CNS pharmacology: general and local anesthetics MCQs With Answer

CNS pharmacology: general and local anesthetics MCQs With Answer is a concise, high-yield quiz set designed for M.Pharm students preparing for advanced pharmacology exams. This collection emphasizes mechanistic understanding, clinical application, pharmacokinetics and toxicity of both general and local anesthetics. Each question challenges students on drug-receptor interactions, physicochemical properties affecting onset and duration, metabolism and enzyme involvement, adverse effects and emergency management, and perioperative considerations. Answers are provided to reinforce learning and self-assessment. Use these MCQs to deepen your comprehension, identify weak areas, and bridge theoretical knowledge with clinical pharmacology applicable to anesthetic practice and pharmaceutical care.

Q1. Which pharmacokinetic property of inhaled general anesthetics most directly determines the speed of induction and recovery?

• Oil:gas partition coefficient
• Blood:gas partition coefficient
• Minimum alveolar concentration (MAC)
• Vapor pressure at room temperature

Correct Answer: Blood:gas partition coefficient

Q2. Minimum alveolar concentration (MAC) is best described as:

• The concentration producing loss of consciousness in 50% of patients
• The alveolar concentration preventing movement in response to noxious stimulus in 50% of patients
• The concentration producing analgesia in 50% of patients
• The blood concentration that correlates with respiratory depression in 50% of patients

Correct Answer: The alveolar concentration preventing movement in response to noxious stimulus in 50% of patients

Q3. Which general anesthetic is most associated with emergence delirium and dissociative anesthesia mediated by NMDA receptor antagonism?

• Propofol
• Ketamine
• Etomidate
• Thiopental

Correct Answer: Ketamine

Q4. Propofol’s primary mechanism of producing sedation and hypnosis is:

• Activation of NMDA receptors
• Potentiation of GABA-A receptor chloride current and direct agonism at high doses
• Blockade of voltage-gated sodium channels
• Agonism at alpha-2 adrenergic receptors in locus coeruleus

Correct Answer: Potentiation of GABA-A receptor chloride current and direct agonism at high doses

Q5. Which intravenous induction agent is most likely to cause adrenal suppression by inhibiting 11β-hydroxylase and thus is used cautiously in septic patients?

• Thiopental
• Propofol
• Etomidate
• Ketamine

Correct Answer: Etomidate

Q6. Malignant hyperthermia is triggered by certain anesthetics and characterized by uncontrolled calcium release from the sarcoplasmic reticulum; the acute pharmacologic treatment is:

• Dantrolene sodium to inhibit ryanodine receptor-mediated calcium release
• Sodium bicarbonate to reduce metabolic acidosis only
• Halothane to competitively antagonize calcium release
• Succinylcholine infusion to stabilize the sarcolemma

Correct Answer: Dantrolene sodium to inhibit ryanodine receptor-mediated calcium release

Q7. Which feature differentiates amide local anesthetics from ester local anesthetics pharmacokinetically?

• Amides are primarily hydrolyzed by plasma cholinesterases
• Amides are metabolized mainly in the liver by cytochrome P450 enzymes
• Amides produce methemoglobinemia more commonly than esters
• Amides have a much shorter duration of action than esters

Correct Answer: Amides are metabolized mainly in the liver by cytochrome P450 enzymes

Q8. The clinical observation that smaller, myelinated fibers are blocked by local anesthetics before larger, unmyelinated fibers explains which order of blockade?

• Pain → Temperature → Touch → Pressure
• Proprioception → Motor → Pain → Temperature
• Motor → Proprioception → Temperature → Pain
• Pressure → Touch → Temperature → Pain

Correct Answer: Pain → Temperature → Touch → Pressure

Q9. Which property of a local anesthetic most strongly correlates with its potency?

• pKa relative to physiological pH
• Lipid solubility
• Protein binding in plasma
• Molecular weight

Correct Answer: Lipid solubility

Q10. The main mechanism by which local anesthetics reduce neuronal excitability is:

• Enhancement of GABAergic transmission at synapses
• Blockade of voltage-gated sodium channels, preventing action potential propagation
• Inhibition of acetylcholine release at neuromuscular junction
• Activation of potassium channels to hyperpolarize the membrane

Correct Answer: Blockade of voltage-gated sodium channels, preventing action potential propagation

Q11. Which factor causes a slowed onset of local anesthetic action in infected or inflamed tissue?

• Increased tissue perfusion carrying drug away
• Alkaline pH favoring non-ionized form
• Acidic pH increasing ionized form, reducing membrane penetration
• Increased protein binding of the anesthetic

Correct Answer: Acidic pH increasing ionized form, reducing membrane penetration

Q12. Which local anesthetic has the highest risk of producing methemoglobinemia when administered in large topical or systemic doses?

• Procaine
• Prilocaine
• Lidocaine
• Bupivacaine

Correct Answer: Prilocaine

Q13. During a high spinal anesthesia, which physiological effect is most likely to occur due to excessive cephalad spread of local anesthetic in the subarachnoid space?

• Hypertension due to sympathetic overactivity
• Bradycardia and hypotension due to block of sympathetic outflow and cardioaccelerator fibers
• Increased respiratory drive from medullary stimulation
• Isolated lower limb motor block without autonomic effects

Correct Answer: Bradycardia and hypotension due to block of sympathetic outflow and cardioaccelerator fibers

Q14. Which adverse reaction is most characteristic of systemic local anesthetic toxicity affecting the heart?

• Prolonged QT due to potassium channel blockade only
• Refractory ventricular arrhythmias and negative inotropy, especially with bupivacaine
• Isolated hypertension from sympathetic stimulation
• AV nodal enhancement and increased contractility

Correct Answer: Refractory ventricular arrhythmias and negative inotropy, especially with bupivacaine

Q15. The recommended first-line emergency treatment for severe systemic local anesthetic toxicity presenting with cardiovascular collapse is:

• Intravenous lipid emulsion therapy (20% lipid emulsion bolus and infusion)
• High-dose epinephrine only
• Intravenous sodium bicarbonate for alkalinization
• Immediate dialysis to remove drug

Correct Answer: Intravenous lipid emulsion therapy (20% lipid emulsion bolus and infusion)

Q16. Which statement about succinylcholine use during anesthesia is correct?

• Succinylcholine is a nondepolarizing neuromuscular blocker reversed by neostigmine
• It is metabolized rapidly by plasma butyrylcholinesterase, and deficiency prolongs its action
• It prevents malignant hyperthermia and is preferred in MH-susceptible patients
• It acts by blocking presynaptic acetylcholine release

Correct Answer: It is metabolized rapidly by plasma butyrylcholinesterase, and deficiency prolongs its action

Q17. Addition of epinephrine to a local anesthetic solution primarily provides which pharmacologic advantage?

• Speeds onset by increasing pH of the solution
• Prolongs duration by vasoconstriction, reducing systemic absorption
• Prevents allergic reactions to esters
• Converts amide anesthetics into esters for faster metabolism

Correct Answer: Prolongs duration by vasoconstriction, reducing systemic absorption

Q18. Use-dependent blockade by local anesthetics means that these drugs preferentially bind to which state of the sodium channel?

• Resting (closed) state only
• Activated (open) and inactivated states more than resting state
• Permanent block of the pore irrespective of state
• Only to fully deactivated channels

Correct Answer: Activated (open) and inactivated states more than resting state

Q19. Which inhalational anesthetic is most likely to sensitize the myocardium to catecholamines and has been historically associated with arrhythmias?

• Isoflurane
• Sevoflurane
• Halothane
• Nitrous oxide

Correct Answer: Halothane

Q20. Which local anesthetic is most appropriate for prolonged peripheral nerve blocks requiring long duration and high potency, but with notable cardiotoxicity risk?

• Lidocaine
• Articaine
• Bupivacaine (levobupivacaine as less cardiotoxic enantiomer)
• Procaine

Correct Answer: Bupivacaine (levobupivacaine as less cardiotoxic enantiomer)

Download