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From: e Date: 24 May 2006 Time: 22:36:09 +1100 Remote Name: 58.167.176.170 Comments: my understanding is this is a very simple idea that often confuses... it is simply a way of representing how the balance between redistribution and metabolism/excretion changes as you continue to infuse a drug. if you give a bolus (let's describe it as an 'infusion' over 10 seconds) of something lipid soluble like thiopentone, after the 'infusion' stops the half life in plasma will be very quick because of redistribution. right? now if you give a patient an infusion of thio' for an hour, then after the infusion stops the half life will be mmmmuch longer... now if you've been running an infusion for days (apparently they use to do this for head-injury) then when you turn it off the plasma half-life will be longer still, from memory, about 32 hours. (because, of course the fat is almost saturated and releases it back into the plasma as the live struggles to mash up the thio) You can plot these three scenarios as three points on a graph (half-life on the y, duration of infusion on the x) draw a line between the three lines and you have a 'context-sensitive half-life curve' for thiopentone. did that make sense? it's not rocket science but I may not have put it properly... others may need to disagree or clarify