FRET-based fluorescent probe for drug assay from amino acid@gold-carbon nanoparticles.

Biocompatible and luminescent nanostructures synthesized by capping gold-carbon nanoparticles (HOOC-4-C6H4-AuNPs) with amino acids tyrosine, tryptophan, and cysteine were used for the quantitative estimation of ranitidine (RNH), a peptic ulcer and gastroesophageal reflux drug. We applied a fluorescence quenching mechanism to investigate the viability of the energy transfer based on gold-carbon nanosensors. Förster resonance energy transfer (FRET) calculations showed a donor-acceptor distance of 1.69 nm (Tyr@AuNPs), 2.27 nm (Trp@AuNPs), and 2.32 nm (Cys@AuNPs). The constant time-resolved fluorescence lifetime measurements supported the static quenching nature. This method was successfully utilized in the detection and quantification of RNH, with a limit of detection (LOD) of 0.174, 0.56, and 0.332 µM for Tyr@AuNP, Trp@AuNP, and Cys@AuNP bioconjugates, respectively. This approach was also successful in the quantification of RNH in spiked serum samples.

Effect of food on the pharmacokinetics of omeprazole, pantoprazole and rabeprazole.

BACKGROUND: The pharmacokinetics of proton pump inhibitors (PPIs) may be affected by food intake. We aimed to evaluate the effect of food on the pharmacokinetics of omeprazole, rabeprazole, and pantoprazole. SETTING: The study population comprised 186 healthy volunteers participating in 6 bioequivalence clinical trials. METHOD: Subjects were evaluated to determine the effect of a high-fat breakfast on the pharmacokinetics of omeprazole (n = 36), rabeprazole (n = 69), and pantoprazole (n = 81). MAIN OUTCOME MEASURE: Drug plasma concentrations were measured using high-performance liquid chromatography coupled to mass spectrometry. RESULTS: Food affected the pharmacokinetics of omeprazole (increased Tmax and decreased AUC and Cmax), pantoprazole (increased Tmax and decreased AUC), and rabeprazole (increased Tmax, Cmax and half-life). Food increased variability in Tmax for all 3 drugs, delaying absorption around 3 to 4 h and until 20 h in some subjects. CONCLUSION: As food delays the absorption of PPIs and increases their variability, it would be better to administer these drugs under fasting conditions. TRIAL REGISTRATION: European Union Drug Regulating Authorities Clinical Trials Database: EudraCT : 2004-003863-59 (registration date 05/MAR/2004), EudraCT 2006-001162-17 (registration date 17-MAR-2006), EudraCT: 2007-002489-37 (registration date 12-JUN-2007), EudraCT: 2007-002490-31 (registration date 12-JUN-2007), EudraCT: 2010-024029-19 (registration date 23-NOV-2010).

Comparison of zinc acetate hydrate and polaprezinc for zinc deficiency in patients on maintenance hemodialysis: A single-center, open-label, prospective randomized study.

The efficacy and safety of zinc acetate hydrate (ZAH) for zinc supplementation in patients on maintenance hemodialysis (MHD) remains unknown. In this prospective, single-center, open-label, parallel-group trial for MHD patients with serum zinc level <70 µg/dL, we compared ZAH (zinc; 50 mg/day) and polaprezinc (PPZ; zinc; 34 mg/day) beyond 6-month administration in a 1:1 randomization manner. The ZAH and PPZ groups had 44 and 47 patients, respectively. At 3 months, the change rate of serum zinc levels in the ZAH group was significantly higher than that in the PPZ group. Three months after the study, serum copper levels significantly decreased in the ZAH group, but not in the PPZ group. No significant differences were noted in anemia management in either group. ZAH was superior to PPZ in increasing serum zinc levels. Clinicians should note the stronger decline in serum copper levels when using ZAH for MHD patients.

Comparative pharmacokinetics of Omeprazole and its metabolites in poor and extensive metabolizer Pakistani healthy volunteers and a review of different studies.

This study was designed to evaluate a comparative single dose (40mg) pharmacokinetics (PK) of Omeprazole (OMP) and its two metabolites, 5-hydroxy Omeprazole (5-OH-OMP) and Omeprazole sulphone (OMP-S) in poor (PM) and extensive (EM) metabolizer Pakistani healthy adult volunteers. The frequency of CYP2C19 and CYP3A4 varies widely in different populations. The present study was conducted to evaluate the PK of OMP and its two metabolites in Pakistani population and to review different studies conducted after administration of single dose of OMP. Twenty two subjects were enrolled in this study and divided into two groups. The CYP2C19 phenotyping was evaluated by the metabolic ratio of OMP to 5-OH-OMP. It was a single dose, open label study and the blood samples from subjects were collected at different time intervals until 24 hours. The PK parameters were calculated using the PK-summit software. The metabolic ratio of area under the plasma concentration-time curve AUCOMP/5-OH-OMP was 1.86 ± 0.572 and13.84 ± 2.504 for EM and PM, respectively; maximum plasma concentration (Cmax) of OMP was increased by two folds for PM while the AUC∞ was increased by 3 folds; the Cmax and AUC∞ of 5-OH-OMP decreased for PM by 2 folds while there was 3 fold increase observed in the Cmax and AUC∞ of OMP-S. The PK of OMP and its metabolites in different populations were also discussed, and issues regarding CYP2C19 and CYP3A4 genotyping were also extensively reviewed. In EM of CYP2C19 the concentration of 5-OH-OMP is higher while that of OMP-S is lower. This study as well as reported studies reveals that in PM of CYP2C19 more drugs are available for CYP3A4 to be metabolized. A correlation between CYP2C19 EM and PM activity with CYP3A4 needs to be established.

Evaluation of Omeprazole Limited Sampling Strategies to Estimate Constitutive Cytochrome P450 2C19 Activity in Healthy Adults.

BACKGROUND: Limited sampling strategy (LSS) is a validated method to estimate pharmacokinetic (PK) parameters from a reduced number of samples. Omeprazole is used to phenotype in vivo cytochrome P450 (CYP) 2C19 activity. This study examined an LSS using 2 estimation methods to determine apparent oral clearance (CL/F) and thus CYP2C19 activity. METHODS: Data from 7 previously published studies included healthy subjects receiving a single, oral dose of omeprazole with intensive PK sampling. CL/F was estimated using noncompartmental analysis (NCA) and population PK modeling. LSS was simulated by selecting the 1, 2, 4, and/or 6-hour postdose time points. Linear regression was performed to assess whether CL/F estimated from limited sampling could accurately predict CL/F from the full PK profile. RESULTS: Median CL/F was 23.7 L/h by NCA and 19.3 L/h by population PK modeling. In comparing the LSS NCA estimated versus observed CL/F, all evaluated linear regression models had unacceptable coefficients of determination (r, range: 0.14-0.81). With the population PK approach, 737 plasma concentrations (n = 71) and CYP2C19 genotype data were described with a 1-compartment structural model with mixed zero and first-order absorption and lag time. In comparing the population PK LSS estimated versus observed CL/F, all evaluated linear regression models had unacceptable r (range: 0.02-0.74). Post hoc comparison of CYP2C19 poor metabolizers versus CYP2C19 extensive metabolizers resulted in significantly lower CL/F in poor metabolizers versus extensive metabolizers. CONCLUSIONS: Omeprazole LSS performed poorly in estimating CL/F using 2 separate estimation approaches and does not seem to be a suitable method for determining CYP2C19 activity.

Pharmacokinetics and Pharmacodynamics of Azeloprazole Sodium, a Novel Proton Pump Inhibitor, in Healthy Japanese Volunteers.

The pharmacokinetics (PK) and pharmacodynamics (PD) of proton pump inhibitors differ among cytochrome P450 (CYP) 2C19 genotypes. Therefore, we developed azeloprazole sodium (Z-215), a novel proton pump inhibitor, whose metabolism is not affected by CYP2C19 activity in vitro. However, the PK and PD of azeloprazole sodium have not been evaluated in Japanese subjects. We conducted an open-label, crossover study in healthy Japanese male volunteers to evaluate the plasma concentration and intragastric pH with respect to CYP2C19 genotype after repeated administration of 10, 20, and 40 mg azeloprazole sodium and 10 and 20 mg rabeprazole sodium (rabeprazole). The plasma concentration profile of azeloprazole sodium was similar among genotypes, whereas that of rabeprazole differed. The 24-hour intragastric pH ≥ 4 holding time ratio (pH ≥ 4 HTR) of azeloprazole sodium was similar among genotypes. The pH ≥ 4 HTR was 52.5%-60.3%, 55.1%-65.8%, and 69.4%-77.1% after administration of 10, 20, and 40 mg azeloprazole sodium, respectively, and 59.2%-72.3% and 64.4%-91.2% after administration of 10 and 20 mg rabeprazole, respectively, on the fifth day of dosing. The maximum plasma concentration (Cmax ), area under the plasma concentration-time curve (AUC), and pH ≥ 4 HTR of azeloprazole sodium were proportional to dose. The Cmax , AUC, and pH ≥ 4 HTR on day 5 were slightly higher following administration of 20 mg azeloprazole sodium before comparison with after a meal. No serious adverse events were observed. These results suggest that azeloprazole sodium is useful for treating gastroesophageal reflux disease in all CYP2C19 genotypes.

The Relative Bioavailability, Food Effect, and Drug Interaction With Omeprazole of Momelotinib Tablet Formulation in Healthy Subjects.

Momelotinib is a potent and selective small-molecule inhibitor of JAK1/2 that is under investigation for the treatment of myeloproliferative neoplasms. In a phase 1/2 study in myelofibrosis patients, once-daily dosing of a 300-mg momelotinib capsule was selected for further development based on a favorable benefit:risk profile. A tablet formulation was recently developed for further clinical evaluation. In this study, the relative bioavailability of the tablet formulation versus the initial capsule formulation and the effect of food and omeprazole on the pharmacokinetics of a single-dose momelotinib tablet were evaluated in healthy subjects. The momelotinib tablet, 200 mg, provided plasma exposure equivalent to the 300-mg capsule. Plasma exposure of momelotinib increased less than dose-proportionally from 100 to 800 mg. Food intake modestly increased Cmax (38% and 28% increase for low- and high-fat meals, respectively) and AUCinf (16% and 28% increase for low- and high-fat meals, respectively) for the momelotinib tablet. Omeprazole reduced the exposure of the momelotinib tablet by 36% for Cmax and 33% for AUCinf . Neither the food effect nor the omeprazole effect on momelotinib exposure was considered clinically meaningful because of the safety and efficacy profile of momelotinib.

Pharmacokinetics and Acid Suppressant Efficacy of Esomeprazole after Intravenous, Oral, and Subcutaneous Administration to Healthy Beagle Dogs.

BACKGROUND: Esomeprazole is an S-enantiomer of omeprazole that has favorable pharmacokinetics and efficacious acid suppressant properties in humans. However, the pharmacokinetics and effects on intragastric pH of esomeprazole in dogs have not been reported. OBJECTIVE: To determine the pharmacokinetics of esomeprazole administered via various routes (PK study) and to investigate the effect of esomeprazole on intragastric pH with a Bravo pH monitoring system (PD study). ANIMALS: Seven adult male Beagle dogs and 5 adult male Beagle dogs were used for PK and PD study, respectively. METHODS: Both studies used an open, randomized, and crossover design. In the PK study, 7 dogs received intravenous (IV), subcutaneous (SC), and oral doses (PO) of esomeprazole (1 mg/kg). Each treatment period was separated by a washout period of at least 10 days. Esomeprazole plasma concentrations were measured by HPLC/MS/MS. In the efficacy study, intragastric pH was recorded without medication (baseline pH) and following IV, SC, and PO esomeprazole dosing regimens (1 mg/kg) in 5 dogs. RESULTS: The bioavailability of esomeprazole administered as PO enteric-coated granules and as SC injections was 71.4 and 106%, respectively. The half-life was approximately 1 hour. Mean ± SD percent time intragastric pH was ≥3 and ≥4 was 58.9 ± 21.1% and 40.9 ± 17.3% for IV group, 75.8 ± 16.4% and 62.7 ± 17.7% for SC group, 88.2 ± 8.9% and 82.5 ± 7.7% for PO group, and 12.5 ± 3.6% and 3.7 ± 1.8% for baseline. The mean percent time with intragastric pH was ≥3 or ≥4 was significantly increased regardless of the dosing route (P < .05). CONCLUSION: The PK parameters for PO and SC esomeprazole administration were favorable, and esomeprazole significantly increased intragastric pH after IV, PO, and SC administration. IV and SC administration of esomeprazole might be useful when PO administration is not possible. No significant adverse effects were observed.

Population pharmacokinetic analysis of rebamipide in healthy Korean subjects with the characterization of atypical complex absorption kinetics.

In this study, the population pharmacokinetic (PK) analysis of rebamipide (Reba) in healthy male Korean subjects was analyzed using the nonlinear mixed effects modeling method. The possible effects of physiological covariates and the multidrug resistance (MDR1) gene 3435C>T polymorphism on PK parameters were also investigated. Data were collected from a bioequivalence study, in which 26 subjects who participated in the study were administered a single oral dose of 100 mg Reba; only data from the reference formulation were used. Reba showed a relatively large inter-individual variability (from 2.6- to 3.3-fold) in the PK parameters with double peaks or the concentration plateau after the peak concentration in its serum concentration-time profiles. The population PKs of Reba was best described by a one-compartment model with three fraction absorption processes followed a single Weibull-type function and two first-order kinetics, and lag times. The study suggests that the efflux transporter MDR1 3435C>T allele affects the substantial inter-individual variability in the absorption of Reba according to genetic polymorphism. A significant difference was found in the absorption rate ka 1 among the MDR1 3435C>T genotype groups (P < 0.05) (CT group, 79.8% increase; and TT group, 115% increase). The use of combined MDR1 3435C>T and body mass index as covariates for ka 1 exerted a more significant effect (P < 0.05). In addition, body surface area significantly affected the apparent total clearance (P < 0.05).

Disposition of the anti-ulcer medications ranitidine, cimetidine, and omeprazole following administration of multiple doses to exercised Thoroughbred horses.

The use of anti-ulcer medications, such as cimetidine, ranitidine, and omeprazole, is common in performance horses. The use of these drugs is regulated in performance horses, and as such a withdrawal time is necessary prior to competition to avoid a medication violation. To the authors' knowledge, there are no reports in the literature describing repeated oral administrations of these drugs in the horse to determine a regulatory threshold and related withdrawal time recommendations. Therefore, the objective of the current study was to describe the disposition and elimination pharmacokinetics of these anti-ulcer medications following oral administration to provide data upon which appropriate regulatory recommendations can be established. Nine exercised Thoroughbred horses were administered 20 mg/kg BID of cimetidine or 8 mg/kg BID of ranitidine, both for seven doses or 2.28 g of omeprazole SID for four doses. Blood samples were collected, serum drug concentrations were determined, and elimination pharmacokinetic parameters were calculated. The serum elimination half-life was 7.05 ± 1.02, 7.43 ± 0.851 and 3.94 ± 1.04 h for cimetidine, ranitidine, and omeprazole, respectively. Serum cimetidine and ranitidine concentrations were above the LOQ and omeprazole and omeprazole sulfide below the LOQ in all horses studied upon termination of sample collection.

The effects of dose and diet on the pharmacokinetics of omeprazole in the horse.

This study aimed to investigate the effect of diet and dose on the pharmacokinetics of omeprazole in the horse. Six horses received two doses (1 and 4 mg/kg) of omeprazole orally once daily for 5 days. Each dose was evaluated during feeding either a high-grain/low-fibre (HG/LF) diet or an ad libitum hay (HAY) diet in a four-way crossover design. Plasma samples were collected for pharmacokinetic analysis on days 1 and 5. Plasma omeprazole concentrations were determined by ultra-high pressure liquid chromatography-mass spectrometry. In horses being fed the HG/LF diet, on day 1, the area under the curve (AUC) and maximal plasma concentration (Cmax ) were higher on the 4 mg/kg dose than on the 1 mg/kg dose. The AUC was higher on day 5 compared to day 1 with the 4 mg/kg dose on the HG/LF diet. On days 1 and 5, the AUC and Cmax were higher in horses being fed the HG/LF diet and receiving the 4 mg/kg dose than in horses being fed the HAY diet and receiving the 1 mg/kg dose. These findings suggest that both dose and diet may affect pharmacokinetic variables of omeprazole in the horse.

Study of the effect of CYP2C19 polymorphisms on omeprazole pharmacokinetics by utilizing validated LC-MS/MS and Real Time-PCR methods.

A fully automated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of omeprazole in human plasma. Utilization of 96-well plates and robotic liquid handling workstations, rendered the whole procedure very fast, compared to the manual respective procedure of Liquid-Liquid Extraction (LLE). Sample analysis was performed by reversed phase LC-MS/MS, with positive electrospray ionization, using multiple reaction monitoring (MRM). The method required low plasma volumes and analysis of samples was completed in short run times. It was fully validated and applied to a pharmacokinetic study after per os administration of 20mg tablet formulations of omeprazole. The obtained concentrations were used for the calculation of the basic omeprazole pharmacokinetic parameters. Some variations observed in pharmacokinetic parameters among subjects were attributed to differences of CYP2C19 genotype. Therefore, a novel molecular method was developed in which DNA analysis was conducted by using Real Time-Polymerase Chain Reaction (Real Time-PCR). As source of biological material, Dried Blood Spots (DBS) were utilized, offering an alternative and advantageous strategy for such kind of studies.

Repeated Famotidine Administration Results in a Diminished Effect on Intragastric pH in Dogs.

BACKGROUND: Famotidine is an acid suppressant commonly administered to dogs. Prolonged famotidine use in people results in decreased efficacy, but the effect in dogs is unknown. HYPOTHESIS/OBJECTIVES: To compare the effect of repeated oral administration of famotidine or placebo on intragastric pH and serum gastrin in dogs. We hypothesized that famotidine would have a diminished effect on intragastric pH on day 13 compared to day 1. ANIMALS: Six healthy adult colony Beagles. METHODS: Randomized, 2-factor repeated-measures crossover design. All dogs received oral placebo or 1.0 mg/kg famotidine q12h for 14 consecutive days. Intragastric pH monitoring was used to continuously record intragastric pH on treatment days 1-2 and 12-13. Mean pH as well as mean percentage time (MPT) that intragastric pH was ≥3 or ≥4 were compared between and within groups by analysis of variance. Serum gastrin was measured on days 0, 3, and 12 for each treatment. RESULTS: Continued administration of famotidine resulted in a significant decrease in mean pH, MPT ≥3, and MPT ≥4 (P < .0001) on day 12 and 13. This resulted in a mean decrease in pH by 1.63 on days 12 and 13 compared to days 1 and 2. Furthermore, a mean decrease of MPT ≥3 and MPT ≥4 by 33 and 45% was observed for the same time period, respectively. CONCLUSIONS AND CLINICAL IMPORTANCE: Continued administration of famotidine results in a diminished effect on intragastric pH in dogs. Caution is advised when recommending long-term, daily oral administration of famotidine to dogs.

Pharmacokinetics of ranitidine in preterm and term neonates with gastroesophageal reflux.

BACKGROUND: The aim of this study was to determine the effect of gestational age on pharmacokinetics of ranitidine in newborns with gastroesophageal reflux. METHODS: A prospective, descriptive and pharmacokinetic study was carried out in 30 pre-term and 20 full-term babies. 3 mg/kg of ranitidine was administered intravenously to all the babies and at 0.25, 0.5, 1, 2, 4, and 8 h following the administration, samples of blood were drawn to assess ranitidine levels using high performance liquid chromatographic technique. RESULTS: Pharmacokinetics of ranitidine had a bi-exponential behavior with a half-life elimination of (t1/2el) 2.79 h, area under curve (AUC) of 1688 ng/mL, volume of distribution (Vd) of 1.44 L/kg, and clearance (Cl) of 5.9 L/kg/h. The median plasmatic concentration in pre-terms was 1113 ng/mL and 280 ng/mL in full-terms. Vd, t1/2 and Cl presented high values in preterm although the correlation of Cl with glomerular filtration in term newborns was better. CONCLUSIONS: Plasma levels of ranitidine depend on the gestational age of the newborns. However, the possible relationship between after-birth age and pharmacokinetics of the neonates as their internal organs get matured without minding their gestational background.

Enantioselective determination of (R)- and (S)-lansoprazole in human plasma by chiral liquid chromatography with mass spectrometry and its application to a stereoselective pharmacokinetic study.

A simple and enantioselective method was developed and validated for the simultaneous determination of (R)- and (S)-lansoprazole in human plasma by chiral liquid chromatography with tandem mass spectrometry. Lansoprazole enantiomers and internal standard (esomeprazole) were extracted from plasma using acetonitrile as protein precipitating agent. Baseline chiral separation was achieved within 9.0 min on a Chiralpak IC column (150 mm × 4.6 mm, 5 µm) with the column temperature of 30°C. The mobile phase consisted of 10 mM ammonium acetate solution containing 0.05% acetic acid/acetonitrile (50:50, v/v). The mass spectrometric analysis was performed using a QTrap 5500 mass spectrometer coupled with an electrospray ionization source in positive ion mode. The multiple reactions monitoring transitions of m/z 370.1→252.1 and 346.1→198.1 were used to quantify lansoprazole enantiomers and esomeprazole, respectively. For each enantiomer, no apparent matrix effect was found, the calibration curve was linear over 5.00-3000 ng/mL, the intra- and inter-day precisions were below 10.0%, and the accuracy was -3.8 to 3.3%. Analytes were stable during the study. No chiral inversion was observed during sample storage, preparation procedure and analysis. The method was applied to the stereoselective pharmacokinetic studies in human after intravenous administration of dexlansoprazole or racemic lansoprazole.

The effect of feeding on the pharmacokinetic variables of two commercially available formulations of omeprazole.

The objectives of this study were to investigate the impact of formulation (enteric coated and buffered) and feeding on pharmacokinetic variables associated with the oral administration of omeprazole in the horse. Six thoroughbred racehorses were studied in a crossover design. Each received 2 g of an enteric coated or buffered formulation in both the fed and fasted state. Plasma omeprazole concentrations were determined by UHPLC-MS. The effects of feeding or formulation on AUC0-inf_obs, half-life, Tmax or Cmax were not statistically significant. However, a wider-than-expected degree of variation was present and examination of the raw data suggests that an effect of feeding, wherein the bioavailability of omeprazole may be reduced in the fed animal, may be present. Further investigation in a larger population of animals to assess the factors that contribute to the wide degree of absorption observed is warranted.

Orally given gastroprotective capsaicin does not modify aspirin-induced platelet aggregation in healthy male volunteers (human phase I examination).

Capsaicin is a well-known component of red pepper. Recent studies have shown that capsaicin could prevent gastric ulcer provoked by various NSAID-s like acetylsalicylic acid (ASA). Primary objective of this human clinical phase I trial was to investigate whether two different doses of capsaicin co-administered with ASA could alter the inhibitory effect of ASA on platelet aggregation. 15 healthy male subjects were involved in the study and treated orally with 400 µg capsaicin, 800 µg capsaicin, 500 mg ASA, 400 µg capsaicin+500 mg ASA and 800 µg capsaicin+500 mg ASA. Blood was drawn before and 1, 2, 6 and 24 hours after the drug administration. After that epinephrine induced platelet aggregation was measured by optical aggregometry. Between treatments, volunteers had a 6-day wash-out period. Our results showed that capsaicin had no effect on platelet aggregation, while as expected, ASA monotherapy resulted in a significant and clinically effective platelet aggregation inhibition (p ≤ 0.001). The combined ASA-capsaicin therapies reached equivalent effectiveness in platelet aggregation inhibition as ASA monotherapy. Our investigation proved that capsaicin did not influence the inhibitory effect of ASA on platelet aggregation, thus the capsaicin-ASA treatment would combine the antiplatelet effect of ASA with the possible gastroprotection of capsaicin.

Hydroxylation index of omeprazole in relation to CYP2C19 polymorphism and sex in a healthy Iranian population.

BACKGROUND: Polymorphism of CYP2C19 gene is one of the important factors in pharmacokinetics of CYP2C19 substrates. Omeprazole is a proton pump inhibitor which is mainly metabolized by cytochrome P450 2C19 (CYP2C19). The aim of present study was to assess omeprazole hydroxylation index as a measure of CYP2C19 activity considering new variant allele (CYP2C19*17) in Iranian population and also to see if this activity is sex dependent. METHODS: One hundred and eighty healthy unrelated Iranian individuals attended in this study. Blood samples for genotyping and phenotyping were collected 3 hours after administration of 20 mg omeprazole orally. Genotyping of 2C19 variant alleles *2, *3 and *17 was performed by using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and semi-nested PCR methods. Plasma concentrations of omeprazole and hydroxyomeprazole were determined by high performance liquid chromatography (HPLC) technique and hydxroxylation index (HI) (omeprazole/ hydroxyomeprazole) was calculated. RESULTS: The CYP2C19*17 was the most common variant allele in the studied population (21.6%). Genotype frequencies of CYP2C19*17*17, *1*17, and *2*17 were 5.5%, 28.8% and 3.3% respectively. The lowest and the highest median omeprazole HI was observed in *17*17 and *2*2 genotypes respectively (0.36 vs. 13.09). The median HI of omeprazole in subjects homozygous for CYP2C19*1 was 2.16-fold higher than individuals homozygous for CYP2C19*17 (P < 0.001) and the median HI of CYP2C19*1*17 genotype was 1.98-fold higher than CYP2C19 *17*17 subjects (P < 0.001). However, subjects with CYP2C19*2*17 (median HI: 1.74) and CYP2C19*1*2 (median HI: 1.98) genotypes and also CYP2C19*1*17 (median HI: 0.71) and CYP2C19*1*1 (mean HI: 0.78) did not show any significantly different enzyme activity. In addition, no statistically significant difference was found between women and men in distribution of CYP2C19 genotypes. Furthermore, the hydroxylation index of Omeprazole was not different between women and men in the studied population. CONCLUSION: Our data point out the importance of CYP2C19*2 and CYP2C19*17 variant alleles in metabolism of omeprazole and therefore CYP2C19 activity. Regarding the high frequency of CYP2C19*17 in Iranian population, the importance of this new variant allele in metabolism of CYP2C19 substrates shall be considered.

The pharmacokinetics, pharmacodynamics and safety of oral doses of ilaprazole 10, 20 and 40 mg and esomeprazole 40 mg in healthy subjects: a randomised, open-label crossover study.

BACKGROUND: Ilaprazole, a proton pump inhibitor (PPI) currently in clinical use, may provide improved acid suppression vs. other PPIs. AIM: To compare the pharmacodynamic and pharmacokinetic profiles of ilaprazole and esomeprazole. METHODS: A phase 1, randomised, open-label, single-centre, 4-period crossover study was conducted in 40 healthy volunteers. Ilaprazole 10, 20 or 40 mg or esomeprazole 40 mg was administered once daily for 5 days with ≥5-day washout intervals. Pharmacokinetic blood samples and intragastric pH measurements were collected at scheduled timepoints for 24 h after dosing on Days 1 and 5. RESULTS: Esomeprazole 40 mg provided significantly better pH control during the initial hours (0-4 h) after a single dose, but ilaprazole (particularly 20 and 40 mg) provided significantly better pH control for the entire 24-h period and during evening and overnight hours after single and multiple doses. Increasing ilaprazole doses resulted in dose-proportional increases in peak plasma concentration and area under the plasma concentration vs. time curve following single and multiple doses. Ilaprazole was safe and generally well tolerated; an unexpectedly high incidence of allergic eye and skin reactions were observed but were not specific to any dosing regimen. Plasma gastrin concentrations did not increase proportionately with increasing ilaprazole dose. CONCLUSIONS: Ilaprazole provided significantly better pH control over 24 h and during evening and overnight hours compared with esomeprazole in healthy volunteers, which may translate to greater relief of night-time heartburn in the clinical setting for patients with gastric acid-related disorders.

Efficacy of omeprazole powder paste or enteric-coated formulation in healing of gastric ulcers in horses.

BACKGROUND: GastroGard, an omeprazole powder paste formulation, is considered the standard treatment for gastric ulcers in horses and is highly effective. Gastrozol, an enteric-coated omeprazole formulation for horses, has recently become available, but efficacy data are controversial and sparse. OBJECTIVES: To investigate the efficacy of GastroGard and Gastrozol at labeled doses (4 and 1 mg of omeprazole per kg bwt, respectively, PO q24h) in healing of gastric ulcers. ANIMALS: 40 horses; 9.5 ± 4.6 years; 491 ± 135 kg. METHODS: Prospective, randomized, blinded study. Horses with an ulcer score ≥1 (Equine Gastric Ulcer Council) were randomly divided into 2 groups and treated for 2 weeks each with GastroGard followed by Gastrozol (A) or vice versa (B). After 2 and 4 weeks, scoring was repeated and compared with baseline. Plasma omeprazole concentrations were measured on the first day of treatment after administration of GastroGard (n = 5) or Gastrozol (n = 5). RESULTS: Compared with baseline (squamous score (A) 1.65 ± 0.11, (B) 1.98 ± 0.11), ulcer scores at 2 weeks ((A) 0.89 ± 0.11, (B) 1.01 ± 0.11) and 4 weeks ((A) 1.10 ± 0.12, (B) 0.80 ± 0.12) had significantly decreased in both groups (P < .001), independent of treatment (P = .7). Plasma omeprazole concentrations were significantly higher after GastroGard compared with Gastrozol administration (AUCGG = 2856 (1405-4576) ng/mL × h, AUCGZ = 604 (430-1609) ng/mL × h; P = .03). The bioavailability for Gastrozol was 1.26 (95% CI 0.56-2.81) times higher than for GastroGard. CONCLUSIONS AND CLINICAL IMPORTANCE: Both Gastrozol and GastroGard, combined with appropriate environmental changes, promote healing of gastric ulcers in horses. However, despite enteric coating of Gastrozol, plasma omeprazole concentrations after single labeled doses were significantly higher with GastroGard.