Central Nervous System Pharmacology Practice Questions

Q: In cases of spasticity, which drug is least likely to be used?

Amitriptyline. ***Amitriptyline*** - **Amitriptyline** is a **tricyclic antidepressant** primarily used for treating depression, neuropathic pain, and migraines. - While it has sedative effects, it does not directly act on the mechanisms that reduce muscle tone in spasticity. *Baclofen* - **Baclofen** is a **GABA-B receptor agonist** that reduces the release of excitatory neurotransmitters, effectively decreasing muscle spasticity. - It is one of the most commonly prescribed drugs for spasticity, available in oral and intrathecal forms. *Tizanidine* - **Tizanidine** is an **alpha-2 adrenergic agonist** that works by increasing presynaptic inhibition of motor neurons, thereby reducing muscle tone. - It is frequently used for spasticity associated with multiple sclerosis or spinal cord injury. *Diazepam* - **Diazepam** is a **benzodiazepine** that acts as a GABA-A receptor agonist, enhancing GABA's inhibitory effects on the central nervous system. - It reduces spasticity by causing generalized muscle relaxation, though its sedative properties can be a limiting side effect.

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: 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 role of marijuana in managing AIDS-related cachexia?

Stimulates appetite. **_Stimulates appetite_** - **Marijuana** (cannabis) and its derivatives, particularly **delta-9-tetrahydrocannabinol (THC)**, are known for their **appetite-stimulating effects** which can combat **cachexia** (wasting syndrome) in AIDS patients [1], [2]. - By increasing appetite, marijuana helps patients consume more calories, thereby reducing **weight loss** and improving overall nutritional status. *Reduces viral load* - There is **no scientific evidence** to suggest that marijuana directly reduces the **viral load** in HIV-infected individuals. - **Antiretroviral therapy (ART)** is the primary and proven method for reducing viral load in AIDS patients. *Enhances CD4 cell count* - Marijuana does **not directly enhance** the **CD4 cell count**, which is a key indicator of immune function in HIV/AIDS. - **Improved nutrition** due to appetite stimulation might indirectly support immune health, but it does not directly increase CD4 cells. *Boosts immune response* - The effect of marijuana on the **immune system** is complex and not fully understood, but it is generally **not considered an immune booster**. - Some studies suggest that cannabinoids may have **immunosuppressive properties**, which would be counterproductive in AIDS [2].

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 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 is an antagonist used to reverse the effects of benzodiazepines?

Flumazenil. ***Flumazenil*** - **Flumazenil** is a **competitive antagonist** at the **GABA-A receptor**, specifically binding to the benzodiazepine site. - By blocking benzodiazepines from binding, it rapidly **reverses their sedative and anxiolytic effects**, making it useful in overdose or to awaken patients post-procedure. *Alprazolam* - **Alprazolam** is a **benzodiazepine** itself, acting as a **GABA-A receptor agonist** rather than an antagonist. - It would **potentiate** the effects of other benzodiazepines, leading to increased sedation and respiratory depression, not reversal. *Propofol* - **Propofol** is an **intravenous anesthetic** that works by enhancing the effects of **GABA**, but it is not a specific benzodiazepine antagonist. - It would **deepen sedation** and anesthesia, which is the opposite of reversing benzodiazepine effects. *Naltrexone* - **Naltrexone** is a **mu-opioid receptor antagonist** used to block the effects of opioids in cases of overdose or addiction. - It has **no pharmacological effect** on the benzodiazepine receptor or its actions.

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.

Q: Sodium valproate is not the drug of choice for which of the following seizure types?

Infantile spasms. ***Infantile spasms*** - While valproate can be used as an add-on therapy, it is **not the first-line drug of choice** for infantile spasms, which typically respond better to **ACTH (adrenocorticotropic hormone)** or **vigabatrin**. - Infantile spasms often have a unique **hypsarrhythmia** pattern on EEG and a distinct clinical presentation from other seizure types. *Absence seizures* - Sodium valproate is considered an **effective broad-spectrum antiepileptic drug** used in the treatment of absence seizures. - It works by increasing **GABA concentrations** in the brain, which helps to suppress spike-and-wave discharges characteristic of absence seizures. *Myoclonic seizures* - **Sodium valproate** is a highly effective first-line treatment for various generalized seizure types, including myoclonic seizures. - Its broad mechanism of action, affecting GABAergic and glutamatergic neurotransmission, makes it suitable for these generalized seizure types. *Atonic seizures* - Sodium valproate is a commonly used drug for atonic seizures, especially in the context of **Lennox-Gastaut syndrome**. - It helps to reduce the sudden loss of muscle tone associated with atonic seizures, improving seizure control.

Q: What is the drug of choice for managing status epilepticus?

Lorazepam. ***Lorazepam*** - **Lorazepam** is the preferred first-line agent for status epilepticus due to its rapid onset of action and relatively long duration of anticonvulsant effect (12-24 hours), making it highly effective in stopping ongoing seizures. - Its **lipophilicity** allows it to quickly cross the blood-brain barrier while having less redistribution than diazepam, providing sustained seizure control. - Dose: **0.1 mg/kg IV** (typically 4 mg) administered at 2 mg/min. *Propofol* - **Propofol** is an anesthetic agent used in **refractory status epilepticus** when first and second-line agents have failed. - It carries risks of **hemodynamic instability**, **propofol infusion syndrome** with prolonged use, and requires ICU monitoring with intubation. - Reserved for third-line therapy, not appropriate as initial management. *Thiopentone* - **Thiopentone** is a barbiturate used for **refractory status epilepticus** as a third-line agent. - It has a longer half-life and recovery time compared to benzodiazepines, with significant **cardiovascular depression** and respiratory suppression. - Requires ICU setting with mechanical ventilation and hemodynamic support. *Phenytoin* - **Phenytoin** (or fosphenytoin) is a **second-line agent** used after benzodiazepines if seizures persist. - It has a **slower onset of action** (15-30 minutes) compared to benzodiazepines and requires cardiac monitoring due to risk of arrhythmias. - Loading dose: **20 mg/kg IV** at maximum rate of 50 mg/min to avoid cardiovascular complications.

Question 1

In cases of spasticity, which drug is least likely to be used?

Accepted Answer

Amitriptyline

Answer

Baclofen

Answer

Tizanidine

Answer

Diazepam

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

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 4

What is the role of marijuana in managing AIDS-related cachexia?

Accepted Answer

Stimulates appetite

Answer

Reduces viral load

Answer

Enhances CD4 cell count

Answer

Boosts immune response

Question 5

Adverse effects of phenytoin include the following EXCEPT:

Accepted Answer

Hypercalcemia

Answer

Ataxia

Answer

Hirsutism

Answer

Lymphadenopathy

Question 6

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

Accepted Answer

Vigabatrin

Answer

Levetiracetam

Answer

Phenytoin

Answer

Ethosuximide

Question 7

Which of the following is an antagonist used to reverse the effects of benzodiazepines?

Accepted Answer

Flumazenil

Answer

Alprazolam

Answer

Naltrexone

Answer

Propofol

Question 8

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

Accepted Answer

Levodopa

Answer

Diazepam

Answer

Propranolol

Answer

Metoprolol

Question 9

Sodium valproate is not the drug of choice for which of the following seizure types?

Accepted Answer

Infantile spasms

Answer

Absence seizures

Answer

Myoclonic seizures

Answer

Atonic seizures

Question 10

What is the drug of choice for managing status epilepticus?

Accepted Answer

Lorazepam

Answer

Propofol

Answer

Thiopentone

Answer

Phenytoin

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

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