Central Nervous System Pharmacology Practice Questions

Q: Which of the following drugs is used for smoking cessation?

Varenicline. ***Varenicline*** - **Varenicline** is a **partial agonist** at the **α4β2 nicotinic acetylcholine receptor**, reducing cravings and withdrawal symptoms while decreasing the rewarding effects of nicotine [2]. - It is a first-line pharmacotherapy for **smoking cessation**, often initiated a week before the target quit date. *Gabapentin* - **Gabapentin** is primarily an **anticonvulsant** and is also used to treat **neuropathic pain**. - It is not indicated for **smoking cessation** and acts by modulating **GABAergic neurotransmission**, unrelated to nicotine dependence. *Acamprosate* - **Acamprosate** is used to maintain **abstinence from alcohol** in patients with alcohol dependence. - Its mechanism involves restoring the balance between **excitation and inhibition** in the brain, which is not directly applicable to nicotine dependence. *Nalmefene* - **Nalmefene** is an **opioid system modulator** used for reducing **alcohol consumption** in adults with alcohol dependence [1]. - It acts as an **opioid receptor antagonist**, a mechanism distinct from the neurotransmitter systems involved in nicotine addiction [1].

Q: Which of the following is not an ESTER?

Bupivacaine. ***Bupivacaine*** - Bupivacaine is an **amide-type local anesthetic** because it contains an amide linkage in its chemical structure. - Amide-type local anesthetics are metabolized in the liver, generally having a **longer duration of action** and a lower risk of allergic reactions compared to esters. *Benzocaine* - Benzocaine is an **ester-type local anesthetic**, characterized by an ester linkage that connects the aromatic ring and the amine group, though it lacks a tertiary amine. - It is typically used for **topical applications** due to its poor water solubility and rapid metabolism by plasma esterases. *Amethocaine* - Amethocaine (also known as tetracaine) is an **ester-type local anesthetic**, identifiable by its ester bond. - It has a relatively **long duration of action** for an ester and is often used for spinal anesthesia and topical applications. *Procaine* - Procaine is an **ester-type local anesthetic**, containing the characteristic ester linkage in its chemical structure. - It was one of the first local anesthetics discovered and has a **short duration of action** due to rapid metabolism by plasma pseudocholinesterase.

Q: True about MDMA:

Ecstasy is another name for it. Ecstasy is another name for it - MDMA (3,4-methylenedioxymethamphetamine) is widely known by its street name, Ecstasy [1]. - This name refers to its profound empathogenic effects and sense of well-being it often induces. It is a cocaine congener - MDMA is an amphetamine derivative and acts primarily on serotonin, dopamine, and norepinephrine systems, distinct from cocaine's primary action as a reuptake inhibitor [1], [2]. - While both MDMA and cocaine are stimulants, their chemical structures and primary mechanisms of action are different; MDMA is a substituted amphetamine [1]. Methadone is used to treat withdrawal symptoms - Methadone is an opioid agonist primarily used in the management of opioid dependence and withdrawal symptoms [3]. - MDMA withdrawal symptoms are typically managed with supportive care, focusing on symptom relief and psychological support, as there is no specific pharmacological treatment like methadone for MDMA withdrawal [3]. Causes parkinsonism like syndrome - While MDMA can cause neurotoxicity, particularly affecting serotonergic neurons, it is not typically associated with a direct parkinsonism-like syndrome [2]. - Parkinsonism is primarily linked to dopaminergic system damage, often seen with certain neuroleptics or drugs like MPTP, not MDMA.

Q: Which of the following nerve fibre types is least susceptible to LA blockade?

A alpha. **A alpha** - **A alpha fibers** are the **largest** and most heavily myelinated nerve fibers, responsible for **motor function** and **proprioception**. - Due to their large diameter and thick myelination, they have the **highest conduction velocity** and are the **least susceptible to local anesthetic blockade**, requiring higher concentrations or longer exposure times. *B fibers* - **B fibers** are **preganglionic autonomic fibers** that are myelinated but of relatively small diameter. - They are generally **highly sensitive to local anesthetics**, often being blocked even before A-delta and C fibers, due to their specific physiologic properties like repetitive firing and length of node of Ranvier. *C fibers* - **C fibers** are **unmyelinated** and have the **smallest diameter**, transmitting **pain, temperature, and autonomic information**. - Despite being unmyelinated, their small diameter makes them **highly sensitive to local anesthetics**, as the drug can easily penetrate to block sodium channels. *A beta* - **A beta fibers** are large, myelinated fibers involved in transmitting **touch and pressure sensations**. - While myelinated, they are **smaller than A-alpha fibers** and thus more susceptible to local anesthetic blockade than A-alpha, but less so than C or B fibers.

Q: Which anti-epileptic drug is most likely to cause aplastic anemia?

Carbamazepine. ***Carbamazepine*** - **Carbamazepine** is an anti-epileptic drug that can cause **aplastic anemia** as a rare but serious adverse effect. It is also known to cause other hematological side effects like leukopenia and thrombocytopenia. - Regular monitoring of **complete blood counts** is recommended, especially during the initial phases of treatment, due to this risk. *Phenytoin* - While **phenytoin** can cause various adverse effects, including **folate deficiency** leading to megaloblastic anemia, it is not typically associated with **aplastic anemia**. - Other common side effects include gingival hyperplasia, hirsutism, and Stevens-Johnson syndrome. *Levetiracetam* - **Levetiracetam** is generally well-tolerated and is rarely associated with severe hematological adverse events like **aplastic anemia**. - Its most common side effects are somnolence, asthenia, and behavioral changes. *Valproate* - **Valproate** can cause **thrombocytopenia** and, in rare instances, bone marrow suppression, but it is not a primary cause of **aplastic anemia**. - Its most concerning adverse effects include hepatotoxicity and pancreatitis.

Q: A 50-year-old with Parkinson's disease is on levodopa. Adding which drug helps manage 'wearing-off' effects?

Entacapone. ***Entacapone*** - **Entacapone** is a **COMT inhibitor** that prolongs the action of **levodopa** in the brain by preventing its peripheral breakdown. - This effectively reduces the "wearing-off" phenomenon, where the effects of levodopa diminish before the next dose. *Amantadine* - **Amantadine** is primarily used to treat **dyskinesias** associated with long-term levodopa therapy in Parkinson's disease. - While it has some dopaminergic activity, it is not the primary choice for managing **"wearing-off" fluctuations**. *Selegiline* - **Selegiline** is an **MAO-B inhibitor** that prevents the breakdown of dopamine in the brain, offering mild symptomatic benefit. - It's typically used in early Parkinson's or as an adjunct, but less effective for **"wearing-off"** compared to COMT inhibitors. *Bromocriptine* - **Bromocriptine** is a **dopamine agonist** that directly stimulates dopamine receptors. - It can be used for motor fluctuations but is more commonly associated with side effects and is generally less preferred than newer dopamine agonists for advanced Parkinson's.

Q: Which sedative is most appropriate in a patient with hepatic impairment?

Lorazepam. ***Lorazepam*** - **Lorazepam** is primarily metabolized by **glucuronidation**, a phase II metabolic pathway that is relatively preserved in most forms of hepatic impairment - This makes it a safer choice in patients with **liver disease** compared to other benzodiazepines that rely heavily on oxidative metabolism - Preferred sedative in cirrhosis and acute liver failure *Midazolam* - **Midazolam** is primarily metabolized by the **cytochrome P450 3A4 (CYP3A4)** enzyme system in the liver - Hepatic impairment can significantly reduce **CYP3A4 activity**, leading to prolonged half-life, increased sedative effects, and accumulation of the drug - Should be avoided or dose-reduced in hepatic impairment *Zolpidem* - **Zolpidem** is extensively metabolized by **hepatic cytochrome P450 enzymes**, particularly CYP3A4 and CYP2C9 - In patients with **hepatic impairment**, its clearance is significantly reduced, necessitating dose reduction to avoid excessive sedation and adverse effects - Maximum dose should be limited to 5 mg in hepatic dysfunction *Diazepam* - **Diazepam** undergoes extensive **hepatic oxidative metabolism** via CYP2C19 and CYP3A4 to active metabolites such as **desmethyldiazepam**, which also have long half-lives - In patients with **liver disease**, this metabolism is impaired, leading to prolonged drug action, increased sedation, and accumulation of the parent drug and active metabolites - Active metabolites can accumulate for days to weeks in hepatic impairment

Q: Which of the following drugs is most associated with neuroleptic malignant syndrome?

Haloperidol. ***Haloperidol*** - **Haloperidol** is a potent **first-generation antipsychotic** that strongly blocks **D2 dopamine receptors**. - This strong dopamine antagonism, particularly in the **nigrostriatal pathway**, is a primary mechanism underlying the development of **Neuroleptic Malignant Syndrome (NMS)**. *Clozapine* - Although clozapine is an antipsychotic, it is associated with a **lower risk of NMS** compared to high-potency typical antipsychotics. - Its unique pharmacological profile, including **weak D2 receptor blockade** and antagonism of other receptors, contributes to its reduced NMS risk. *Quetiapine* - Quetiapine is an **atypical (second-generation) antipsychotic** known for its **low risk of extrapyramidal symptoms (EPS)** and thus NMS. - Its relatively **loose binding to D2 receptors** and rapid dissociation significantly lowers the likelihood of severe dopamine blockade. *Olanzapine* - Olanzapine is another **atypical antipsychotic** with a **lower incidence of NMS** compared to typical antipsychotics like haloperidol. - While it has D2 receptor antagonism, it is less potent and more balanced by other receptor effects, leading to a reduced risk of NMS.

Q: Cannabidiol is not used for

Rett syndrome. ***Rett syndrome*** - **Cannabidiol (CBD)** is not an approved or commonly used treatment for Rett syndrome, which is a **neurodevelopmental disorder** primarily affecting girls. - Treatment for Rett syndrome focuses on managing symptoms with supportive care, **physiotherapy**, occupational therapy, and medications for specific issues like seizures or gastrointestinal problems. *Dravet syndrome* - **Cannabidiol (Epidiolex)** is approved in many regions for the treatment of seizures associated with **Dravet syndrome**, a severe form of epilepsy. - It works by modulating the **endocannabinoid system**, which plays a role in seizure control. *Lennox-Gastaut syndrome* - **Cannabidiol (Epidiolex)** is also approved for the treatment of seizures associated with **Lennox-Gastaut syndrome**, another severe and intractable childhood epilepsy. - Its efficacy in reducing seizure frequency in LGS has been demonstrated in clinical trials. *Tuberous sclerosis complex* - While not as widely established as for Dravet or Lennox-Gastaut, **cannabidiol (Epidiolex)** has shown promise and is approved in some regions for treating seizures associated with **tuberous sclerosis complex (TSC)**. - TSC is a genetic disorder causing benign tumors in multiple organs, often leading to epilepsy.

Q: In which of the following conditions are cannabinoids not commonly used for treatment?

Rett syndrome. ***Rett syndrome*** - Cannabinoids are **NOT commonly used** as an established treatment for **Rett syndrome** - While some research is exploring their potential therapeutic role, they remain **investigational only** and lack FDA approval for this indication - Current management focuses on symptomatic treatment including physical therapy, anti-epileptics for seizures, and supportive care - Unlike the other conditions listed, there is **no established cannabinoid therapy** for Rett syndrome in clinical practice *Dravet syndrome* - **Cannabidiol (CBD/Epidiolex)** is **FDA-approved** and commonly used for treatment of seizures associated with **Dravet syndrome** - Demonstrates significant efficacy in reducing seizure frequency in this severe infantile-onset epilepsy - Represents a major therapeutic advance for this treatment-resistant condition *Tuberous sclerosis* - **Cannabidiol (CBD/Epidiolex)** received **FDA approval in 2018** for treatment of seizures associated with **tuberous sclerosis complex (TSC)** - Commonly used as an adjunctive therapy alongside other treatments like vigabatrin or mTOR inhibitors (everolimus) - Clinical trials demonstrated significant reduction in seizure frequency in TSC patients *Lennox-Gastaut Syndrome* - **Cannabidiol (CBD/Epidiolex)** is **FDA-approved** for seizures associated with **Lennox-Gastaut Syndrome (LGS)** - Commonly used in this severe epileptic encephalopathy characterized by multiple seizure types and developmental delay - Effective in reducing seizure burden in patients refractory to traditional anti-epileptic drugs

Question 1

Which of the following drugs is used for smoking cessation?

Accepted Answer

Varenicline

Answer

Gabapentin

Answer

Acamprosate

Answer

Nalmefene

Question 2

Which of the following is not an ESTER?

Accepted Answer

Bupivacaine

Answer

Benzocaine

Answer

Amethocaine

Answer

Procaine

Question 3

True about MDMA:

Accepted Answer

Ecstasy is another name for it

Answer

It is a cocaine congener

Answer

Methadone is used to treat withdrawal symptoms

Answer

Causes parkinsonism like syndrome

Question 4

Which of the following nerve fibre types is least susceptible to LA blockade?

Accepted Answer

A alpha

Answer

B fibers

Answer

A beta

Answer

C fibers

Question 5

Which anti-epileptic drug is most likely to cause aplastic anemia?

Accepted Answer

Carbamazepine

Answer

Phenytoin

Answer

Levetiracetam

Answer

Valproate

Question 6

A 50-year-old with Parkinson's disease is on levodopa. Adding which drug helps manage 'wearing-off' effects?

Accepted Answer

Entacapone

Answer

Amantadine

Answer

Selegiline

Answer

Bromocriptine

Question 7

Which sedative is most appropriate in a patient with hepatic impairment?

Accepted Answer

Lorazepam

Answer

Midazolam

Answer

Zolpidem

Answer

Diazepam

Question 8

Which of the following drugs is most associated with neuroleptic malignant syndrome?

Accepted Answer

Haloperidol

Answer

Clozapine

Answer

Quetiapine

Answer

Olanzapine

Question 9

Cannabidiol is not used for

Accepted Answer

Rett syndrome

Answer

Lennox-Gastaut syndrome

Answer

Dravet syndrome

Answer

Tuberous sclerosis complex

Question 10

In which of the following conditions are cannabinoids not commonly used for treatment?

Accepted Answer

Rett syndrome

Answer

Tuberous sclerosis

Answer

Lennox-Gastaut Syndrome

Answer

Dravet syndrome

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

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