Central Nervous System Pharmacology Practice Questions

Q: What is the treatment for extrapyramidal side effects induced by Haloperidol?

Anticholinergic drugs. ***Anticholinergic drugs (effective treatment)*** - **Anticholinergic medications**, such as **benztropine** or **diphenhydramine**, are the primary treatment for **acute extrapyramidal symptoms (EPS)** like dystonia and parkinsonism induced by antipsychotics like haloperidol. - They work by **blocking muscarinic acetylcholine receptors**, helping to restore the balance between dopamine and acetylcholine in the basal ganglia. *Benzodiazepines (used for anxiety and muscle relaxation)* - While benzodiazepines can offer some relief for **akathisia** (a form of EPS characterized by restlessness) due to their sedative and muscle relaxant properties, they are **not the first-line treatment for other acute EPS** such as dystonia or parkinsonism. - They primarily enhance **GABAergic transmission** and are effective for anxiety and seizure control rather than direct antagonism of EPS mechanisms. *Barbiturates (used as sedative-hypnotic drugs)* - **Barbiturates** are strong central nervous system depressants used for sedation, anesthesia, and seizure control, but are **not indicated for the treatment of EPS**. - Their significant **sedative and addictive potential**, along with a narrow therapeutic index, makes them unsuitable for this purpose. *SSRIs (used for depression and anxiety)* - **SSRIs (Selective Serotonin Reuptake Inhibitors)** are antidepressants that work by increasing serotonin levels in the brain and are used to treat depression, anxiety, and obsessive-compulsive disorder. - They **do not have a direct role** in ameliorating dopamine-acetylcholine imbalance responsible for haloperidol-induced EPS.

Q: Suxamethonium primarily acts on which type of receptors?

Nicotinic acetylcholine receptors. ***Nicotinic acetylcholine receptors*** - **Suxamethonium** is a depolarizing muscle relaxant that acts as an **agonist at nicotinic acetylcholine receptors** at the neuromuscular junction. - This initial activation leads to muscle fasciculations followed by prolonged depolarization, causing **flaccid paralysis**. *Potassium channels* - While some drugs may affect potassium channels to alter neuronal excitability, suxamethonium's primary mechanism of action is not on these channels. - Blocking potassium channels is characteristic of drugs like **certain antiarrhythmics** or **sulfonylureas**. *Calcium channels* - **Calcium channels** play a role in muscle contraction, but they are not the primary target of suxamethonium. - Drugs like **dihydropyridines** (e.g., nifedipine) target calcium channels for their antihypertensive effects. *Chloride channels* - Chloride channels are involved in maintaining resting membrane potential and inhibitory neurotransmission. - Drugs such as **benzodiazepines** indirectly enhance GABA-mediated chloride influx, which is distinct from suxamethonium's action.

Q: Which of the following metal ions is associated with secondary Parkinsonisms?

Manganese (Mn). ***Manganese (Mn)*** - Chronic exposure to high levels of **manganese** can lead to **manganism**, a neurological disorder characterized by **Parkinsonian-like symptoms**, including bradykinesia, rigidity, and gait disturbances [1]. - This is due to manganese accumulation in the **basal ganglia**, particularly the **globus pallidus**, affecting dopaminergic pathways. *Magnesium (Mg)* - **Magnesium** is an essential mineral vital for numerous bodily functions, including nerve and muscle function. - While imbalances can cause neurological issues (e.g., tremors with hypomagnesemia), it is not directly associated with **secondary parkinsonism**. *Selenium (Se)* - **Selenium** is a trace element with antioxidant properties, important for thyroid hormone metabolism and immune function. - Both deficiency and toxicity can cause various health problems, but it is not known to cause **secondary parkinsonism**. *Molybdenum (Mo)* - **Molybdenum** is an essential trace element that functions as a cofactor for several enzymes. - No known association exists between molybdenum exposure, deficiency, or toxicity and the development of **secondary parkinsonism**.

Q: In the context of pharmacology, what is the term 'Mickey Finn' commonly associated with?

Chloral hydrate. ***Chloral hydrate*** - A "Mickey Finn" is a slang term for a drink **laced with a psychoactive drug or incapacitating agent** given to an unsuspecting person. - Historically, **chloral hydrate** was a common substance used for this purpose due to its rapid sedative-hypnotic effects. *Chloroform* - While chloroform is a potent anesthetic and sedative, it is primarily used as an **inhalant** and is not typically administered orally in drinks. - Ingesting chloroform in large quantities can be **fatal due to severe hepatotoxicity and neurotoxicity**. *Methyl alcohol* - **Methyl alcohol (methanol)** is highly toxic and causes severe metabolic acidosis, blindness, and death, even in small amounts. - It does not induce the quick, incapacitating sedative effects associated with a "Mickey Finn" but rather a **delayed, severe poisoning syndrome**. *Ethylene glycol* - **Ethylene glycol** is an antifreeze agent that is also highly toxic, causing kidney failure and metabolic derangements. - Similar to methanol, its effects are **delayed and severe**, not the immediate incapacitating sedation implied by the term "Mickey Finn."

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: Antidepressant drug used in nocturnal enuresis is:

Imipramine. ***Imipramine*** - **Imipramine**, a **tricyclic antidepressant (TCA)**, is frequently used off-label for **nocturnal enuresis** in children [1]. - Its mechanism of action in enuresis is thought to involve a combination of anticholinergic effects (which relax the bladder detrusor muscle) and central nervous system effects (which may increase bladder capacity and arousal from sleep) [1]. *Fluoxetine* - **Fluoxetine** is a **selective serotonin reuptake inhibitor (SSRI)** and is primarily used for depression, anxiety disorders, and OCD [2]. - It is not indicated for the treatment of nocturnal enuresis and does not have the same bladder-relaxing or arousal-modulating properties as imipramine in this context. *Trazodone* - **Trazodone** is a **serotonin antagonist and reuptake inhibitor (SARI)**, commonly prescribed for depression and insomnia due to its prominent sedative effects. - It is not used for nocturnal enuresis and its mechanism of action does not confer benefits for bladder control. *Sertraline* - **Sertraline** is another **selective serotonin reuptake inhibitor (SSRI)** used for a wide range of psychiatric conditions, including depression, anxiety, and panic disorder [2]. - Like fluoxetine, it is not an appropriate treatment for nocturnal enuresis and lacks the specific known effects beneficial for this condition.

Q: Which anti-cholinesterase drug is known for its central nervous system activity?

Physostigmine. ***Physostigmine*** - Unlike most other anti-cholinesterases, **physostigmine** is a **tertiary amine** and is relatively lipid-soluble, allowing it to cross the **blood-brain barrier**. [2] - Its ability to increase acetylcholine in the CNS makes it useful in treating anticholinergic toxicity (e.g., atropine overdose). [2] *Pyridostigmine* - **Pyridostigmine** is a **quaternary amine** and does not readily cross the blood-brain barrier, primarily acting peripherally. - It is mainly used in the long-term management of **myasthenia gravis**. *Edrophonium* - **Edrophonium** is a very short-acting **quaternary amine** that does not cross the blood-brain barrier. [1] - It is primarily used for the **diagnosis of myasthenia gravis** (Tensilon test) due to its rapid onset and short duration of action. [1] *Neostigmine* - **Neostigmine** is also a **quaternary amine** with poor lipid solubility, meaning it has minimal central nervous system activity. [2] - It is commonly used to reverse the effects of **non-depolarizing neuromuscular blockers** and in the treatment of **myasthenia gravis**.

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: Which of the following drugs is not used in the treatment of akathisia?

Haloperidol. ***Haloperidol*** - **Haloperidol** is a typical antipsychotic drug known to **cause** or worsen **akathisia**, rather than treat it. - Akathisia is an extrapyramidal symptom, and **first-generation antipsychotics** like haloperidol are frequent culprits due to their strong **D2 receptor blockade**. *Benzodiazepine* - **Benzodiazepines** like lorazepam or clonazepam are often used to treat akathisia due to their **sedative** and **anxiolytic** properties. - They act by enhancing **GABAergic transmission**, which can help calm the motor restlessness associated with akathisia. *Propranolol* - **Propranolol**, a **beta-blocker**, is a first-line treatment for akathisia, particularly effective for its objective motor symptoms. - It works by reducing **adrenergic activity**, which is thought to contribute to the motor restlessness. *Trihexyphenidyl* - **Trihexyphenidyl** is an **anticholinergic** agent primarily used to treat **parkinsonian-like extrapyramidal symptoms** (e.g., dystonia, pseudoparkinsonism). - While sometimes used for generalized EPS, it is **less effective** for the specific motor restlessness of akathisia compared to beta-blockers or benzodiazepines.

Question 1

What is the treatment for extrapyramidal side effects induced by Haloperidol?

Accepted Answer

Anticholinergic drugs

Answer

Barbiturates

Answer

SSRIs

Answer

Benzodiazepines

Question 2

What is the mechanism of action of Curare drugs as muscle relaxants?

Accepted Answer

Act competitively on Ach receptors blocking post-synaptically

Answer

Persistently depolarizing at Neuromuscular junction

Answer

Repetitive stimulation of Ach receptors on muscle end plate

Answer

Inhibiting the calcium channel on presynaptic membrane

Question 3

Suxamethonium primarily acts on which type of receptors?

Accepted Answer

Nicotinic acetylcholine receptors

Answer

Potassium channels

Answer

Calcium channels

Answer

Chloride channels

Question 4

Which of the following metal ions is associated with secondary Parkinsonisms?

Accepted Answer

Manganese (Mn)

Answer

Magnesium (Mg)

Answer

Selenium (Se)

Answer

Molybdenum (Mo)

Question 5

In the context of pharmacology, what is the term 'Mickey Finn' commonly associated with?

Accepted Answer

Chloral hydrate

Answer

Chloroform

Answer

Methyl alcohol

Answer

Ethylene glycol

Question 6

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 7

Antidepressant drug used in nocturnal enuresis is:

Accepted Answer

Imipramine

Answer

Fluoxetine

Answer

Trazodone

Answer

Sertraline

Question 8

Which anti-cholinesterase drug is known for its central nervous system activity?

Accepted Answer

Physostigmine

Answer

Edrophonium

Answer

Pyridostigmine

Answer

Neostigmine

Question 9

What effect does morphine have on muscle tone?

Accepted Answer

Increased muscle tone

Answer

Respiratory stimulation

Answer

Decreased muscle tone

Answer

Mydriasis

Question 10

Which of the following drugs is not used in the treatment of akathisia?

Accepted Answer

Haloperidol

Answer

Benzodiazepine

Answer

Propranolol

Answer

Trihexyphenidyl

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

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