(125) Can oral fluid replace urine and blood drug testing as the gold standard in the pain management industry?

Abstract

Historically, urine is the matrix of choice for the identification of illicit and pharmaceutical drugs and blood is the preferred matrix for interpretation of biologically active drug levels. Urine offers the advantage of high analyte concentration coupled with reasonably long detection; however, interpretation is limited as analytical results solely indicate past exposure and the matrix is highly susceptible to adulteration. Blood provides a window into total body drug concentration, allowing for dose correlations at steady state; however, due to invasive and costly collection, improved methods to interpret therapeutic drug concentration are desirable. Oral fluid, a direct filtrate of the blood, has shown great promise as an alternative matrix with the potential to revolutionize clinical toxicology. The utility of oral fluid in relation to the other matrices was explored by examining differences in positivity rates between urine and oral fluid samples, as well as by assessing patient compliance to a known dosing regimen based on oral fluid drug levels, a task currently performed using blood. A retrospective comparison of drug testing results obtained from 4560 unobserved urine and 2368 observed oral fluid collections averaged a 3-fold increase in positivity of traditional drugs of abuse including 6-AM, THC, and cocaine and a 10-fold increase in positivity of prescription medications with established histories of misuse, such as oxycodone and hydrocodone, when oral fluid was the testing matrix. In a separate study, paired oral fluid and plasma samples were simultaneously collected from patients prescribed basic opiates, permitting compliance monitoring using both matrices. Concordance between the oral fluid and plasma drug concentrations in relation to the expected therapeutic steady state range showed 78.4%, 69.8%, and 90.3% agreement for oxycodone, hydrocodone, and morphine respectively. These findings are two illustrations of the potential oral fluid holds as the new gold standard matrix for therapeutic drug monitoring. Historically, urine is the matrix of choice for the identification of illicit and pharmaceutical drugs and blood is the preferred matrix for interpretation of biologically active drug levels. Urine offers the advantage of high analyte concentration coupled with reasonably long detection; however, interpretation is limited as analytical results solely indicate past exposure and the matrix is highly susceptible to adulteration. Blood provides a window into total body drug concentration, allowing for dose correlations at steady state; however, due to invasive and costly collection, improved methods to interpret therapeutic drug concentration are desirable. Oral fluid, a direct filtrate of the blood, has shown great promise as an alternative matrix with the potential to revolutionize clinical toxicology. The utility of oral fluid in relation to the other matrices was explored by examining differences in positivity rates between urine and oral fluid samples, as well as by assessing patient compliance to a known dosing regimen based on oral fluid drug levels, a task currently performed using blood. A retrospective comparison of drug testing results obtained from 4560 unobserved urine and 2368 observed oral fluid collections averaged a 3-fold increase in positivity of traditional drugs of abuse including 6-AM, THC, and cocaine and a 10-fold increase in positivity of prescription medications with established histories of misuse, such as oxycodone and hydrocodone, when oral fluid was the testing matrix. In a separate study, paired oral fluid and plasma samples were simultaneously collected from patients prescribed basic opiates, permitting compliance monitoring using both matrices. Concordance between the oral fluid and plasma drug concentrations in relation to the expected therapeutic steady state range showed 78.4%, 69.8%, and 90.3% agreement for oxycodone, hydrocodone, and morphine respectively. These findings are two illustrations of the potential oral fluid holds as the new gold standard matrix for therapeutic drug monitoring.