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Systems and methods to determine body drug concentration from an oral fluid

  • US 10,073,069 B2
  • Filed: 04/21/2014
  • Issued: 09/11/2018
  • Est. Priority Date: 04/23/2013
  • Status: Active Grant
First Claim
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1. A method for determining a donor'"'"'s adherence to a dosing regimen, the method comprising the steps of:

  • collecting a sample of oral fluid from the donor;

    determining the pH of the oral fluid sample;

    readying the sample for transport and analysis by placing the sample in an appropriate buffer, and sealing and packing the sample;

    determining a concentration of the drug in the in the oral fluid sample;

    calculating an expected plasma steady state minimum drug concentration (Cssmin) and an expected plasma steady state maximum drug concentration (Cssmax);

    calculating an equivalent expected oral fluid steady state minimum drug concentration (Smin) and an expected oral fluid steady state maximum drug concentration (Smax) using Cssmin and according to the following steps;

    if the drug is an acidic drug, determine Smin and Smax using Eq. 5 by inputting Cssmin and Cssmax for P and solving for Smin and Smax (S);


    S/P=[1+10(pHs-pKa)×

    fp]/[1+10(pHp-pKa)×

    fs]; and





    Eq. 5;

    if the drug is a basic drug, determine Smin and Smax using Eq. 6 by inputting Cssmin and Cssmax for P and solving for Smin and Smax (S);


    S/P=[1+10(pKa-pHs)×

    fp]/[1+10(pKa-pHp)×

    fs];





    Eq. 6;

    wherein;

    pHs is a pH of saliva to be determined at the time of collection;

    pHp is a pH of plasma;

    pKa is a dissociation constant of the drug;

    fp is a free fraction of the drug in plasma; and

    fs is free fraction of the drug in saliva; and

    determining whether measured oral fluid drug concentration of the donor complies with the dosing regimen of the drug, at steady state, if the measured oral fluid drug concentration is within the range between Smax and Smin, wherein the step of determining the oral fluid drug concentration comprises preparing the sample for toxicological measurement of drug content and extracting the drug from the sample using mixed-mode cationic exchange columns.

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