Central Nervous System Pharmacology Practice Questions

Q: Which dopamine receptor blocker is commonly used for intractable Sydenham chorea?

Haloperidol. ***Haloperidol*** - Haloperidol is a **typical antipsychotic** and **dopamine D2 receptor blocker** commonly used for severe or intractable Sydenham chorea due to its efficacy in controlling **hyperkinetic movements**. - Its mechanism of action involves reducing dopaminergic overactivity in the **basal ganglia**, which is implicated in the pathogenesis of chorea. - While effective, it carries a risk of **extrapyramidal side effects** and requires monitoring. *Valproate* - Valproate is an **anticonvulsant** and **mood stabilizer** that IS actually used as a **first-line treatment** for Sydenham chorea, often preferred due to better tolerability compared to typical antipsychotics. - However, valproate is **not a dopamine receptor blocker** - it works through GABAergic mechanisms and sodium channel blockade. - The question specifically asks for a dopamine receptor blocker, making haloperidol the correct answer. *Warfarin* - Warfarin is an **anticoagulant** prescribed to prevent **thromboembolic events**, and has no role in the treatment of Sydenham chorea. - Its mechanism involves inhibiting **vitamin K-dependent clotting factors**, which is unrelated to neurological movement disorders. *Risperidone* - Risperidone is an **atypical antipsychotic** that blocks both **dopamine D2** and **serotonin 5-HT2A receptors**. While it can be effective for chorea, it is generally considered a **second-line agent**. - It may be used when typical antipsychotics are poorly tolerated, offering potentially lower risk of **extrapyramidal side effects** compared to haloperidol, though it still carries risks.

Q: What is the drug of choice (DOC) for smoking cessation?

Varenicline. ***Varenicline*** - **Varenicline** is a **partial nicotinic receptor agonist** that reduces both the cravings for nicotine and the pleasurable effects of smoking. - It is considered a **first-line agent** for smoking cessation due to its effectiveness in increasing abstinence rates. *Acamprosate* - **Acamprosate** is a medication used to maintain abstinence from **alcohol dependence** by modulating GABA and glutamate neurotransmission. - It is **not indicated** for smoking cessation and has no direct mechanism of action related to nicotine addiction. *Thalidomide* - **Thalidomide** is an **immunomodulatory drug** with anti-angiogenic and anti-inflammatory properties, primarily used in conditions like **multiple myeloma** and **leprosy**. - It has **severe teratogenic effects** and is not used for smoking cessation due to its complex mechanism and significant side effect profile. *Tryptophan* - **Tryptophan** is an **essential amino acid** that serves as a precursor to **serotonin**, a neurotransmitter involved in mood regulation and sleep. - While it can impact mood, it is **not an approved or effective treatment** for directly addressing nicotine dependence or cravings.

Q: What is the primary component extracted from the Cannabis Indica plant used in traditional medicine?

Flowers of Cannabis Indica. ***Flowers of Cannabis Indica*** - The **flowers** (also called buds or flowering tops) are the primary component extracted from *Cannabis Indica* for traditional and modern medicinal use. - The female flowers contain the highest concentration of **trichomes**, which produce cannabinoids such as **THC** and **CBD**. - In traditional medicine systems including Ayurveda, the **flowering tops** were the principal medicinal part used. - The flowers are the **primary botanical source** from which all cannabis-based medicines are derived. *Resin of Cannabis Indica* - Resin refers to concentrated **secondary extracts** like hashish or cannabis oil, which are processed products derived from the flowers. - While resin has high cannabinoid content, it is not the primary plant component but rather a concentrated derivative. - Resin is obtained by processing the trichomes from the flowers, making it a downstream product. *Leaves of Cannabis Indica* - While leaves contain some cannabinoids, their concentration is generally much **lower** compared to the flowers. - Leaves are less commonly used as the primary medicinal component due to their significantly lower potency. - They may be used in some traditional preparations but are not the primary component. *Stem of Cannabis Indica* - The stem primarily consists of **fibrous material** and has minimal cannabinoid concentration. - It is not traditionally used as a medicinal component due to its lack of significant active ingredients. - Stems are primarily used for fiber (hemp) rather than medicinal applications.

Q: Which triptan is available in nasal spray form?

Sumatriptan. ***Sumatriptan*** - **Sumatriptan** is available in multiple formulations, including **oral, subcutaneous injection, and nasal spray**, making it versatile for migraine treatment [1], [2]. - The nasal spray formulation allows for **faster absorption** and onset of action, which can be beneficial for patients with nausea or vomiting during migraine attacks [1]. *Rizatriptan* - **Rizatriptan** is primarily available in **oral tablet** and **orally disintegrating tablet** (ODT) forms [2]. - It does not have a commonly available nasal spray formulation for migraine treatment [2]. *Naratriptan* - **Naratriptan** is available as an **oral tablet** and is known for its **longer half-life** and generally milder side effect profile compared to sumatriptan [2]. - It is not available in a nasal spray formulation [2]. *Frovatriptan* - **Frovatriptan** is available exclusively as an **oral tablet** and is notable for having the **longest half-life** among triptans, making it useful for preventing recurring migraines [2]. - There is no nasal spray formulation for frovatriptan [2].

Q: What is the primary mechanism of action of zonisamide?

Sodium channels. ***Sodium channels (Correct Answer)*** - Zonisamide's primary mechanism involves **blocking voltage-sensitive sodium channels**, which stabilizes neuronal membranes and inhibits repetitive neuronal firing. - This action helps to prevent the propagation of **seizure activity** in the brain. *GABA receptors* - While zonisamide has some weak effects on GABA, it is not its **primary mechanism of action** for antiepileptic efficacy. - Drugs like **benzodiazepines** and **barbiturates** primarily act by enhancing GABAergic transmission. *T-type calcium channels* - Zonisamide also blocks T-type calcium channels, contributing to its broad-spectrum antiepileptic activity, but this is a **secondary mechanism** compared to its sodium channel blockade. - **Ethosuximide** is a classic example of a drug primarily acting on T-type calcium channels, especially for absence seizures. *Cl- channels* - Zonisamide does not primarily act on **chloride channels**; these are often modulated by GABA receptors. - Drugs that act directly on chloride channels are not typically used as **antiepileptics** in the same way.

Q: Where is the benzodiazepine binding site located on GABA receptors?

γ-subunit. ***γ-subunit*** - The **benzodiazepine binding site** is located at the interface between the **α and γ subunits** of the GABA-A receptor, with the **γ-subunit (especially γ2) being essential** for benzodiazepine sensitivity. - The presence of the **γ2 subunit** is **mandatory** for benzodiazepine binding - receptors lacking this subunit are **insensitive to benzodiazepines**. - Benzodiazepines bind to this site and act as **positive allosteric modulators**, increasing the frequency of **chloride channel opening** in response to GABA. - This is the **standard answer** for NEET-PG and medical PG examinations in India. *α-subunit* - The **α-subunit** contributes to forming the benzodiazepine binding pocket at the α-γ interface. - Different **α-subunit isoforms** (α1, α2, α3, α5) determine the pharmacological profile and tissue distribution of benzodiazepine effects. - However, the **α-subunit alone** cannot bind benzodiazepines without the γ-subunit. *β-subunit* - The **β-subunit** contains the primary binding site for **GABA** itself. - It does not participate in benzodiazepine binding but is crucial for the receptor's overall function and GABAergic signaling. *δ-subunit* - The **δ-subunit** replaces the γ-subunit in certain GABA-A receptor subtypes that mediate **tonic inhibition**. - Receptors containing **δ-subunits** are **insensitive to benzodiazepines** but sensitive to neurosteroids and certain general anesthetics. - This is a key distinguishing feature between phasic (γ-containing) and tonic (δ-containing) GABA-A receptors.

Q: What is the classification of Lorcaserin?

Anti-obesity. ***Anti-obesity*** - Lorcaserin is a selective **serotonin 5-HT₂C receptor agonist** that works by promoting satiety and reducing food intake. - It is prescribed as a long-term treatment for **weight management** in adults who are obese or overweight with at least one weight-related comorbidity. *Anti-anxiety* - Anti-anxiety medications, such as **benzodiazepines** or **SSRIs**, primarily target neurotransmitters like GABA or serotonin 5-HT₁A receptors to reduce anxiety symptoms. - Lorcaserin's primary mechanism of action is distinct, focusing on the 5-HT₂C receptor for appetite regulation, not anxiety. *Anti-smoking* - Anti-smoking medications, like **varenicline** or **bupropion**, are designed to reduce nicotine cravings and withdrawal symptoms. - Their mechanisms often involve nicotinic acetylcholine receptors or dopamine and norepinephrine reuptake inhibition, which differs from lorcaserin's action. *Anti-helminthic* - Anti-helminthic drugs are used to treat **parasitic worm infections** by paralyzing or killing the worms. - Common examples include **albendazole** or **mebendazole**, which have no relation to appetite control or obesity treatment.

Q: What effect does morphine have on muscle tone?

Increased muscle tone. ***Increased muscle tone*** - Morphine **increases skeletal muscle tone** and can cause muscle rigidity, particularly with rapid IV administration (truncal rigidity). - It significantly increases **smooth muscle tone** in various organs including the sphincter of Oddi (causing biliary colic), bladder sphincter (causing urinary retention), and GI tract (causing constipation). - This increased tone in sphincters and smooth muscle is a well-documented effect mediated through **opioid receptor activation**. *Bradycardia (not increased heart rate)* - Morphine typically causes **bradycardia** (decreased heart rate) due to vagal stimulation and central effects, not tachycardia. - Increased heart rate would be atypical and not a primary pharmacological effect of morphine. *Miosis (not mydriasis)* - Morphine characteristically causes **miosis** (pinpoint pupils) due to stimulation of the Edinger-Westphal nucleus of the oculomotor nerve. - Mydriasis (dilated pupils) is seen with anticholinergics or sympathomimetics, not opioids. *Respiratory depression (not stimulation)* - Morphine causes **respiratory depression**, not stimulation, by reducing the responsiveness of brainstem respiratory centers to CO2. - This is one of the most dangerous adverse effects and the primary cause of death in opioid overdose.

Q: In ophthalmology, if a patient is allergic to aminoesters, which local anesthetic can be safely used?

Prilocaine. **Local anesthetics are classified into two chemical groups: esters (aminoesters) and amides. Allergies to esters typically do not cross-react with amides.** ***Prilocaine*** - **Prilocaine** is an **amide-type local anesthetic**, and allergies to **aminoesters** typically do not cross-react with **amides**. - It is a safe alternative in patients with a known allergy to **ester-type local anesthetics**. *Cocaine* - **Cocaine** is an **ester-type local anesthetic**, sharing a similar chemical structure with **aminoesters**. - Patients allergic to **aminoesters** are likely to experience a **cross-reaction** with **cocaine**. *Procaine* - **Procaine** is a classic **ester-type local anesthetic** (an aminoester). - An allergy to aminoesters directly implies an allergy to **procaine** due to its chemical classification. *Tetracaine* - **Tetracaine** is also an **ester-type local anesthetic** (an aminoester). - It is contraindicated in patients with an allergy to **aminoesters** due to the high risk of **allergic reaction**.

Q: Which anaesthetic belongs to the ester group?

Procaine. ***Procaine*** - **Procaine** is a classical **ester-type** local anesthetic, characterized by an ester linkage between the aromatic and amine parts of its chemical structure. - Ester-type local anesthetics are metabolized by **plasma pseudocholinesterase**, leading to a shorter duration of action compared to amides. *Benzocaine* - **Benzocaine** is also an ester local anesthetic, but it is typically used topically due to its poor water solubility and absorption. - While an ester, the question implies a common injectable agent, making procaine a more representative answer for the "ester group" in general anesthetic use. *Lignocaine* - **Lignocaine** (also known as lidocaine) is an **amide-type** local anesthetic, which can be identified by an amide linkage in its chemical structure. - Amide local anesthetics are primarily metabolized in the **liver** and generally have a longer duration of action than esters. *Propofol* - **Propofol** is a **short-acting intravenous general anesthetic** and is not classified as a local anesthetic or belonging to the ester group. - It works by potentiation of **GABA-A receptors** and is used for induction and maintenance of general anesthesia.

Question 1

Which dopamine receptor blocker is commonly used for intractable Sydenham chorea?

Accepted Answer

Haloperidol

Answer

Warfarin

Answer

Risperidone

Answer

Valproate

Question 2

What is the drug of choice (DOC) for smoking cessation?

Accepted Answer

Varenicline

Answer

Acamprosate

Answer

Thalidomide

Answer

Tryptophan

Question 3

What is the primary component extracted from the Cannabis Indica plant used in traditional medicine?

Accepted Answer

Flowers of Cannabis Indica

Answer

Leaves of Cannabis Indica

Answer

Resin of Cannabis Indica

Answer

Stem of Cannabis Indica

Question 4

Which triptan is available in nasal spray form?

Accepted Answer

Sumatriptan

Answer

Rizatriptan

Answer

Naratriptan

Answer

Frovatriptan

Question 5

What is the primary mechanism of action of zonisamide?

Accepted Answer

Sodium channels

Answer

GABA receptors

Answer

Cl- channels

Answer

T-type calcium channels

Question 6

Where is the benzodiazepine binding site located on GABA receptors?

Accepted Answer

γ-subunit

Answer

β-subunit

Answer

δ-subunit

Answer

α-subunit

Question 7

What is the classification of Lorcaserin?

Accepted Answer

Anti-obesity

Answer

Anti-anxiety

Answer

Anti-smoking

Answer

Anti-helminthic

Question 8

What effect does morphine have on muscle tone?

Accepted Answer

Increased muscle tone

Answer

Respiratory stimulation

Answer

Decreased muscle tone

Answer

Mydriasis

Question 9

In ophthalmology, if a patient is allergic to aminoesters, which local anesthetic can be safely used?

Accepted Answer

Prilocaine

Answer

Procaine

Answer

Cocaine

Answer

Tetracaine

Question 10

Which anaesthetic belongs to the ester group?

Accepted Answer

Procaine

Answer

Lignocaine

Answer

Propofol

Answer

Benzocaine

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

On this page

Practice by Chapter

Want unlimited practice?