Abstract: A method of determining a molecular descriptor of absorption for a candidate compound is disclosed. The method includes: providing a test solution comprising one or more candidate compounds; contacting the test solution with a simulated biological membrane to partition the one or more candidate compounds into the membrane detecting the presence or amount of the one or more candidate compound in the membrane at one or more permeation times; and determining a molecular descriptor of absorption using the presence or amount of the one or more candidate compound in the membrane at the one or more permeation times. In one aspect the invention provides a skin-imitating membrane, and one or more percutaneous absorption parameters are determined. In another aspect the membrane is disposed on a fiber. In another aspect the test solution is contacted with two or more simulated biological membranes to partition the one or more candidate compounds into the membranes.

Abstract: A method of determining a molecular descriptor of absorption for a candidate compound is disclosed. The method includes: providing a test solution comprising one or more candidate compounds; contacting the test solution with a simulated biological membrane to partition the one or more candidate compounds into the membrane detecting the presence or amount of the one or more candidate compound in the membrane at one or more permeation times; and determining a molecular descriptor of absorption using the presence or amount of the one or more candidate compound in the membrane at the one or more permeation times. In one aspect the invention provides a skin-imitating membrane, and one or more percutaneous absorption parameters are determined. In another aspect the membrane is disposed on a fiber. In another aspect the test solution is contacted with two or more simulated biological membranes to partition the one or more candidate compounds into the membranes.

Abstract: A first aspect of the invention is a method of estimating a withdrawal interval for an adjusted dose of a compound from a prior withdrawal time for a corresponding prior dose of that compound, corresponding half-life data and a tolerance concentration, for a tissue of interest. The method comprises selecting an adjusted dose for the compound for which a withdrawal interval is to be determined, and extrapolating a withdrawal interval from (a) the prior dose, (b) the prior withdrawal time, (c) the half-life data, and (d) the tolerance concentration. The process is useful for determining a withdrawal interval for an extralabel (i.e., non-approved) use of a drug in the same or a different jurisdiction for which a previous use has been approved, and can be used to determine an appropriate withdrawl interval for a drug in food products exported from one jurisdiction to another. Data processing systems and computer program products for carrying out the foregoing are also disclosed.