Central Nervous System Pharmacology Practice Questions

Q: The drug of choice for infantile spasms in a patient with tuberous sclerosis is:

Vigabatrin. ***Vigabatrin*** - **Vigabatrin** is considered the **first-line treatment** for **infantile spasms** associated with **tuberous sclerosis complex (TSC)**. - Its mechanism of action involves **irreversibly inhibiting GABA transaminase**, thereby increasing GABA levels in the brain. - It has shown **superior efficacy** in TSC-related infantile spasms compared to other antiepileptic drugs, with response rates of 70-95% in this specific population. - While ACTH (adrenocorticotropic hormone) is an alternative first-line agent for non-TSC infantile spasms, vigabatrin is specifically preferred in TSC due to its effectiveness and the underlying pathophysiology. *Lamotrigine* - While an effective **antiepileptic drug** for various seizure types, **lamotrigine** is not the primary choice for infantile spasms, especially in the context of TSC. - It works by blocking **voltage-gated sodium channels** and modulating calcium channels, but its efficacy for infantile spasms is generally lower than first-line options. - Lamotrigine is more commonly used for focal seizures and generalized tonic-clonic seizures. *Levetiracetam* - **Levetiracetam** is a broad-spectrum antiepileptic drug, but it is typically used as a **second-line or adjunctive therapy** for infantile spasms. - Its primary mechanism involves binding to the **synaptic vesicle protein 2A (SV2A)**, modulating neurotransmitter release. - While well-tolerated, it has not demonstrated the same level of efficacy as vigabatrin or ACTH for infantile spasms. *Tiagabine* - **Tiagabine** works by blocking the reuptake of **GABA** through GABA transporter 1 (GAT-1), thereby increasing GABAergic transmission. - It is **not indicated for infantile spasms** and is primarily used for focal seizures. - Tiagabine can sometimes precipitate or worsen non-convulsive status epilepticus and spike-wave stupor, making it inappropriate for this condition.

Q: The use of levodopa is avoided in which of the following patients?

Psychosis. ***Psychosis*** - Levodopa increases **dopaminergic activity** in the brain, which can significantly worsen or induce **psychotic symptoms** like hallucinations and delusions. - Patients with pre-existing psychosis or a history of psychotic episodes are at high risk, making levodopa a **contraindicated** treatment. *Alzheimer's disease* - While Alzheimer's patients may experience motor symptoms, levodopa is generally not avoided unless there are specific **parkinsonian features** responsive to dopamine. - The primary symptoms of Alzheimer's are **cognitive decline**, which levodopa does not treat and could potentially worsen agitation or confusion in advanced stages. *Amyotrophic lateral sclerosis* - **ALS** is a progressive neurodegenerative disease affecting motor neurons, leading to muscle weakness and atrophy. - Levodopa is **not effective** in treating ALS because the disease pathology does not involve dopamine deficiency. *Essential tremor* - Essential tremor is a movement disorder primarily treated with **beta-blockers** or **anti-seizure medications**. - Levodopa has **no established efficacy** in treating essential tremor, and its use is unrelated to its pathophysiology.

Q: Which of the following is not a treatment option for patients with relapsing-remitting multiple sclerosis?

Cyclophosphamide. ***Cyclophosphamide*** - This is an **immunosuppressant** primarily used in severe autoimmune conditions or certain cancers, not a standard maintenance treatment for **relapsing-remitting multiple sclerosis (RRMS)**. - While it has been explored for severe, rapidly worsening MS, it is not considered a first-line or common treatment option for RRMS due to its significant toxicity and side effect profile. *IFN-β1b* - **Interferon beta-1b** is a well-established **disease-modifying therapy** for RRMS, shown to reduce the frequency and severity of relapses. - It works by modulating the immune system to decrease inflammation and demyelination in the central nervous system. *IFN-β1a* - **Interferon beta-1a** (both intramuscular and subcutaneous formulations) is also a widely used **disease-modifying therapy** for RRMS. - Similar to interferon beta-1b, it helps to reduce relapse rates and slow the progression of disability in patients with RRMS. *Glatiramer acetate* - This is another common **disease-modifying therapy** for RRMS, which acts as a "decoy" myelin basic protein. - It works by inducing **T-cell anergy** and shifting the immune response from pro-inflammatory to anti-inflammatory, reducing attacks on myelin.

Q: Acute opioid withdrawal is characterized by which of the following symptoms?

Rhinorrhea, Piloerection, Insomnia. ***Rhinorrhea, Piloerection, Insomnia*** - **Rhinorrhea** (runny nose) and **piloerection** (goosebumps) are classic autonomic signs of opioid withdrawal, often described as "cold turkey." - **Insomnia** is a common and distressing symptom of opioid withdrawal, reflecting the hyperactivity of the central nervous system. *Rhinorrhea, Piloerection, Miosis* - While **rhinorrhea** and **piloerection** are characteristic of opioid withdrawal, **miosis** (pupil constriction) is a symptom of **opioid intoxication**, not withdrawal. - Opioid withdrawal typically causes **mydriasis** (pupil dilation) due to sympathetic overactivity. *Rhinorrhea, Piloerection, Constipation* - **Rhinorrhea** and **piloerection** are correct signs of opioid withdrawal. However, **constipation** is a well-known side effect of **opioid use** itself, not a symptom of opioid withdrawal. - Opioid withdrawal more commonly presents with **diarrhea** as gastrointestinal motility increases. *Insomnia, Constipation* - **Insomnia** is a symptom of opioid withdrawal, but **constipation** is not; rather, it is associated with opioid use. - This option also omits other key withdrawal symptoms such as **rhinorrhea** and **piloerection**.

Q: What is the most common side effect of haloperidol?

Akathisia. ***Akathisia*** - **Akathisia** is one of the **most common extrapyramidal symptoms (EPS)** associated with haloperidol, occurring in **20-75% of patients**. - It is characterized by a feeling of **inner restlessness** and an **inability to stay still**, often manifesting as pacing, rocking, or shifting weight. - Haloperidol, a high-potency **first-generation antipsychotic**, has a high propensity to cause EPS, including akathisia, due to its **strong dopamine D2 receptor blockade** in the nigrostriatal pathway. - Along with drug-induced parkinsonism, akathisia is among the most frequently encountered side effects with haloperidol use. *Hypotension* - While orthostatic hypotension can occur with antipsychotics, particularly those with strong **alpha-1 adrenergic blockade** (e.g., lower potency first-generation antipsychotics like chlorpromazine, or some second-generation antipsychotics), it is not the most common side effect of haloperidol. - Haloperidol has relatively **weak alpha-1 blocking activity** compared to other antipsychotics. *Dryness of mouth* - **Dryness of mouth (xerostomia)** is a common anticholinergic side effect of some antipsychotics, but it is not the most common or prominent side effect of haloperidol. - Haloperidol has relatively **weak anticholinergic activity** compared to lower potency antipsychotics. *Tic disorder* - **Tic disorders** are characterized by sudden, rapid, recurrent, nonrhythmic motor movements or vocalizations. - While haloperidol can be used to **treat severe tics** (e.g., in Tourette syndrome), it is not a common side effect of the medication itself; rather, it is a condition that antipsychotics like haloperidol may target therapeutically.

Q: What is the preferred first-line treatment for a young patient (under 65 years) newly diagnosed with Parkinson's disease?

Dopamine agonist. ***Dopamine agonist*** - For younger patients (typically under 65-70 years) with Parkinson's disease, **dopamine agonists** (e.g., pramipexole, ropinirole) are traditionally preferred as initial therapy to delay the introduction of levodopa. - This approach aims to reduce the risk of **motor complications** (e.g., dyskinesias, motor fluctuations) associated with long-term levodopa use. - This represents the **classical treatment strategy** commonly taught for medical examinations, though current clinical practice increasingly emphasizes individualized treatment decisions. *Levodopa* - While the **most effective symptomatic treatment** for Parkinson's disease, levodopa is traditionally reserved for older patients or those with more severe symptoms requiring greater symptomatic control. - Long-term use of levodopa, especially when started young, has been associated with **motor complications** like dyskinesia and wearing-off phenomena. - However, levodopa provides superior quality of life benefits and remains the gold standard for motor symptom control. *MAO-B inhibitor* - **MAO-B inhibitors** (e.g., selegiline, rasagiline) offer **mild symptomatic benefit** and may have neuroprotective properties. - Their efficacy for significant motor symptoms is less than dopamine agonists or levodopa. - They are often used as **adjunct therapy** or in very early disease with mild symptoms, not typically as first-line monotherapy for managing primary motor symptoms in younger patients. *Amantadine* - **Amantadine** is primarily used to relieve **levodopa-induced dyskinesia** in later stages of Parkinson's disease. - It also has mild symptomatic benefit for tremor and rigidity but is **not a first-line agent** due to weaker efficacy compared to dopamine agonists. - Side effects include livedo reticularis and confusion, particularly in elderly patients.

Q: Adverse effects of phenytoin include the following EXCEPT:

Hypercalcemia. ***Hypercalcemia*** - Phenytoin can actually lead to **hypocalcemia** due to its effect on vitamin D metabolism, increasing its degradation and leading to osteomalacia or rickets [1]. - Therefore, **hypercalcemia** is not an expected adverse effect of phenytoin use. *Lymphadenopathy* - **Generalized lymphadenopathy** is a known, though less common, adverse effect of phenytoin, sometimes mimicking lymphoma. - It's part of a broader hypersensitivity reaction that can occur with the drug. *Ataxia* - **Ataxia** is a common dose-dependent adverse effect of phenytoin, especially at higher therapeutic or toxic levels [1], [2]. - It manifests as impaired coordination and balance due to cerebellar dysfunction [1]. *Hirsutism* - **Hirsutism**, or excessive hair growth, is a well-known chronic side effect of phenytoin [1]. - This effect is more aesthetically concerning than medically dangerous and is particularly common in young women [1].

Q: Which of the following is a pure opioid antagonist?

Naloxone. ***Naloxone*** - **Naloxone** is a pure opioid antagonist that rapidly reverses the effects of opioid agonists by competing for opioid receptor binding sites [1,2]. - It has a high affinity for μ-opioid receptors and acts as a competitive antagonist [1], making it clinically useful for treating **opioid overdose**. *Buprenorphine* - **Buprenorphine** is a **partial opioid agonist** at the μ-opioid receptor and an antagonist at the κ-opioid receptor [4]. - It can precipitate withdrawal in opioid-dependent individuals if administered while full agonists are present due to its partial agonistic activity. *Pentazocine* - **Pentazocine** is a **mixed opioid agonist-antagonist**, acting as a partial agonist or antagonist at μ-opioid receptors and an agonist at κ-opioid receptors. - Its effects can vary, including analgesia (kappa agonism) and potential for withdrawal symptoms in opioid-dependent individuals (mu antagonism). *Morphine* - **Morphine** is a potent **full opioid agonist** that primarily acts on μ-opioid receptors, producing analgesia, sedation, and euphoria [3]. - It does not block opioid receptors; instead, it activates them, leading to its therapeutic and adverse effects.

Q: Which of these anticonvulsants causes a contraction of the visual field?

Vigabatrin. ***Vigabatrin*** - **Vigabatrin** is known to cause **irreversible concentric visual field constriction** in a significant percentage of patients, often leading to a permanent reduction in peripheral vision. - This adverse effect, often termed Vigabatrin-associated Visual Field Defect (VAVFD), is due to its impact on the **retina** and is thought to involve GABAergic pathways in the visual system. *Levetiracetam* - **Levetiracetam** is generally well-tolerated and is not commonly associated with significant visual field defects. - Common side effects are primarily neurological, such as **somnolence**, **dizziness**, and **behavioral changes**. *Phenytoin* - **Phenytoin** is more likely to cause dose-related ocular side effects such as **nystagmus** (involuntary eye movements) and **diplopia** (double vision), rather than a contraction of the visual field. - Long-term use can also lead to **gingival hyperplasia** and **hirsutism**. *Ethosuximide* - **Ethosuximide** is primarily used for **absence seizures** and its common side effects are gastrointestinal (**nausea**, **vomiting**, **anorexia**) and neurological (**drowsiness**, **dizziness**, **headache**). - It does not typically cause visual field constriction, which is a rare and specific side effect of certain other anticonvulsants.

Q: Which of the following drugs is not suitable for the management of essential tremors?

Levodopa. ***Levodopa*** - **Levodopa** is primarily used to treat **Parkinson's disease**, specifically targeting its hallmark **bradykinesia** and **rigidity**, not essential tremor. - Its mechanism of action involves increasing dopamine levels in the brain, which is not an effective strategy for essential tremor, and it may even **exacerbate tremor** in some cases. *Diazepam* - **Diazepam**, a **benzodiazepine**, can be used as an adjunct in essential tremor management, particularly for patients experiencing significant **anxiety** that exacerbates their tremor. - It acts by enhancing the effect of **GABA**, leading to a calming effect and muscle relaxation, which can mildly reduce tremor severity. *Metoprolol* - **Metoprolol** is a **beta-blocker** that can be used for essential tremor, especially when **propranolol** is not tolerated or contraindicated. - It works by blocking beta-adrenergic receptors, which helps to reduce the physiological tremor component and is often effective for patients with a triggered or anxiety-related tremor. *Propranolol* - **Propranolol** is considered a **first-line treatment** for essential tremor due to its efficacy in reducing tremor amplitude, particularly in the hands. - It is a non-selective beta-blocker that reduces **sympathetic nervous system** overactivity, which contributes to tremor pathogenesis.

Question 1

The drug of choice for infantile spasms in a patient with tuberous sclerosis is:

Accepted Answer

Vigabatrin

Answer

Lamotrigine

Answer

Levetiracetam

Answer

Tiagabine

Question 2

The use of levodopa is avoided in which of the following patients?

Accepted Answer

Psychosis

Answer

Amyotrophic lateral sclerosis

Answer

Alzheimer's disease

Answer

Essential tremor

Question 3

Which of the following is not a treatment option for patients with relapsing-remitting multiple sclerosis?

Accepted Answer

Cyclophosphamide

Answer

IFN-β1b

Answer

IFN-β1a

Answer

Glatiramer acetate

Question 4

Acute opioid withdrawal is characterized by which of the following symptoms?

Accepted Answer

Rhinorrhea, Piloerection, Insomnia

Answer

Rhinorrhea, Piloerection, Miosis

Answer

Rhinorrhea, Piloerection, Constipation

Answer

Insomnia, Constipation

Question 5

What is the most common side effect of haloperidol?

Accepted Answer

Akathisia

Answer

Hypotension

Answer

Dryness of mouth

Answer

Tic disorder

Question 6

What is the preferred first-line treatment for a young patient (under 65 years) newly diagnosed with Parkinson's disease?

Accepted Answer

Dopamine agonist

Answer

MAO-B inhibitor

Answer

Amantadine

Answer

Levodopa

Question 7

Adverse effects of phenytoin include the following EXCEPT:

Accepted Answer

Hypercalcemia

Answer

Ataxia

Answer

Hirsutism

Answer

Lymphadenopathy

Question 8

Which of the following is a pure opioid antagonist?

Accepted Answer

Naloxone

Answer

Buprenorphine

Answer

Pentazocine

Answer

Morphine

Question 9

Which of these anticonvulsants causes a contraction of the visual field?

Accepted Answer

Vigabatrin

Answer

Levetiracetam

Answer

Phenytoin

Answer

Ethosuximide

Question 10

Which of the following drugs is not suitable for the management of essential tremors?

Accepted Answer

Levodopa

Answer

Diazepam

Answer

Propranolol

Answer

Metoprolol

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

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