reuptake and, thus, is not classified as an SNRI. *Sertraline* - **Sertraline** is another widely prescribed antidepressant that is also a **selective serotonin reuptake inhibitor (SSRI)**. - It works mainly by increasing serotonin availability in the synaptic cleft. *Aripiprazole* - **Aripiprazole** is an **atypical antipsychotic** medication, often used as an adjunct therapy for depression, but its primary mechanism is partial agonism at dopamine D2 and serotonin 5-HT1A receptors, and antagonism at serotonin 5-HT2A receptors. - It is not classified as a selective serotonin and norepinephrine reuptake inhibitor.
Question 9: A 72 year old lady is severely depressed. For the past 2 days she has suicidal thoughts with an actual intent to die. Which of the following is best suitable to alleviate the symptoms?
- A. ECT (Correct Answer)
- B. Selegiline
- C. Haloperidol + Chlorpromazine
- D. Amitriptyline
Explanation: ***ECT (Electroconvulsive Therapy)*** - **ECT** is the most effective and rapid treatment for severe depression, especially when associated with active **suicidal ideation** and intent. - Its quick onset of action (often within days) makes it vital in situations requiring urgent symptom alleviation to ensure patient safety. - **First-line treatment** for geriatric depression with suicidal risk and when rapid response is needed. *Selegiline* - **Selegiline** is a monoamine oxidase inhibitor (MAOI) used for depression and Parkinson's disease, but its antidepressant effects are not immediate. - It would not sufficiently address the patient's acute suicidal intent due to its slower therapeutic onset (several weeks). *Haloperidol + Chlorpromazine* - This combination consists of **antipsychotics**, primarily used for conditions with psychotic features or severe agitation but not as a primary treatment for severe depression with suicidal ideation. - While they might provide some sedation, they do not treat the underlying depressive disorder effectively and rapidly enough to resolve acute suicidal intent. *Amitriptyline* - **Amitriptyline** is a tricyclic antidepressant (TCA) that can be effective for depression but has a delayed onset of action (2-4 weeks). - **Highly contraindicated in suicidal patients** due to its extreme lethality in overdose (cardiotoxic effects). - Its slow therapeutic effect would not be appropriate for an urgent situation involving active suicidal thoughts with intent.
Question 10: Venlafaxine comes under which class of drugs?
- A. Monoamine oxidase inhibitors
- B. Serotonin receptor antagonist
- C. Selective serotonin reuptake inhibitor
- D. Serotonin-norepinephrine reuptake inhibitor (SNRI) (Correct Answer)
Explanation: ***Serotonergic noradrenergic reuptake inhibitor*** - **Venlafaxine** is an antidepressant that works by inhibiting the reuptake of both **serotonin** and **norepinephrine**, making it a **Serotonin-Norepinephrine Reuptake Inhibitor (SNRI)**. - This dual mechanism contributes to its efficacy in treating **major depressive disorder**, **anxiety disorders**, and **neuropathic pain**. *Monoamine oxidase inhibitors* - **MAOIs** inhibit the enzyme **monoamine oxidase**, which metabolizes neurotransmitters like **serotonin**, **norepinephrine**, and **dopamine**. - They are associated with significant **food and drug interactions**, unlike venlafaxine. *Serotonin receptor antagonist* - These drugs *block* **serotonin receptors**, often used as **antiemetics** (e.g., ondansetron) or in some **antipsychotics**. - They do not primarily increase serotonin or norepinephrine levels via reuptake inhibition. *Selective serotonin reuptake inhibitor* - **SSRIs** (e.g., fluoxetine, sertraline) primarily inhibit the reuptake of **serotonin**, with minimal effect on other neurotransmitters. - While venlafaxine affects serotonin, it also significantly impacts norepinephrine, distinguishing it from SSRIs.
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