Central Nervous System Pharmacology Practice Questions

Q: Which of the following is not true about benzodiazepines?

REM, and Stage 3 and 4 sleep is increased. **REM, and Stage 3 and 4 sleep is increased** - Benzodiazepines actually **decrease REM sleep** and **slow-wave sleep** (Stages 3 and 4) while increasing Stage 2 sleep. - This alteration in sleep architecture contributes to less restorative sleep despite inducing sedation. *Can produce ataxia* - Benzodiazepines can cause **ataxia**, especially at higher doses, due to their depressant effects on the **cerebellum** and motor coordination centers. - This side effect is a common concern, particularly in older adults, increasing the risk of falls. *Has GABA facilitatory but no GABA mimetic action* - Benzodiazepines **facilitate the action of GABA** by increasing the *frequency* of chloride channel opening, leading to enhanced inhibitory neurotransmission. - They do not directly activate GABA receptors in the absence of GABA, meaning they have no direct **GABA mimetic action**. *Produces muscle relaxation by action on spinal cord* - Benzodiazepines exert their **muscle relaxant effects** primarily by enhancing *GABAergic inhibition* in the **spinal cord** and **brainstem**. - This leads to a reduction in skeletal muscle tone and can be beneficial in treating muscle spasms.

Q: Which drug is given in the pain due to diabetic neuropathy?

Gabapentin. ***Gabapentin*** - **Gabapentin** is a first-line agent often prescribed for neuropathic pain, including that caused by **diabetic neuropathy**. - It works by modulating voltage-gated **calcium channels**, reducing neurotransmitter release in the pain pathways. *Lamotrigine* - While an antiepileptic drug, **lamotrigine** is primarily used for **epilepsy** and **bipolar disorder**. - It is not a first-line treatment for **diabetic neuropathic pain**. *Na valproate* - **Sodium valproate** is an anticonvulsant and mood stabilizer, mainly used for epilepsy, **bipolar disorder**, and **migraine prophylaxis**. - It is not typically recommended for the management of **diabetic neuropathic pain**. *Morphine* - **Morphine** is a strong opioid analgesic used for severe acute or chronic pain. - While it can alleviate pain, it is generally considered a **second-line or third-line agent** for **neuropathic pain** due to risks of dependence and side effects.

Q: What is the drug of choice for aborting the acute attack of migraine?

Triptans such as sumatriptan. ***Triptans such as sumatriptan*** - **Triptans** are **serotonin 5-HT1B/1D receptor agonists** that cause **vasoconstriction** of intracranial blood vessels and inhibit pronociceptive neuropeptide release, making them highly effective for acute migraine attacks. - They are considered the **first-line specific treatment** for moderate to severe migraine pain or when NSAIDs are ineffective. *NSAIDs such as indomethacin* - **NSAIDs** are effective for mild to moderate migraine attacks but are generally **less effective** than triptans for severe attacks. - While they can reduce inflammation and pain, their mechanism of action is **non-specific** compared to triptans in targeting migraine pathology. *Opioids such as morphine* - **Opioids** are generally **not recommended** for acute migraine treatment due to their potential for **abuse, dependence**, and lack of specific anti-migraine effects. - They can also worsen migraine outcomes over time and contribute to **medication overuse headache**. *Glucocorticoids* - **Glucocorticoids** like dexamethasone may be used as **adjunctive therapy** to prevent migraine recurrence, particularly in status migrainosus. - However, they are **not the primary drug of choice** for aborting an acute attack due to their slower onset of action and broad side effect profile.

Q: Which of the following is a contraindication for the use of triptans?

Ischemic heart disease. ***Ischemic heart disease*** - Triptans are **serotonin 5-HT1B/1D receptor agonists** [1] that cause **vasoconstriction**, including of coronary arteries [2] - This is an **absolute contraindication** - coronary vasoconstriction can precipitate angina, myocardial infarction, or coronary vasospasm in patients with compromised cardiac blood flow [2] - Other absolute cardiovascular contraindications include previous MI, coronary artery vasospasm (Prinzmetal angina) [2], and **uncontrolled/severe hypertension** *Controlled hypertension* - Patients with **well-controlled hypertension** can generally use triptans safely with appropriate monitoring - While triptans may cause transient blood pressure elevation due to vasoconstriction, this is clinically insignificant when baseline BP is adequately controlled - **Uncontrolled or severe hypertension** (BP >140/90 mm Hg or severe elevations) is an absolute contraindication, but controlled hypertension is not *Hepatic failure* - Most triptans undergo hepatic metabolism, so **severe hepatic impairment** requires dose reduction or avoidance of certain triptans - This is a **precaution or relative contraindication** requiring dose adjustment, not an absolute contraindication like ischemic heart disease - Some triptans (e.g., sumatriptan) have alternative elimination routes and may be preferred in hepatic disease *None of the options* - This is incorrect because **ischemic heart disease** is a definitive absolute contraindication for all triptans [2] - The vasoconstrictive mechanism makes triptans unsafe in any condition with compromised coronary blood flow [2]

Q: Which drug is used to prolong the action of local anesthetics in hypertensive patients?

Felypressin. ***Felypressin*** - Felypressin is a **vasoconstrictor** that prolongs the action of local anesthetics by reducing their systemic absorption without causing significant **alpha-adrenergic stimulation**, making it a safer option for hypertensive patients. - It acts as a **vasopressin V1 receptor agonist**, leading to vasoconstriction primarily in the splanchnic and skeletal muscle beds, with less impact on cardiac function compared to adrenergic vasoconstrictors. *Clonidine* - Clonidine is an **alpha-2 adrenergic agonist** used as an adjuvant to local anesthetics, primarily for its **sedative** and **analgesic** properties, and to some extent for prolongation of block. - While it can prolong local anesthetic action, its primary use is not as a direct vasoconstrictor to reduce systemic absorption, and it can cause **hypotension** and **bradycardia**, which might complicate care in some hypertensive patients. *Dexmedetomidine* - Dexmedetomidine is a highly selective **alpha-2 adrenergic agonist** used for its **sedative** and **analgesic** effects, and as an adjunct to local anesthetics to prolong their duration. - Similar to clonidine, its primary role is not as a direct vasoconstrictor to minimize systemic absorption, and it carries the risk of **hypotension** and **bradycardia**, making it less ideal solely for vasoconstriction in hypertensive patients. *Noradrenaline* - Noradrenaline (norepinephrine) is a potent **alpha-1 adrenergic agonist** that causes intense vasoconstriction, which would significantly prolong the action of local anesthetics. - However, its strong vasoconstrictive effects and potential for **systemic arterial hypertension** and tachycardia make it generally contraindicated or used with extreme caution in hypertensive patients due to the risk of exacerbating their condition.

Q: Withdrawal of which of the following substances is most commonly associated with piloerection?

Morphine. ***Morphine*** - **Piloerection**, or "goosebumps," is a classic symptom of **opioid withdrawal**, particularly from strong opioids like morphine, due to sympathetic nervous system overactivity. - This sympathetic hyperactivity also manifests as **dilated pupils**, rhinorrhea, lacrimation, and sweating during opioid withdrawal. *Cannabis* - Withdrawal symptoms from **cannabis** typically include irritability, anxiety, sleep disturbances, and decreased appetite, but not prominent piloerection. - The sympathetic activation seen with opioid withdrawal is generally absent in cannabis withdrawal. *Smoking* - **Nicotine withdrawal** is characterized by irritability, anxiety, difficulty concentrating, and increased appetite, but **piloerection** is not a common or prominent symptom. - Nicotine withdrawal primarily affects neuropsychological functions and cravings, rather than leading to significant sympathetic overdrive causing skin manifestations. *Alcohol* - **Alcohol withdrawal** can be severe, including tremors, hallucinations, and seizures (delirium tremens), but **piloerection** is not a hallmark symptom. - Alcohol withdrawal primarily involves central nervous system hyperexcitability and autonomic dysfunction, but "goosebumps" are not typically reported as a key feature.

Q: Which of the following is not a use of Thiopentone?

As antidepressant. As antidepressant - **Thiopentone** is a short-acting **barbiturate** and a potent central nervous system depressant, with no known antidepressant properties. [1] - Its mechanism of action involves enhancing **GABAergic inhibition**, leading to sedation and anesthesia, not mood elevation. *Induction of anesthesia* - **Thiopentone** is a classic intravenous anesthetic, often used for **rapid induction of general anesthesia** due to its fast onset of action. [2], [4] - It quickly crosses the **blood-brain barrier** to produce unconsciousness, making it effective for this purpose. [4] *Medically induced coma* - **Thiopentone** can be used to induce and maintain a **medically induced coma**, particularly in cases of severe head injury or status epilepticus, to reduce metabolic demand and cerebral edema. [3] - Its ability to significantly suppress brain activity makes it suitable for **neuroprotection** in critical care settings. [3] *As truth serum* - Historically, **thiopentone** (often referred to as **sodium pentothal**) has been colloquially known as a **"truth serum"** due to its ability to lower inhibitions and make subjects more loquacious. - While it can facilitate questioning by making individuals less guarded, its effectiveness as a reliable truth serum is largely unsubstantiated and ethically controversial.

Q: Local anaesthetic causing methemoglobinemia is ?

Benzocaine. ***Benzocaine*** - **Benzocaine** is a common cause of **methemoglobinemia**, particularly with topical application or excessive doses. - It converts **ferrous iron (Fe2+)** in hemoglobin to **ferric iron (Fe3+)**, leading to impaired oxygen binding and delivery. *Dibucaine* - **Dibucaine** is an amide-type local anesthetic with a long duration of action. - While it can cause systemic toxicity, it is **not commonly associated** with methemoglobinemia. *Chloroprocaine* - **Chloroprocaine** is an ester-type local anesthetic known for its rapid hydrolysis by plasma cholinesterases. - Its short half-life and rapid metabolism make **methemoglobinemia an unlikely side effect**. *Procaine* - **Procaine** is another ester-type local anesthetic, the first synthetic local anesthetic. - While all ester-type local anesthetics have a theoretical risk, **procaine is rarely implicated** in causing clinically significant methemoglobinemia compared to benzocaine.

Q: Which of the following serotonin receptors is classified as an ionotropic receptor?

5-HT3. ***5-HT3*** - The 5-HT3 receptor is unique among serotonin receptors as it is the **only ionotropic receptor**, meaning it directly gates an ion channel upon ligand binding. - Activation of 5-HT3 receptors leads to rapid **depolarization** of the neuronal membrane through the influx of **sodium and potassium ions**, mediating fast excitatory neurotransmission. *5-HT1A* - The 5-HT1A receptor is a **G-protein coupled receptor (GPCR)** and is inhibitory, primarily located pre- and post-synaptically in the brain. - Activation leads to a decrease in **cAMP** levels and opening of **potassium channels**, resulting in hyperpolarization. *5-HT1B* - The 5-HT1B receptor is also a **GPCR**, primarily found on presynaptic terminals where it acts as an **autoreceptor** to inhibit serotonin release. - Similar to 5-HT1A, its activation inhibits adenylyl cyclase activity, leading to reduced **cAMP** levels. *5-HT2A* - The 5-HT2A receptor is a **GPCR** that couples to the Gq protein, leading to increased **inositol triphosphate (IP3)** and **diacylglycerol (DAG)**. - This pathway activates protein kinase C and mobilizes intracellular calcium, typically leading to **excitatory effects** in various brain regions.

Question 1

Which of the following is not true about benzodiazepines?

Accepted Answer

REM, and Stage 3 and 4 sleep is increased

Answer

Can produce ataxia

Answer

Has GABA facilitatory but no GABA mimetic action

Answer

Produces muscle relaxation by action on spinal cord

Question 2

Which drug is given in the pain due to diabetic neuropathy?

Accepted Answer

Gabapentin

Answer

Lamotrigine

Answer

Na valproate

Answer

Morphine

Question 3

What is the drug of choice for aborting the acute attack of migraine?

Accepted Answer

Triptans such as sumatriptan

Answer

NSAIDs such as indomethacin

Answer

Opioids such as morphine

Answer

Glucocorticoids

Question 4

Which of the following statements about the anti-Parkinson drug levodopa is true?

Accepted Answer

Only a small percentage of administered levodopa crosses the blood-brain barrier (approximately 2%).

Answer

Levodopa is an active metabolite of dopamine.

Answer

About 50% of administered levodopa is peripherally converted to dopamine.

Answer

Levodopa is not used in the management of hepatic coma.

Question 5

Which of the following is a contraindication for the use of triptans?

Accepted Answer

Ischemic heart disease

Answer

Hepatic failure

Answer

Controlled hypertension

Answer

None of the options

Question 6

Which drug is used to prolong the action of local anesthetics in hypertensive patients?

Accepted Answer

Felypressin

Answer

Clonidine

Answer

Dexmedetomidine

Answer

Noradrenaline

Question 7

Withdrawal of which of the following substances is most commonly associated with piloerection?

Accepted Answer

Morphine

Answer

Cannabis

Answer

Smoking

Answer

Alcohol

Question 8

Which of the following is not a use of Thiopentone?

Accepted Answer

As antidepressant

Answer

Induction of anesthesia

Answer

Medically induced coma

Answer

As truth serum

Question 9

Local anaesthetic causing methemoglobinemia is ?

Accepted Answer

Benzocaine

Answer

Dibucaine

Answer

Chloroprocaine

Answer

Procaine

Question 10

Which of the following serotonin receptors is classified as an ionotropic receptor?

Accepted Answer

5-HT3

Answer

5-HT1A

Answer

5-HT1B

Answer

5-HT2A

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

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