Does Anyone Know?

[stupidhippo]

so the half life calculators here then dont work. Why the sudden drop since it would make sense that the concentratons would go like this

half life 7 days

week 1 200 mg
week 2 100 mg
week 3 50 mg
week 4 25 mg etc................

why does it inactivate according to some other logic than the half life one? u know the explanation to this.

[shortie]

so the half life calculators here then dont work. Why the sudden drop since it would make sense that the concentratons would go like this

half life 7 days

week 1 200 mg
week 2 100 mg
week 3 50 mg
week 4 25 mg etc................

why does it inactivate according to some other logic than the half life one? u know the explanation to this.

I understand where you are coming from, but you are thinking in terms a radioactive half life which is a measure of the decay of an unstable substance. Steroid half live are about gear being released from it's ester, in this case there is some of the residual gear left in the body after two half lives time, but not in any quantity. If you check on the roid calc, you will see that according to them prop will still leave 1mg active in your body up to a week and a half after used, but what is one gram, in this case insignificant. The way I look at it that the half life represents the amount that is released in a given period of time I.E. 100 mg with a 5 day half life should release 10 mg ed, therefore in 10 days it should be almost completely gone.

[stupidhippo]

The way I look at it that the half life represents the amount that is released in a given period of time I.E. 100 mg with a 5 day half life should release 10 mg ed, therefore in 10 days it should be almost completely gone.

Im pretty sure this is wrong. They teach us (in pharmacology) that it usually takes 4 half lives for the concentration to get that small that its considered out of the system . And that is only based on that after 4 half lives 94 % of the stuff is gone. 100 /2 =50 /2 =25 /2=12.5 /2= 6.25 after 4 half lives it should still have the 6 % left. Since the concentration always divides equally so it is logical that when the amount gets smaller it doesnt get metabolized with the same speed anymore. The reason I asked this was does anyone know how the steroid ester metabolis / halflife works actually since the half-life system is not that precise.

[shortie]

While the essence of what I said I still feel is correct I think I have found the right way to look at this, I do not believe all the active agent is gone within the active life, but the measureable consequential portion is gone. Qoute from William Llewellyn:

There are a number of factors that can affect the potency of a particular drug compound. One such factor, and perhaps one of the most important, is the half-life of the agent. In medicine, the term half-life refers to the duration it takes for half of a given drug dosage to break down in the body. It is not half of the total activity time, as this figure always refers to the time it takes to metabolize 50% of what is in still the body. For example, if we inject 100mg a steroid with a half-life of 4 hours, at the four-hour mark we should have only 50mg left as active. After another four hours have passed the drug is still in the body, however another half-life has expired and the total active dosage will be around 25mg. It may take several half-lives before the drug is completely inactive.

A good way to illustrate half-life is through the "flipping penny" experiment. I remember it well from my high school earth sciences class, and I'm sure many of you have probably done this exercise as well. This experiment involves placing 100 pennies inside a flat, closeable box. It is big enough that the pennies can sit side by side comfortably without overlapping each other. We begin with them all facing "heads-up". Next we close the box, give it a good shake, and then open it back up again. We then proceed to remove all pennies that are now "tails-up" in the box. This process is repeated until all of the pennies have been flipped and are removed from the box. We find that with each shake we loose about half of them. Around 50 the first flip, 25 the second, a dozen of so on the third, and so on. Although half of the original amount are tailed and removed on the first flip, it takes many successive tries to clear them all. And usually there are a couple of kids in the class that just can't seem to get the last few over without a lot of work. This illustrates well the way in which we measure drug metabolism in the body. Half-life is not an easy reference for the total time a drug will be found active in the body, but more a guide to optimizing a dosing schedule and avoiding unwanted peaks and troughs.