Drugs that are cognates of other drugs...effect?

Factual Questions
1

About 15 years ago, I was prescribed a medicine, the name of which I cannot remember. But, IIRC, I looked it up in a What is Your Drug doing to you, or something like that kind of book, and it was a combo of 120 mg. of one drug, and 30 mg. of another. I soon lost my insurance after that, so I couldn’t afford going to the doc for a scrip, and I was also in my “who needs a dr. anyway?” stage, so, I just bought the two, in the named doses, and it seemed to me the effect was the same. So, question: Other than self-prescribing, which I know was dangerous, and foolish, if not illegal, was my concoction the same, essentially, as what I would get with the prescribed medicine, or was I making some witches brew that only a coroner would have been able to determine?

thanks,
hh

2

In my extremely limited knowledge of pharmacology, my answer is ‘maybe’. The active ingredients perform the actual work of the drug. But other listed ‘inactive’ ingredients may increase bioavailability (absorption), optimal time release, etc. Thus, taking the two component active ingredients together in the right doses MAY have a similar effect as taking the original drug, but also could be significantly different depending on the final composition of the drug.

I don’t think it’s a big deal if you’re talking about mild pain relief, skin cream moisturizer, or what have you, but I definitely wouldn’t go that route for any major health issue or chronic illness.

3

:smiley:

Roger that! Like I said, I was in my self medication phase…it didn’t help that at that same time, the guy that delivered his wife’s baby, via home made C-section, only inspired me! (Hey! who needs one of these overpaid doctors, anyway! I was drinking a lot at the time, if you can believe it!:D)
At any rate, I made it, and 'at 'ere stuff ain’t never gonna happen again!

hh

4

A possible (much simplified) scenario.

Imagine the following recipes:

ComboDrug: Drug A + Drug B + Inert1+ Inert2 + Inert 3

TabletA 120mg: Drug A + Inert1 + Inert4 + Inert5

TabletB: DrugB + Inert2+ Inert3+Inert5+Inert6

Clearly, Inert1, 2 and 3 have been proven to be safe (does not cause drug degradation, abnormal biochemistry, etc) with Drug A and Drug B, since they are in ComboDrug. Inert5 is also safe with both, as both TabletA and TabletB contain it.

The problems become Inert 4 and 6. 4 has not been proven to not degrade or affect the performance of Drug B, and likewise Inert6 isn’t known to be safe with Drug A. Of course, there’s probably a ton of data at the various pharma companies about this stuff, but due to the testing they did, they chose those recipes, and as a consumer you can’t know if some inerts caused problems, or offered no benefits, or was just too expensive, or what.
The other aspect of this is what the recipe is designed to do. ComboDrug may be designed to release DrugA in 30 mins or less and DrugB in no less than 4 hours, but TabletA might be designed to release DrugA in no less than 1 hour and TabletB be designed to release DrugB in under 45mins.

In cases like this, you are clearly not medicating the condition in the same manner, since the effects of each drug hit your system at different times. One serious risk here is the compounding of side effects - if both drugs tend to cause a few minutes of rapid heart rate as they hit your system, then having that happen at the same time could make things very, very bad for you! Also, the different release times to your system could mean that the effects wear off sooner (or later), and sticking to the same dose schedule (or a random one of your own making) could mean that you under or overmedicate your medical condition, and uneven dosing could increase the risk of side effects and complications.
OR ComboDrug was specifically designed to replace a TabletA+TabletB dosing regimen, and is therefore just as good or more effective than either one together or apart, or by coincidence, ComboDrug just happens to behave the same way as TabletA and TabletB taken together, but wasn’t studied in direct comparison to them.
So, essentially, it completely depends on a bunch of stuff, and there is no general answer to your question! If you knew which medication you were replacing and the names of the 2 others as well, a doctor or pharmacist may be able to tell you whether the alternate dosing regimen was safe.

5

I see what you’re getting at, but remember almost any combo drug, maybe even all, was created for the convenience of not having to take each separately. And that’s the point. You know they’ve already been taken separately for years, and by some people still on an ongoing basis. In other words, if they’re safe together in one pill, you can be guaranteed they were, and are, safe together in two different pills.

As an aside, these combo drug pills are big for blood pressure control (where people often need multiple agents) and certain antibiotic preparations.

6

Yeah, I realize most combos are created to replace a multi-pill regimen, but I can imagine some cases where it isn’t that clear-cut for the patient. I was thinking along the lines of DrugB being something like Tylenol, and someone trying to make a combo with a Fast Acting formulation rather than a Long Lasting one, or something like that. That could potentially cause problems, or at least not treat the medical condition as well as the more appropriate formulation would.

I don’t think the two drugs would interact, since they don’t in the combo. But their biochemical effects on the body could behave differently if their relative doses in the body vary greatly, and again, the medical condition could be under/over medicated.

I don’t really think the Inert ingredients taken in two separate pills could interact all that much with the other pill’s drug once the patient has taken it, but it’s not impossible. Some drug products are really sensitive to weird stuff, but that is definitely a very small percentage of all the drugs out there, and probably not really worth considering. I admit I kind of wrote that part of the post as a worst-case-scenario thought experiment. I have no clue what the likelihood of any of it is :slight_smile:

7

IANAP, but that sounds like a potentially unsafe guarantee, consider the following scenarios:

Combo drug developed specifically to aleviate an adverse side-effect caused by the interaction of two inert components occurring in a two-pill regime

Combo drug developed to replace two specific separate pills, other pills exist with the same amount of active ingredients, but otherwise different formulation from the two that were intended to be combined.

8

Mangetout I can’t think of any scenarios in real life like the ones you suggest.

The main reason combination drugs are used are to prevent the pesky side effect of “patient not taking their pills”. It is a lot easier to take one pill than two.

If you take the two separate preparations according to each individual drug’s direction, you should be fine. Really.

FWIW- my formulary contains interactions between drugs. That is, named ACTIVE ingredients. It DOES NOT contain interactions between excipients- mostly because, I suspect they don’t occur. They tend to be things like “sucrose”, “lactate” and “Citric Acid”.

9

One big advantage of them is the whole insurance copay thing. If your prescription plan says “5 dollars per generic” or whatever, most people would rather pay 5 bucks total for a combo pill, vs. 5 for each of the two ingredients.

Me, I’d personally prefer to take the meds separately. Too hard to titrate the individual medications if needed. Then again, I’m one of those folks who generally complies with medical instructions. Someone who was more forgetful might well have better results with a combo - that way you can’t forget to take one of the ingredients.

10

As long as the two separate preparations you are taking are the two which the combo was designed to replace. In general, I wouldn’t expect the average patient to know that there might be a difference between long-lasting and quick release versions of drugs that are otherwise labelled the same: Drug B 100mg Extended or Drug B 100mg Fast Acting are not interchangeable and will treat the medical condition differently. So there’s a risk if a patient is buying them on their own/illegally, because they might be getting the wrong thing.

I realise that everything I said about this is of much greater concern in a test tube in the drug development lab than in a person, but I just want to clarify where my thought process was coming from.

There is no concern of things like sucrose and lactose and citric acid interfering with* one another*. What there is a concern about, is things like citric acid reacting with a basic drug molecule, causing it to degrade into molecules that either a)have no pharmaceutical effects, b) are harmful to the patient. Every drug molecule is tested with each excipient individually in a stability study to ensure that the ingredients that are known to be inert to humans are also inert to the drug. This is how certain recipes are chosen and rejected, and also in some cases determine the packaging needed (water-sensitive might be packaged with a can of dessicant, for example). This is more of a long-term inter-action, though, which is why this train of thought is incorrect on my part.

So I had been thinking that in a very, very unlikely hypothetical situation, taking DrugA with another that has ExcipientB which caused degradation in the lab could be a bad thing, but the mixture in the mouth/stomach/GI tract is so short-term that, really, the pH changes in the body, other foods consumed, etc in a patient are infinitely more likely to cause problems! So this isn’t really a risk at all, but just, as I said, a worst-case scenario thought experiment of ridiculously low probability. I think I have been scarred by that one in-development drug I worked on that tended to flip out when magnesium (sulfate) was present…