title: Analysis of highly potent amidine containing inhibitors of serine proteases and their N-hydroxylated prodrugs (amidoximes).
abstract: The development of serine protease inhibitors often results in the discovery of new lead compounds containing strong basic amidine functions that usually suffer from poor absorption from the intestine. In order to improve oral bioavailability of these drugs, prodrug principles such as the conversion of amidines into amidoximes may be applied. In this work, two HPLC-based separation methods of serine protease inhibitors (amidines) and their N-hydroxylated prodrugs have been developed and characterised. This was performed by evaluating 11 distinct amidine-amidoxime pairs with different physicochemical parameters (clogP: -3 to 5.1). The HPLC methods developed allowed excellent separation of the compound pairs examined. Also, the possible selection of different separation techniques (i.e. adsorption- and ion-pair-chromatography) permits universal application. Moreover, both techniques are compatible with mass spectrometry and are superior to the previously described methods. In summary, both HPLC methods are suitable for the separation of most amidoxime-prodrugs currently in clinical or preclinical development.
authors.affiliation: Department of Pharmaceutical and Medicinal Chemistry, Christian-Albrechts-University of Kiel, Kiel, Germany.
authors.forename: Joscha
authors.initials: J
authors.lastname: Kotthaus
authors.forename: Torsten
authors.initials: T
authors.lastname: Steinmetzer
authors.forename: Andreas
authors.initials: A
authors.lastname: van de Locht
authors.forename: Bernd
authors.initials: B
authors.lastname: Clement
mesh_terms: D000284:Administration, Oral; D000578:Amidines / Q000737:chemistry / Q000494:pharmacology*; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D006900:Hydroxylation; D007408:Intestinal Absorption / Q000187:drug effects; D013058:Mass Spectrometry; D011355:Prodrugs / Q000737:chemistry / Q000494:pharmacology*; D012680:Sensitivity and Specificity; D057057:Serine Proteases / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D000578:Amidines; D011355:Prodrugs; D015842:Serine Proteinase Inhibitors; D057057:Serine Proteases