Psychostimulants — MCQs

10 questions

Pharmacodynamics deals with:-

Modafinil is approved by FDA for treatment of all except:

A 30-year-old male presents with a history of consuming an unknown substance. On examination, the patient has diaphoresis, headache, and features resembling acute coronary spasm. Which of the following clinical features is least likely to be present in this patient?

A 78-year-old woman is brought to the clinic by her daughter due to concerns about her mother's mood. The patient's husband of 48 years passed away six months ago after a lengthy illness due to metastatic colon cancer. Since then, she reports having a poor appetite, decreased interest in activities, and frequent thoughts about dying. She is started on nortriptyline to help improve her mood and functional status. Which of the following is a common side effect of nortriptyline?

Atomoxetine is used in the management of which of the following conditions?

The preferred drug for treating ADHD in a 7-year-old boy, whose father has a history of substance abuse:

Which of the following is a selective norepinephrine reuptake inhibitor that can be used for the treatment of ADHD?

Effect of dopamine on renal vessels?

Q10

Which of the following antidepressants is least likely to have sexual side effects?

Psychostimulants Indian Medical PG Practice Questions and MCQs

Question 1: Pharmacodynamics deals with:-

A. Latency of onset
B. Mechanism of action of a drug (Correct Answer)
C. Transport of drug across the biological membranes
D. Mode of excretion of a drug

Explanation: Detailed study of the **Mechanism of action of a drug** [1][2] - **Pharmacodynamics** describes what the **drug does to the body**, including its **molecular targets** and biochemical effects [3]. - This involves the study of the drug's mechanisms to produce its therapeutic or toxic effects [2]. *Latency of onset* - **Latency of onset** refers to the time it takes for a drug to start producing its effects, which is a pharmacokinetic rather than a pharmacodynamic parameter. - It deals with the drug's absorption and distribution rather than its interaction with the body once it reaches its site of action. *Transport of drug across the biological membranes* - The **transport of drugs across biological membranes** is a key aspect of **pharmacokinetics**, specifically absorption and distribution [1]. - This process determines how much drug reaches its target site, not how it interacts with the target. *Mode of excretion of a drug* - The **mode of excretion** of a drug (e.g., renal, hepatic) falls under **pharmacokinetics**, addressing how the body gets rid of the drug. - This process influences the drug's duration of action and elimination half-life, not its mechanism of action.

Question 2: Modafinil is approved by FDA for treatment of all except:

A. Narcolepsy
B. Shift work sleep disorder (SWSD)
C. Obstructive sleep apnea syndrome (OSAS)
D. Lethargy in depression (Correct Answer)

Explanation: ***Lethargy in depression*** - Modafinil is **not FDA-approved** for treating lethargy or fatigue specifically in the context of depression. Its primary indications are for disorders of excessive daytime sleepiness. - While it may be used off-label in some cases for depression-related fatigue, it lacks formal FDA approval and specific efficacy data for this indication. *Narcolepsy* - Modafinil is **FDA-approved** as a wakefulness-promoting agent for the treatment of excessive daytime sleepiness associated with **narcolepsy**. - It helps reduce the frequency and severity of sleep attacks by promoting wakefulness through effects on **dopamine**, **norepinephrine**, and **histamine** systems in the brain. *Shift work sleep disorder (SWSD)* - Modafinil is **FDA-approved** to improve wakefulness in patients with excessive sleepiness associated with **shift work sleep disorder**. - It helps individuals working non-traditional hours (night shifts, rotating shifts) maintain alertness during their work periods. *Obstructive sleep apnea syndrome (OSAS)* - Modafinil is **FDA-approved** as an **adjunctive treatment** for residual excessive daytime sleepiness in patients with **obstructive sleep apnea/hypopnea syndrome (OSAHS)** who are receiving adequate treatment with CPAP. - It addresses persistent sleepiness that remains even after appropriate primary airway management.

Question 3: A 30-year-old male presents with a history of consuming an unknown substance. On examination, the patient has diaphoresis, headache, and features resembling acute coronary spasm. Which of the following clinical features is least likely to be present in this patient?

A. Hypertension
B. Tachycardia
C. Hyperthermia
D. Bradycardia (Correct Answer)
E. Mydriasis

Explanation: ***Bradycardia*** - The presented symptoms of diaphoresis, headache, and coronary spasm are consistent with **stimulant intoxication** (e.g., cocaine, amphetamines). - Stimulants typically cause **tachycardia** due to sympathetic overactivity, making bradycardia the least likely finding. *Hypertension* - **Stimulant intoxication** leads to increased sympathetic activity, causing **vasoconstriction** and elevated blood pressure. - This is a common and expected finding in cases presenting with coronary spasm due to substance abuse. *Tachycardia* - **Sympathetic overstimulation** from an unknown substance, particularly stimulants, directly increases heart rate. - This symptom closely aligns with the patient's presentation of diaphoresis and coronary spasm. *Hyperthermia* - Elevated body temperature is a frequent consequence of **stimulant overdose** due to increased metabolic activity and impaired thermoregulation. - **Diaphoresis** (sweating) can be a compensatory mechanism for hyperthermia or a direct effect of sympathetic activation. *Mydriasis* - **Pupillary dilation** is a characteristic finding in sympathomimetic toxidrome caused by stimulant drugs. - This occurs due to alpha-adrenergic stimulation of the radial muscle of the iris and is commonly seen with cocaine or amphetamine use.

Question 4: A 78-year-old woman is brought to the clinic by her daughter due to concerns about her mother's mood. The patient's husband of 48 years passed away six months ago after a lengthy illness due to metastatic colon cancer. Since then, she reports having a poor appetite, decreased interest in activities, and frequent thoughts about dying. She is started on nortriptyline to help improve her mood and functional status. Which of the following is a common side effect of nortriptyline?

A. weight loss
B. impaired cardiac contractility
C. heart block
D. anticholinergic side effects (Correct Answer)

Explanation: ***Anticholinergic side effects*** - **Nortriptyline** is a **tricyclic antidepressant (TCA)** known for its significant **antimuscarinic** activity, leading to anticholinergic effects. - Common anticholinergic side effects include **dry mouth, blurred vision, constipation, urinary retention**, and **tachycardia**. *Impaired cardiac contractility* - While TCAs can have **cardiac effects** (e.g., QT prolongation, arrhythmias), **impaired cardiac contractility** is not a common or typical direct side effect at therapeutic doses. - Other drug classes, such as certain **beta-blockers** or **calcium channel blockers**, are more commonly associated with this effect. *Weight loss* - **Weight gain** is a more common side effect associated with many antidepressants, including some TCAs. - While some individuals may experience initial appetite changes, **sustained weight loss** is not a characteristic side effect of **nortriptyline**. *Heart block* - TCAs can cause **conduction abnormalities** like **prolonged QRS duration** and **QT interval prolongation**, especially in overdose or in patients with pre-existing cardiac conditions. - However, direct **heart block** (e.g., AV block) is a less common side effect, usually associated with higher doses or specific patient vulnerabilities.

Question 5: Atomoxetine is used in the management of which of the following conditions?

A. Bipolar disorder
B. Schizophrenia
C. Depression
D. ADHD (Correct Answer)

Explanation: ***Correct: ADHD*** * **Atomoxetine** is a **selective norepinephrine reuptake inhibitor (SNRI)** primarily used in the management of **Attention-Deficit/Hyperactivity Disorder (ADHD)**. * It is a **non-stimulant** medication, making it a suitable alternative for patients who do not respond to or cannot tolerate traditional stimulant medications for ADHD. * FDA-approved in 2002, atomoxetine remains an important treatment option, particularly for patients with concerns about stimulant abuse potential or those with comorbid anxiety disorders. *Incorrect: Bipolar disorder* * **Bipolar disorder** is typically treated with mood stabilizers (e.g., lithium, valproate), antipsychotics, and sometimes antidepressants, but atomoxetine is not a first-line or common treatment option. * While some ADHD symptoms can overlap with bipolar disorder, atomoxetine is specifically designed for ADHD and lacks the broad mood-stabilizing effects needed for bipolar disorder. *Incorrect: Schizophrenia* * **Schizophrenia** is a severe mental disorder treated primarily with **antipsychotic medications** that target dopamine and serotonin systems. * Atomoxetine does not have efficacy in treating the positive or negative symptoms of schizophrenia and is not indicated for this condition. *Incorrect: Depression* * While atomoxetine affects **norepinephrine**, some SNRIs (e.g., venlafaxine, duloxetine) are used for depression. However, atomoxetine's primary indication and efficacy profile are not for treating **major depressive disorder**. * Its mechanism of action is more specifically tailored to the neurochemical imbalances seen in ADHD rather than the broader neurotransmitter dysregulation in depression.

Question 6: The preferred drug for treating ADHD in a 7-year-old boy, whose father has a history of substance abuse:

A. Clonidine
B. Atomoxetine (Correct Answer)
C. Dexamphetamine
D. Methylphenidate

Explanation: ***Atomoxetine*** - As a **non-stimulant**, atomoxetine is preferred in patients where stimulant use is contraindicated or when there's a concern for **substance abuse potential**, such as a parental history. - It specifically inhibits the **norepinephrine transporter**, leading to increased norepinephrine levels in the prefrontal cortex, improving ADHD symptoms. *Clonidine* - While clonidine is sometimes used for ADHD, particularly for **hyperactivity** or **tics**, it is not generally considered first-line and can cause **sedation**. - Its mechanism primarily involves stimulating central alpha-2 adrenergic receptors, which can help with impulse control but is distinct from the primary action of atomoxetine. *Dexamphetamine* - This is a **stimulant medication** and is highly effective for ADHD, but it carries a higher potential for **abuse and diversion**, making it less suitable given a family history of substance abuse. - Its mechanism involves increasing dopamine and norepinephrine levels in the brain, which can be reinforcing and contribute to its abuse potential. *Methylphenidate* - Similar to dexamphetamine, methylphenidate is a **stimulant** and a first-line treatment for ADHD, but its potential for **abuse** makes it a less desirable choice in this specific clinical context. - It acts as a norepinephrine-dopamine reuptake inhibitor, increasing the availability of these neurotransmitters, but like other stimulants, its controlled substance status is a concern.

Question 7: Which of the following is a selective norepinephrine reuptake inhibitor that can be used for the treatment of ADHD?

A. Reboxetine
B. Methylphenidate
C. Guanfacine
D. Modafinil
E. Atomoxetine (Correct Answer)

Explanation: ***Atomoxetine*** - **Atomoxetine** is a **selective norepinephrine reuptake inhibitor (SNRI)** that is **FDA-approved specifically for the treatment of ADHD** in children, adolescents, and adults. - It works by **selectively blocking the presynaptic norepinephrine transporter**, increasing norepinephrine availability in the prefrontal cortex and other brain regions involved in attention and impulse control. - Unlike stimulant medications, atomoxetine is **not a controlled substance** and is considered a first-line **non-stimulant option** for ADHD treatment. - It is particularly useful in patients with comorbid anxiety, tic disorders, or substance abuse concerns. *Reboxetine* - While **reboxetine** is technically a **selective norepinephrine reuptake inhibitor**, it is primarily used as an **antidepressant** and is **not approved for ADHD treatment**. - It has been investigated off-label for ADHD, but it is not a standard or recommended treatment option. - Reboxetine has **limited global availability** and has been withdrawn from many markets due to efficacy concerns. *Methylphenidate* - **Methylphenidate** is a **stimulant** medication that inhibits the reuptake of both **dopamine and norepinephrine**, making it **non-selective**. - It is a first-line treatment for ADHD, but its mechanism of action involves dual monoamine reuptake inhibition, not selective norepinephrine reuptake. *Guanfacine* - **Guanfacine** is an **alpha-2 adrenergic agonist**, not a norepinephrine reuptake inhibitor. - It works by stimulating postsynaptic alpha-2A receptors in the prefrontal cortex, which enhances prefrontal cortex function and improves attention and impulse control. *Modafinil* - **Modafinil** is a wakefulness-promoting agent with a **complex, non-selective mechanism** involving dopamine, norepinephrine, histamine, and orexin systems. - It is primarily used for **narcolepsy** and excessive daytime sleepiness, not as a primary ADHD treatment. - It is **not classified as a selective norepinephrine reuptake inhibitor**.

Question 8: Effect of dopamine on renal vessels?

A. Increased permeability
B. No effect
C. Vasodilatation (Correct Answer)
D. Vasoconstriction

Explanation: ***Vasodilatation*** - Dopamine, at **low doses**, acts on D1 receptors in the renal vasculature, leading to **renal vasodilation**. - This effect increases **renal blood flow** and **glomerular filtration rate**, improving kidney perfusion. *Increased permeability* - **Increased permeability** of renal vessels is not a primary direct effect of dopamine but rather a feature of inflammatory processes or damage. - This typically leads to protein leakage, which is distinct from dopamine's hemodynamic actions. *No effect* - This option is incorrect because dopamine has distinct and well-documented effects on renal vessels. - Dopamine is commonly used in clinical practice for its **pharmacological effects** on the kidneys, such as increasing urine output and renal blood flow. *Vasoconstriction* - While dopamine can cause vasoconstriction at **high doses** by activating alpha-1 adrenergic receptors, its primary and most significant effect on renal vessels at **lower, therapeutic doses** is vasodilation. - **Vasoconstriction** would decrease renal blood flow, which is contrary to the desired effect of dopamine in renal support.

Question 9: Match the following drugs in Column A with their contraindications in Column B. | Column A | Column B | | :-- | :-- | | 1. Morphine | 1. QT prolongation | | 2. Amiodarone | 2. Thromboembolism | | 3. Vigabatrin | 3. Pregnancy | | 4. Estrogen preparations | 4. Head injury |

A. A-1, B-3, C-2, D-4
B. A-4, B-1, C-3, D-2 (Correct Answer)
C. A-3, B-2, C-4, D-1
D. A-2, B-4, C-1, D-3

Explanation: ***A-4, B-1, C-3, D-2*** - **Morphine** is contraindicated in **head injury** as it can increase intracranial pressure and mask neurological symptoms. - **Amiodarone** is contraindicated in patients with **QT prolongation** due to its risk of inducing more severe arrhythmias like Torsades de Pointes. - **Vigabatrin** is contraindicated during **pregnancy** due to its potential for teratogenicity and adverse effects on fetal development. - **Estrogen preparations** are contraindicated in patients with a history of **thromboembolism** due to their increased risk of blood clot formation. *A-1, B-3, C-2, D-4* - This option incorrectly matches **Morphine** with QT prolongation and **Estrogen preparations** with head injury, which are not their primary contraindications. - It also incorrectly links **Vigabatrin** with thromboembolism and **Amiodarone** with pregnancy. *A-3, B-2, C-4, D-1* - This choice incorrectly associates **Morphine** with pregnancy and **Vigabatrin** with head injury, which are not the most critical or direct contraindications. - It also misaligns **Amiodarone** with thromboembolism and **Estrogen preparations** with QT prolongation. *A-2, B-4, C-1, D-3* - This option incorrectly matches **Morphine** with thromboembolism and **Amiodarone** with head injury, which are not their most significant contraindications. - It also incorrectly links **Vigabatrin** with QT prolongation and **Estrogen preparations** with pregnancy.

Question 10: Which of the following antidepressants is least likely to have sexual side effects?

A. Amitriptyline
B. Fluoxetine
C. Venlafaxine
D. Mirtazapine (Correct Answer)

Explanation: ***Mirtazapine*** - **Mirtazapine** is an atypical antidepressant (NaSSA - Noradrenergic and Specific Serotonergic Antidepressant) that works by blocking alpha-2 adrenergic receptors, enhancing serotonin and norepinephrine release [1]. - It has the **lowest incidence of sexual side effects** among antidepressants because it blocks 5-HT2 and 5-HT3 receptors while avoiding significant 5-HT1A stimulation, which is responsible for sexual dysfunction with SSRIs [1]. - It may even **improve libido** in some cases due to its unique receptor profile and histamine antagonism that can enhance sleep quality. *Amitriptyline* - **Amitriptyline** is a tricyclic antidepressant (TCA) with broad receptor actions, including anticholinergic and antihistaminic effects. - TCAs like amitriptyline can cause **sexual dysfunction** (including erectile dysfunction and decreased libido) due to their anticholinergic properties and effects on multiple neurotransmitter systems, though typically less severe than SSRIs. *Fluoxetine* - **Fluoxetine** is a selective serotonin reuptake inhibitor (SSRI), and while effective for depression, it is associated with a **high incidence of sexual side effects** (30-70% of patients) [2]. - These side effects include **decreased libido**, **anorgasmia**, and **erectile dysfunction**, caused by increased serotonergic activity at 5-HT2 receptors in areas regulating sexual function [2]. *Venlafaxine* - **Venlafaxine** is a serotonin-norepinephrine reuptake inhibitor (SNRI), increasing both serotonin and norepinephrine levels in the brain [1]. - Like SSRIs, SNRIs such as venlafaxine frequently cause **sexual dysfunction**, with common complaints including reduced libido and difficulty achieving orgasm due to enhanced serotonergic neurotransmission [1].

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