Stability studies of principal illicit drugs in oral fluid: Preparation of reference materials for external quality assessment schemes

Montserrat Ventura, Simona Pichini, Rosa Ventura, Piergiorgio Zuccaro, Roberto Pacifici, Rafael De La Torre

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    17 Citations (Scopus)

    Abstract

    Data on the stability of drugs of abuse in oral fluid are needed to define the optimal transportation and storage conditions when this biological fluid has to be used for off-site screening and confirmation analyses, as well as in the preparation of reference material for external quality assessment schemes. The short-term and long-term stability of opiates, cocaine, amphetamines, and methylenedioxy derivatives in unstimulated oral fluid was evaluated in different storage conditions, with and without the addition of citrate buffer and sodium azide. Short-term stability was evaluated at 25°C and 37°C for up to 7 days. Long-term stability was evaluated at different time intervals for up to 2 months at 4°C and -20°C. The effect of three different freezing and thawing cycles was also studied. No significant loss of amphetamines and methylenedioxy derivatives, morphine, codeine, and benzoylecgonine was observed under any of the investigated conditions. Conversely, hydrolysis of the ester bonds of cocaine and 6-MAM, leading to the formation of benzoylecgonine and morphine, respectively, was observed under all the applied conditions when oral fluid was not buffered and preserved. The addition of citrate buffer (pH, 4) and sodium azide (0.1%) to oral fluid prevented their degradation during up to 7 days of storage at 25°C and 37°C and up to 2 months at 4°C and -20°C. The stability of the principal illicit drugs spiked in buffered and stabilized oral fluid is adequate for transportation of collected samples at ambient temperature and for shipment and storage of reference materials for external quality assessment schemes. © 2007 Lippincott Williams & Wilkins, Inc.
    Original languageEnglish
    Pages (from-to)662-665
    JournalTherapeutic Drug Monitoring
    Volume29
    Issue number5
    DOIs
    Publication statusPublished - 1 Oct 2007

    Keywords

    • Amphetamines
    • Cocaine
    • Opiates
    • Oral fluid
    • Stability

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