Science Buddies: "Ask an Expert"

Hi, I need help with my project on... What pain reliever dissolves the fastest in stomach acid. I am using hydrochloric acid as a substitute. For my experiment my variable will be the the form of medicine; either a pill or tablet. My constant will be the amount of acid used throughout. I have some questions.

1. How much hydrochloric acid should I use to dissolve the pills or tablets?
2. Should I dilute the acid? If so, by how much?
3. Should I stir the pain reliever while it is in the acid?
4. What would my control be?
5. Are gelcaps commonly used? And should I include them in my testing?
Thanks!

Hi Olivia this sounds like a very interesting project.

First a safety note, HCl( especially at high molarity) is very harmful and can burn wholes in clothes and skin. Handel this with extreme care and use proper faculties and supervision.
The answers two your first two questions depend on the molarity of the Hydrochloric acid. If you use a high molar mixture you need less acid then a lower molar one. However the higher the molarity more dangerous the substance is.
The third questions really depends on how you want to run your experiment. If you stir in the pain reliever (assuming you've crushed it before hand), it will dissolve faster than the whole tablet because of its greater surface area. This could potentially eliminate size as a variable, since different sized tables might affect how quickly they are dissolved.
The answer to the forth question would probably be a placebo (sugar) pill. It contains no active ingredients so you can see how fast HCl normally dissolves things.
And finally to the 5th question, I think gelcaps are used in some pain relives. In your experiment you could see if this has any affect on how fast it is dissolved.

Best of wishes

Thank you very much! Your advice will really help me with my project!

Hi Olivia,

You have a great project, and have already gotten some very good, detailed advice. I just wanted to note that the pH of stomach acid is around 1 to 2, so if you want to create an environment most like that of the stomach, you should consider getting some pH paper and noting the pH of your solution.

The reason the liquid in your stomach is so acidic is because the parietal cells in the stomach actually produce HCl. So HCl is the perfect acid to use in order to mimic stomach acid! Just be aware of your pH during your experiment, because it's an important variable.

Good luck!
Heather

Thanks I changed my question a little bit so now it is... What over-the-counter pain reliever or slow dissolving pain reliever dissolves the fastest in stomach acid? I am comparing the rates and my variable is the tablets of the pain relievers. I just don't know now what my hypothesis should be? Also, what is PH paper?

Hi Olivia,

Your hypothesis is your prediction of what will happen. In this case, your hypothesis will be a prediction of which pain reliever you think will dissolve the fastest in stomach acid. Keep in mind that the type of tablet will influence how fast it will dissolve, so you should try to compare all the same type of tablet. For example, liquid-gel pills are designed to dissolve faster than regular tablets, so try to keep all of them the same type. That way you are only comparing the medicine, not the physical differences in the pills.

For more about generating a hypothesis, you can refer to the Science Buddies info: https://www.sciencebuddies.org/science- ... esis.shtml

To answer your second question, pH paper, also known as pH indicator paper, is paper that changes color when you dip it in a liquid. The color it turns tells you the approximate pH of your liquid. It is a fast and easy way to test pH (instead of using a pH meter, which is an expensive piece of equipment). You can type "pH paper," "pH indicator paper," or "pH test strips" into Google to find more information about it.

Hope that helps!

Heather

I am planning to use all tablets. They are similar to pills just a little bit different so like you said I will be comparing the medicines. And thanks for the website it really helped out a lot!

Does anyone know of any over-the-counter non name brand 12 or 24 hour slow working pain relievers?

Hi Olivia,

I don't know any off the top of my head, but most pharmacies have generic versions of medicines. For example, Walgreens, CVS, or Longs typically has its own generic version of each medication, usually on the same shelf as the name-brand medication. Keep in mind that the active ingredient is usually the same.

Hope that helps!
Heather

I have searched some of those places you listed but I have not found any yet. Hopefully some store does though!

I am making my graphs right now and I was wondering for my topic if a line graph or a bar graph would show my information better? Or does it even matter?

Hi Olivia,

Line graphs and bar graphs are meant to show different things. Line graphs usually show continuous data, such as change over time or a change in something with temperature. Bar graphs usually show categorical data - things that are being compared across categories or in ways that are not connected continuously.

The way you presented your hypothesis, it sounds as if a bar graph may be the best way to display your data. The categories would be the names of the pills, and the height or length of each bar would show the rate at which that pill dissolved.

If you wanted to use a line graph, you could graph the amount dissolved over time. You could use different colored lines (or different line patterns) for each pill, and show how each dissolved. The rate would be the slope of your line, but your line graph would also show if there were any changes in the rate; in other words, maybe one pill started dissolving slowly and then dissolved quickly, or vice versa. If all of the pills showed a constant rate or a similar pattern, then a bar graph would really be the simplest choice.

Let us know if you have any more questions!

Cheers,
Heather

I will make bar graphs then because what you are explaining is exactly what pertains to my project. Thanks!