anesthesia Q

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anesthesia Q

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drk1980
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01/14/06 - 01:11 PM

An anesthesiologist is attempting to explain to the pre-med student who is shadowing him how anesthesia works. He states that the potency of the anesthetic is based upon?
1. Solubility in blood
2. Solubility in lipid
3. Dose given
4. Respiration rate

msyamp
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01/14/06 - 01:12 PM

soulubility in lipid

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Geroo
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01/14/06 - 02:03 PM

right

ssrpk
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01/14/06 - 02:11 PM

i think solubility factor should affect the onset of action, i am leaning towards the dose which is best represented by MAC values [for inhaled anesthetics]

please correct with explanation if i am wrong!

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robin082006
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01/14/06 - 02:15 PM

the drug needs to go through the lipid nerve cell membrane to cause anesthesia, so solubility in lipid is reasonable

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Geroo
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01/14/06 - 02:20 PM

I think when u compare potency of two drugs u need to make dose constant,so at a constand dose the more lipid solubile drug will be more potent.make sense?

drk1980
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01/14/06 - 03:56 PM

solubility in lipid is correct!
good explanation provided already.
more to add, potency=1/MAC. MAC is the accepted valid measure of potency of inhalational GA's because it remains fairly constant for a given species even under varying conditions.
MAC of many general anesthetics shows excellent correlation with their oil/gas partition coefficient. This reflects the capacity of the anestheitc to enter the CNS and attain sufficient concentration in neuronal membrane.
Blood/gas partition coefficient a measure of blood solubility determines the rate of induction or recovery.

ssrpk
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01/14/06 - 07:13 PM

drk1980 wrote:
MAC of many general anesthetics shows excellent correlation with their oil/gas partition coefficient.

that explains everything!

thanks a lot

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mjl1717
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01/15/06 - 08:08 AM

Yeah, drk in slang language I knew "you opened another can of worms" Just a few pts via Goodman &Gillman. 1)For most of pharm you think is it "lipophilic"? Solubility in body tissue is related to blood:gas partition coefficient which is related to OLIVE OIL: GAS parttition coefficient . Greater the oil: gas partition the greater the capcity of the fatty tissues to absorb the agent and the slower the equilibration of the tissue. The slower the equilibration of the anaethetic with fatty tissue the longer the period of induction of anaetheisa & elimination after discontinuation of the anaethetic prolonged administration. *** If nothing else remember: measure of POTENCY, use MAC minimal alveolar conc. (some books use minimum anaethetic conc.)directly related to OIL: GAS partion coefficient. Nitric oxide has a very high MAC of 105 fast onset and recovery. Halothane has low MAC of 0.75- slow onset and slower recovery. Many times with anaethesia they are combined to minimize certain advantages and disadvantages. Good q baby, it calls for more then just understanding, but especially in this case being able to master and manipulate the info. From what i see anaethesia is testable but like another world. nod

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DrPak
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01/16/06 - 07:42 AM

#10

Great question! The oil/gas partition coeffienent coorelation was a point. It explains why MAC is related to potency.

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