Patrick asked
I was wondering whether my son, who is taking the following medications should be showing a "false positive" for the "BUP" (buprenorphine) test. He says it's a combination of the medications that are showing it but I don't know if that's true or not. He takes the following: Lunesta Klonipin (PRN) Seroquel Neurontin Wellbutrin XL Omeprazole Flonase Lactulose (PRN) Opsumit Adcirca Warfarin Pamelor Oxycodone-Acetaminophen (PRN) Thanks!
Answer
Receiving a 'false positive' on a urine drug test for buprenorphine (one of the active ingredients in Suboxone) is actually a fairly well known problem, especially if the person being tested is on other opioid medications (buprenorphine is classified an an opioid). There have been multiple studies discussing and dissecting the issue.
The issue lies with the actual drug test. The most common type of drug test utilized is known as the "Enzyme Linked Immunoassay" (EIA) test. EIA tests utilize antibodies to react to specific opiates. Basically, when a specified opioid is present in a test urine sample, an antibody binds to it, which produces a reaction. When a reaction occurs, it is recorded as a 'positive' result.
Unfortunately, there is a significant problem with 'cross-reactivity' in these EIA tests and they occur when a patient is taking other opioid medications. Opioid samples can occasionally react with the wrong antibody (i.e. 'cross react), resulting in a false positive. Worsening the problem, there are studies that show some non-opioid drugs can also cause positive opioid tests.
There is another commonly used drug test known as CEDIA (Closed Enzyme Donor Immunoassay) that uses the same principles as the EIA test. The CEDIA test has the same cross reactivity problem unfortunately. One major study on the subject reported that codeine, tramadol, methadone and morphine all produced false positives for buprenorphine on a drug test.
If you are concerned about a positive result from a drug test that you do not agree with, you need to have a discussion with your doctor and/or the testing agency. There may have some options:
- Ask the retake the drug test. While false positives do occur, they are relatively uncommon. The more tests that are taken, the more likely you will get an accurate result.
- Ask to change the sensitivity of the drug test. Drug tests are designed with a certain cutoff concentrations, which is the lowest point in which a positive result occurs. If a test uses too low of a cutoff concentration, the likelihood of a 'positive' results increases... potentially a 'false positive'.
- Lastly, you may ask to use a more definitive test, a gas chromatography/mass spectroscopy test. While significantly more expensive and cumbersome, this is one of the only true methods to get a undeniably accurate result. This test actually separates and analyzes the different molecules in a drug sample and doesn't rely on an antibody reaction.
So, all in all, false positives results do happen and it puts both the patient and prescriber in a difficult situation. It is important to have open communication with the doctor and build a trusting doctor/patient relationship.
