Abstract: Methods and reagents are disclosed for enhancing the bioavailability of a hydrophobic drug, and in some embodiments for determining a hydrophobic drug, in a sample suspected of containing a hydrophobic drug. A combination is formed in a medium where the combination comprises the sample, a hemolytic agent where a determination of the hydrophobic drug is conducted, and a bioavailability agent for the hydrophobic drug. The bioavailability agent comprises an ionic detergent comprising a chain of at least 10 carbon atoms or a non-ionic detergent comprising a chain of at least 15 repeating ethylene oxide units or propylene oxide units or a combination of ethylene oxide units and propylene oxide units. The concentration of the bioavailability agent in the medium is sufficient to enhance the bioavailability of the hydrophobic drug.