The Pharmacokinetics Research Of Ilaprazole

Ilaprazole is a new proton pump inhibitor designed for the treatment of gastric ulcers. Our study consists of four parts, determination of ilapraozle and its two metabolites in human plasma by LC-MS/MS, Identification of ilaprazole urinary metabolites in human by high-performance liquid chromatography-tandem mass spectrometry and stopped-flow high-performance liquid chromatography-nuclear magnetic resonance experiments, pharmacokinetics of the new proton pump inhibitor ilaprazole in Chinese healthy subjects in relation to CYP3A5 and CYP2C19 genotypes and the effect of standard Triple-Drug therapy for helicobacter pylori eradication on the pharmacokinetcs of Ilaprazole.An analytical method based on liquid chromatography and electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) has been improved and validated for the quantitative measurement of ilaprazole and it's two metablites in human plasma. Separation of analytes and the internal standard (IS) omeprazole was performed on a Thermo HyPURITY C18 column (150×2.1mm,5μm) with a mobile phase consisting of 10mM ammonium formate water solution-acetonitrile (50:50,v/v) at a flow rate of 0.25 mL/min. The API4000 triple quadrupole mass spectrometer was operated in multiple reaction monitoring mode via positive electrospray ionization interface using the transition m/z 367.2→m/z184.0 for ilaprazole, m/z 383.3→m/z184.1 for ilaprazole sulfone, m/z 351.2→m/z168.1 for ilaprazole thiol ether and m/z 346.2→m/z 198.0 for omeprazole. The method was linear over the concentration range of 0.23-2400.00 ng/mL for ilaprzole,0.05-105.00 ng/mL for ilaprazole thiol ether and 0.06-45.00 ng/mL for ilaprazole sulfone, respectively. The intra- and inter- day prcisions were all less than 15% in terms of relative standard deviation (R.S.D), and the accuracy was within 15% in terms of relative error (R.E) for ilaprazole, ilaprazole sulfone and ilaprazole thiol ether. The lower limit of quantification (LLOQ) was identifiable and reproducible at 0.23,0.05 and 0.06 ng/mL with acceptable precision and accuracy for ilaprazole, ilaprazole sulfone and ilaprazole thiol ether, respectively. The validated method offered sensitivity and wide linear concentration range. This method was successfully applied for the evaluation of pharmacokinetics of ilaprazole and it's two metablites after single oral doses of 5 mg ilaprazole to 12 Chinese healthy volunteers.The structural elucidation of ilaprazole metabolites in human urine was described by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and stopped-flow liquid chromatography-nuclear magnetic resonance (HPLC-NMR) experiments. Urinary samples were precipitated by sodium carbonate solution, and then extracted by liquid-liquid extraction with methyl chloride after adding ammonium acetate buffer. The enriched sample was separated using a C18 reversed-phase column with the mobile phase composed of acetonitrile and 0.05 mol/l ammonium acetate buffer in a gradient solution, and then directly coupled MS/MS detection in an on-line mode or 1H-NMR (500 MHz) spectroscopic detection in a stopped-flow mode. Four sulfide metabolites, ilaprazole sulfide,12-hydroxy-ilaprazole sulfide,11,12-dihydroxy-ilaprazole sulfide and ilaprazole sulfide A were identified from the combined MS/MS and NMR data with those of the parent drug and available standard without actually isolating them. The result testified that the described method could be widely applied in rapid detection and identification of novel metabolites.This study is to investigate the kinetic characteristics of a new PPI ilaprazole in Chinese healthy subjects and the association with CYP3A5 and CYP2C19 polymorphisms.21 subjects were selected and treated with 10mg ilaprazole according to their CYP3A5*3 genotypes. The plasma concentrations of ilaprazole and its metabolites were monitored by LC-MS/MS method.The Cmax, AUC(0-6), AUC(0-48) and AUC(0-∞) of ilaprazole were all significantly different across the 3 CYP3A5 genotypes (including 4 of CYP3A5*1/*1,4 of*1/*3,3 of *3/*3; Pb0.05) in CYP2C19 wild-type subjects (CYP2C19 wt/wts), similar variety of Cmax and AUC(0-6) among CYP3A5 genotypes (including 3 of CYP3A5*1/*1,3 of *1/*3,4 of *3/*3; Pb0.05) were also observed in CYP2C19 heterozygous subjects (CYP2C19 wt/mts). The sulfoxidation metabolic index indicates that the CYP3A5*1/*1,*1/*3 (low-expressers), and *3/*3 (no-expressers) groups have medium, lowest and highest activities on ilaprazole metabolism, inconsistent with genotype-based CYP3A5 enzymatic activity. Further analysis showed no correlation between ilaprazole metabolism and CYP2C19 genotypes, evidenced by that the AUC(0-∞) of ilaprazole from either CYP3A5*1/*1 or CYP3A5*1/*3 groups was much higher in CYP2C19 wt/wts (n=4) than that in CYP2C19 wt/mts (n=3) (Pb0.001), but the Cmax and AUC(0-6) of ilaprazole from CYP3A5*3/*3 groups, were significantly lower in CYP2C19 wt/wts (n=3) compared to CYP2C19 wt/mts (n=4) (Pb0.01). There was no demonstrated relationship between ilaprazole metabolism and CYP3A5 polymorphisms.This is a controled, two-period, cross over study. During the first stage all the subjects were orally administrated ilaprazole(5mg) or standard Triple-Drug therapy for helicobacter pylori eradication bid for six continuous days. On the first and seventh day after the morning administation of ilaprazole 5ml of blood samples were drawn from subjects at 0,0.5,1,1.5,2,3,4,6,8,12,24,48 and 72 hours, and urine were collected for 24 hours. After one week's wash out period on the second stage of study the subjects were drawn 8 ml of blood sample on the same time points. Plasma concentrations of ilaprazole were determined by a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method, all of the pharmacokinetic parameters were calculated by use of DAS Ver 2.0. The results were ilaprazole of standard Triple-Drug therapy for helicobacter pylori eradication absorbtion rate and absorbtion amount is significantly decreased than single dose of ilaprazole, the absorbtion rate and absorbtion amount of the major metabolite ilaprazole sulfone is significantly decreased than single dose group as well. The absorbtion rate and absorbtion amount of metabolite ilaprazole sulfide is higher the single dose group.