Determination of free fractions

Abstract

The invention relates to methods for the determination of pharmacological properties of substances, such as, e.g., chemical substances. The invention also relates to methods and kits for use in the determination of the free fraction, fu, of pharmacologically active compounds in aqueous solutions and serum. The invention also relates to the above methods in which solid particles, coated with a lipophilic medium, are used.

1 . A kit for use in a method for determining the free fraction of a substance, the kit comprising: a plate having multiple cavities; particles having a lipophilic surface; a protein-free aqueous medium; and a protein-containing aqueous medium, the kit being adapted to: incubate, in a first cavity of the plate, the substance with a suspension of the particles in the protein-free aqueous medium, the particles and the protein-free medium being erythrocyte free; and incubate, in a separate cavity of the plate, the substance with a suspension of the particles in the protein-containing aqueous medium, the particles and the protein-containing medium being erythrocyte-free, whereby a distribution of the substance between the particles and the protein-free medium is determinable, a distribution of the substance between the particles and the protein-containing aqueous medium is determinable, and the free fraction of the substance from the distributions is determinable. 
     
     
         2 . The kit of  claim 1 , wherein the particles having a lipophilic surface comprise particles having a solid core, particles having a solid core that is a silica bead, or Transil® particles. 
     
     
         3 . The kit of  claim 1 , wherein the particles having a lipophilic surface comprise a ferromagnetic core. 
     
     
         4 . The kit of  claim 1 , wherein the protein-free aqueous medium is a buffer solution. 
     
     
         5 . The kit of  claim 1 , wherein the protein-containing aqueous medium is plasma. 
     
     
         6 . The kit of  claim 1 , further comprising a second protein-containing aqueous medium, and wherein the plate has at least three cavities, whereby the kit is adapted to incubate, in the third cavity, the substance with a suspension of the particles in the second protein-containing aqueous medium, the particles and the second protein-containing medium being erythrocyte free, and whereby a distribution of the substance between the particles and the second protein-free medium is determinable. 
     
     
         7 . The kit of  claim 6 , wherein the protein-containing aqueous media are plasma from of two different species.