Central Nervous System Pharmacology Practice Questions

Q: Nephrotoxic agent is:

Methoxyflurane. ***Methoxyflurane*** - Methoxyflurane undergoes significant **metabolism** in the liver, releasing **fluoride ions** and dichloroacetic acid. - The fluoride ions can cause **dose-dependent high-output renal failure** by interfering with the kidney's concentrating ability, leading to nephrotoxicity. *N2O (Nitrous Oxide)* - While widely used, N2O is known for its ability to **oxidize vitamin B12**, which can impair methionine synthase activity. - It does not directly cause nephrotoxicity but is associated with **bone marrow suppression** with prolonged or repeated exposure. *Halothane* - Halothane is a potent **hepatotoxin**, primarily linked to **halothane-induced hepatitis**, ranging from mild liver enzyme elevation to fulminant hepatic failure. - It is not primarily associated with nephrotoxicity; its main organ toxicity concern is the **liver**. *Isoflurane* - Isoflurane is largely **excreted unchanged** by the lungs, with minimal metabolism. - Due to its low metabolism and minimal production of inorganic fluoride, it has a **low risk of nephrotoxicity**.

Q: Which of the following medications in the treatment of Parkinson's disease is an NMDA antagonist?

Amantadine. ***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.

Q: Modafinil is used for

Narcolepsy. ***Narcolepsy*** - **Modafinil** is a **wakefulness-promoting agent** primarily used to improve wakefulness in patients with excessive daytime sleepiness associated with **narcolepsy**. - Its mechanism involves increasing levels of **dopamine** and **norepinephrine** in specific brain regions, promoting alertness without significant cardiovascular or euphoric effects. *Psychogenic erectile dysfunction* - This condition is typically treated with **phosphodiesterase-5 (PDE5) inhibitors** like sildenafil or tadalafil, which improve blood flow to the penis. - Modafinil has no established role in the treatment of erectile dysfunction, as it does not directly affect the physiological mechanisms of erection. *Orthostatic hypotension* - **Orthostatic hypotension** is managed by increasing blood volume and venoconstriction, often using medications like **fludrocortisone** or **midodrine**. - While modafinil has some sympathomimetic properties, it is not a first-line or common treatment for orthostatic hypotension. *OCD* - **Obsessive-compulsive disorder (OCD)** is primarily treated with **selective serotonin reuptake inhibitors (SSRIs)** and cognitive-behavioral therapy (CBT). - Modafinil is not indicated for OCD and would not address the underlying pathology of obsessions and compulsions.

Q: Drug of choice in absence seizures:

Valproate. ***Valproate*** - **Valproate** is considered a **first-line drug for absence seizures**, particularly effective for **all types of generalized seizures** including absence, myoclonic, and tonic-clonic seizures. - It works by increasing GABA levels and modulating voltage-gated sodium channels, which helps to stabilize neuronal excitability. - **Advantage**: Provides **broad-spectrum coverage**, making it the preferred choice when **mixed seizure types** are present or when **juvenile absence epilepsy** is suspected. - **Note**: **Ethosuximide** is also a first-line drug for **pure typical absence seizures** (especially in children), but valproate is often preferred when broader anticonvulsant coverage is needed. *Carbamazepine* - **Carbamazepine** is effective for **focal (partial) seizures** and **generalized tonic-clonic seizures**. - It can **exacerbate or worsen absence seizures**, making it contraindicated in this seizure type. - Mechanism: Blocks voltage-gated sodium channels, which is ineffective for absence seizures. *Phenytoin* - **Phenytoin** is primarily used for **focal (partial) seizures** and **generalized tonic-clonic seizures**. - Like carbamazepine, **phenytoin can worsen absence seizures** and is contraindicated. - Its mechanism of action (sodium channel blockade) is not suitable for absence seizures. *BZD (Benzodiazepines)* - While benzodiazepines like **clonazepam** can be used as **adjunctive therapy** for refractory absence seizures, they are **not first-line drugs**. - **Limitations**: Sedation, tolerance development, and dependence risk. - **Diazepam** and **lorazepam** are reserved for **acute seizure management** (status epilepticus) rather than chronic seizure control.

Q: Drugs used in management of migraine include the following except?

Ethosuximide. ***Ethosuximide*** - **Ethosuximide** is an anti-epileptic drug primarily used to treat **absence seizures** by blocking T-type calcium channels [1]. - It has no established role in the **acute** or **prophylactic** management of migraine headaches. *Topiramate* - **Topiramate** is an anti-epileptic drug that is also approved for **migraine prophylaxis**. - Its mechanism of action in migraine includes modulating **GABA receptors**, blocking **voltage-sensitive sodium channels**, and inhibiting **carbonic anhydrase** [2]. *Valproate* - **Valproate** (valproic acid) is an anti-epileptic drug and mood stabilizer commonly used for **migraine prevention**. - Its migraine prophylactic effect is believed to involve increasing **GABA levels** and modulating **neurotransmitter release** [1]. *Verapamil* - **Verapamil** is a **calcium channel blocker** sometimes used off-label for **migraine prophylaxis**, particularly in cases of difficult-to-treat migraines or specific subtypes like **hemiplegic migraine**. - It works by reducing cerebral vasospasm and stabilizing neuronal membranes.

Q: What does Parkinsonism treatment primarily involve?

Balance of Ach & dopamine in striatum. ***Balance of Ach & dopamine in striatum*** - Parkinsonism involves a **dopamine deficiency** in the **nigrostriatal pathway**, leading to an imbalance with **acetylcholine (ACh)**. - Treatment aims to restore this **dopamine-ACh balance**, typically by increasing dopamine activity (levodopa, dopamine agonists) or reducing ACh activity (anticholinergics) in the **striatum**. *Dopamine antagonism* - **Dopamine antagonism** would worsen Parkinsonism symptoms by further reducing dopamine's effects. - Antipsychotic medications that are dopamine antagonists can actually induce **drug-induced parkinsonism**. *Dopamine release* - While increasing **dopamine availability** is part of treatment, this option is too narrow and doesn't capture the crucial aspect of balancing it against acetylcholine. - Treatment focuses on the **overall balance** between these neurotransmitter systems rather than just dopamine alone. *Serotonin enhancement* - **Serotonin** is not the primary neurotransmitter involved in Parkinsonism pathophysiology. - The core defect is in the **dopaminergic-cholinergic balance**, not serotonin systems, though serotonin may play a minor role in some non-motor symptoms.

Q: Which is not used in status epilepticus?

Metformin. ***Metformin*** - **Metformin** is an **oral hypoglycemic agent** used to treat **type 2 diabetes mellitus** and has no role in the management of seizures or status epilepticus. - Its primary mechanism involves decreasing **hepatic glucose production** and improving **insulin sensitivity**. *Lorazepam* - **Lorazepam** is a first-line treatment for **status epilepticus** due to its rapid onset of action and efficacy in terminating seizures. - It enhances the effect of **GABA** (gamma-aminobutyric acid) at the GABA-A receptor, leading to neuronal hyperpolarization and reduced excitability. *Phenytoin* - **Phenytoin** is a common second-line agent used in status epilepticus, administered after benzodiazepines, to maintain seizure control. - It works by blocking **voltage-gated sodium channels**, thereby stabilizing neuronal membranes and preventing repetitive firing. *Phenobarbitone* - **Phenobarbitone** (phenobarbital) is an effective antiepileptic drug, often considered as a second or third-line agent in status epilepticus, especially when other treatments fail. - It acts primarily by enhancing the activity of **GABA** at the GABA-A receptor, similar to benzodiazepines, but with a longer duration of action.

Q: Toxic focal myopathy is an adverse effect of:

Narcotics. ***Narcotics*** - **Narcotics**, particularly **pentazocine**, when injected repeatedly into the same muscle group, can lead to **toxic focal myopathy**. - This condition involves localized muscle damage, necrosis, and woody fibrosis at the injection site due to the direct toxic effect of the drug on muscle tissue. - Pentazocine-induced myopathy is a well-documented adverse effect in patients with chronic intramuscular injections. *Penicillin* - **Penicillin** is generally associated with **hypersensitivity reactions** like rash, anaphylaxis, or interstitial nephritis. - It is not typically known to cause focal myopathy as a direct adverse effect. *Aminoglycosides* - **Aminoglycosides** are primarily associated with **nephrotoxicity** and **ototoxicity**. - They can also cause **neuromuscular blockade**, but not focal muscle damage through direct toxicity to muscle tissue. *Insulin* - **Insulin** administration can cause **lipohypertrophy** or **lipoatrophy** at injection sites due to fat tissue changes. - However, it does not directly lead to **toxic focal myopathy** involving muscle tissue damage.

Q: Drugs used in Alzheimer's disease are all EXCEPT:

Biperidin. ***Biperidin*** - **Biperidin** is an **anticholinergic drug** primarily used to treat **Parkinson's disease** and **drug-induced extrapyramidal symptoms**. - Its **anticholinergic effects** can worsen cognitive function in Alzheimer's patients, making it unsuitable for their treatment. *Memantine* - **Memantine** is an **NMDA receptor antagonist** that helps regulate glutamate activity in the brain. - It is used to treat **moderate to severe Alzheimer's disease** by preventing overstimulation of neurons. *Rivastigmine* - **Rivastigmine** is a **cholinesterase inhibitor** used to treat mild to moderate Alzheimer's disease. - It works by increasing levels of **acetylcholine** in the brain, improving communication between nerve cells. *Donepezil* - **Donepezil** is another **cholinesterase inhibitor** commonly prescribed for mild to moderate Alzheimer's disease. - It helps to improve **cognitive function** by enhancing cholinergic neurotransmission.

Q: Prophylaxis for migraine -

Amitriptyline. ***Amitriptyline*** - **Amitriptyline**, a **tricyclic antidepressant**, is commonly used for migraine prophylaxis due to its neuromodulatory effects that can reduce headache frequency and severity. - It works by affecting neurotransmitters like **serotonin** and **norepinephrine**, which play a role in migraine pathophysiology. *Nifedipine* - **Nifedipine** is a **calcium channel blocker** primarily used for hypertension and angina, not typically for migraine prophylaxis. - While other calcium channel blockers like **verapamil** can be used for migraine, nifedipine is not a first-line or common choice. *Sumatriptan* - **Sumatriptan** is an **abortive medication** used to treat acute migraine attacks once they have started. - It works by constricting blood vessels and blocking pain pathways in the brain, but it is not used for chronic prevention. *Diazepam* - **Diazepam** is a **benzodiazepine** primarily used for anxiety, muscle spasms, and seizures due to its sedative and anxiolytic properties. - It is not indicated for migraine prophylaxis and can sometimes worsen headaches with chronic use or withdrawal.

Question 1

Nephrotoxic agent is:

Accepted Answer

Methoxyflurane

Answer

N2O

Answer

Halothane

Answer

Isoflurane

Question 2

Which of the following medications in the treatment of Parkinson's disease is an NMDA antagonist?

Accepted Answer

Amantadine

Answer

Selegiline

Answer

Entacapone

Answer

Ropinirole

Question 3

Modafinil is used for

Accepted Answer

Narcolepsy

Answer

Psychogenic erectile dysfunction

Answer

Orthostatic hypotension

Answer

OCD

Question 4

Drug of choice in absence seizures:

Accepted Answer

Valproate

Answer

Carbamazepine

Answer

Phenytoin

Answer

BZD

Question 5

Drugs used in management of migraine include the following except?

Accepted Answer

Ethosuximide

Answer

Topiramate

Answer

Valproate

Answer

Verapamil

Question 6

What does Parkinsonism treatment primarily involve?

Accepted Answer

Balance of Ach & dopamine in striatum

Answer

Dopamine antagonism

Answer

Dopamine release

Answer

Serotonin enhancement

Question 7

Which is not used in status epilepticus?

Accepted Answer

Metformin

Answer

Lorazepam

Answer

Phenytoin

Answer

Phenobarbitone

Question 8

Toxic focal myopathy is an adverse effect of:

Accepted Answer

Narcotics

Answer

Penicillin

Answer

Aminoglycosides

Answer

Insulin

Question 9

Drugs used in Alzheimer's disease are all EXCEPT:

Accepted Answer

Biperidin

Answer

Memantine

Answer

Rivastigmine

Answer

Donepezil

Question 10

Prophylaxis for migraine -

Accepted Answer

Amitriptyline

Answer

Sumatriptan

Answer

Diazepam

Answer

Nifedipine

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

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