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  • nalexogol reported as hydromorphone?

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    Old 02-19-2017, 06:07 PM   #1
    michaelb7's Avatar
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    nalexogol reported as hydromorphone?


    I need help trying to resolve a "false positive" issue that I believe may be resulting from my doctor's lab rep not believing there is any need for him to tell the lab that I'm taking a relatively new drug (one that might be a close spectral match for an existing one).

    I am wearing a fentanyl patch 100mcg/72h for severe pain and Opana IR (oxymorphone) for breakthrough pain.

    I had previously been taking hydromorphone for B/T pain, but my doc changed it last summer to Opana IR. He said he no longer prescribes dilaudid "because of it's increasing stigma".

    After I switched from dilaudid to opana, BOTH began appearing in my urine tests, which use GC/MS.

    I had begun taking Movantik for Opoid Induced Constipation while I was still taking dilaudid. At the time, the hydromorphone count reported increased by a large amount. After I switched from dilaudid to Opana IR, the report showed the oxymorphone, but also showed a hydromorphone count similar to what it had been before I bagan taking Movantik.

    I've been tested several times at varying intervals, w/processing always done by Millennium Labs.

    I noticed on the report that despite my taking ten prescriptions, including Movantik (nalexogol), the only drugs Millennium was aware of my being prescribed were Fentanyl and Opana. I pointed out that neither Movantik nor my other Rx's were reported to Millennium, but the doctor said "It does not matter; they don't look for them".

    None of the other drugs listed on my chart (zoloft, bupropion, Xarelto, metoprolol, modafinil, androderm, etc) were known to Millennium, either.

    I had found articles indicating that naloxone (upon which Movantik is based) can cause false immunoassay positives, although I've not found anything about naloxone (or -egol) and GC/MS. What I did read implied that what is cared about is the closest spectral value (SV) to one in a spectral library, further implying that if the SV for hydromorphone is the closest match to the ion examined, it might be reported as hydromorphone, unless an SV for naloxegol is added to the GC/MS machine's library.

    Still, I don't expect much change with my next "pop" urine test, which will be the one that gets me "discharged" for taking a drug that I'm not taking (with the concomitant stigma and difficulty getting into another practice), unless I can find a solution.

    Any guidance or other help offered would be greatly appreciated.

    Many thanks, in advance,


    Last edited by Moderator1; 02-19-2017 at 06:14 PM.

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    Old 02-19-2017, 11:38 PM   #2
    michaelb7's Avatar
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    Re: nalexogol involvement in hydromorphone false positive?

    P.S. After writing the above, I came across an article stating that naloxone is a "structural analogue of oxymorphone".

    Since two different molecules, both present, cant both be oxymorphone, could this be a source of confusion for the GC-MS technician, who is forced to find a distinction? and then considers the next closest spectral match in it's spectral library to be hydromorphone?

    Would I be correct in making the uneducated guess that after the ionization process, the relevant portions of naloxone and naloxegol could be identical (with the PEG addition disregarded), making the previous paragraph have the same truth value if the compound naloxegol is substituted for naloxone in the first sentence?

    Again, any suggestion(s) for how to resolve the issue, or (educated guesses about what is happening that I might be able to print for the doctor) would be greatly appreciated.

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    false positive, hydromorphone

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