Absorbtion half-life of an enema solution?

Okay, pharmacists, chemists, and medical professionals out there: If you are doing an enema solution, a component of which is being absorbed through the bowel, what is the practical half-life of the solution? In other words, how long do you have to retain until you have "used up" half of the active ingredient? I am sure there is some variation compound to compound, but in general terms, what could one expect?

Another way of looking at this question is, when do you arrive at the point where you are wasting our time retaining the enema because the benefit is diminished.

I doesn't work by a half life.

The absorption rate of an enema solution is multifactorial and will vary person to person and even with the same person from day to day.

The concentration of the solution, hygroscopic nature of the solutes, the hyper or hypotonic nature of the solution, the chemicals dissolved, the degree of hydration of the person, how rapidly the given person absorbs water from the colon in general, if in fact the solution is absorbable from the colon (hypertonic solutions will draw water into the colon, so NOTHING will be absorbed, the list goes on. . . .

For the most part, the rate of absorption of, say water, is much LESS than most people believe.

After a while, once the feces is broken up, the only reason to keep holding the enema is for the fun of it.

Epsom salt DOES reduce, and in high doses can even reverse the absorption!

Any saline laxative does this, Fleet Enema, Milk Of Magnesia, Magnesium Citrate, they all work basically by increasing water in the bowel. That is done by essentially interfering with that absorption from the contents to the walls of the bowel. That's what makes overdose dangerous.

Fair enough. Complex problem w/o a simple answer. Should have figured as much.

Guess the stuff you might be absorbing would be totally dependent on the electrolyte balance on each side of the colon wall. So it is an unanswerable question.

Of course, we are still going to attempt to infuse our bodies with whatever, -wine enema for instance, or coffee, or herbal teas, etc. Just that we have no control over how much is absorbed and how fast. Lord knows that some medications were administered rectally in the past so it certainly is effective in a grand overview sense.

. . . .some medications were administered rectally in the past so it certainly is effective in a grand overview sense.

Actually it wasn't so good for most medication as the absorption is not very predictable, which is why it isn't used very much any more.

Rectal administration is usually used if the patient is nauseous and can't hold anything down, still antiemetics can be used with oral meds.

I'm less concerned about the "half life" and more about getting a theraputic dose, and retaining it long enough to do essentially 80+ percent of what it's capable of!!