What Happens When A Pill Gets Inside Your Body?

This was the last item I posted on the blog Nov 6 before we took it down a few days later to start the overhaul.  In case you didn’t get a chance to read it, I’m reprinting it.

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She was a saleswoman prone to bipolar mood swings, stable on a brand name prescription mood stabilizer.  It had originally been marketed as an anticonvulsant and her medication was doing its job.  She recently returned to full-time work after a manic attack had cost her both her marriage and the custody of her child.

“I don’t have the insurance I once did; I now sell home decoration instead of heating fuel like I used to.  The money is better, but now all of a sudden the cost of my medication is really ridiculous.  The generic is lots cheaper.”

I looked into her old chart, into the past drug levels.  They were all normal, smack dab in the middle of therapeutic range.

Switching to generic might might things a lot less stable.  I had to tell her that.  It is not without risk.

I also told her that I try to train patients who are on a generic of anything to tell me if and when the pill looks different, changing in color or from a capsule to a pill or vice versa.  Generics have a wide range of variation.  They are not bad, and people do not self-destruct if they get pills from Canada or Mexico or some southeast Asian company that would be hard to find on a map.  The change is not in the quality of the pill.  It is in the effective strength of the pill.

Here are the actual laws for anyone who actually wants to review them:

Basically, a generic and a brand name have to have exactly the same amount of the “active substance;” that is, of the drug.  But a pill has a lot more in it than active substance.  It has, for example, an “excipient,” an inactive “filler” that fills up the volume of the pill or capsule.  Then there is an outer coating.  That can contain coloring or sugar or other things.

I have actually had some cases when someone has an allergy or sensitivity to something in the filler or the coating.  Sometimes, that means a change to generic.  Sometimes that means having a special form of the drug made “to order” by a compounding pharmacy.  As always, lmy motto is “whatever it takes” for the health of the patient.  Luckily, such cases are rare.

Most of the time, however, these factors like the excipient and the coating, do not cause allergies.  Most of the time they do change how fast and how well a drug can be absorbed.  I watch especially closely in patients who have any kind of disease in their stomach or gastrointestinal tract.

There are other factors, besides the nature of the pill and the nature of the stomach, that can change how well a pill gets absorbed.  One common one is taking antacids with a pill, for many are absorbed less well when the stomach is less acid.

The availability of a drug to the blood stream is called “bioavailability.”

Under the law, the generic alternative to a drug can vary by up to 20% from the brand name drug.  That means that if somebody is going from a generic that has 20% less than the name brand to a generic with 20% more, there can be as much as a 40% difference in blood levels.  The worst differences I have seen in my personal practice have been on the order of 30%, and we do what we can to adjust the dose of the drug.  I can’t recall ever needing to change drugs. for this reason.

Checking blood levels is never enough.  A good doctor treats the patient, not the blood tests. It is important to check how the patient feels.  Many drugs requiring blood levels are used to treat bipolar illness.  So it is necessary to check and to see if the patient has any signs of mania or any signs of depression.

There are a million of these, so it is almost impossible to think of them before they become problems.  But if I discover one when it is already a problem, I can usually fix things pretty quickly.

When somebody is changing from brand to generic, or vice versa, it is a pretty sure bet we are looking for changes in the coating and excipient, which could mean a change in the effective amount of drug that can get into the blood stream.

Some drugs have what you call a “low therapeutic index,” which means there may not be all that much space between how much it takes to work and how much it takes to get toxic.  These are typically the drugs that people get blood levels for.  I train all my patients to tell me when the color or shape of their prescription drug pill changes (meaning the pharmacy has switched suppliers of generic drugs — usually for reasons of cheaper cost), but I am extra super careful to tell people to tell me if they are on a drug that is regularly monitored for a blood level, because a change from generic to brand or vice versa or between generics can drive a blood level crazy.

In the case described here, We simply changed to the generic and told my patient to be watchful.  My saleswoman had no signs of mania and she also had no signs of depression, after two weeks on the generic drug.  (I had told her to call me if there were.)  We repeated the blood level.  It had gone down by about 10%.  Everything else seemed normal.  She was still within therapeutic range.

She asked me, “If the drug level went down, don’t you have to raise it so that it was what it was before?”

It was a reasonable question and I believe a patient deserves to understand what is happening with their treatment.  “No, darling.  10% is not so much and it does not seem to make a difference in what you think or feel.  I do not treat numbers.  If you feel good on this generic, we keep it as it is.  You need to call me if you feel manic or if you feel depressed, or if you have a drug side effect, or if the shape or color of your pill changes, which probably means they have changed generic.  Then, we check the level again.  If not, we just continue and get a level when we previously agreed we would need to.”

She agreed with that answer.  Last I heard, she was doing fine.

Knowing what is in a pill, how it works, and knowing how it gets through to body to where it needs to be is an absolutely crucial part of being a doctor.

There is one interesting footnote here.  A lot of people are buying drugs, often generics, over the counter or by prescription in foreign countries, usually Canada or Mexico because they are the most convenient.  The savings may be great.  People, usually people I suspect are from or somehow influenced by the agenda of drug companies, say this is a dangerous and horrible practice.  It is neither dangerous nor horrible.  Usually the pills are exactly the same as the ones offered in the United States.  Check labels carefully and names of manufacturers to know what you are getting.  Know that changes in the origin of a drug can change the potency. Foreign countries have laws about the safety and efficacy of medication.  Work this through as intelligently as you can.  I would hope that members of the medical profession are open minded enough , and free enough from the grasp of pharmaceutical companies, to work with this.