Sevoflurane potency relative to isoflurane—true or false?

• A. Not testable
• B. True
• C. False
• D. Cannot be determined

Answer: (B)

The main idea here is comparing potency using MAC (minimum alveolar concentration). Potency and MAC are inversely related: the lower the MAC, the more potent the anesthetic.

For these two agents, isoflurane has a lower MAC than sevoflurane (roughly around 1.1–1.3% for isoflurane vs about 2–2.5% for sevoflurane in adults). That means isoflurane is more potent, because it achieves anesthesia at a smaller concentration. Therefore, sevoflurane is less potent than isoflurane.

So the true statement is that sevoflurane’s potency relative to isoflurane is lower (it requires a higher concentration to achieve the same effect). If a statement claimed the opposite, it would be incorrect. This concept helps explain why different volatile anesthetics are dosed differently and why their MAC values are a key reference in practice.