Posted by Larry Hoover on November 1, 2004, at 23:14:35
In reply to What does 'half-life' mean ?, posted by redscarlet on November 1, 2004, at 21:43:49
> Can someone please explain this, I see it and don't understand.
When a drug is absorbed into your body from the gut, it reaches what is called the peak plasma concentration. The drug will be metobolized (changed, or broken down, as by the liver), it will be excreted in urine, or in bile. So, from that peak concentration, it continuously falls, because the drug is getting used up and disposed of. The time it takes for that concentration to fall by 1/2 is the half life. It's pretty typical to take a new dose of a drug at about the time it reaches that 1/2 life point. In other words, if the half life is eight hours, you take it three times a day. That way, the amount in your blood doesn't fall so low that you start to go into withdrawals, or lose drug efficacy, before the next scheduled dose.
> And where can you find out about your meds's 'half-life' ?
I use Rxlist: http://www.rxlist.com/
You put the drug name in the search box, and it comes up with a list of drugs that have similar names (fuzzy search; it helps if you didn't spell it right, because you often can still find it). If you select the *generic* name of the drug (e.g. citalopram rather than the brand name Celexa), you'll get a very detailed report under a half dozen headings. Under the Clinical Pharmacology heading, you'll find information about half life.
The data you see there will be averages. There are reasons the numbers may not apply to you, specifically, but I can help you figure that out, if you're wondering about it.
> Thanks
You're welcome.
Lar
poster:Larry Hoover
thread:410376
URL: http://www.dr-bob.org/babble/20041029/msgs/410413.html