Determination of lansoprazole and two of its metabolites by liquid–liquid extraction and automated column-switching high-performance liquid chromatography: application to measuring CYP2C19 activity

Exploring the impact of ethnicity on drug pharmacokinetics using PBPK models: A case study with lansoprazole in Japanese subjects

AIMS

The aim of this study is to demonstrate the use of PBPK modelling to explore the impact of ethnic differences on drug PK.

METHODS

A PBPK model developed for lansoprazole was used to predict the clinical PK of lansoprazole in Japanese subjects by incorporating the physiological parameters of a Japanese population into the model. Further verification of the developed Japanese population with clinical studies involving eight other CYP substrates-omeprazole, ticlopidine, alprazolam, midazolam, nifedipine, cinacalcet, paroxetine and dextromethorphan-was also carried out.

RESULTS

The PK of lansoprazole in both Caucasian and Japanese subjects was well predicted by the model as the observed data were within the 5th and 95th percentiles across all the clinical studies. In age- and sex-matched simulations in both the Caucasian and Japanese populations, the predicted PK (mean ± SD) of a single oral dose of 30-mg lansoprazole was higher in the Japanese population in all cases, with more than twofold higher AUC of 5.98 ± 6.43 mg/L.h (95% CI: 4.72, 7.24) vs. 2.46 ± 2.45 mg/L.h (95% CI: 1.98, 2.94) in one scenario. In addition, in two out of the nine clinical DDIs of lansoprazole and the additional CYP substrates simulated using the Japanese population, the predicted DDI in Japanese was more than 1.25-fold that in Caucasians, indicating an increased DDI liability.

CONCLUSIONS

By accounting for various physiological parameters that characterize a population in a PBPK model, the impact of the different identified interethnic differences on the drug's PK can be explored, which can inform the adoption of drugs from one region to another.

CYP2C19 and CYP3A4 activity and ADP-induced platelet reactivity in prasugrel- or ticagrelor-treated STEMI patients: monocentric study in PRAGUE-18 trial participants

We assessed the contribution of CYP2C19 and CYP3A4 metabolic activity to the ADP-induced platelet aggregation 1h and 24h after a loading dose of 60 mg prasugrel or 180 mg ticagrelor in patients with ST-elevation myocardial infarction (STEMI). Further, we assessed the contribution of CYP2C19 polymorphisms and medication to the CYP enzymatic activity.Patients with STEMI were randomly assigned to the treatment with prasugrel (n = 51) or ticagrelor (n = 46). Metabolic activity of CYP2C19 and CYP3A4 was assessed by the rate of 5-hydroxylation and sulfoxidation of lansoprazole. Further, patients were genotyped for CYP2C19 *2 and *17 alleles.In prasugrel-treated patients, high ADP-induced platelet reactivity 1h after the loading dose positively correlated with 5OH-lansoprazole/lansoprazole ratio (r = 0.44, p = 0.002), a marker of CYP2C19 metabolic activity, and negatively with lansoprazole-sulfone/lansoprazole ratio, which reflects CYP3A4 metabolic activity (r = -0.35, p = 0.018).CYP2C19 poor metabolizers had lower 5OH-lansoprazole/lansoprazole ratio and higher lansoprazole-sulfone/lansoprazole ratio, but without any effect on the ADP-induced platelet reactivity. The treatment with amiodarone, a CYP3A4 inhibitor, influenced neither the metabolic ratios nor the ADP-induced platelet reactivity.The CYP3A4 and CYP2C19 metabolic activity is associated with ADP-induced platelet reactivity in prasugrel-treated, but not ticagrelor-treated patients with STEMI.

Pharmacodynamics and Pharmacokinetics of a New Type of Compound Lansoprazole Capsule in Gastric Ulcer Rats and Beagle Dogs: Importance of Adjusting Oxidative Stress and Inflammation

The aim of this study was to investigate the pharmacodynamics and pharmacokinetics of a new type of compound lansoprazole capsule in gastric ulcer rats and beagle dogs in order to confirm whether it is more effective in treating gastric ulcers and its rapid absorption. A rat model of gastric ulcers was used to evaluate the anti-ulcerogenic effect of the compound lansoprazole capsule. A fast and sensitive UPLC-MS/MS method was developed to detect lansoprazole in dog plasma. Macroscopic and histological evaluation results revealed that the compound lansoprazole capsule is more effective in treating gastric ulcers as it was able to significantly reduce the gastric ulcer compared to the other groups. Additionally, it was able to enhance the expression of the antioxidant enzyme superoxide dismutase (SOD) and suppress lipid peroxidation as indicated by the reduction of malondialdehyde (MDA) and H⁺-K⁺-ATP activity. Furthermore, this capsule increased the expression of mucosal vascular endothelial growth factor (VEGF) and cyclic oxygenase 2 (COX-2). The established UPLC-MS/MS method was successfully applied to the evaluation of pharmacokinetic parameters of lansoprazole in beagle dogs. The results indicate that the compound lansoprazole capsule had an advantage of rapid absorption. This study demonstrated that the compound lansoprazole capsule has better gastroprotective activity and that this might be related to its positive influence on oxidative stress and inflammation. This new type of compound lansoprazole capsule may be potentially useful in preclinical therapy.

Investigation of the bioequivalence of two lansoprazole formulations in healthy Chinese volunteers after a single oral administration

The objective of this study was to compare two lansoprazole products (the reference brand enteric-coated capsules and the test generic enteric-coated tablets), and the key pharmacokinetic (PK) parameters for both formulations and their metabolites were assessed. The study used an open-label, randomized two-period crossover design with an 8-day washout period between doses in 24 healthy subjects under fasting conditions. The concentration of lansoprazole and its two metabolites was determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The in vitro release of lansoprazole from the test and reference formulations was within the acceptable limits. The relationship between concentration and peak area ratio was found to be linear within the range for lansoprazole and metabolites. The point estimates (ratios of geometric mean) of lansoprazole and two main metabolites were between 94.3% and 105.1% for AUC_0-t, AUC_0-∞, and C_max. No statistically significant difference between the two formulations was found. The results of in vitro and in vivo suggested equivalent clinical efficacy of the two brands.

Evaluation of lansoprazole as a probe for assessing cytochrome P450 2C19 activity and genotype-phenotype correlation in childhood

PURPOSE

Lansoprazole, a cytochrome P450 2C19 (CYP2C19) substrate, has been widely used in children to manage acid-related diseases. CYP2C19 exhibits marked genetic polymorphisms, and distribution of these polymorphisms varies among different ethnic groups. There is limited data regarding the use of probe drugs for determining CYP2C19 activity in children. The aim of this study was to evaluate lansoprazole as an in vivo phenotyping probe for assessing CYP2C19 activity in children.

METHODS

The CYP2C19*2, *3, and *17 variants were determined in 244 children. Three hours after a single oral dose of lansoprazole (n = 94) or omeprazole (n = 19), plasma lansoprazole and 5-hydroxy lansoprazole or omeprazole and 5-hydroxy omeprazole concentrations were analyzed by high-performance liquid chromatography.

RESULTS

The CYP2C19*17 was the most frequent variant allele (24.4%). The group of patients with CYP2C19*17*17 genotype had a 70% lower (p < 0.05) mean lansoprazole plasma concentration compared with the CYP2C19*1*1 genotype group, whereas the CYP2C19*2*2 group had 6.9-fold higher (p < 0.01) mean lansoprazole plasma concentration. Lansoprazole metabolic ratios (lansoprazole/5-hydroxy-lansoprazole) were found to be significantly lower in the *17*17 [mean ± standard deviation (SD); 2.8 ± 2.1] group and higher in the *2*2 group (63.5 ± 12.2) compared with that of the *1*1 genotype group (6.1 ± 4.5).

CONCLUSION

According to our results from a Turkish pediatric population, lansoprazole is a suitable probe drug for phenotyping CYP2C19. The CYP2C19*2 and *17 variants should be taken into consideration in predicting the clinical outcome of therapy with lansoprazole in the pediatric population.

Clinical usefulness of limited sampling strategies for estimating AUC of proton pump inhibitors

Cytochrome P450 (CYP) 2C19 (CYP2C19) genotype is regarded as a useful tool to predict area under the blood concentration-time curve (AUC) of proton pump inhibitors (PPIs). In our results, however, CYP2C19 genotypes had no influence on AUC of all PPIs during fluvoxamine treatment. These findings suggest that CYP2C19 genotyping is not always a good indicator for estimating AUC of PPIs. Limited sampling strategies (LSS) were developed to estimate AUC simply and accurately. It is important to minimize the number of blood samples because of patient's acceptance. This article reviewed the usefulness of LSS for estimating AUC of three PPIs (omeprazole: OPZ, lansoprazole: LPZ and rabeprazole: RPZ). The best prediction formulas in each PPI were AUC(OPZ)=9.24 x C(6h)+2638.03, AUC(LPZ)=12.32 x C(6h)+3276.09 and AUC(RPZ)=1.39 x C(3h)+7.17 x C(6h)+344.14, respectively. In order to optimize the sampling strategy of LPZ, we tried to establish LSS for LPZ using a time point within 3 hours through the property of pharmacokinetics of its enantiomers. The best prediction formula using the fewest sampling points (one point) was AUC(racemic LPZ)=6.5 x C(3h) of (R)-LPZ+13.7 x C(3h) of (S)-LPZ-9917.3 x G1-14387.2×G2+7103.6 (G1: homozygous extensive metabolizer is 1 and the other genotypes are 0; G2: heterozygous extensive metabolizer is 1 and the other genotypes are 0). Those strategies, plasma concentration monitoring at one or two time-points, might be more suitable for AUC estimation than reference to CYP2C19 genotypes, particularly in the case of coadministration of CYP mediators.

The effect of CYP2C19 activity on pharmacokinetics of lansoprazole and its active metabolites in healthy subjects

CONTEXT

Lansoprazole is a gastric proton-pump inhibitor and has been demonstrated to be effective in the treatment of various peptic diseases. The effects of CYP2C19 activity on the pharmacokinetics of lansoprazole and its active metabolites in Chinese subjects have not previously been evaluated.

OBJECTIVE

The study aimed to evaluate the effects of CYP2C19 activity in healthy Chinese volunteers.

MATERIALS AND METHODS

Twenty-two healthy volunteers were recruited for an open trial and received a single dose of 30 mg lansoprazole. Using a validated LC-MS/MS method, we measured the plasma concentrations of lansoprazole, 5-hydroxylansoprazole, and lansoprazole sulfone. The genotype of CYP2C19 was identified by polymerase chain reaction (PCR) analysis of single nucleotide polymorphisms (SNPs). Subjects were genotypically classified into the following three groups on the basis of PCR-SNP analysis for CYP2C19: homozygous EM (hmEM) group, heterozygous EM (htEM) group, and PM group. To test differences in pharmacokinetic parameters among the three groups, analysis of variance (ANOVA) after log-transformation of data was used.

RESULTS AND CONCLUSION

Our results indicated that there were significant differences (p < 0.001) between the hmEM and PM groups, between the htEM and PM groups, and between the hmEM and htEM groups in C(max), AUC(0-t), and AUC(0-inf) of lansoprazole and lansoprazole sulfone. There were also significant differences (p < 0.001) between the hmEM and PM groups, and between the htEM and PM groups in C(max) of 5-hydroxylansoprazole.

Simultaneous determination of lansoprazole and its metabolites 5'-hydroxy lansoprazole and lansoprazole sulphone in human plasma by LC-MS/MS: application to a pharmacokinetic study in healthy volunteers

A highly sensitive and specific liquid chromatography coupled with tandem mass spectrometric (LC-MS/MS) method has been developed and validated for the simultaneous determination of lansoprazole and its metabolites 5'-hydroxy lansoprazole and lansoprazole sulphone. The detection was operated with multiple reaction-monitoring (MRM) using the electrospray ionization technique. The assay procedure involved precipitation of plasma samples with acetonitrile after indapamide was added as internal standard (IS). The chromatographic separation was achieved with a mixture of methanol-0.2% ammonium acetate and 0.1% methanoic acid in water (75:25, v/v) as mobile phase on an Inertsil ODS-3 column. The method was proved to be accurate and precise with linearity ranges of 10-4,000 ng/ml, 5.0-400 ng/ml, and 1.0-400 ng/ml for lansoprazole, 5'-hydroxy lansoprazole and lansoprazole sulphone, respectively, with the correlation coefficients (r) better than 0.999. The lower limits of quantification (LLOQ) were 2.0 ng/ml, 2.0 ng/ml, and 0.5 ng/ml for lansoprazole, 5'-hydroxy lansoprazole and lansoprazole sulphone, respectively. The intra- and inter-day precision and accuracy values were found to be within the assay variability limits (R.S.D.% within +/-15) in accordance with FDA guidelines. The validated LC-MS/MS method has been successfully applied for the determination of lansoprazole and its metabolites in human plasma.

Simultaneous spectrophotometric determination of lansoprazole and domperidone in capsule dosage form

Two simple, accurate and precise spectrophotometric methods have been developed for simultaneous determination of lansoprazole and domperidone in pharmaceutical dosage form. Method A involves formation of Q-absorbance equation at 256.0 nm (isoabsorptive point) and at 294.2 nm while method B is two wavelength method where 277.6 nm, 302.1 nm were selected as lambda(1) and lambda(2) for determination of lansoprazole and 231.3 nm, 292.0 nm were selected as lambda(1) and lambda(2) for determination of domperidone. Both the methods were validated statistically and recovery studies were carried out. The Beer's law limits for each drug individually and in mixture was within the concentration range of 5-50 mug/ml. Linearity of lansoprazole and domperidone were in the range of 24-36 mug/ml and 8-12 mug/ml, respectively. The proposed methods have been applied successfully to the analysis of the cited drugs either in pure form or in pharmaceutical formulations with good accuracy and precision. The method herein described can be employed for quality control and routine analysis of drugs in pharmaceutical formulations.

Simultaneous Determination of Warfarin Enantiomers and Its Metabolite in Human Plasma by Column-Switching High-Performance Liquid Chromatography With Chiral Separation

A simple and sensitive column-switching high-performance liquid chromatographic method for the simultaneous determination of warfarin enantiomers and their metabolites, 7-hydroxywarfarin enantiomers, in human plasma is described. Warfarin enantiomers, 7-hydroxywarfarin enantiomers, and an internal standard, diclofenac sodium, were extracted from 1 mL of a plasma sample using diethyl ether-chloroform (80:20, v/v). The extract was injected onto column I (TSK precolumn BSA-C8, 5 microm, 10 mm x 4.6 mm inside diameter) for cleanup and column II (Chiralcel OD-RH analytical column, 150 mm x 4.6 mm inside diameter) coupled with a guard column (Chiralcel OD-RH guard column, 10 mm x4.6 mm inside diameter) for separation. The mobile phase consisted of phosphate buffer-acetonitrile (84:16 v/v, pH 2.0) for clean-up and phosphate buffer-acetonitrile (45:55 v/v, pH 2.0) for separation. The peaks were monitored with an ultraviolet detector set at a wavelength of 312 nm, and total time for chromatographic separation was approximately 25 minutes. The validated concentration ranges of this method were 3 to 1000 ng/mL for (R)- and (S)-warfarin and 3 to 200 ng/mL for (R)- and (S)-7-hydroxywarfarin. Intra- and interday coefficients of variation were less than 4.4% and 4.9% for (R)-warfarin and 4.8% and 4.0% for (S)-warfarin, and 5.1% and 4.2% for (R)-7-hydroxywarfarin and 5.8% and 5.0% for (S)-7-hydroxywarfarin at the different concentrations. The limit of quantification was 3 ng/mL for both warfarin and 7-hydroxywarfarin enantiomers. This method was suitable for therapeutic drug monitoring of warfarin enantiomers and was applied in a pharmacokinetic study requiring the simultaneous determination of warfarin enantiomers and its metabolite, 7-hydroxywarfarin enantiomers, in human volunteers.

Assessment of 4-nitro-1,8-naphthalic anhydride reductase activity in homogenates of bakers’ yeast by reversed-phase high-performance liquid chromatography

A simple reversed-phase high-performance liquid chromatographic (RP-HPLC) method was developed for the simultaneous determination of yield and conversion ratio of 4-nitro-1,8-naphthalic anhydride to 4-amino-1,8-naphthalic anhydride following incubation with a crude bakers' yeast homogenate. The analytes were separated on a C18 column in gradient mode. The detection limit of 4-amino-1,8-naphthalic anhydride is 10ng/microl when using a 10microl sample injection volume. The nitroreductase activity in the homogenate system can be assessed during the bioconversion process. The method can be used for the simultaneous detection of 4-hydroxylamino-1,8-naphthalic anhydride, an intermediate with limited stability.

Sensitive Determination of Itraconazole and Its Active Metabolite in Human Plasma by Column-switching High-performance Liquid Chromatography With Ultraviolet Detection

A simple and sensitive column-switching high-performance liquid chromatographic method for the simultaneous determination of itraconazole (ITZ) and its active metabolite, hydroxyitraconazole (HIT) in human plasma is described. ITZ, HIT, and an internal standard, R051012, were extracted from 1 mL of alkalinized plasma sample using n-heptane-chloroform (60:40, vol/vol). The extract was injected onto column I (TSK precolumn BSA-ODS/S, 5 microm, 10 x 4.6 mm ID) for clean-up and column II (Develosil C8-5 column, 5 microm, 150 x 4.6 mm ID) for separation. The mobile phase consisted of phosphate buffer-acetonitrile (68:32 vol/vol, pH 6.0) for clean-up and phosphate buffer-acetonitrile (35:65 vol/vol, pH 6.0) for separation. The peaks were monitored with an ultraviolet detector set at a wavelength of 263 nm, and total time for chromatographic separation was about 24 minutes. The validated concentration ranges of this method were 3 to 500 ng/mL for ITZ and 3 to 1000 ng/mL for HIT. Mean recoveries were 59.7% for ITZ and 72.8% for HIT. Intraday and interday coefficients of variation were less than 4.6% and 5.0% for ITZ, and 4.6% and 4.9% for HIT at the different concentrations. The limit of quantification was 3 ng/mL for both ITZ and HIT. This method was suitable for therapeutic drug monitoring of ITZ and HIT, and was applied to pharmacokinetic studies in human volunteers.

Identification of a Single Time-point for Plasma Lansoprazole Measurement That Adequately Reflects Area Under the Concentration-Time Curve

The objective of this study was to identify a single time-point for plasma lansoprazole measurement that adequately reflects area under the plasma lansoprazole concentration-time curve (AUC) after administration of lansoprazole alone or together with coadministration with CYP mediators. A randomized double-blind placebo-controlled crossover study design in 3 phases was conducted at intervals of 2 weeks. Eighteen healthy Japanese volunteers, comprising 3 CYP2C19 genotype groups, took a single oral 60-mg dose of lansoprazole after three 6-day pretreatments, that is, clarithromycin 800 mg/d, fluvoxamine 50 mg/d, and placebo. Blood samplings (10 mL each) for determination of lansoprazole were taken up to 24 hours after the administration of lansoprazole. Correlation between plasma lansoprazole concentrations at various time points and AUC0-24 were analyzed. Although there were significant differences in the pharmacokinetic parameters of lansoprazole during clarithromycin and placebo among CYP2C19 genotypes, the differences were not found during fluvoxamine. The plasma concentrations 3, 4, 6, and 8 hours after administration (C3, C4, C6, and C8, respectively) were highly correlated with AUC0-24 in coadministration with placebo, clarithromycin, and fluvoxamine (r>0.8, P<0.001). In particular, C6 showed a correlation coefficient of 0.940, 0.992, and 0.953 in coadministration with placebo, clarithromycin, and fluvoxamine, respectively, and was the most appropriate for estimating AUC0-24. The present study demonstrates that AUC of lansoprazole can be estimated by using a single time-point at C6. This method of plasma concentration monitoring at one time-point might be more suitable for AUC estimation than reference to CYP2C19 genotypes, particularly in coadministration of CYP mediators.

Effects of clarithromycin on lansoprazole pharmacokinetics between CYP2C19 genotypes

AIMS

Lansoprazole is a substrate of CYP2C19 and CYP3A. The aim of this study was to compare the inhibitory effects of clarithromycin, an inhibitor of CYP3A on the metabolism of lansoprazole between CYP2C19 genotypes.

METHODS

A two-way randomized double-blind, placebo-controlled crossover study was performed. Eighteen volunteers, of whom six were homozygous extensive metabolizers (EMs), six were heterozygous EMs and six were poor metabolizers (PMs) for CYP2C19, received two 6-day courses of either clarithromycin 800 mg or placebo daily in a randomized fashion with a single oral dose of lansoprazole 60 mg on day 6 in all cases. Plasma concentrations of lansoprazole and its metabolites, 5-hydroxylansoprazole and lansoprazole sulphone were monitored up to 24 h after dosing.

RESULTS

During placebo administration, the mean AUC0, infinity of lansoprazole in homozygous EMs, heterozygous EMs and PMs were 4652 (95% CI, 2294, 7009) ng ml(-1) h, 8299 (4784, 11814) ng ml(-1) h and 25293 (17643, 32943) ng ml(-1) h (P < 0.001), respectively. Clarithromycin treatment significantly increased Cmax by 1.47-fold, 1.71-fold and 1.52-fold and AUC0, infinity of lansoprazole by 1.55-fold, 1.74-fold, and 1.80-fold in these genotype groups, respectively, whereas elimination half-life was prolonged only in PMs. The clarithromycin-mediated percent increase in pharmacokinetic parameters such as Cmax, AUC0, infinity or elimination half-life did not differ between the three CYP2C19 genotypes.

CONCLUSIONS

The present study indicates that there are significant drug interactions between lansoprazole and clarithromycin in all CYP2C19 genotype groups probably through CYP3A inhibition. The bioavailability of lansoprazole might, to some extent, be increased through inhibition of P-glycoprotein during clarithromycin treatment.