Introduction: Inhalation anesthetics play a central role in general anesthesia, and Isoflurane is a widely taught volatile agent in pharmacology for B. Pharm students. This concise, keyword-rich overview covers isoflurane mechanism of action, pharmacokinetics, minimum alveolar concentration (MAC), metabolism, clinical uses, adverse effects, monitoring, and safety considerations. Understanding solubility, hemodynamic effects, interactions with neuromuscular blockers, and complications like malignant hyperthermia is essential for pharmacists involved in perioperative care and drug counselling. Focused study with clinical scenarios and targeted questions will reinforce critical concepts. Now let’s test your knowledge with 50 MCQs on this topic.
Q1. What is the primary mechanism of action proposed for isoflurane?
- Inhibition of acetylcholinesterase
- Activation of NMDA receptors
- Potentiation of GABA-A receptor-mediated inhibitory neurotransmission
- Blockade of sodium channels in peripheral nerves
Correct Answer: Potentiation of GABA-A receptor-mediated inhibitory neurotransmission
Q2. Which parameter best describes the potency of isoflurane?
- Blood/gas partition coefficient
- Minimum alveolar concentration (MAC)
- Oil/gas partition coefficient
- Metabolic clearance
Correct Answer: Minimum alveolar concentration (MAC)
Q3. A lower blood/gas partition coefficient for a volatile anesthetic implies:
- Slower induction and recovery
- Faster induction and recovery
- Higher potency
- Greater lipid solubility
Correct Answer: Faster induction and recovery
Q4. Compared with halothane, isoflurane has which of the following characteristics?
- Higher metabolism by the liver
- Greater myocardial depression
- Less hepatotoxicity and better cardiovascular stability
- Lower MAC
Correct Answer: Less hepatotoxicity and better cardiovascular stability
Q5. The blood/gas partition coefficient of isoflurane is approximately:
- 0.42
- 1.4
- 3.0
- 6.0
Correct Answer: 1.4
Q6. What effect does isoflurane have on systemic vascular resistance (SVR)?
- Increases SVR markedly
- No effect on SVR
- Decreases SVR causing hypotension
- Increases SVR only in hypovolemia
Correct Answer: Decreases SVR causing hypotension
Q7. Which of the following is a known adverse effect of isoflurane related to the respiratory system?
- Bronchospasm induction
- Marked bronchoconstriction in all patients
- Respiratory depression and decreased tidal volume
- Increased mucous secretion
Correct Answer: Respiratory depression and decreased tidal volume
Q8. Isoflurane is primarily eliminated from the body by:
- Hepatic biotransformation to active metabolites
- Metabolism by plasma esterases
- Exhalation via the lungs
- Renal excretion of unchanged drug
Correct Answer: Exhalation via the lungs
Q9. Which patient population typically requires a lower MAC for isoflurane?
- Young healthy adults
- Neonates
- Elderly patients
- Patients with chronic pain
Correct Answer: Elderly patients
Q10. Isoflurane can trigger malignant hyperthermia in susceptible individuals because it:
- Inhibits skeletal muscle calcium uptake
- Directly increases intracellular calcium release in skeletal muscle
- Blocks ryanodine receptors preventing calcium release
- Depletes ATP without affecting calcium
Correct Answer: Directly increases intracellular calcium release in skeletal muscle
Q11. The most important monitoring parameter to assess depth of anesthesia with isoflurane is:
- End-tidal concentration of isoflurane
- Urine output
- Serum isoflurane level
- Blood glucose
Correct Answer: End-tidal concentration of isoflurane
Q12. Which organ is most associated with rare but serious toxicity from older volatile agents, less so with isoflurane?
- Kidney
- Heart
- Liver
- Lungs
Correct Answer: Liver
Q13. An increase in cardiac output will, all else equal, affect anesthetic uptake by:
- Slowing alveolar partial pressure rise for a soluble agent
- Speeding alveolar partial pressure rise for a soluble agent
- Having no effect on uptake
- Removing the need to adjust vaporizer settings
Correct Answer: Slowing alveolar partial pressure rise for a soluble agent
Q14. Diffusion hypoxia after discontinuation of isoflurane is caused by:
- Rapid uptake of nitrogen into blood
- Rapid washout of anesthetic into alveoli diluting oxygen
- Increased metabolic consumption of oxygen
- Bronchial hyperreactivity
Correct Answer: Rapid washout of anesthetic into alveoli diluting oxygen
Q15. Which statement about isoflurane metabolism is true?
- It is extensively metabolized to fluoride ions
- It undergoes minimal hepatic metabolism (~0.2%)
- It is converted mainly to toxic trifluoroacetic acid
- It is primarily broken down by plasma cholinesterase
Correct Answer: It undergoes minimal hepatic metabolism (~0.2%)
Q16. The MAC of isoflurane in a healthy 40-year-old adult is approximately:
- 0.2%–0.4%
- 1.2%–1.3%
- 3.0%–4.0%
- 6.0%–8.0%
Correct Answer: 1.2%–1.3%
Q17. Which of the following increases MAC for isoflurane?
- Hypothermia
- Administration of opioids
- Acute alcohol intoxication
- Youth (younger age)
Correct Answer: Youth (younger age)
Q18. Isoflurane’s effect on cerebral blood flow (CBF) is typically:
- Decreased due to vasoconstriction
- Increased due to cerebral vasodilation at clinical doses
- No change in CBF
- Variable but always decreases intracranial pressure
Correct Answer: Increased due to cerebral vasodilation at clinical doses
Q19. Which monitoring reduces risk when using volatile agents like isoflurane in long procedures?
- Continuous EEG alone
- End-tidal anesthetic concentration and capnography
- Pulse oximetry alone
- Hourly arterial blood gas only
Correct Answer: End-tidal anesthetic concentration and capnography
Q20. Isoflurane is classified chemically as a:
- Hydrocarbon ether
- Fluorinated methyl isopropyl ether
- Chloroform derivative
- Organophosphate
Correct Answer: Fluorinated methyl isopropyl ether
Q21. Combining isoflurane with which drug class commonly reduces MAC?
- Beta blockers
- Opioids
- Loop diuretics
- Thiazide diuretics
Correct Answer: Opioids
Q22. Which isoflurane property contributes to faster emergence compared to more soluble agents?
- High tissue solubility
- Low blood/gas partition coefficient
- Extensive hepatic metabolism
- High potency (low MAC)
Correct Answer: Low blood/gas partition coefficient
Q23. Which of the following is a cardiovascular effect of isoflurane?
- Marked increase in myocardial contractility
- Coronary vasodilation and potential coronary steal
- Severe bradycardia in all patients
- Complete preservation of baroreceptor reflex
Correct Answer: Coronary vasodilation and potential coronary steal
Q24. In the setting of severe hypotension with isoflurane, the first-line management is:
- Increase isoflurane concentration
- Administer intravenous fluids and vasopressors
- Immediately give succinylcholine
- Stop all monitoring
Correct Answer: Administer intravenous fluids and vasopressors
Q25. Which volatile anesthetic has a lower blood/gas partition coefficient than isoflurane?
- Desflurane
- Enflurane
- Ether
- Halothane
Correct Answer: Desflurane
Q26. Occupational exposure limits for isoflurane are important because chronic exposure may cause:
- Immediate cardiac arrest
- Chronic neurologic symptoms and reproductive risks
- Total immunity to anesthesia
- Heightened sense of smell
Correct Answer: Chronic neurologic symptoms and reproductive risks
Q27. Which of the following increases the speed of induction with isoflurane?
- High fresh gas flow and high inspired concentration
- Low minute ventilation
- High cardiac output
- Increased solubility in blood
Correct Answer: High fresh gas flow and high inspired concentration
Q28. Which inhalation agent is preferred for rapid control of anesthetic depth because of its very low blood solubility?
- Enflurane
- Desflurane
- Isoflurane
- Halothane
Correct Answer: Desflurane
Q29. Which statement about isoflurane and renal function is correct?
- Isoflurane causes severe renal failure in all patients
- It produces negligible fluoride ion liberation compared with methoxyflurane
- It is contraindicated in patients with any renal impairment
- It is primarily cleared renally
Correct Answer: It produces negligible fluoride ion liberation compared with methoxyflurane
Q30. Which clinical situation is a relative contraindication to volatile anesthetic use like isoflurane?
- History of malignant hyperthermia susceptibility
- Controlled hypertension
- Elective minor surgery with local anesthesia possible
- Obesity
Correct Answer: History of malignant hyperthermia susceptibility
Q31. Combining isoflurane with nitrous oxide typically results in:
- Decreased anesthetic depth due to antagonism
- MAC sparing effect reducing required isoflurane concentration
- Complete abolition of isoflurane effects
- Increased metabolism of isoflurane
Correct Answer: MAC sparing effect reducing required isoflurane concentration
Q32. Which of the following is a feature of isoflurane regarding airway irritation?
- Highly irritating causing frequent laryngospasm
- Less pungent than desflurane but may still irritate airway
- Completely non-irritating in all patients
- Always causes coughing and bronchospasm
Correct Answer: Less pungent than desflurane but may still irritate airway
Q33. For pregnant patients, which consideration about isoflurane is important?
- Isoflurane is teratogenic and absolutely contraindicated
- Use lowest effective concentration and monitor uterine tone and fetal status
- Isoflurane has no placental transfer
- It enhances uterine contractions intraoperatively
Correct Answer: Use lowest effective concentration and monitor uterine tone and fetal status
Q34. Which physiologic change reduces the MAC of isoflurane?
- Hyperthermia
- Chronic alcohol use
- Hypotension
- Administration of sedative-hypnotics
Correct Answer: Administration of sedative-hypnotics
Q35. Isoflurane exposure poses environmental concerns because it:
- Breaks down ozone completely
- Is a greenhouse gas that can contribute to atmospheric warming
- Has no environmental impact after exhalation
- Turns into harmless water vapor
Correct Answer: Is a greenhouse gas that can contribute to atmospheric warming
Q36. Which drug interaction with isoflurane can potentiate hypotension?
- Concurrent use of intravenous vasopressors
- Use of beta-adrenergic agonists
- Concurrent use of other vasodilators or antihypertensives
- Administration of antacids
Correct Answer: Concurrent use of other vasodilators or antihypertensives
Q37. Which is a benefit of using isoflurane over more soluble agents in long surgeries?
- Accumulation in fat causing prolonged recovery
- Better hemodynamic stability and predictable recovery
- Extremely rapid metabolism requiring monitoring
- Absolute lack of renal effects
Correct Answer: Better hemodynamic stability and predictable recovery
Q38. Clinical signs of inadequate anesthesia under isoflurane include:
- Stable hemodynamics and no movement
- Hypertension, tachycardia, lacrimation, and movement
- Profound bradycardia and hypothermia only
- Improved reflexes
Correct Answer: Hypertension, tachycardia, lacrimation, and movement
Q39. The use of isoflurane in patients with elevated intracranial pressure requires caution because it:
- Decreases cerebral blood flow and increases intracranial pressure
- Increases cerebral blood flow and may raise intracranial pressure
- Has no effect on cerebral hemodynamics
- Directly reduces intracranial pressure
Correct Answer: Increases cerebral blood flow and may raise intracranial pressure
Q40. Which monitoring device helps detect early malignant hyperthermia when using isoflurane?
- Continuous temperature and end-tidal CO2 monitoring
- Pulse oximetry alone
- Standard ECG only
- Urine dipstick
Correct Answer: Continuous temperature and end-tidal CO2 monitoring
Q41. Compared to sevoflurane, isoflurane is:
- More expensive and less stable
- More pungent and may irritate airways more
- Less pungent and causes no cardiovascular effects
- Associated with higher incidence of compound A formation
Correct Answer: More pungent and may irritate airways more
Q42. Which of the following best describes the oil/gas partition coefficient and its relevance?
- It indicates potency; higher values mean higher potency
- It indicates rate of induction; higher values mean faster induction
- It measures blood solubility only
- It is irrelevant to anesthetic pharmacology
Correct Answer: It indicates potency; higher values mean higher potency
Q43. In a patient with severe COPD, using isoflurane requires caution because it may:
- Eliminate the need for ventilation
- Cause bronchodilation in all cases
- Worsen ventilation–perfusion mismatch and increase CO2 retention
- Completely prevent atelectasis
Correct Answer: Worsen ventilation–perfusion mismatch and increase CO2 retention
Q44. The term “MAC-awake” refers to:
- The MAC value at which 50% of patients die
- The concentration at which most patients open their eyes to command
- The maximal allowed concentration in operating rooms
- Minimum alveolar concentration for infants only
Correct Answer: The concentration at which most patients open their eyes to command
Q45. Which emergency drug is indicated for malignant hyperthermia triggered by isoflurane?
- Sodium bicarbonate
- Dantrolene
- Atropine
- Propranolol
Correct Answer: Dantrolene
Q46. Which statement about the effect of isoflurane on renal blood flow is correct?
- Isoflurane markedly increases renal blood flow in all doses
- It may reduce renal perfusion due to systemic hypotension
- It directly constricts renal arteries causing ischemia
- It has no hemodynamic effects on the kidney
Correct Answer: It may reduce renal perfusion due to systemic hypotension
Q47. Which safety practice reduces occupational exposure to isoflurane in operating rooms?
- Using low-flow anesthesia circuits without scavenging
- Proper scavenging systems and leak testing of anesthesia machines
- Leaving vaporizers open in the OR when not in use
- Using only open-drop techniques
Correct Answer: Proper scavenging systems and leak testing of anesthesia machines
Q48. Isoflurane’s pungency makes it less suitable for:
- Maintenance anesthesia with an endotracheal tube
- Mask induction, especially in pediatric patients
- Use with intravenous induction agents
- Procedures requiring high inspired oxygen
Correct Answer: Mask induction, especially in pediatric patients
Q49. Which laboratory test would be most useful to evaluate acute hepatic injury after volatile anesthetic exposure?
- Serum creatinine only
- Serum transaminases (AST/ALT)
- Urinalysis for glucose
- Complete blood count only
Correct Answer: Serum transaminases (AST/ALT)
Q50. The concept of “second gas effect” in inhalation anesthesia refers to:
- Enhanced uptake of a second gas due to rapid uptake of the first gas
- Slower uptake of all gases when combined
- Metabolic interaction between inhalational and intravenous agents
- Only relevant to nitrogen and not volatile agents
Correct Answer: Enhanced uptake of a second gas due to rapid uptake of the first gas
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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