Interference of herbal drinks with urinalysis for drugs of abuse

Recently there have been claims among drug users that some herbal drinks interfere with urinalysis for drugs of abuse and yield false positive results. Proof of such claims has yet to be shown. Screening for drugs of abuse is usually carried out using fluorescence polarization immunoassay (FPIA) or thin-layer chromatography (TLC). Fifty herbal samples which are considered among the most purchased herbs in the consumer market were used to investigate such claims. The drug groups that were tested for included amphetamines, opiates, barbiturates, cocaine metabolite, methadone, and their analogs. The herbs were analyzed at different concentrations (0.1, 1, 3, and 5 g/100 mL of distilled water) using TLC and FPIA to determine if any interfere with urinalysis for drugs of abuse and yield false positive results. For the FPIA test, the sample infusions were analyzed directly using the automated ADX analyzer (Abbott Laboratory). For TLC, infusions of the herbs were added to a solid-phase extraction column (pH 9.25), then extracted with a methylene chloride-isopropanol solvent system. At this pH, neutral, basic, and acidic drugs of abuse are extractable. The developed chromatographic plates were sprayed sequentially with several reagents. None of the herbs in the concentration ranges screened showed any interference with TLC or FPIA, indicating the invalidity of such claims.