Central Nervous System Pharmacology Practice Questions

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 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: 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 drug pairs is correctly matched?

Peripheral decarboxylase inhibitor - Benserazide. ***Peripheral decarboxylase inhibitor - Benserazide*** - **Benserazide** is a **peripheral decarboxylase inhibitor** that is commonly co-administered with **levodopa** to prevent its metabolism in the periphery. - By inhibiting the breakdown of levodopa outside the brain, **more levodopa can cross the blood-brain barrier**, where it is then converted to dopamine. *MAO-A inhibitor - Selegiline* - **Selegiline** is an **MAO-B inhibitor**, not an MAO-A inhibitor. It selectively inhibits the enzyme **monoamine oxidase B**, which is responsible for dopamine breakdown in the brain. - **MAO-A inhibitors** (like moclobemide) are primarily used as antidepressants, as they inhibit the breakdown of serotonin and norepinephrine. *COMT inhibitor - Rasagiline* - **Rasagiline** is an **MAO-B inhibitor**, similar to selegiline, used in the treatment of **Parkinson's disease** to reduce the breakdown of dopamine. - **COMT inhibitors** (like entacapone and tolcapone) block the enzyme **catechol-O-methyltransferase**, another enzyme involved in the peripheral and central metabolism of levodopa and dopamine. *Dopamine agonist - Amantadine* - **Amantadine** is an **antiviral drug** that also has **anti-Parkinsonian effects**, primarily through its influence on dopamine release and reuptake, as well as NMDA receptor antagonism. - While it modulates dopamine, it is not classified as a direct **dopamine agonist**; true dopamine agonists (like pramipexole and ropinirole) directly stimulate dopamine receptors.

Q: In the context of patients with liver failure, how does temazepam compare to diazepam?

Safer for patients with liver failure. ***Safer for patients with liver failure*** - Temazepam is primarily metabolized by **conjugation** (glucuronidation), resulting in inactive metabolites that are readily excreted by the kidneys. - This metabolic pathway is generally less impaired in the presence of **liver dysfunction** compared to oxidative metabolism. *Has a longer duration of action than diazepam* - Temazepam generally has a **shorter half-life** and duration of action compared to diazepam. - Diazepam's prolonged effect is largely due to its **active metabolites** which have long half-lives. *Undergoes extensive hepatic metabolism* - While temazepam does undergo hepatic metabolism, its primary pathway is **conjugation**, which is less reliant on the oxidative enzyme systems that are often compromised in liver failure. - In contrast, diazepam undergoes extensive **oxidative metabolism**, making it more problematic in liver dysfunction. *Has active metabolites that can accumulate in liver failure* - Temazepam's main metabolites are **inactive glucuronides**, which do not accumulate to produce significant pharmacological effects, even in liver failure. - **Diazepam**, however, is metabolized to active compounds like **desmethyldiazepam** and **oxazepam**, which can accumulate and cause prolonged sedation in liver failure.

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: Which of the following antiepileptic drugs is associated with causing congenital heart disease in the fetus?

Valproate. ***Valproate*** - **Valproate** is associated with the **highest overall risk of major congenital malformations** among antiepileptic drugs, affecting **10-20%** of exposed fetuses - While **neural tube defects** (spina bifida) are the most characteristic malformation, **cardiac defects** (including atrial septal defects, ventricular septal defects, and coarctation of aorta) occur in approximately **2-3%** of exposed pregnancies - The teratogenic risk is **dose-dependent**, with higher doses (>1000 mg/day) carrying substantially greater risk - Valproate is classified as **FDA Category X** (contraindicated in pregnancy) due to its high teratogenic potential *Phenytoin* - **Phenytoin** is associated with **fetal hydantoin syndrome**, which includes craniofacial abnormalities, limb defects, nail hypoplasia, and growth restriction - Cardiac defects do occur with phenytoin exposure (particularly septal defects), with an estimated risk of **2-3%** - However, the **overall rate of major malformations** is lower than valproate (approximately 6-10%) - While cardiac defects are part of the phenytoin teratogenicity spectrum, valproate carries a higher absolute risk *Carbamazepine* - **Carbamazepine** is primarily associated with **neural tube defects** (0.5-1% risk), particularly spina bifida - The overall risk of major congenital malformations is **approximately 4-6%**, lower than both valproate and phenytoin - Cardiac defects can occur but are less frequently reported compared to other malformations *Barbiturates* - **Barbiturates** (such as phenobarbital) have teratogenic potential including cardiac defects and cleft palate - The overall risk of major malformations is **estimated at 5-7%** - While cardiac defects have been reported, the evidence base is less robust than for valproate, and the absolute risk is lower

Q: All of the following about thiopentone are true except which one?

IV injection is painless. ***IV injection is painless*** - Thiopentone is a **barbiturate anesthetic** that is known to cause **pain on injection** due to its **alkaline pH** and propensity to cause local irritation. - This characteristic makes the statement that its IV injection is painless incorrect, as pain and venous irritation are common side effects. *It decreases ICP* - Thiopentone, like other barbiturates, causes **cerebral vasoconstriction**, leading to a decrease in **cerebral blood flow** and **intracranial pressure (ICP)**, making it useful in neurosurgical settings. - This effect is due to a reduction in **cerebral metabolic rate for oxygen (CMRO2)**, which couples with cerebral blood flow. *It has anticonvulsant action* - Thiopentone is a potent **anticonvulsant** because it enhances the inhibitory effects of **GABA** in the central nervous system, which helps to suppress seizure activity. - It is used to terminate **status epilepticus** that is refractory to other treatments. *It can cause reflex tachycardia* - Thiopentone can cause **peripheral vasodilation** and a decrease in **blood pressure**, which may trigger a **reflex tachycardia** as the body attempts to compensate for the reduced systemic vascular resistance. - This effect is generally mild but can be more pronounced in hypovolemic patients or at higher doses.

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.

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.

Question 1

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 2

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 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 drug pairs is correctly matched?

Accepted Answer

Peripheral decarboxylase inhibitor - Benserazide

Answer

Dopamine agonist - Amantadine

Answer

COMT inhibitor - Rasagiline

Answer

MAO-A inhibitor - Selegiline

Question 5

In the context of patients with liver failure, how does temazepam compare to diazepam?

Accepted Answer

Safer for patients with liver failure

Answer

Has a longer duration of action than diazepam

Answer

Undergoes extensive hepatic metabolism

Answer

Has active metabolites that can accumulate in liver failure

Question 6

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 7

Which of the following antiepileptic drugs is associated with causing congenital heart disease in the fetus?

Accepted Answer

Valproate

Answer

Carbamazepine

Answer

Phenytoin

Answer

Barbiturates

Question 8

All of the following about thiopentone are true except which one?

Accepted Answer

IV injection is painless

Answer

It has anticonvulsant action

Answer

It can cause reflex tachycardia

Answer

It decreases ICP

Question 9

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

Question 10

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

Accepted Answer

Morphine

Answer

Cannabis

Answer

Smoking

Answer

Alcohol

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

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