What interferes with methodone for your urine to come up as a opiate?

Answer 1

Because it's an opioid agonist, methadone (not "methodone") is considered to be an opiate by the majority of medical professionals, therefore nothing has to interfere with it for ones urine to test positive for opiates. If samples are analyzed by an immunoassay method, and a sample is positive for any drug tested, then the sample is typically analyzed using gas chromatography coupled with mass spectrometry (GC/MS). I know that if my sample tested positive for something that was analyzed by immunoassay, then I would demand that it be analyzed by GC/MS or they would be speaking to my lawyer next. People's lives can be ruined by a false positive drug test. That is why the company or person running the test better make darn sure that a positive result is truly a positive result.

Some drug tests for "Opiates" only analyze a sample for morphine and morphine derivatives such as heroin, codeine, oxycodone, hydrocodone, hydromethone, and possibly a few others. Other "Opiate" drug tests look for the ones just listed plus the synthetic opiates such as methadone, fentanyl, and meperidine (Demerol™). At least in the USA, methadone is not prescribed nearly as often, nor is it nearly as available on the street as morphine and its derivatives. Hence, a person is less likely to be tested for it. It simply depends on what tests the person in charge of the drug testing program chooses, or must choose in some cases, although it's a very good bet that that person doesn't know jack about drug testing. In the vast majority of cases, the decision is based on how many bucks a drug-testing lab can get a company to spend on drug testing.

The two basic methods used to test for drugs have already been mentioned: Immunoassay and GC/MS. Drug tests performed by immunoassay methods are inherently less sensitive and less discriminating than tests performed by GC/MS. That is, analyses by immunoassay have significantly higher detection limits and are much more likely to yield a false positive result compared to GC/MS analyses. For those reasons, higher cut-off limits are assigned to every analyte concentration result determined by an immunoassay method in order to eliminate, or at least to significantly reduce, the number of false positives. By definition, a cut-off limit cannot be less than the method detection limit for any given analyte, and it is usually considerably higher. This means that if a drug or its metabolite is detected in a sample, but the sample result for that drug or metabolite is at or below the cut-off limit, then the sample will be reported as "Negative" for that drug.

There are definitely several different analytical methods that test for methadone. If methadone is looked for on a drug test, and the one being tested has taken it in the previous 5-10 days, then the person being tested will usually test positive for it. The reason methadone can still be detected five or more days after the last dose is due to its long biological half life and its preferred solubility in ones adipose tissue (fat).

The report for a typical partial drug screen for opiates will usually look something like the semi-phoney one below:

ANALYTE DRUG RESULT DET. LIMIT CUT-OFF LIMIT POS./NEG.

(ηg/mL) (ηg/mL) (ηg/mL) (+/-)

methadone methadone 335 60 500 -

6-acetylmorphine heroin < 85 85 200 -

oxymorphone oxycodone 475 100 200 +

α- & β-oxymorphol oxymorphone <30 30 100 -

hydrocodone hydrocodone 700 60 500 +

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