Definition: "half-life"? No guessing, please.

**The Baron** · 04-20-2005, 01:10 PM

I am fixing to write a little prog that calculates, based on shot history, dosage, and halflife, the amount of a drug still in the body. This will not be some hokey little java applet that drops turds and cookies all over your puter... this will be a small DOS app that you download and keep, and run when you like, whether you are online or off. Anyway, I just need to verify just EXACTLY what is meant by "half-life". Is it that length of time that it takes for the body to eliminate half of the drug? That is the obvious answer, but is it technically correct? I need to know before I start writing code. Can I work under the assumption that if the subject injected 200mg of a drug 10 days ago and it has a half-life of 10 days, that he still has 100mg of it in his body? Is this too simplistic a view?

**Iowa** · 04-20-2005, 01:14 PM

The time required for half the quantity of a drug or other substance deposited in a living organism to be metabolized or eliminated by normal biological processes.

I knew that biology degree was good for something.

**Scrub** · 04-20-2005, 01:27 PM

There is a good description on a half life here:
http://www.steroid.com/halflife.php

**joevette** · 04-20-2005, 02:19 PM

Originally Posted by The Baron

I am fixing to write a little prog that calculates, based on shot history, dosage, and halflife, the amount of a drug still in the body. This will not be some hokey little java applet that drops turds and cookies all over your puter... this will be a small DOS app that you download and keep, and run when you like, whether you are online or off. Anyway, I just need to verify just EXACTLY what is meant by "half-life". Is it that length of time that it takes for the body to eliminate half of the drug? That is the obvious answer, but is it technically correct? I need to know before I start writing code. Can I work under the assumption that if the subject injected 200mg of a drug 10 days ago and it has a half-life of 10 days, that he still has 100mg of it in his body? Is this too simplistic a view?

Yep, you've got it. It's just the ammount of time it takes for the body to use up half of the product.