Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology Indian Medical PG Practice Questions and MCQs

Question 721: Rivastigmine & donepezil are drugs used predominantly in the management of ?

A. Dissociation
B. Dementia (Correct Answer)
C. Delusions
D. Depression

Explanation: ***Dementia*** - **Rivastigmine** and **donepezil** are **acetylcholinesterase inhibitors** that increase acetylcholine levels in the brain. - This mechanism is primarily used to improve **cognitive function** in patients with **Alzheimer's disease** and other forms of dementia. *Dissociation* - Dissociation involves a mental process causing a lack of connection between thoughts, memory, and identity, and is not typically treated with cholinesterase inhibitors. - Management often involves **psychotherapy** and sometimes anti-anxiety medications or antidepressants, if comorbid conditions are present. *Delusions* - Delusions are fixed, false beliefs often associated with psychotic disorders like **schizophrenia** or severe mood disorders. - Treatment primarily involves **antipsychotic medications**, not acetylcholinesterase inhibitors. *Depression* - Depression is a mood disorder characterized by persistent sadness and loss of interest. - It is typically treated with **antidepressants** (e.g., SSRIs, SNRIs), psychotherapy, or lifestyle changes, none of which include rivastigmine or donepezil.

Question 722: All of the following can be used in increased intracranial tension (ICT) except:

A. Thiopentone
B. Acetazolamide
C. Mannitol
D. Ketamine (Correct Answer)

Explanation: ***Ketamine*** - **Ketamine** is known to increase **cerebral blood flow** and **intracranial pressure (ICP)**, making it contraindicated in situations of increased ICT. - Its mechanism involves **cerebral vasodilation** and direct central nervous system stimulation, which can exacerbate existing intracranial hypertension. *Thiopentone* - **Thiopentone** is a barbiturate that reduces cerebral metabolic rate, leading to decreased **cerebral blood flow** and **ICP**. - It is often used for neuroprotection and to manage acute increases in ICT due to its potent vasoconstrictive effects on cerebral vessels. *Acetazolamide* - **Acetazolamide** is a **carbonic anhydrase inhibitor** that reduces **cerebrospinal fluid (CSF) production**, thus lowering ICT. - It is particularly useful in conditions like **idiopathic intracranial hypertension (pseudotumor cerebri)** where CSF overproduction contributes to elevated pressure. *Mannitol* - **Mannitol** is an **osmotic diuretic** that creates an osmotic gradient, drawing water from the brain parenchyma into the intravascular space, thereby reducing brain volume and **ICP**. - It is a rapid-acting agent frequently used in emergency settings for acute management of increased ICT.

Question 723: Which of the following is used in the treatment of Multiple Sclerosis:

A. Interferon Alpha
B. Infliximab
C. Interferon gamma
D. Interferon Beta (Correct Answer)

Explanation: ***Interferon Beta*** - **Interferon beta** is a disease-modifying therapy commonly used for **relapsing-remitting multiple sclerosis (RRMS)** to reduce the frequency and severity of relapses. - It works by modulating the immune system, decreasing inflammation and preventing demyelination in the central nervous system. *Interferon Alpha* - **Interferon alpha** is primarily used in the treatment of certain **cancers** (e.g., leukemia, melanoma) and **viral infections** (e.g., chronic hepatitis B and C). - It does not have a recognized role in the standard treatment protocols for multiple sclerosis. *Infliximab* - **Infliximab** is a **monoclonal antibody** that targets **tumor necrosis factor-alpha (TNF-α)** and is used in the treatment of inflammatory conditions like rheumatoid arthritis, Crohn's disease, and ulcerative colitis. - While TNF-α plays a role in inflammation, **anti-TNF therapy** has been shown to potentially worsen MS and is generally contraindicated. *Interferon gamma* - **Interferon gamma** is a pro-inflammatory cytokine that can exacerbate MS symptoms and **increase disease activity**. - It is **not used** in the treatment of multiple sclerosis and in fact, some studies suggest it may be detrimental.

Question 724: Which of the following drugs is commonly used in narcoanalysis?

A. Scopolamine
B. Opium
C. Atropine
D. Thiopentone (Correct Answer)

Explanation: ***Thiopentone*** - **Thiopentone** (a **barbiturate**) is commonly used in narcoanalysis due to its ability to induce a **trance-like state**, lowering inhibitions and making individuals more suggestible. - In this state, it's believed that a person's conscious defenses are reduced, potentially leading to the disclosure of information that might otherwise be withheld. *Scopolamine* - While sometimes referred to as "truth serum," **scopolamine** (an **anticholinergic**) primarily causes disorientation, confusion, and amnesia, making it unsuitable for reliable information extraction in narcoanalysis. - Its effects can lead to unreliable and hallucinated responses rather than factual memories. *Opium* - **Opium** is a narcotic analgesic that causes sedation and euphoria but does not reliably facilitate the extraction of truthful information for investigative purposes. - It can depress the central nervous system, but the effects are not conducive to a clear, communicative state required for narcoanalysis. *Atropine* - **Atropine** is an **anticholinergic** drug primarily used to block muscarinic acetylcholine receptors, leading to effects like pupil dilation, dry mouth, and increased heart rate. - It does not induce the specific mental state required for narcoanalysis and would instead cause significant physiological side effects and confusion.

Question 725: Which is given to prevent relapse in multiple sclerosis?

A. Corticosteroids
B. IFN-gamma
C. Cyclosporine
D. IFN-beta (Correct Answer)

Explanation: ***Correct: IFN-beta*** - **Interferon-beta** is a disease-modifying therapy (DMT) commonly prescribed to **reduce the frequency and severity of relapses** and slow disease progression in **relapsing-remitting multiple sclerosis (RRMS)** [1], [2]. - Its mechanism of action involves **modulating the immune system**, reducing inflammation, and preventing immune cells from attacking the myelin sheath in the central nervous system. *Incorrect: Corticosteroids* - **Corticosteroids** (e.g., methylprednisolone) are primarily used for **acute treatment of MS relapses** to shorten their duration and severity, not for long-term relapse prevention [1]. - Their long-term use is limited by significant side effects, making them unsuitable as chronic preventive therapy [1]. *Incorrect: IFN-gamma* - **Interferon-gamma** has been shown to **exacerbate MS symptoms** and increase relapse rates, making it contraindicated in MS treatment. - It promotes a **pro-inflammatory immune response**, which is detrimental in an autoimmune demyelinating disease like MS. *Incorrect: Cyclosporine* - **Cyclosporine** is an immunosuppressant primarily used to prevent **organ transplant rejection** and in some severe autoimmune conditions. - While it has immunomodulatory properties, it is **not a first-line or standard treatment for MS relapse prevention** due to its significant toxicity profile (e.g., nephrotoxicity) and less favorable efficacy compared to approved DMTs.

Question 726: All of the following are Anticholinesterases used in Alzheimer's disease except

A. Donepezil
B. Rivastigmine
C. Memantine (Correct Answer)
D. Galantamine

Explanation: ***Memantine*** - While used in Alzheimer's disease, **memantine** is an **NMDA receptor antagonist**, not an anticholinesterase. - It works by blocking excessive **glutamatergic stimulation**, which is implicated in neurodegeneration. *Donepezil* - **Donepezil** is an **acetylcholinesterase inhibitor** used to treat mild to moderate Alzheimer's disease. - It increases the availability of **acetylcholine** in the synaptic cleft, improving cognitive function. *Rivastigmine* - **Rivastigmine** is a **cholinesterase inhibitor** that acts on both **acetylcholinesterase** and **butyrylcholinesterase**. - It is approved for the treatment of mild to moderate Alzheimer's disease and Parkinson's disease dementia. *Galantamine* - **Galantamine** is an **acetylcholinesterase inhibitor** and an **allosteric potentiator of nicotinic acetylcholine receptors**. - It enhances cholinergic neurotransmission and is used in the treatment of mild to moderate Alzheimer's disease.

Question 727: All of the following can be used for prophylaxis of migraine except

A. Topiramate
B. Valproate
C. Sumatriptan (Correct Answer)
D. Propranolol

Explanation: ***Sumatriptan*** - Sumatriptan is a **triptan**, a class of drugs primarily used for the **acute treatment** of migraine attacks, not for prophylaxis. - It works by constricting intracranial blood vessels and inhibiting pro-inflammatory neuropeptide release. *Topiramate* - **Topiramate** is an **antiepileptic drug** commonly used for migraine prophylaxis, especially in patients with associated epilepsy. - Its mechanism of action involves various pathways, including modulation of **GABA** and **glutamate** receptors. *Valproate* - **Valproate** (Divalproex sodium) is another **antiepileptic drug** effective in preventing migraine headaches. - It works by increasing **GABA** levels in the brain and stabilizing neuronal membranes. *Propranolol* - **Propranolol** is a **beta-blocker** widely used for migraine prophylaxis, particularly in patients with co-occurring hypertension or anxiety. - It acts by preventing cerebral vasodilation and influencing central serotonergic pathways.

Question 728: Opioid antagonist that can be given orally –

A. Naltrexone (Correct Answer)
B. Pentazocine
C. Naloxone
D. Nalbuphine

Explanation: ***Naltrexone*** - **Naltrexone** is an opioid antagonist used for treating **opioid dependence** and alcohol dependence. - It has good oral bioavailability and is administered orally, typically as a daily dose. *Pentazocine* - **Pentazocine** is an opioid agonist-antagonist, primarily acting as an **agonist** at kappa opioid receptors and a weak antagonist or partial agonist at mu opioid receptors. - It is not a pure opioid antagonist and thus cannot reverse opioid effects effectively. *Naloxone* - **Naloxone** is a pure opioid antagonist primarily used to reverse **acute opioid overdose** due to its rapid onset and short duration of action. - While it can be given orally, it has very **low oral bioavailability** due to extensive first-pass metabolism, making it unsuitable for chronic oral administration. *Nalbuphine* - **Nalbuphine** is an opioid agonist-antagonist, similar to pentazocine, acting as an **agonist** at kappa opioid receptors and an antagonist at mu opioid receptors. - It is typically administered parenterally for pain relief and is not used as an oral opioid antagonist.

Question 729: A young male, Farhan, suffers from a seizure disorder which is characterized by tonic rigidity of limbs followed in 20-30 seconds by tremors progressing to massive jerking of the body. This clonic phase lasts for 1-3 minutes. The anti-seizure drug of choice for this patient is:

A. Clonazepam
B. Ethosuximide
C. Valproic acid (Correct Answer)
D. Fosphenytoin

Explanation: ***Valproic acid***\n- The description of tonic rigidity followed by tremors and massive jerking of the body is characteristic of a **generalized tonic-clonic seizure (GTCS)** [1], [2].\n- **Valproic acid** is a **broad-spectrum antiepileptic drug** and is considered the **drug of choice** for GTCS due to its efficacy across multiple seizure types and favorable profile for long-term management [1].\n- It is the **most commonly recommended first-line agent** for newly diagnosed GTCS in most clinical guidelines [1].\n\n*Clonazepam*\n- **Clonazepam** is a benzodiazepine primarily used for absence seizures, myoclonic seizures, and status epilepticus [1].\n- While it has broad anti-seizure activity, it is **not first-line monotherapy** for long-term management of GTCS due to concerns about **tolerance, dependence, and sedation** [1].\n\n*Ethosuximide*\n- **Ethosuximide** is **specifically indicated only for absence seizures** (petit mal seizures).\n- It has **no efficacy against tonic-clonic seizures** and would be completely inappropriate for this patient.\n\n*Fosphenytoin*\n- **Fosphenytoin** is a prodrug of phenytoin and is an effective treatment for generalized tonic-clonic seizures [1].\n- While phenytoin/fosphenytoin is a valid first-line option for GTCS, **valproic acid is generally preferred** as the drug of choice due to its **broader spectrum of activity**, better tolerability profile, and effectiveness across more seizure types [1].\n- Fosphenytoin is commonly used in both acute management (status epilepticus) and chronic therapy, but requires monitoring for side effects like gingival hyperplasia, hirsutism, and drug interactions.

Question 730: All of the following drugs are used in prophylaxis of migraine, except

A. Levetiracetam (Correct Answer)
B. Propranolol
C. Topiramate
D. Flunarizine

Explanation: ***Levetiracetam*** - **Levetiracetam** is an antiepileptic drug primarily used for the treatment of seizures. - It is **not indicated** or commonly used for the prophylaxis of migraine. *Propranolol* - **Propranolol** is a non-selective beta-blocker that is a well-established and effective medication for migraine prophylaxis. - It helps reduce the frequency and severity of migraine attacks. *Topiramate* - **Topiramate** is an antiepileptic drug that is also approved and widely used for migraine prophylaxis. - Its mechanism of action in migraine prevention includes modulating neurotransmitters and ion channels. *Flunarizine* - **Flunarizine** is a calcium channel blocker commonly used for migraine prophylaxis, especially in Europe and other regions. - It helps stabilize vascular tone and neuronal excitability, reducing migraine frequency.

Practice by Chapter

General Anesthetics

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Local Anesthetics

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Sedative-Hypnotics

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Antiepileptic Drugs

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Antiparkinsonian Drugs

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Opioid Analgesics

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Drugs of Abuse and Addiction

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Psychostimulants

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Hallucinogens

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CNS Stimulants and Cognitive Enhancers

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