Patent ID: 8329143

Claim:
A method for determining the rate constant (k) of the clearance of a first molecule and a second molecule by a kidney in an animal, the method comprising: administering the first molecule and the second molecule to the animal, wherein the kidney clears the second molecule from the animal at a rate lower than the rate at which the kidney clears the first molecule from the animal; determining the molecular ratio (R B /R A ) of the first molecule to the second molecule in the animal over a period of time to obtain a time series of molecular ratios (R B /R A ) (t) , the molecular ratio (R B /R A ) being determined using the following equation: R B /R A =I B /I A , wherein I B is the level of the first molecule in the animal and I A is the level of the second molecule in the animal; and determining the rate constant (k) from the time series of molecular ratios (R B /R A ) (t) using the equation: ( R B /R A ) (t) =c+a *exp(− kt ), wherein c is a constant, a is a pre-exponential factor, and t is time.