Determination of the arpromidine-type histamine H-2-receptor agonist N-1-[3-(3,4-difluorophenyl)-3-(2-pyridyl)propyl]-N-2-[3-(1H-imidazol-4-yl)propyl]guanidine and corresponding N-3-alkoxycarbonylguanidines by HPLC and CE1

The highly potent cardiohistaminergic N'-[3-(3,4-difluorophenyl)-3-(2-pyridyl)propyl]-N-2-[3-(1H-imidazol-4-yl)propyl]guanidine 1 and the corresponding putative prodrugs, the N-ethoxycarbonyl and N-Boc-substituted guanidines 2 and 3, were analysed by isocratic reversed phase ion-pairing HPLC and capillary zone electrophoresis (CZE) using W-detection. At 210 nm the limits of detection of the high precision HPLC method (Nucleosil 100-7, C-18, 52% methanol/48% sodium, phosphate buffer (50 mM, pH 3.0) containing 25 mM sodium pentanesulphonate, 1 ml/min, 65 degrees C) were around 0.1 mu M with a sample size of 50 mu l and between 2-4 mu M for the optimised CZE method (fused silica capillary (75 cmX50 mu m I.D.), 200 mM lithium phosphate buffer, pH 6.0 hydrodynamic injection (20 psi . s) 20 kV; 30 degrees C) with a reproducible sample size of approx. 34 nl. The HPLC method was applied to determine the binding of 1 to serum albumin and to analyse 1-3 in serum, with dansyl-L-phenylalanine as internal standard, where as hydrolysis kinetics of 2 and 3 were measured with CZE. In addition, compounds 1-3 were quantified in urine by CZE using quinine sulphate as internal standard.