There are always questions regarding Drug Tests/Urine Tests, that sort fo thing. If we put any info or experiences we have under one thread it'll make it easier to find.

 

Claude..if you find that list of drugs that can cause false positives maybe you could post it here when you have time.

 

I'll start with this one I found in The Journal of the American Medical Association on:

 

 

A DGReview of :"Quinolones and False-Positive Urine Screening for Opiates by Immunoassay Technology"
Journal of the American Medical Association (JAMA)

01/07/2002
By Anne MacLennan

 

Doctors and other health professionals must pay greater attention to the potential for common medications to cross-react with frequently-used testing assays for substance abuse.

Millions of assays are performed in various settings each year to monitor for substance abuse. However, cross-reactions of licit drugs with assays for illicit ones are not uncommon and produce false positives results that, in turn, lead to invalid conclusions.

These researchers sought to evaluate the cross-reactivity of quinolone antimicrobials in common opiate (urine) screening assays and to assess the in vivo implications of this phenomenon.

The reactivity of 13 quinolones was tested in five commercial opiate screening assays from September 1998 to March 1999.

Quinolones included in the study were levofloxacin, ofloxacin, pefloxacin, enoxacin, moxifloxacin, gatifloxacin, trovafloxacin, sparfloxacin, lomefloxacin, ciprofloxacin, clinafloxacin, norfloxacin, and nalidixic acid.

The researchers confirmed the cross-reactivity of levofloxacin or ofloxacin with these opiate-screening assays in six healthy volunteer study participants.

Main outcome measure was opiate assay activity (threshold for positive result, 300 ng/mL of morphine).

In at least one of the assays, nine of the quinolones caused assay results above the threshold for a positive result. Four of the assay systems caused false-positive results for at least one quinolone.

Of the 13 compounds, 11 caused some opiate activity by at least one assay system. At least one compound caused opiate assay activity in all five assay systems.

Levofloxacin, ofloxacin, and perfloxacin were most likely to lead to a false-positive opiate result. Positive results were obtained in urine from all six volunteers.

To minimize the potential for invalid test interpretation, greater attention must be paid to the cross-reactivity of quinolones with immunoassays for opiates, these researchers conclude.
JAMA. 2001;286:3115-3119. "Quinolones and False-Positive Urine Screening for Opiates by Immunoassay Technology"