Central Nervous System Pharmacology Practice Questions

Q: Secobarbital is what type of barbiturate?

Short acting barbiturate. ***Short acting barbiturate*** - **Secobarbital** is classified as a short-acting barbiturate, with an onset of action of 15-30 minutes and a duration of 3-6 hours. - Due to its rapid onset and relatively short duration, it has been used as a **sedative-hypnotic** for inducing sleep. *Long acting barbiturate* - **Long-acting barbiturates** like **phenobarbital** have a prolonged duration of action, typically lasting 10-16 hours. - They are primarily used as **antiepileptics** due to their sustained effects. *Intermediate acting barbiturate* - **Intermediate-acting barbiturates** such as **amobarbital** have durations of action between 6-10 hours. - They were historically used for insomnia, but their use has declined due to safer alternatives. *Ultra short acting barbiturate* - **Ultra-short-acting barbiturates** like **thiopental** have an extremely rapid onset (seconds) and very short duration (minutes). - They are mainly used for **induction of anesthesia** due to their quick action and rapid redistribution.

Q: Which of the following statements is incorrect about morphine use?

It can be used in Head injury. ***It can be used in Head injury*** - Morphine is generally **contraindicated** in patients with **head injuries** due to its potential to **increase intracranial pressure**, mask neurological signs, and cause respiratory depression. - The elevated CO2 levels from respiratory depression can lead to cerebral vasodilation, further exacerbating intracranial pressure. *It can be used in Hypotension but with caution* - Morphine can cause **histamine release** and **vasodilation**, potentially worsening existing hypotension. - While possible, it requires careful monitoring and often necessitates concomitant use of **vasopressors** in hypotensive patients. *It can be used in diabetes mellitus* - Morphine use is generally considered safe in patients with **diabetes mellitus**, as it does not directly interfere with glucose metabolism or insulin sensitivity. - However, **renal impairment**, common in long-standing diabetes, can affect morphine excretion and necessitate dose adjustments. *It can be used for severe pain management in selected patients* - Morphine is a potent **opioid analgesic** and is highly effective for managing severe pain in various clinical settings. - Its use is indicated when other less potent analgesics are insufficient, and it is crucial to select patients carefully based on their overall health and potential for adverse effects.

Q: Methemoglobinemia is seen with which of the following agents?

Prilocaine. ***Correct: Prilocaine*** - **Prilocaine** is a local anesthetic known to cause **methemoglobinemia**, especially at higher doses or in susceptible individuals - It metabolizes into **ortho-toluidine**, which oxidizes hemoglobin to methemoglobin - This is a well-recognized adverse effect, particularly when doses exceed 600 mg or in susceptible populations *Incorrect: Tetracaine* - While a local anesthetic, **tetracaine** is not typically associated with causing **methemoglobinemia** - Its primary concern is often related to **systemic toxicity** if absorbed in large quantities *Incorrect: Bupivacaine* - **Bupivacaine** is a widely used local anesthetic, but it is not a common cause of **methemoglobinemia** - It is more famously associated with **cardiotoxicity** at high systemic concentrations *Incorrect: Procaine* - **Procaine** is an ester-type local anesthetic with a lower incidence of systemic toxicity and is not known to cause **methemoglobinemia** - It is more often associated with **allergic reactions** due to its metabolite, **para-aminobenzoic acid (PABA)**

Q: What is the preferred concentration range of lidocaine for topical anesthesia?

2-4%. ***Correct Option: 2-4%*** - **Lidocaine** is an **amide-type local anesthetic** commonly used for topical anesthesia to numb localized areas before minor procedures. - The **preferred concentration range for topical application is 2-4%**, which provides effective anesthesia with an acceptable safety profile. - **2% lidocaine gel/cream** is commonly used for skin and genital mucosa. - **4% lidocaine** is standard for oral and respiratory mucous membranes. - **5% lidocaine patches** are used for post-herpetic neuralgia. - This concentration range balances **clinical efficacy** with **minimal systemic toxicity risk**. *Incorrect Option: <2%* - Concentrations below **2%** are generally **suboptimal** for achieving significant topical anesthesia. - These lower concentrations result in **insufficient pain relief** or require longer application times. - While 0.5-1% solutions exist, they are primarily used for infiltration anesthesia, not topical application. *Incorrect Option: 7-12%* - Concentrations in the **7-12%** range are **too high** for routine topical use and increase the risk of **systemic toxicity**. - These concentrations are not standard in clinical practice for general topical anesthesia. - Higher concentrations increase absorption without proportional improvement in efficacy. *Incorrect Option: 12-15%* - Concentrations in the **12-15%** range are **excessively high** and pose substantial **risk of systemic absorption and toxicity**. - Such high concentrations are **not recommended** for topical anesthesia in clinical practice. - Even 10% sprays (used for oropharyngeal anesthesia) require strict dose limitations to prevent toxicity.

Q: A patient has frequent migraine attacks. Which of the following drugs is recommended for prophylaxis?

Propranolol. **Correct: Propranolol** - Propranolol is a **beta-blocker** commonly used for **migraine prophylaxis** [1] - It is **FDA-approved** and considered a **first-line agent** for preventing migraine attacks [1] - It works by reducing the frequency and severity of migraine attacks through its effects on vascular tone and neuronal excitability [1] *Incorrect: Pindolol* - Pindolol is a beta-blocker but is **less effective for migraine prophylaxis** compared to propranolol - It has **intrinsic sympathomimetic activity (ISA)**, which reduces its efficacy in preventing migraines - Not a preferred agent for migraine prevention *Incorrect: Ergotamine* - Ergotamine is used for **acute treatment** of migraine attacks, **not for prophylaxis** [2] - It works by constricting blood vessels and is a vasoconstrictor [2] - **Not suitable for daily preventive use** due to potential side effects, risk of ergotism, and medication overuse headaches (rebound headaches) [2] *Incorrect: None of the options* - This option is incorrect because **propranolol** is a well-established and recommended drug for migraine prophylaxis according to current guidelines

Q: Entacapone acts by inhibiting which of the following enzyme?

COMT. ***Correct: COMT*** - **Entacapone** is a selective, reversible **COMT (Catechol-O-Methyltransferase) inhibitor** [1], [2] - Acts **peripherally** (does not cross blood-brain barrier) [1], [2] - Used as **adjunct to levodopa/carbidopa** in Parkinson's disease [2] - **Mechanism:** Prevents peripheral conversion of levodopa to 3-O-methyldopa, thereby **increasing levodopa bioavailability** and prolonging its duration of action [1], [2] - Reduces "wearing-off" phenomenon in Parkinson's patients [2] *Incorrect: MAO-A* - Monoamine oxidase-A metabolizes dopamine, norepinephrine, and serotonin - **Moclobemide** is a reversible MAO-A inhibitor (antidepressant) - Not the mechanism of entacapone *Incorrect: MAO-B* - Monoamine oxidase-B preferentially metabolizes dopamine in the CNS - **Selegiline and rasagiline** are MAO-B inhibitors used in Parkinson's disease [2] - These work centrally, unlike entacapone which is peripheral [2] *Incorrect: Decarboxylase* - DOPA decarboxylase converts levodopa to dopamine - **Carbidopa and benserazide** are decarboxylase inhibitors (given with levodopa) [2] - Entacapone works downstream by inhibiting COMT, not decarboxylase

Q: Which of the following drugs can cause hypotension by releasing histamine from mast cells?

Morphine. ***Correct Option - Morphine*** **Morphine** and other opioids can cause **non-immunologic histamine release** from mast cells, leading to **vasodilation**, bronchoconstriction, and systemic hypotension. - The release of histamine directly causes a decrease in **peripheral vascular resistance**, contributing to a drop in blood pressure - This is a **direct pharmacological effect**, not an allergic reaction - Other opioids with similar effects include **codeine** and **meperidine** *Incorrect Option - Procaine* **Procaine** is a local anesthetic that can cause hypotension primarily due to its **direct vasodilatory effect** and cardiovascular depression, rather than histamine release. - While allergic reactions to procaine (which involve histamine) can occur, hypotension in this context is usually related to **systemic absorption** and cardiovascular depression - The mechanism is NOT direct mast cell degranulation *Incorrect Option - Sulfadiazine* **Sulfadiazine** is an antibiotic that may cause hypotension as part of an **allergic reaction** (e.g., anaphylaxis), which would involve histamine. - However, it does not typically cause **direct, non-immunologic histamine release** from mast cells as a primary mechanism - Any histamine release would be **immunologic** (allergic), not direct pharmacological mast cell degranulation *Incorrect Option - Aspirin* **Aspirin** (acetylsalicylic acid) can cause significant hypotension in cases of **overdose** or severe intolerance. - Primary mechanism involves **prostaglandin synthesis inhibition**, which can influence vascular tone - May cause cardiovascular depression in overdose - Does NOT cause direct histamine release from mast cells

Q: What deficiency is commonly associated with the use of Dilantin (phenytoin)?

Folic acid deficiency. ***Folic acid deficiency*** - **Phenytoin** is known to interfere with **folate metabolism** and absorption in the gastrointestinal tract, leading to a deficiency. - This deficiency can result in **megaloblastic anemia** with prolonged use. *Thiamine deficiency* - **Thiamine deficiency** (beriberi) is not typically associated with phenytoin use but rather with alcoholism, malnutrition, or malabsorption. - While certain antiepileptics might cause various nutritional deficiencies, thiamine is not a primary concern with phenytoin. *Nicotinamide deficiency* - **Nicotinamide (niacin) deficiency** causes pellagra and is characterized by dermatitis, diarrhea, and dementia. It is not directly linked to phenytoin. - This deficiency is often seen in individuals with diets poor in niacin, like corn-based diets, or in chronic alcoholism. *Riboflavin deficiency* - **Riboflavin deficiency** (ariboflavinosis) can cause angular stomatitis, cheilosis, and glossitis, but it is not a common side effect of phenytoin. - While various drug interactions can affect nutrient levels, phenytoin's primary known interaction is with folate.

Q: A 67-year-old man with Parkinson disease has experienced an increasingly dry mouth for the past 3 months, and this interferes with eating and swallowing. He has noted dry eyes as well. On physical examination, he has minimal tremor at rest; there are no other abnormal findings. Laboratory studies show no detectable autoantibodies. Which of the following is the most likely cause for his findings?

Anticholinergic drug use. ***Anticholinergic drug use***- Many medications used to treat **Parkinson disease** have **anticholinergic effects**, which can lead to **dry mouth (xerostomia)** and **dry eyes (xerophthalmia)** due to reduced glandular secretions [1].- The patient's presentation of worsening dry mouth and dry eyes aligns well with the side effects of such medications.*Alcohol ingestion*- While chronic alcohol use can contribute to **dehydration** and indirectly affect salivary production, it is typically not the primary cause of such pronounced and progressive symptoms in this context, nor does it commonly cause dry eyes.- The patient's symptoms are more consistent with a direct pharmacological effect rather than general dehydration from alcohol.*Candidiasis*- Oral candidiasis usually presents with **white plaques** on the oral mucosa, **soreness**, or difficulty swallowing due to pain, not primarily dry mouth and dry eyes.- The physical examination did not reveal any other abnormal findings, making candidiasis less likely as the primary cause.*Sialadenitis with blockage of salivary duct*- **Sialadenitis** (inflammation of salivary glands) or salivary duct obstruction typically causes **pain**, **swelling**, and localized tenderness in the affected gland, often exacerbated by eating.- This condition generally affects salivation but does not explain the concurrent dry eyes, making it an unlikely sole cause for both symptoms.

Q: Which of the following drugs is primarily used for the treatment of Parkinson's disease?

Levodopa. ***Levodopa*** - Levodopa is a **dopamine precursor** that crosses the blood-brain barrier and is converted to dopamine in the brain, replacing the depleted dopamine in Parkinson's disease [1], [2]. - It is considered the **most effective drug** for managing the motor symptoms of Parkinson's disease, particularly in the early and moderate stages [2], [4]. *Mazindol* - **Mazindol** is an appetite suppressant used for obesity and acts primarily as a norepinephrine-dopamine reuptake inhibitor. - It is **not indicated** for the treatment of Parkinson's disease. *Benserazide* - **Benserazide** is a **peripheral DOPA decarboxylase inhibitor** that does not cross the blood-brain barrier [1]. - It is used in combination with levodopa (e.g., in co-beneldopa) to prevent the peripheral metabolism of levodopa, increasing its availability to the brain, but it is **not used alone** to treat Parkinson's disease [1]. *Bromocriptine* - **Bromocriptine** is a **dopamine agonist** that directly stimulates dopamine receptors in the brain [3]. - While used in Parkinson's disease, it is generally considered a **second-line treatment** or used as an adjunct to levodopa, and not the primary drug [3].

Question 1

Secobarbital is what type of barbiturate?

Accepted Answer

Short acting barbiturate

Answer

Long acting barbiturate

Answer

Intermediate acting barbiturate

Answer

Ultra short acting barbiturate

Question 2

Which of the following statements is incorrect about morphine use?

Accepted Answer

It can be used in Head injury

Answer

It can be used in Hypotension but with caution

Answer

It can be used in diabetes mellitus

Answer

It can be used for severe pain management in selected patients

Question 3

Methemoglobinemia is seen with which of the following agents?

Accepted Answer

Prilocaine

Answer

Tetracaine

Answer

Bupivacaine

Answer

Procaine

Question 4

What is the preferred concentration range of lidocaine for topical anesthesia?

Accepted Answer

2-4%

Answer

7-12%

Answer

12-15%

Answer

<2%

Question 5

A patient has frequent migraine attacks. Which of the following drugs is recommended for prophylaxis?

Accepted Answer

Propranolol

Answer

None of the options

Answer

Pindolol

Answer

Ergotamine

Question 6

Entacapone acts by inhibiting which of the following enzyme?

Accepted Answer

COMT

Answer

MAO-A

Answer

MAO-B

Answer

Decarboxylase

Question 7

Which of the following drugs can cause hypotension by releasing histamine from mast cells?

Accepted Answer

Morphine

Answer

Sulfadiazine

Answer

Procaine

Answer

Aspirin

Question 8

What deficiency is commonly associated with the use of Dilantin (phenytoin)?

Accepted Answer

Folic acid deficiency

Answer

Thiamine deficiency

Answer

Nicotinamide deficiency

Answer

Riboflavin deficiency

Question 9

A 67-year-old man with Parkinson disease has experienced an increasingly dry mouth for the past 3 months, and this interferes with eating and swallowing. He has noted dry eyes as well. On physical examination, he has minimal tremor at rest; there are no other abnormal findings. Laboratory studies show no detectable autoantibodies. Which of the following is the most likely cause for his findings?

Accepted Answer

Anticholinergic drug use

Answer

Alcohol ingestion

Answer

Candidiasis

Answer

Sialadenitis with blockage of salivary duct

Question 10

Which of the following drugs is primarily used for the treatment of Parkinson's disease?

Accepted Answer

Levodopa

Answer

Mazindol

Answer

Benserazide

Answer

Bromocriptine

Central Nervous System Pharmacology — MCQs

Central Nervous System Pharmacology — MCQs

On this page

Practice by Chapter

Want unlimited practice?