Central Nervous System Pharmacology Practice Questions

Q: Antiviral drug amantadine is approved for treating which of the following conditions?

Parkinsonism. ***Parkinsonism*** - **Amantadine** is an **antiviral agent** that also has **anti-Parkinsonian effects**, particularly useful for treating **dyskinesias** associated with long-term levodopa therapy. - It acts by influencing **dopaminergic neurotransmission** and has **NMDA receptor antagonist** properties. *Schizophrenia* - Schizophrenia is primarily treated with **antipsychotic medications** that target **dopamine** and **serotonin receptors**. - **Amantadine** is not indicated for the treatment of psychosis or other symptoms of schizophrenia. *Depression* - Depression is typically managed with **antidepressants** that modulate **serotonin**, **norepinephrine**, or **dopamine** levels. - **Amantadine** does not have established efficacy as an antidepressant drug. *Alzheimer's disease* - Treatment for Alzheimer's disease often involves **cholinesterase inhibitors** and **NMDA receptor antagonists** like memantine for cognitive symptoms. - While amantadine is an NMDA receptor antagonist, it is **not approved** or commonly used for the primary treatment of Alzheimer's disease.

Q: The following symptoms may be seen in opium withdrawal:

Lacrimation. ***Lacrimation*** - Opioid withdrawal is characterized by **autonomic hyperactivity**, leading to symptoms like **lacrimation** (tearing), rhinorrhea (runny nose), and piloerection. - This is a rebound effect from the chronic opioid suppression of the parasympathetic nervous system. *Tremors* - While tremors can occur in various withdrawal syndromes, they are more characteristic of **alcohol** or **benzodiazepine withdrawal**, which involve GABAergic systems. - Opioid withdrawal can cause muscle aches and spasms, but **significant, sustained tremors** are not a primary diagnostic criterion. *Dry nose and mouth* - **Dry mouth** is a common side effect of opioid use, due to their anticholinergic effects, but during **withdrawal**, patients experience increased secretions like rhinorrhea and **lacrimation**. - **Dry nose** is also contrary to the typical presentation of opioid withdrawal, which involves a **runny nose**. *Constipation* - **Constipation** is a well-known side effect of chronic opioid use due to reduced gut motility. - During withdrawal, patients typically experience **diarrhea** and abdominal cramping, as gut motility returns and often becomes hyperactive.

Q: Which of the following statements is FALSE regarding drugs in the treatment of Parkinsonism?

Amantadine is more effective than levodopa. ***Amantadine is more effective than levodopa*** - This statement is **false** because **levodopa** is considered the **gold standard** and most effective treatment for symptomatic Parkinsonism, especially for bradykinesia and rigidity [1, 2]. - While amantadine can be helpful for dyskinesias and offers modest symptomatic relief, its efficacy is significantly **less than levodopa** [1]. *Amantadine causes ankle edema* - This statement is **true**. **Amantadine** is known to cause **peripheral edema**, particularly in the ankles and feet, as a common side effect [1]. - This adverse effect can be managed by reducing the dose or discontinuing the drug if bothersome. *Levodopa is effective in reducing tremors* - This statement is **true**, though with an important caveat. **Levodopa** does reduce tremor in Parkinson's disease, but it is **less effective for tremor** compared to its dramatic effects on bradykinesia and rigidity [1]. - Among parkinsonian symptoms, **tremor responds least well to levodopa** and may require additional agents like anticholinergics or propranolol for optimal control. - Nevertheless, levodopa does provide tremor reduction in most patients, making this statement true overall. *Anti-muscarinic agents are effective in drug-induced Parkinsonism* - This statement is **true**. **Anticholinergic (anti-muscarinic) agents** like benztropine and trihexyphenidyl are often used to treat **drug-induced Parkinsonism**, particularly symptoms like tremor and dystonia [1, 2]. - This form of Parkinsonism is typically caused by dopamine receptor blocking drugs (antipsychotics), making anticholinergics effective by rebalancing cholinergic overactivity.

Q: Which of the following drugs is not effective in the treatment of trigeminal neuralgia?

Acetaminophen. ***Acetaminophen*** - **Acetaminophen** is a common **analgesic** and antipyretic but lacks the direct effect on neuronal hyperexcitability required for treating **neuropathic pain** conditions like trigeminal neuralgia. - Its mechanism of action primarily involves inhibiting prostaglandin synthesis peripherally and centrally, which is insufficient for managing the sharp, stabbing pain of **trigeminal neuralgia**. *Carbamazepine* - **Carbamazepine** is considered the **first-line treatment** for trigeminal neuralgia due to its efficacy in stabilizing hyperexcitable nerve membranes. - It works by blocking **voltage-gated sodium channels**, thereby reducing the firing of trigeminal nerve fibers. *Phenytoin sodium* - **Phenytoin** is an **antiepileptic drug** that can be used as a second-line or adjunctive treatment for trigeminal neuralgia. - Similar to carbamazepine, it acts by **inhibiting voltage-gated sodium channels**, thereby preventing repetitive firing of action potentials. *Baclofen* - **Baclofen** is a **GABA-B receptor agonist** that can be used in combination with carbamazepine or as an alternative for patients who do not respond to or tolerate carbamazepine. - It helps reduce the intensity and frequency of pain by **inhibiting excitatory neurotransmitter release** in the brainstem trigeminal nucleus.

Q: Which local anesthetic is considered the most cardiotoxic?

Bupivacaine. ***Bupivacaine*** - **Bupivacaine** is an amide-type local anesthetic associated with significant **cardiotoxicity** due to its high lipid solubility and slow dissociation from cardiac sodium channels. - This can lead to severe **arrhythmias** and myocardial depression, making it particularly dangerous in systemic overdose. *Procaine* - **Procaine** is an ester-type local anesthetic with a relatively low potential for cardiotoxicity. - Its rapid metabolism by **plasma pseudocholinesterase** limits systemic exposure and reduces the risk of cardiac effects. *Prilocaine* - **Prilocaine** is an amide-type local anesthetic that is generally less cardiotoxic than bupivacaine. - Its primary concern is the potential to cause **methemoglobinemia** at higher doses, a side effect not directly related to cardiotoxicity. *Ropivacaine* - **Ropivacaine** is an amide-type local anesthetic developed as an alternative to bupivacaine with a reduced cardiotoxicity profile. - It exhibits a more favorable **therapeutic index** for cardiac effects due to its chemical structure and faster dissociation from cardiac sodium channels.

Q: Which of the following drugs is the most commonly prescribed first-line treatment for Alzheimer's disease?

Donepezil. ***Donepezil*** - **Donepezil** is a **centrally acting, reversible acetylcholinesterase inhibitor** and is widely considered the **first-line treatment** for mild to moderate Alzheimer's disease due to its efficacy and once-daily dosing. - It works by increasing the concentration of **acetylcholine** in the synaptic cleft, thereby enhancing cholinergic transmission in the brain. *Rivastigmine* - **Rivastigmine** is also an **acetylcholinesterase inhibitor**, available in oral and transdermal patch formulations, and is used for mild to moderate Alzheimer's. - While effective, it is often considered a **second-line** or alternative agent due to potential for more gastrointestinal side effects compared to donepezil. *Galantamine* - **Galantamine** is another **acetylcholinesterase inhibitor** with an additional mechanism of action as an **allosteric potentiator of nicotinic acetylcholine receptors**. - It is effective in mild to moderate Alzheimer's but is not typically the very first choice given the established prevalence and convenience of donepezil. *Memantine* - **Memantine** is an **NMDA receptor antagonist** and works by blocking the effects of excessive **glutamate**, which is thought to contribute to neurodegeneration in Alzheimer's. - It is generally prescribed for **moderate to severe Alzheimer's disease** and is not considered a first-line treatment for early stages.

Q: Which group of afferent fibers is most sensitive to local anesthetics?

Group B fibers. ***Group B fibers***- These are **small, myelinated preganglionic autonomic fibers** that are the **MOST sensitive** to local anesthetics [1].- Their **small diameter combined with myelination** makes them highly susceptible to blockade at the **nodes of Ranvier**.- The classic order of sensitivity is: **B > C > A-delta > A-gamma > A-beta > A-alpha** [1].*Group C fibers*- These are **unmyelinated, small-diameter fibers** transmitting **dull pain and temperature** sensations.- They are the **second most sensitive** to local anesthetics after B fibers.- While their small diameter makes them susceptible, the lack of myelination means blockade occurs more slowly than in B fibers.*Group A fibers*- This group includes **large-diameter, myelinated fibers** (A , A , A , A ) transmitting motor, proprioception, touch, and sharp pain signals.- Their **larger diameter** provides **greater resistance** to local anesthetic blockade.- A-delta fibers (sharp pain) are more sensitive than other A fibers but still less sensitive than B and C fibers.*Group D fibers*- There is **no standard "Group D"** fiber classification in neurophysiology.- The standard classifications are **A (alpha, beta, gamma, delta), B, and C fibers** based on diameter and myelination status.

Q: Which of the following is a short-acting benzodiazepine?

Midazolam. ***Midazolam*** - **Midazolam** is a **short-acting benzodiazepine** with a rapid onset and short duration of action, mainly due to its high lipid solubility and rapid metabolism. - It is often used for **premedication**, **sedation** for procedures, and induction of **anesthesia**. *Lorazepam* - **Lorazepam** is an **intermediate-acting benzodiazepine** with a half-life of 10-20 hours. - It is commonly used for **anxiety**, **insomnia**, and *status epilepticus*, but its duration of action is longer than truly short-acting agents. *Diazepam* - **Diazepam** is a **long-acting benzodiazepine** with a half-life ranging from 20 to 100 hours, largely due to its active metabolites, such as **nordiazepam**. - It is used for conditions requiring sustained effects, such as **chronic anxiety**, **muscle spasms**, and **alcohol withdrawal**. *Temazepam* - **Temazepam** is an **intermediate-acting benzodiazepine** with a half-life of 8-20 hours. - It is primarily prescribed for **insomnia** due to its relatively quick onset and moderate duration of action, which is not as short as midazolam.

Q: Which of the following local anesthetic agents is a vasoconstrictor?

Cocaine. ***Cocaine*** - Cocaine is unique among local anesthetics as it is a potent **vasoconstrictor**, inhibiting **norepinephrine reuptake** at nerve terminals. - This vasoconstrictive property reduces bleeding and prolongs its anesthetic effect, but also contributes to its cardiotoxicity. *Lignocaine* - Lignocaine (Lidocaine) is an **amide-type local anesthetic** that causes **vasodilation**, which can lead to increased systemic absorption and a shorter duration of action [1]. - Due to its vasodilatory effect, **epinephrine** is often added to lignocaine to limit systemic absorption, prolong its effect, and reduce bleeding [1]. *Bupivacaine* - Bupivacaine is a long-acting **amide-type local anesthetic** that typically causes **vasodilation**, similar to lignocaine. - Its high potency and long duration of action make it suitable for local infiltrations and epidural anesthesia, but it also increases the risk of **cardiotoxicity** [1]. *Tetracaine* - Tetracaine is a potent and long-acting **ester-type local anesthetic** that also causes **vasodilation**. - It is primarily used for **spinal anesthesia** and topical applications and is usually combined with vasoconstrictors to prolong its effect.

Q: Which of the following drugs can be used as a transdermal patch for the treatment of Parkinson's disease?

Rotigotine. ***Rotigotine*** - **Rotigotine** is a **dopamine agonist** that is formulated as a **transdermal patch** for continuous delivery, improving compliance and reducing "off" times in Parkinson's disease. - The patch provides steady drug levels, minimizing motor fluctuations often seen with oral medications. *Levodopa* - Levodopa is the **most effective drug** for Parkinson's, but it's administered **orally** and has a short half-life, requiring frequent dosing. - While it can be combined with carbidopa/benserazide to prevent peripheral conversion, it is not available as a transdermal patch. *Apomorphine* - Apomorphine is a **potent dopamine agonist** used for rapid relief of "off" episodes; however, it is administered via **subcutaneous injection**. - It is not available in a transdermal patch formulation due to its chemical characteristics and rapid action. *Selegiline* - **Selegiline** is a **MAO-B inhibitor** that slows the breakdown of dopamine and is used as an adjunct in Parkinson's, and is available in **oral** and **sublingual forms**. - While it has transdermal formulations for depression (e.g., Emsam), it is not used as a patch for Parkinson's disease treatment.

Question 1

Antiviral drug amantadine is approved for treating which of the following conditions?

Accepted Answer

Parkinsonism

Answer

Depression

Answer

Alzheimer's disease

Answer

Schizophrenia

Question 2

The following symptoms may be seen in opium withdrawal:

Accepted Answer

Lacrimation

Answer

Tremors

Answer

Constipation

Answer

Dry nose and mouth

Question 3

Which of the following statements is FALSE regarding drugs in the treatment of Parkinsonism?

Accepted Answer

Amantadine is more effective than levodopa

Answer

Levodopa is effective in reducing tremors

Answer

Amantadine causes ankle edema

Answer

Anti-muscarinic agents are effective in drug-induced Parkinsonism

Question 4

Which of the following drugs is not effective in the treatment of trigeminal neuralgia?

Accepted Answer

Acetaminophen

Answer

Phenytoin sodium

Answer

Carbamazepine

Answer

Baclofen

Question 5

Which local anesthetic is considered the most cardiotoxic?

Accepted Answer

Bupivacaine

Answer

Procaine

Answer

Prilocaine

Answer

Ropivacaine

Question 6

Which of the following drugs is the most commonly prescribed first-line treatment for Alzheimer's disease?

Accepted Answer

Donepezil

Answer

Rivastigmine

Answer

Galantamine

Answer

Memantine

Question 7

Which group of afferent fibers is most sensitive to local anesthetics?

Accepted Answer

Group B fibers

Answer

Group A fibers

Answer

Group C fibers

Answer

Group D fibers

Question 8

Which of the following is a short-acting benzodiazepine?

Accepted Answer

Midazolam

Answer

Lorazepam

Answer

Diazepam

Answer

Temazepam

Question 9

Which of the following local anesthetic agents is a vasoconstrictor?

Accepted Answer

Cocaine

Answer

Lignocaine

Answer

Bupivacaine

Answer

Tetracaine

Question 10

Which of the following drugs can be used as a transdermal patch for the treatment of Parkinson's disease?

Accepted Answer

Rotigotine

Answer

Apomorphine

Answer

Levodopa

Answer

Selegiline

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

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