Re: Does the liquid you take pills with effect it's dissolving rate?

Krista, thanks for the question.

The rate at which a drug is dissolved in a solution depends upon its 
chemico-physical characteristics.  In other words, some drugs like to 
dissolve in acidic environments, while others like to dissolve in more 
basic environments (acidic being a pH lower than 7.0, basic being 
environments higher than 7.0).  However, drug manufacturers take this into 
account when they package a drug.

So, the short answer without any explanation would be: 1) it depends on 
your drug, 2) what you’re drinking with it, 3) where the drug is absorbed, 
4) rate of gastric-emptying (this means how much, and how often your 
stomach contents are emptied into the duodenum of the small intestine).  
Following is a whole lot of explanation.  I hope it makes sense.

So, by way of example, let’s look at what happens in the gastrointestinal 
tract (essentially from the mouth through the large intestine).  Let’s say 
you take a drug like aspirin.  Aspirin is what we call a weak acid.  When 
it is placed in water with a pH of 7.0 it likes to release hydrogen ions, 
and by doing so, it lowers the pH a little bit, thereby making the 
solution a little more acidic.  As it releases the hydrogen ions it also 
begins to dissolve a little, such that hydrogen ion release causes it to 
become charged (it has a negative charge), and the water begins to 
surround it.  This is what happens when something becomes dissolved.

I think your question though, getting back to it, has more to do with 
absorption of the drug into the body.  And this is what can be a bit of a 
confusing subject (I have a few colleagues here who had trouble with this 
concept when it was first introduced – and we study this stuff for a 
living!!).  So let’s go back to aspirin.  You ingest the aspirin, and its 
going on it little trek through the mouth, down the esophagus, and into 
the stomach.  The stomach has a really low pH, depending on various 
circumstances (like what ya ate, stress levels, other drugs, etc…) can be 
from about 1.0 to 3.5.  For reference, that’s what we call in the field – 
very acidic (hint: don’t vomit on your parent’s car – stomach acid will 
take the paint right off!!!!  How’s that for potent?).  So now our drug, 
aspirin, is in your stomach just hangin’ out talking to the friendly 
peptic enzymes, havin’ a little party.  Well, these acids in the stomach 
cause some of the aspirin to become charged by taking a hydrogen ion off.  
But some of the aspirin is much happier with its friend hydrogen still 
attached, and like Linus from Peanuts and his blanket, won’t give it up to 
anyone!  

Now then, as you may know, cells have what’s referred to as a plasma 
membrane.  This plasma membrane keeps things the cell doesn’t like out, 
and keeps what the cell likes in.  But some things have to pass through 
the cell, right?  Well, it just so happens that items which are what we 
call lipophilic (from the Latin meaning “loves fat”; lipid = fat, philic = 
love) can actually cross the cell membrane without too much problem, and 
will do so in order to go from an area of high concentration to an area of 
low concentration (what we refer to as “moving down a concentration 
gradient”).  Now then the stomach is made up of cells, and these cells 
aren’t too different from other cells.  And aspirin has a preference in 
this highly acidic environment to keep its friend hydrogen with it, 
meaning it does not have a charge, and because of aspirin’s chemical make-
up it is very lipophilic.  What does all this mean?  Well, aspirin is 
going to cross from the lumen side (the hollow area where the food is) 
into the cells of the stomach, and then from there to the stomach 
capillaries (and into the abdominal veins, and to the heart, and go 
through the whole circulation thing – I’ll not go into detail about that).

Okay, we’re almost done here – I’m sorry to drag you through all that 
chemistry (unless you enjoyed it, and if you did, I’d suggest a career in 
biological chemistry for ya).  Okay, so we’re back to this liquid you’re 
drinking with the pills.  It is very difficult to alter the pH of the 
stomach via the stuff you eat and drink, but if you eat, or drink, enough 
of it, it can be done.  In other words, you don’t want to ingest a lot of 
baking soda (you can just take my word for it – it will give you the worst 
gassy feeling on earth and you’ll feel like your stomach is trying to walk 
through your skin!).  So I guess what I mean to say is, it doesn’t matter 
so much what you drink at the time of drug administration “within reason”, 
as much as it does what you did prior to taking the drug.  If you drink OJ 
prior to taking aspirin, it’s not going to do anything, but possibly give 
you a more upset stomach if taken on an empty stomach.  On the other hand, 
if you just drank some Pepsi earlier (or coke, or mountain dew, or your 
caffeinated beverage of choice) then you’ll have an increased rate of drug 
absorption (due to increased heart rate, something I didn’t go into so 
much).  If you drink something like, well I can’t think of anything too 
basic in liquid form, but if you drank something that is basic and then 
took aspirin, you could alter the amount and rate of drug absorption in 
the stomach, but not so much in the intestines (since very little aspirin 
is absorbed in the intestines compared to stomach).  But if your drug is 
more basic, take all the OJ ya want, and you’re not going to alter the 
absorption of the drug in the stomach (since it won’t get absorbed 
there).  The basic drug will be absorbed in the intestines, and even then 
the OJ won’t matter because of the pancreatic secretions into the duodenum 
neutralize all of the acidity coming from the stomach!

The last item of importance to your question is the rate of gastric 
emptying.  If you’re not feeling well at all and your stomach contents are 
being emptied quite a bit, and your bowels are moving like a boat in a 
hurricane (bowel movements result in your need to expel the solid waste – 
lack of bowel movements would be constipation – and that’s not a good 
thing) then rate of drug absorption will be lowered.  If drug isn’t in the 
compartment where it’s ordinarily absorbed then it won’t be absorbed.  So 
aspirin, which isn’t absorbed in the intestines so much compared to 
stomach, would not be absorbed because it is not in the stomach long 
enough.  In this case, it wouldn’t really matter what you drank with your 
aspirin.

Thanks for your excellent question, and I hope that made things a little 
clearer.  If you still have questions about this, feel free to e-mail me, 
and I'll try to explain further!

Lyle