How to tell if a placebo group is taking regimen as they're supposed to?

February 5, 2009 1:15 AM

In double-blind clinical trials, is there a common drug put into the placebo group and the test groups drug to test to make sure the participants are taking the drug correctly?

I understand that the administers of the drug are blind, and can't know WHICH group you're in (placebo v. active drug), but is there a way they test your urine to know IF you're taking the drug?

Perhaps somebody has worked in clinical trials or participated in them and knows.

This question is purely out of concern that I didn't report a few food allergies I have and I'm concerned they might put something else in the pills to make sure I'm taking them.

posted by ilovehistory to science & nature (5 comments total)

This would be highly unethical, and highly unlikely. I have never heard of an extra level of manipulation across the board to confirm that someone was indeed taking pills in a clinical trial.
posted by No New Diamonds Please at 1:28 AM on February 5

I'm a clinical research tech. There's no way a lab would secretly add another drug to the study drug/placebo without your consent. I assume that you read and signed a thorough informed consent form when you began screening for the study. If there's nothing in the consent form indicating what you described as an aspect of the study, it wouldn't happen. Clinical research trials are vetted by an institutional review board whose purpose is to make sure subjects are being treated ethically, and as NNDP said, this would be super unethical and would never get approved.

On the other hand, placebo pills/capsules do contain what they call "inert" ingredients, and depending on your food allergies that might be a problem. We fill our placebo capsules with lactose powder or corn starch; flour is another common filler. We actually screen potential subjects out if they're lactose-intolerant (which should give you an idea of how carefully these things are monitored). If you're worried, it can't hurt to let the lab know about your food allergies. Good luck, guinea pig!!
posted by granted at 2:03 AM on February 5

Not only would they not do this, but many times the control drug is not a placebo but another treatment; for example you could do a trial comparing aspirin and ibuprofen for pain relief and no one would know during the trial which of the two drugs they were getting. So depending on the trial you are in you may not be getting a placebo at all. Other factors come into play as well. I was once in a trial looking at the effect of scopolamine on memory; it involved taking different doses of scopolamine or a placebo and undergoing a variety of neurological tests. As a placebo they used another drug, glycopyrrolate, as both drugs give you a dry mouth but only scopolamine affects the brain. (As an aside, I could still tell which drug I got because the scopolamine gave me a pleasant buzz). So as granted says, talk to the people doing the study and they may be able to tell you what is in the control drug/placebo, or at least tell you if your allergies are a concern.
posted by TedW at 5:21 AM on February 5

What you are suggesting would just complicate an already too damn complex to believe data set. Unless your trial is being run out of Joseph Mengele Memorial Hospital and they're slipping a radioactive tracer in there without your consent or knowlege, you can pretty much assume that they're not doing this

Do make sure the people running the trial know your allergies. There is drug substance and all that they add to it make it into a pill, plus all that goes into placebo (or current best standard of treatment). It would really suck to be fine with the drug, but deathly allergic to the green dye they used to make the pill look different from the red oval shaped pill of that size.
posted by Kid Charlemagne at 6:30 AM on February 5

Usually, unless the study is specifically about compliance, they don't factor this in; the analysis is based purely on which group (control/test) the individual was placed into and not whether they took the drug -- even if that drug was the treatment drug. There's an entire literature about how to best analyze data when the subjects aren't compliant with the protocol or drop out; if you google around for "intent to treat analysis" you'll find tons (here's an overview on wikipedia).

All that being said, Kid Charlemagne and others have it right: make sure the drs running the trial know your allergies.
posted by Westringia F. at 10:52 AM on February 5