The blood:gas partition coefficient is the ratio of concentration of anesthetic in the blood vs. in the lungs when a steady state is reached. Blood/gas partition coefficient is an expression of solubility of the drug in plasma, and less soluble agents have a faster onset/offset.
MAC (minimum alveolar concentration) is the concentration of anesthetic in the lungs where 50% of the population does not move in response to a surgical srtandard stimulus. It is analogous to ED50 in other areas of pharmacology. MAC is increased with decreasing solubility (decreaseing blood/gas partition coefficients) and decreased potency. If you think about it this would make sense because if a drug is less soluble or not as potent, you have to administer more of the drug and thus would have to have a higher minimal alveolar concentration to see an effect. [FA2020 p549]
NOTE: MAC is additive so if you mix two gases at 0.75% of their MACs, you get a total 1.5% MAC. Thus for the question, you are essentially administering the same TOTAL MAC to each group, so it is not the difference in MAC that is causing the difference observed.
The brain:gas partition coefficient, more commonly called the oil:gas partition coefficient, is used as a surrogate for the amount of anesthetic in the brain and corresponds to lipid solubility. CNS drugs must be lipid soluble or actively transported. As these are inhlaed anesthetics, the lipid solubility actually does not greatly contribute to time of onset/offset; instead the plasma solubility is the limiting factor. Oil/gas partition coefficient would be associated with the drug potency.
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The blood:gas partition coefficient is the ratio of concentration of anesthetic in the blood vs. in the lungs when a steady state is reached. Blood/gas partition coefficient is an expression of solubility of the drug in plasma, and less soluble agents have a faster onset/offset.
MAC (minimum alveolar concentration) is the concentration of anesthetic in the lungs where 50% of the population does not move in response to a surgical srtandard stimulus. It is analogous to ED50 in other areas of pharmacology. MAC is increased with decreasing solubility (decreaseing blood/gas partition coefficients) and decreased potency. If you think about it this would make sense because if a drug is less soluble or not as potent, you have to administer more of the drug and thus would have to have a higher minimal alveolar concentration to see an effect. [FA2020 p549]
NOTE: MAC is additive so if you mix two gases at 0.75% of their MACs, you get a total 1.5% MAC. Thus for the question, you are essentially administering the same TOTAL MAC to each group, so it is not the difference in MAC that is causing the difference observed.
The brain:gas partition coefficient, more commonly called the oil:gas partition coefficient, is used as a surrogate for the amount of anesthetic in the brain and corresponds to lipid solubility. CNS drugs must be lipid soluble or actively transported. As these are inhlaed anesthetics, the lipid solubility actually does not greatly contribute to time of onset/offset; instead the plasma solubility is the limiting factor. Oil/gas partition coefficient would be associated with the drug potency.