Posted by Janelle on April 4, 2002, at 23:50:20
Hi there!
1) I'm afraid because I typed it all in caps and there is another thread right below it all in caps that my other question regarding half-lives might get missed, so could you please go back up to the HALF-LIFE thread I started and answer the question that begins with "RELATIONSHIP BETWEEN" ... you could answer it up there, that would be great, thanks!
2) Please humor me and bear with me a bit more here cuz I'm still not getting the whole story with this half-life stuff (no pun intended!) ...
Okay, taking your example of a drug concentration of 100mg/l with a 2 hour half-life, the drug would be reduced as follows(?):
1PM 100 mg/l
3PM 50 mg/l
5PM 25 mg/l
7PM 12.5 mg/l
9PM 6.25 mg/l
11PM 3.125 mg/l
1 AM 1.56 mg/l (I suppose at this point the drug could be considered out of the body)Adding this up, I'm getting 6 half-lives, but you said that after FIVE half-lives, a drug is considered gone??
ALSO, what confuses me even more is what if the concentration was doubled, and it was 200 mg/l of the drug with a 2 hour half life -- wouldn't it take MORE half-lives to get rid of the higher concentration of the drug?
I would think that the higher the concentration of a drug, the more half-lives it would take to eliminate it???????
So, I don't understand how no matter what the concentration of a drug, it is always 5 half lives to eliminate it from the body??????? How can this be? HELP!!!!!!!!
Thanks!
poster:Janelle
thread:101843
URL: http://www.dr-bob.org/babble/20020402/msgs/101909.html