Ask A Scientist© General Science Archive

>
name       Rachel
>
Question - Hello, I am looking for some information to help me with
my science project. I am in the 7th grade and doing my science project on
Advil. I want to compare the various forms (tablets, caplets, gelcaps
and liqui-gels) and see which product will dissolve fastest. Assuming that
the product that dissolves the fastest will be the product that will
start to work the fastest in the body.
However I do need some information which I am having trouble finding.

First: In trying to emulate the digestive system I need to use some sort
of acid product. Since I can't use anything hazardous I was going to use
Vinegar. Where could I find the average acid level of the digestive
system? Household distilled vinegar is 5% acid.

Second: Once an object(tablet,caplet,gelcap,liqui-gel) is swallowed how
long does it take to get to the stomach? Does it start to dissolve before
it reaches the stomach?

>Rachel,
>The pH of the stomach varies a lot!! -- from ~1 at night if the stomach is
>empty, to about 3.5 or even higher if the stomach is full of food and
>depending upon what food. That's a big range -- a change in H+
>concentration somewhere between 1000 and 10,000.
>
>The acid in the stomach is hydrochloric acid, which is available in a 30%
>solution at hardware stores under the name [muriatic acid]. It is used for
>cleaning bricks and concrete.
>
>I DO NOT RECOMMEND THAT YOU USE THIS UNLESS YOU ARE BEING SUPERVISED BY YOUR
>SCIENCE TEACHER. IT HAS A VERY IRRITATING SMELL AND CAN CAUSE SKIN BURNS.
>
>You will need some sort of buffer solution. Specific formulas for buffer
>solutions at
>various pH values can be found in: The Handbook of Chemsitry and Physics,
>Lange's Handbook or Chemistry, or any text on analytical chemistry.
>
>Passage time through the esophagus is a matter of a few seconds -- think
>about how fast you can drink water. The pH of the mouth and esophagus is
>essentially neutral or slightly acidic -- pH in the range of 5-7. You can
>probably ignore the time of passage into the stomach.
>
>Remember to stir the solutions as you measure the time each one takes to
>dissolve.
>Vince Calder

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 Hi Rachel:
good project idea:  Vinegar should work ok, however, stomach acid is
>about 100 times more acidic than that. Lemon juice is a bit more acidic than
vinegar, you should try them both.
As far as how long it takes for a pill to get to the stomach -- Try
>looking in a "Family Medical Guide" which can be found at your local library, or
>by giving your family medical doctor a call.
Katie Page

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