Hexylcaine MCQs With Answer

Hexylcaine MCQs With Answer

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Hexylcaine MCQs With Answer is a focused study set tailored for B. Pharm students to master clinical and pharmaceutical aspects of Hexylcaine, a local anesthetic. This resource covers pharmacology, mechanism of action, ADME, formulation, dosing, toxicity, and adverse effects, plus practical considerations for administration, monitoring, and emergency management. Questions emphasize structure–activity relationships, pKa and onset, lipid solubility and potency, protein binding, and interactions with vasoconstrictors. Each MCQ includes clear, evidence-based answers to reinforce learning and exam preparedness. Use this targeted practice to strengthen pharmacotherapeutics knowledge, clinical reasoning, and safe handling of local anesthetics. Now let’s test your knowledge with 30 MCQs on this topic.

Q1. What is the primary molecular mechanism by which Hexylcaine produces local anesthesia?

  • Blocking voltage-gated sodium channels in nerve membranes
  • Enhancing GABAergic inhibition in the spinal cord
  • Antagonizing NMDA receptors on peripheral nerves
  • Inhibiting acetylcholinesterase at the neuromuscular junction

Correct Answer: Blocking voltage-gated sodium channels in nerve membranes

Q2. Which clinical application best describes typical uses of Hexylcaine?

  • Local infiltration and peripheral nerve block for minor procedures
  • Chronic systemic analgesia for neuropathic pain
  • First-line therapy for generalized seizures
  • Oral antihypertensive agent

Correct Answer: Local infiltration and peripheral nerve block for minor procedures

Q3. Which physicochemical property most directly influences the onset of action of Hexylcaine?

  • pKa relative to tissue pH
  • Molecular weight alone
  • Color of the formulation
  • Manufacturer’s country of origin

Correct Answer: pKa relative to tissue pH

Q4. Increased lipid solubility of Hexylcaine primarily affects which clinical property?

  • Potency of the anesthetic
  • pKa of the drug
  • Ability to chelate calcium
  • Production of local metabolites

Correct Answer: Potency of the anesthetic

Q5. Adding epinephrine to a Hexylcaine formulation is used mainly to:

  • Prolong duration of anesthesia by vasoconstriction
  • Increase systemic absorption to speed recovery
  • Neutralize the pH of the local solution
  • Convert Hexylcaine into an amide derivative

Correct Answer: Prolong duration of anesthesia by vasoconstriction

Q6. Protein binding of Hexylcaine influences which of the following?

  • Duration of action and free drug concentration
  • Color of the solution
  • Immediate allergic potential in all patients
  • Ability to form ionic complexes with epinephrine

Correct Answer: Duration of action and free drug concentration

Q7. Early signs of systemic local anesthetic toxicity from Hexylcaine typically include:

  • CNS excitation such as tinnitus, circumoral numbness, and tremor
  • Isolated painless jaundice
  • Gradual hair loss over weeks
  • Immediate bronchodilation

Correct Answer: CNS excitation such as tinnitus, circumoral numbness, and tremor

Q8. First-line emergency therapy for severe systemic toxicity (cardiac arrest) due to local anesthetics like Hexylcaine includes:

  • Intravenous lipid emulsion therapy in addition to ACLS measures
  • Oral activated charcoal
  • Topical corticosteroid application
  • High-dose vitamin K infusion

Correct Answer: Intravenous lipid emulsion therapy in addition to ACLS measures

Q9. Allergic reactions to local anesthetics are most commonly associated with which class?

  • Ester-type local anesthetics
  • Amide-type local anesthetics
  • Synthetic opioid analgesics
  • Nonsteroidal anti-inflammatory drugs

Correct Answer: Ester-type local anesthetics

Q10. The primary metabolic pathway for ester local anesthetics involves which enzyme system?

  • Plasma pseudocholinesterases (butyrylcholinesterase)
  • CYP450 3A4-mediated hepatic oxidation
  • Renal tubular glucuronidation
  • Mitochondrial beta-oxidation

Correct Answer: Plasma pseudocholinesterases (butyrylcholinesterase)

Q11. In infected or inflamed tissues, efficacy of Hexylcaine is reduced because:

  • Lower pH increases ionization and reduces membrane penetration
  • Higher temperature accelerates drug metabolism to inactive forms
  • Bacterial enzymes convert Hexylcaine into an antagonist
  • Tissue ischemia increases the non-ionized fraction excessively

Correct Answer: Lower pH increases ionization and reduces membrane penetration

Q12. For a peripheral nerve block using Hexylcaine, which precaution reduces the risk of intravascular injection?

  • Aspirate before injection and inject incrementally with frequent aspiration
  • Always inject the full calculated dose as a single bolus rapidly
  • Mix Hexylcaine with a systemic anticoagulant
  • Give the injection without any monitoring

Correct Answer: Aspirate before injection and inject incrementally with frequent aspiration

Q13. Which property determines the proportion of Hexylcaine that is non-ionized at physiological pH?

  • The drug’s pKa value
  • Its molecular color
  • The bottle label font size
  • The ambient room humidity

Correct Answer: The drug’s pKa value

Q14. How should dosing of Hexylcaine be adjusted for pediatric patients?

  • Calculated precisely by weight with reduced maximum dose limits
  • Use the same adult fixed dose for simplicity
  • Double the adult dose to account for faster metabolism
  • Administer only orally in children

Correct Answer: Calculated precisely by weight with reduced maximum dose limits

Q15. Which monitoring is essential during administration of long-acting Hexylcaine for major nerve blocks?

  • Continuous ECG, blood pressure, and oxygen saturation monitoring
  • Only intermittent visual checks without equipment
  • Monitoring of scalp hair growth as an early toxicity marker
  • Urine dipstick testing every 2 minutes

Correct Answer: Continuous ECG, blood pressure, and oxygen saturation monitoring

Q16. The concept of maximum recommended dose for Hexylcaine is intended to:

  • Limit systemic toxicity while achieving effective anesthesia
  • Ensure pharmacists sell more units per vial
  • Standardize taste of topical preparations
  • Prevent the drug from binding to glass vials

Correct Answer: Limit systemic toxicity while achieving effective anesthesia

Q17. Which anatomical sites are generally advised against using Hexylcaine with a vasoconstrictor like epinephrine?

  • End-artery areas such as fingers, toes, penis, and ear lobes
  • Large muscle groups like the quadriceps
  • The scalp for hair growth stimulation
  • Subcutaneous tissue in the abdomen for lipomas

Correct Answer: End-artery areas such as fingers, toes, penis, and ear lobes

Q18. Which mechanism explains preferential blockade of small-diameter pain fibers by Hexylcaine?

  • Smaller, less myelinated fibers have more persistent sodium channel activity and are blocked earlier
  • Pain fibers actively pump out Hexylcaine faster than motor fibers
  • Pain fibers do not express sodium channels
  • Hexylcaine selectively binds to opioid receptors on pain fibers

Correct Answer: Smaller, less myelinated fibers have more persistent sodium channel activity and are blocked earlier

Q19. For prevention of allergic reactions when a patient has a history of ester anesthetic allergy, the safest approach is to:

  • Choose an amide local anesthetic after allergy assessment
  • Administer a higher dose of the same ester to overcome allergy
  • Mix two different esters to dilute the allergen
  • Avoid any local anesthesia and proceed with general anesthesia always

Correct Answer: Choose an amide local anesthetic after allergy assessment

Q20. Hexylcaine’s duration of action can be prolonged by which pharmaceutical strategy?

  • Adding a vasoconstrictor such as epinephrine to reduce systemic absorption
  • Decreasing the lipid solubility of the molecule
  • Increasing the pH to extremely alkaline values for stability
  • Administering the drug simultaneously with high-dose diuretics

Correct Answer: Adding a vasoconstrictor such as epinephrine to reduce systemic absorption

Q21. The phenomenon of tachyphylaxis to repeated local anesthetic injections is most likely due to:

  • Progressive tissue alkalinization and reduced drug access to nerve fibers
  • Instant permanent nerve destruction by the first dose
  • Accumulation of Hexylcaine in hair follicles
  • Conversion of the drug into an analgesic antagonist

Correct Answer: Progressive tissue alkalinization and reduced drug access to nerve fibers

Q22. Which statement about regional anesthesia with Hexylcaine in pregnancy is most appropriate?

  • Use the lowest effective dose with careful monitoring; many local anesthetics are commonly used in pregnancy
  • All local anesthetics are absolutely contraindicated in pregnancy
  • Pregnant patients require double dosing due to increased plasma volume
  • Regional anesthesia causes permanent fetal neurotoxicity in all cases

Correct Answer: Use the lowest effective dose with careful monitoring; many local anesthetics are commonly used in pregnancy

Q23. Which laboratory abnormality increases the risk of prolonged action of ester local anesthetics similar to Hexylcaine?

  • Low butyrylcholinesterase activity leading to slower metabolism
  • High urinary pH accelerating renal excretion
  • Excessive platelet count increasing plasma binding

Correct Answer: Low butyrylcholinesterase activity leading to slower metabolism

Q24. Local anesthetic potency, onset, and duration are best matched as:

  • Potency correlates with lipid solubility; onset correlates with pKa; duration correlates with protein binding and vasodilation
  • Potency correlates with pKa; onset correlates with viscosity; duration correlates with bottle color
  • Potency correlates with molecular size only; onset and duration are random
  • All three properties depend only on the patient’s body mass index

Correct Answer: Potency correlates with lipid solubility; onset correlates with pKa; duration correlates with protein binding and vasodilation

Q25. Which clinical sign suggests early cardiovascular toxicity from Hexylcaine?

  • Bradyarrhythmia or conduction block progressing to hypotension
  • Sudden, painless improvement in vision
  • Transient increase in height
  • Mild rash on the fingertip only

Correct Answer: Bradyarrhythmia or conduction block progressing to hypotension

Q26. When preparing Hexylcaine for topical mucosal anesthesia, which formulation consideration is important?

  • Use appropriate concentration and vehicle designed for mucosal absorption to avoid irritation
  • Always add systemic anticoagulants to enhance penetration
  • Topical formulations should be highly alkaline (pH > 11)
  • Combine with systemic antibiotics to prevent local side effects

Correct Answer: Use appropriate concentration and vehicle designed for mucosal absorption to avoid irritation

Q27. The “ion trapping” phenomenon explains poor efficacy of Hexylcaine in infected tissues because:

  • Acidic tissue pH traps the drug in ionized form, preventing membrane penetration
  • Infection increases tissue temperature which degrades the drug instantly
  • Bacteria produce enzymes that pump Hexylcaine into the bloodstream
  • Infected tissue has excessive lipid content sequestering the drug

Correct Answer: Acidic tissue pH traps the drug in ionized form, preventing membrane penetration

Q28. During administration of Hexylcaine, which immediate step is recommended if seizures occur from systemic absorption?

  • Secure airway, give oxygen, and treat seizures with benzodiazepines
  • Give high-dose epinephrine intramuscularly only
  • Administer oral aspirin immediately
  • Ignore the seizure and continue injection slowly

Correct Answer: Secure airway, give oxygen, and treat seizures with benzodiazepines

Q29. Which factor most increases the risk of local anesthetic systemic toxicity (LAST) when using Hexylcaine?

  • Accidental intravascular injection or rapid absorption from highly vascular site
  • Administering the drug after a fatty meal
  • Mixing with saline in a glass syringe
  • Applying the drug below body temperature

Correct Answer: Accidental intravascular injection or rapid absorption from highly vascular site

Q30. Best practices for safe handling and storage of Hexylcaine solutions include:

  • Storing as recommended (protected from light when indicated), using aseptic technique, and discarding single‑use vials after one use
  • Leaving opened vials at room temperature indefinitely for future use
  • Mixing multiple vials into a single container to conserve product
  • Storing only in direct sunlight to sterilize the solution

Correct Answer: Storing as recommended (protected from light when indicated), using aseptic technique, and discarding single‑use vials after one use

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