STUDIES ON NONCOVALENT ASSOCIATIONS OF IMMUNOSUPPRESSIVE DRUGS WITH SERUM-ALBUMIN USING PNEUMATICALLY ASSISTED ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

Pneumatically assisted electrospray ionization (ion-spray) mass spectrometry was employed in the detection of non-covalent interactions of inmunosuppressive drugs with proteins. Non-covalent complexes of albumin (rat and bovine) with FK506, dihydro-FK506, and FK520 were observed. No complexation was detected between albumin and cyclosporin A (CsA), even at a protein-ligand molar ratio of 1:20. It is suggested that the lack of detection of an albumin-CsA non covalent complex may be attributed to dissociation of the weakly associated species during ion vaporization. Nonetheless, preliminary results indicate that ion-spray mass spectrometry has potential in qualitative evaluation of drug-plasma protein interaction.