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Fadel C, Łebkowska-Wieruszewskac B, Serih F, Lisowski A, Poapolathep A, Giorgi M. Comparative pharmacokinetics of intravenous and subcutaneous pantoprazole in sheep and goats. Vet J 2024; 305:106138. [PMID: 38761957 DOI: 10.1016/j.tvjl.2024.106138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 05/13/2024] [Accepted: 05/13/2024] [Indexed: 05/20/2024]
Abstract
Abomasal ulcers are a significant concern in intensive animal farming due to their impact on animal health and productivity. While proton pump inhibitors (PPIs) such as pantoprazole (PTZ) show promise in treating these ulcers, data on PTZ's pharmacokinetics (PK) in adult goats and sheep are limited. This study aims to fill this gap by investigating and comparing PTZ's PK in these species following single intravenous (IV) and subcutaneous (SC) administrations. Five healthy male goats and sheep were included in the study. PTZ concentrations in plasma samples were determined using a validated analytical method. Non-compartmental analysis was conducted, and statistical comparisons were made between IV and SC administrations and between species. Sheep and goats showed similar systemic exposure levels regardless of the administration route. However, sheep had a shorter t1/2 due to a higher Vd compared to goats. Cl values were comparable in both species, with low extraction ratio values. There were no significant differences in Cmax and Tmax between the two species with regards to SC administration, and complete bioavailability was observed. The MAT exceeded the t1/2 in both species, indicating a potential flip-flop phenomenon. Considering the AUC as a predictor for drug efficacy, and observing no significant differences in systemic exposure between sheep and goats for any route of administration, dosage adjustment between the two species may not be necessary. In field settings, SC administration proves more practical, providing not only complete bioavailability but also a longer half-life compared to IV. Further studies are warranted to explore the PK/PD of PTZ in small ruminants with abomasal ulcers, to fully comprehend its therapeutic efficacy in such scenarios.
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Affiliation(s)
- Charbel Fadel
- Department of Veterinary Sciences, University of Pisa, Viale delle Piagge, 2, Pisa, PI 56124, Italy; Department of Veterinary Medicine, Lebanese University, Faculty of Agronomy Bldg., University Street, Dekwaneh, Beirut, Lebanon
| | - Beata Łebkowska-Wieruszewskac
- Department of Pharmacology, Toxicology and Environmental Protection, University of Life Sciences in Lublin, 13 Akademicka Street, Lublin 20-950, Poland
| | - Firas Serih
- Department of Veterinary Sciences, University of Sassari, Via Vienna, 2, Sassari, SS 07100, Italy
| | - Andrew Lisowski
- Institute of Animal Breeding and Biodiversity Conservation, University of Life Sciences in Lublin, 13 Akademicka Street, Lublin 20-950, Poland
| | - Amnart Poapolathep
- Faculty of Veterinary Medicine, Department of Pharmacology, Kasetsart University, 50 Paholyothin Road, Bangkok 10900, Thailand
| | - Mario Giorgi
- Department of Veterinary Sciences, University of Pisa, Viale delle Piagge, 2, Pisa, PI 56124, Italy; Department of Veterinary Sciences, University of Sassari, Via Vienna, 2, Sassari, SS 07100, Italy.
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2
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Yu D, Zhang Q, De Jaegher B, Liu J, Sui Q, Zheng X, Wei Y. Effect of proton pump inhibitor on microbial community, function, and kinetics in anaerobic digestion with ammonia stress. BIORESOURCE TECHNOLOGY 2021; 319:124118. [PMID: 32957047 DOI: 10.1016/j.biortech.2020.124118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
The proton pump is a convincing mechanism for ammonia inhibition in anaerobic digestion, which explained how the ammonia accumulated intercellularly due to diffusion of free ammonia. Proton pump inhibitor (PPI) was dosed for mitigating the accumulation in anaerobic digestion with ammonia stress, with respect to kinetics. Results show PPI inhibited β-oxidation of fatty acids by targeting ATPase in anaerobic digestion with ammonia stress. Alternatively, PPI stimulated syntrophic acetate oxidization. Random forest located key genera as syntrophic consortia. Methane increased 18.72 ± 7.39% with 20 mg/L PPI at the first peak, consistent with microbial results. The deterministic Gompertz kinetics and stochastic Gaussian processes contributed 97.63 ± 8.93% and 2.37 ± 8.93% in accumulated methane production, respectively. Thus, the use of PPI for anaerobic digestion allowed mitigate ammonia inhibition based on the mechanism of proton pump, facilitate intercellularly ammonia accumulation, stimulate syntrophic consortia, and eliminate uncertainty of process failure, which resulted in efficient methane production under ammonia stress.
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Affiliation(s)
- Dawei Yu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; Department of Water Pollution Control Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China; BIOMATH, Department of Data Analysis and Mathematical Modelling, Ghent University, Coupure Links 653, Ghent 9000, Belgium
| | - Qingqing Zhang
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; Department of Water Pollution Control Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; School of Environment & Natural Resources, Renmin University of China, Beijing 100872, China
| | - Bram De Jaegher
- BIOMATH, Department of Data Analysis and Mathematical Modelling, Ghent University, Coupure Links 653, Ghent 9000, Belgium
| | - Jibao Liu
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; Department of Water Pollution Control Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qianwen Sui
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; Department of Water Pollution Control Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiang Zheng
- School of Environment & Natural Resources, Renmin University of China, Beijing 100872, China.
| | - Yuansong Wei
- State Key Joint Laboratory of Environmental Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; Department of Water Pollution Control Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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3
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Escoffier J, Arnaud B, Kaba M, Hograindleur JP, Le Blévec E, Martinez G, Stévant I, Ray PF, Arnoult C, Nef S. Pantoprazole, a proton-pump inhibitor, impairs human sperm motility and capacitation in vitro. Andrology 2020; 8:1795-1804. [PMID: 32609951 DOI: 10.1111/andr.12855] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 06/15/2020] [Accepted: 06/25/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND The effects of PPIs on human sperm fertilizing capacity were poorly investigated although these drugs are widely over-used. Two publications retrospectively studied relationships between any PPI intake and sperm parameters from patients consulting at infertility clinics, but the conclusions of these reports were contradictory. Only two reports investigated the effects of lansoprazole and omeprazole on sperm motility and found lansoprazole to be deleterious and omeprazole to be neutral for sperm motility. The inconsistency of the PPI effect in the previous reports emphasizes the need for more basic research on human spermatozoa, taking into account the hypothesis that the different PPI drugs may have different effects on sperm physiology. OBJECTIVES Do PPIs, which are among the most widely sold drug in the word, impact negatively human sperm capacitation and sperm motility? MATERIALS AND METHODS The effects of PPIs on human sperm maturation and motility were analyzed by CASA, flow cytometry, and Western blot. RESULTS We tested the impact of 6 different PPIs on human sperm motility and capacitation. We showed that pantoprazole, but not the other PPIs, decreased sperm progressive motility and capacitation-induced sperm hyperactivation. We therefore investigated further the effects of pantoprazole on sperm capacitation, and we observed that it had a significant deleterious effect on the capacitation-induced hyperpolarization of the membrane potential and capacitation-associated protein phosphorylation. DISCUSSION AND CONCLUSION Our results indicate that exposure to pantoprazole has an adverse effect on the physiological competence of human spermatozoa. As the capacitation process takes place within the female tract, our results suggest that PPIs intake by the female partner may impair in vivo sperm maturation and possibly fertilization. Moreover, the absence of adverse effect by PPIs on mouse sperm emphasizes the need to develop reprotox assays using human material to better assess the effects of medication intake on sperm physiology.
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Affiliation(s)
- Jessica Escoffier
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland.,Université Grenoble Alpes, Equipe "Génétique, Epigénétique et Thérapies de l'Infertilité", IAB, CNRS UMR 5309, Grenoble, France
| | - Bastien Arnaud
- Université Grenoble Alpes, Equipe "Génétique, Epigénétique et Thérapies de l'Infertilité", IAB, CNRS UMR 5309, Grenoble, France
| | - Mayis Kaba
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland
| | - Jean Pascal Hograindleur
- Université Grenoble Alpes, Equipe "Génétique, Epigénétique et Thérapies de l'Infertilité", IAB, CNRS UMR 5309, Grenoble, France
| | - Emilie Le Blévec
- Université Grenoble Alpes, Equipe "Génétique, Epigénétique et Thérapies de l'Infertilité", IAB, CNRS UMR 5309, Grenoble, France
| | - Guillaume Martinez
- Université Grenoble Alpes, Equipe "Génétique, Epigénétique et Thérapies de l'Infertilité", IAB, CNRS UMR 5309, Grenoble, France
| | - Isabelle Stévant
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland
| | - Pierre F Ray
- Université Grenoble Alpes, Equipe "Génétique, Epigénétique et Thérapies de l'Infertilité", IAB, CNRS UMR 5309, Grenoble, France.,CHU Grenoble Alpes, UM GI-DPI, Grenoble, France
| | - Christophe Arnoult
- Université Grenoble Alpes, Equipe "Génétique, Epigénétique et Thérapies de l'Infertilité", IAB, CNRS UMR 5309, Grenoble, France
| | - Serge Nef
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland
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4
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Engevik AC, Kaji I, Goldenring JR. The Physiology of the Gastric Parietal Cell. Physiol Rev 2020; 100:573-602. [PMID: 31670611 PMCID: PMC7327232 DOI: 10.1152/physrev.00016.2019] [Citation(s) in RCA: 101] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 10/10/2019] [Accepted: 10/13/2019] [Indexed: 12/11/2022] Open
Abstract
Parietal cells are responsible for gastric acid secretion, which aids in the digestion of food, absorption of minerals, and control of harmful bacteria. However, a fine balance of activators and inhibitors of parietal cell-mediated acid secretion is required to ensure proper digestion of food, while preventing damage to the gastric and duodenal mucosa. As a result, parietal cell secretion is highly regulated through numerous mechanisms including the vagus nerve, gastrin, histamine, ghrelin, somatostatin, glucagon-like peptide 1, and other agonists and antagonists. The tight regulation of parietal cells ensures the proper secretion of HCl. The H+-K+-ATPase enzyme expressed in parietal cells regulates the exchange of cytoplasmic H+ for extracellular K+. The H+ secreted into the gastric lumen by the H+-K+-ATPase combines with luminal Cl- to form gastric acid, HCl. Inhibition of the H+-K+-ATPase is the most efficacious method of preventing harmful gastric acid secretion. Proton pump inhibitors and potassium competitive acid blockers are widely used therapeutically to inhibit acid secretion. Stimulated delivery of the H+-K+-ATPase to the parietal cell apical surface requires the fusion of intracellular tubulovesicles with the overlying secretory canaliculus, a process that represents the most prominent example of apical membrane recycling. In addition to their unique ability to secrete gastric acid, parietal cells also play an important role in gastric mucosal homeostasis through the secretion of multiple growth factor molecules. The gastric parietal cell therefore plays multiple roles in gastric secretion and protection as well as coordination of physiological repair.
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Affiliation(s)
- Amy C Engevik
- Departments of Surgery and of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Vanderbilt University Medical Center and the Nashville VA Medical Center, Nashville, Tennessee
| | - Izumi Kaji
- Departments of Surgery and of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Vanderbilt University Medical Center and the Nashville VA Medical Center, Nashville, Tennessee
| | - James R Goldenring
- Departments of Surgery and of Cell and Developmental Biology and the Epithelial Biology Center, Vanderbilt University School of Medicine, Vanderbilt University Medical Center and the Nashville VA Medical Center, Nashville, Tennessee
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5
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Benchamana A, Mori H, MacDougald OA, Soodvilai S. Regulation of adipocyte differentiation and metabolism by lansoprazole. Life Sci 2019; 239:116897. [PMID: 31644894 DOI: 10.1016/j.lfs.2019.116897] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/17/2019] [Accepted: 09/20/2019] [Indexed: 12/20/2022]
Abstract
AIMS Lansoprazole (LPZ) is one of the most commonly prescribed drugs for treatment of acid-related diseases, and it is increasingly recognized for its potential application as an anti-diabetic therapy. Although LPZ target tissues remain poorly understood, possible sites of action include adipose tissue. In this study, we assessed effects of LPZ on adipocyte differentiation and function by using 3T3-L1 preadipocytes and HFD-induced obesity mice as an in vitro and in vivo model, respectively. MAIN METHODS Oil red O staining and intracellular triacylglycerol content were used to determine lipid accumulation. Glucose uptake was performed to measure mature adipocyte function. Expression of adipocyte genes was determined by qRT-PCR and immunoblotting. KEY FINDINGS LPZ has dual effects on differentiation of 3T3-L1 cells. At low concentrations, LPZ enhanced adipocyte differentiation via induction of PPARγ and C/EBPα, two master adipogenic transcription factors, as well as lipogenic proteins, ACC1 and FASN. Increasing of adipocyte number subsequently increased basal and insulin-stimulated glucose uptake, and expression of Glut4 mRNA. Conversely, high concentrations of LPZ strongly inhibited differentiation and expression of PPARγ and C/EBPα, and maintained expression of preadipocytes markers, β-catenin and Pref-1. Inhibition of adipogenesis by LPZ reduced mature adipocyte number, Glut4 mRNA expression and insulin-stimulated glucose uptake. In addition, treatment with LPZ at 200 mg/kg significantly reduced body weight gain and total fat mass in HFD-induced obese mice. SIGNIFICANCE These results indicate that effects of LPZ on adipocyte differentiation are dependent on concentration and are correlated with PPARγ and C/EBPα.
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Affiliation(s)
- Ameena Benchamana
- Research Center of Transport Protein for Medical Innovation, Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand; University of Michigan Medical School, Department of Molecular & Integrative Physiology, Ann Arbor, MI, USA
| | - Hiroyuki Mori
- University of Michigan Medical School, Department of Molecular & Integrative Physiology, Ann Arbor, MI, USA
| | - Ormond A MacDougald
- University of Michigan Medical School, Department of Molecular & Integrative Physiology, Ann Arbor, MI, USA
| | - Sunhapas Soodvilai
- Research Center of Transport Protein for Medical Innovation, Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand; Excellent Center for Drug Discovery (ECDD), Faculty of Science, Mahidol University, Bangkok, Thailand.
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6
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Sobrino-Cossío S, Teramoto-Matsubara O, Mateos-Pérez G, Abdo-Francis JM, Tawil J, Olguín-Ramírez C, Orozco-Gamiz A, Galvis-García ES. In search of the grail: A race for acid suppression. REVISTA DE GASTROENTEROLOGIA DE MEXICO (ENGLISH) 2019; 84:344-356. [PMID: 31239096 DOI: 10.1016/j.rgmx.2019.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 03/26/2019] [Accepted: 04/30/2019] [Indexed: 06/09/2023]
Abstract
Proton pump inhibitors are the reference standards for the treatment of acid-related diseases. Acid suppression in gastroesophageal reflux disease is associated with a high rate of mucosal cicatrization, but symptom response differs among endoscopic phenotypes. Extraesophageal manifestations have a good clinical response in patients that present with abnormal acid exposure (diagnostic test) in the esophagus. Proton pump inhibitors have shown their effectiveness for reducing symptom intensity in nighttime reflux and sleep disorders, improving quality of life and work productivity. That can sometimes be achieved through dose modifications by splitting or increasing the dose, or through galenic formulation. Proton pump inhibitors are not exempt from controversial aspects related to associated adverse events. Technological development is directed at improving proton pump inhibitor performance through increasing the half-life, maximum concentration, and area under the curve of the plasma concentrations through galenic formulation, as well as creating safer and more tolerable drugs. The present review is focused on the mechanisms of action, pharmacokinetic properties, and technological advances for increasing the pharmacologic performance of a proton pump inhibitor.
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Affiliation(s)
- S Sobrino-Cossío
- Hospital Ángeles del Pedregal, Ciudad de México, México; Gástrica, Centro Avanzado en Endoscopia y Estudios Funcionales, Ciudad de México, México.
| | - O Teramoto-Matsubara
- Gástrica, Centro Avanzado en Endoscopia y Estudios Funcionales, Ciudad de México, México; Centro Médico ABC, Ciudad de México, México
| | - G Mateos-Pérez
- Hospital Ángeles del Pedregal, Ciudad de México, México; Hospital Ángeles Acoxpa, Ciudad de México, México
| | - J M Abdo-Francis
- Gástrica, Centro Avanzado en Endoscopia y Estudios Funcionales, Ciudad de México, México; Hospital Ángeles Acoxpa, Ciudad de México, México
| | - J Tawil
- Departamento de Trastornos Funcionales Digestivos, Gedyt-Gastroenterología Diagnóstica y Terapéutica, Buenos Aires, Argentina
| | - C Olguín-Ramírez
- Gástrica, Centro Avanzado en Endoscopia y Estudios Funcionales, Ciudad de México, México
| | - A Orozco-Gamiz
- Gastrolab Laboratorio de Fisiología Gastrointestinal, Guadalajara, Jalisco, México
| | - E S Galvis-García
- Gástrica, Centro Avanzado en Endoscopia y Estudios Funcionales, Ciudad de México, México; Hospital General de México «Dr. Eduardo Liceaga», Ciudad de México, México
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7
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Sobrino-Cossío S, Teramoto-Matsubara O, Mateos-Pérez G, Abdo-Francis J, Tawil J, Olguín-Ramírez C, Orozco-Gamiz A, Galvis-García E. In search of the grail: A race for acid suppression. REVISTA DE GASTROENTEROLOGÍA DE MÉXICO (ENGLISH EDITION) 2019. [DOI: 10.1016/j.rgmxen.2019.04.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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8
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Loisios-Konstantinidis I, Paraiso RLM, Fotaki N, McAllister M, Cristofoletti R, Dressman J. Application of the relationship between pharmacokinetics and pharmacodynamics in drug development and therapeutic equivalence: a PEARRL review. J Pharm Pharmacol 2019; 71:699-723. [DOI: 10.1111/jphp.13070] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 01/19/2019] [Indexed: 12/18/2022]
Abstract
Abstract
Objectives
The objective of this review was to provide an overview of pharmacokinetic/pharmacodynamic (PK/PD) models, focusing on drug-specific PK/PD models and highlighting their value added in drug development and regulatory decision-making.
Key findings
Many PK/PD models, with varying degrees of complexity and physiological understanding have been developed to evaluate the safety and efficacy of drug products. In special populations (e.g. paediatrics), in cases where there is genetic polymorphism and in other instances where therapeutic outcomes are not well described solely by PK metrics, the implementation of PK/PD models is crucial to assure the desired clinical outcome. Since dissociation between the pharmacokinetic and pharmacodynamic profiles is often observed, it is proposed that physiologically based pharmacokinetic and PK/PD models be given more weight by regulatory authorities when assessing the therapeutic equivalence of drug products.
Summary
Modelling and simulation approaches already play an important role in drug development. While slowly moving away from ‘one-size fits all’ PK methodologies to assess therapeutic outcomes, further work is required to increase confidence in PK/PD models in translatability and prediction of various clinical scenarios to encourage more widespread implementation in regulatory decision-making.
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Affiliation(s)
| | - Rafael L M Paraiso
- Institute of Pharmaceutical Technology, Goethe University, Frankfurt am Main, Germany
| | - Nikoletta Fotaki
- Department of Pharmacy and Pharmacology, Faculty of Science, University of Bath, Bath, UK
| | | | - Rodrigo Cristofoletti
- Division of Therapeutic Equivalence, Brazilian Health Surveillance Agency (ANVISA), Brasilia, Brazil
| | - Jennifer Dressman
- Institute of Pharmaceutical Technology, Goethe University, Frankfurt am Main, Germany
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9
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Yari A, Zolali A, Karimian K. On the Mechanism of Formation and the Synthesis of Pantoprazole Sodium Sesquihydrate-Related Compound E: A Phantom Chemical Entity. ACS OMEGA 2019; 4:737-744. [PMID: 31459358 PMCID: PMC6648569 DOI: 10.1021/acsomega.8b00845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Accepted: 12/03/2018] [Indexed: 06/10/2023]
Abstract
A mechanism for the formation of pantoprazole related compound E (RC E) is proposed involving the formation of a radical cation in the pH range of 5-8. pH dependence of RC E is demonstrated, and the contribution of the difluoromethoxy group in stabilizing the C-6 free radical, a prerequisite to the formation of the dimer byproduct, is discussed. Also, the synthesis of pantoprazole RC E is reported using the benzidine rearrangement.
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Affiliation(s)
- Ahmad Yari
- Andisheh
Pharmaceutical Sciences R&D, Ajand Pharma
Holding Inc., Yousefabad,
Jahanara Avenue, 23rd Street No. 8, Tehran 1438933743, Iran
| | - Amin Zolali
- Andisheh
Pharmaceutical Sciences R&D, Ajand Pharma
Holding Inc., Yousefabad,
Jahanara Avenue, 23rd Street No. 8, Tehran 1438933743, Iran
| | - Khashayar Karimian
- Andisheh
Pharmaceutical Sciences R&D, Ajand Pharma
Holding Inc., Yousefabad,
Jahanara Avenue, 23rd Street No. 8, Tehran 1438933743, Iran
- Institute
of Biochemistry and Biophysics, University
of Tehran, P.O. Box 13145-1384, Tehran 1417466191, Iran
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10
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Sun LN, Cao Y, Li YQ, Fang YQ, Zhang HW, Wang MF, Xie LJ, Chen J, Yang ZC, Bian ML, Li H, Zhang PP, Wei JF, Meng L, Zhang XH, Zhao P, Wang YQ. Impact of Gastric H+/K+-ATPase rs2733743 on the Intragastric pH-Values of Dexlansoprazole Injection in Chinese Subjects. Front Pharmacol 2017; 8:670. [PMID: 29018343 PMCID: PMC5614982 DOI: 10.3389/fphar.2017.00670] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 09/07/2017] [Indexed: 12/13/2022] Open
Abstract
Background: Not all patients with acid-related disorders receiving proton pump inhibitor (PP) treatment get adequate gastric pH control. The genetic variation of receptors, metabolic enzymes, and transporters are known to cause failures of therapies. We have conducted a study to evaluate the influence of gastric H+/K+-ATPase, CYP2C19, and ABCB1 polymorphisms on the pharmacokinetic and pharmacodynamic profiles of dexlansoprazole injection in healthy Chinese subjects. Methods: A total of 51 subjects were enrolled for pharmacokinetic and pharmacodynamic study after a single intravenous administration of 20 or 30 mg dexlansoprazole. Plasma concentrations were determined using a chiral liquid chromatography-mass spectrometry method. The intragastric pH and baseline-adjusted intragastric pH parameters were introduced to evaluate the pharmacodynamic characters. Genotyping was performed by polymerase chain reaction. Results: The pharmacokinetic parameters were significantly influenced by CYP2C19 phenotypes, and gastric acid secretion inhibition were affected by both gastric H+/K+-ATPase and CYP2C19 polymorphisms. Gastric H+/K+-ATPase genotypes had greater effects than CYP2C19 genotypes on the suppression of gastric acid secretion. Conclusion: Gastric H+/K+-ATPase polymorphism may be one of the main reasons that cause insufficient gastric acid inhibition.
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Affiliation(s)
- Lu-Ning Sun
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Yang Cao
- Department of Gastroenterology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Yue-Qi Li
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Yun-Qian Fang
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Hong-Wen Zhang
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Mei-Feng Wang
- Department of Gastroenterology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Li-Jun Xie
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Juan Chen
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Zhi-Cheng Yang
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Ming-Liang Bian
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Hao Li
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Pei-Pei Zhang
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Ji-Fu Wei
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Ling Meng
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China
| | - Xue-Hui Zhang
- Department of Pharmacy, Jiangsu Shengze HospitalSuzhou, China
| | - Ping Zhao
- Department of Pharmacy, Jiangsu Shengze HospitalSuzhou, China
| | - Yong-Qing Wang
- Research Division of Clinical Pharmacology, First Affiliated Hospital with Nanjing Medical UniversityNanjing, China.,Department of Pharmacy, Jiangsu Shengze HospitalSuzhou, China
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11
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Paresi CJ, Liu Q, Li YM. Benzimidazole covalent probes and the gastric H(+)/K(+)-ATPase as a model system for protein labeling in a copper-free setting. MOLECULAR BIOSYSTEMS 2017; 12:1772-80. [PMID: 26952080 DOI: 10.1039/c6mb00024j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Affinity probes are useful tools for determining molecular targets and elucidating mechanism of action for novel, bioactive compounds. In the case of covalent inhibitors, activity based probes are particularly valuable for ensuring acceptable selectivity margins. However, there is a variety of bioorthogonal chemistry reactions available for modifying compounds of interest with clickable tags. Here, we describe a direct comparison of tetrazine ligation and strain promoted azide-alkyne cycloaddition using benzimidazole based probes to bind their known target, the gastric proton pump, ATP4A. This study validates the use of chemical probes for target identification and illustrates the superior efficiency of tetrazine ligation for copper-free click systems. In addition, we have identified several novel binding partners of benzimidazole probes: Isoform 2 of deleted in malignant brain tumors 1 protein (DMBT1) and three uncharacterized proteins.
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Affiliation(s)
- Chelsea J Paresi
- Chemical Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA. and Program of Pharmacology, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA
| | - Qi Liu
- Chemical Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA.
| | - Yue-Ming Li
- Chemical Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10065, USA. and Program of Pharmacology, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA
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12
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Tringali A, Manta R, Sica M, Bassotti G, Marmo R, Mutignani M. Comparing intravenous and oral proton pump inhibitor therapy for bleeding peptic ulcers following endoscopic management: a systematic review and meta-analysis. Br J Clin Pharmacol 2017; 83:1619-1635. [PMID: 28181291 DOI: 10.1111/bcp.13258] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 12/28/2016] [Accepted: 01/31/2017] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND AND AIMS The efficacy of proton pump inhibitors (PPIs) has been demonstrated for bleeding peptic ulcers but the route of administration remains controversial. Several studies have demonstrated that high-dose oral PPIs are as effective as intravenous PPIs in reducing recurrent bleeding. However, current guidelines recommend intravenous PPIs after endoscopic treatment. Previous data based on numbers that were too small to enable a firm conclusion to be reached suggested that oral and intravenous PPIs had equivalent efficacy. We undertook a meta-analysis to compare oral and intravenous PPIs in patients with bleeding peptic ulcers after endoscopic management. METHODS A literature search was undertaken using MEDLINE, EMBASE and the Cochrane Library, between 1990 and February 2016, to identify all randomized controlled trials (RCTs) that assessed the efficacy of PPIs administered by different routes. Nine RCTs, involving 1036 patients, were analysed. Outcomes were: recurrent bleeding, blood transfusion requirement, duration of hospital stay, a need for repeat endoscopy, surgery and 30-day mortality. RESULTS There were no differences in the rebleeding rates [odds ratio (OR) 0.93, 95% confidence interval (CI) 0.60, 1.46; P = 0.77], need for surgery (OR 0.77, 95% CI 0.25, 2.40; P = 0.65), need for repeat endoscopy (OR 0.69, 95% CI 0.39, 1.21; P = 0.19), need for blood transfusion [(MD) -0.03, 95% CI -0.26, 0.19; P = 0.76], duration of hospital stay (MD -0.61, 95% CI -1.45, 0.23; P = 0.16) or 30-day mortality (OR 0.89, 95% CI 0.27, 2.43; P = 0.84) according to the route of administration. CONCLUSIONS Oral PPIs represent better value for money, with clinical efficacy equivalent to intravenous PPIs.
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Affiliation(s)
- Alberto Tringali
- Endoscopy Unit, Niguarda Hospital, Piazza Ospedale Maggiore 3, 20162, Milan, Italy
| | - Raffaele Manta
- Endoscopy Unit, Niguarda Hospital, Piazza Ospedale Maggiore 3, 20162, Milan, Italy
| | - Mariano Sica
- Endoscopy Unit, Niguarda Hospital, Piazza Ospedale Maggiore 3, 20162, Milan, Italy
| | - Gabrio Bassotti
- Gastroenterology & Hepatology Section, Department of Medicine, University of Perugia Medical School, Perugia, Italy
| | - Riccardo Marmo
- Gastroenterologia ed Endoscopia Digestiva del PO di Polla, Salerno, Italy
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13
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Numico G, Fusco V, Franco P, Roila F. Proton Pump Inhibitors in cancer patients: How useful they are? A review of the most common indications for their use. Crit Rev Oncol Hematol 2017; 111:144-151. [DOI: 10.1016/j.critrevonc.2017.01.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 01/02/2017] [Accepted: 01/23/2017] [Indexed: 02/08/2023] Open
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14
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Sakai H, Fujii T, Takeguchi N. Proton-Potassium (H+/K+) ATPases: Properties and Roles in Health and Diseases. Met Ions Life Sci 2016; 16:459-83. [DOI: 10.1007/978-3-319-21756-7_13] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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15
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Biju PG, Gubrij I, Garg S, Gupta PK, Hauer-Jensen M, Burnett AF. Radiation lethality potentiation in total body irradiated mice by a commonly prescribed proton pump inhibitor, Pantoprazole sodium. Int J Radiat Biol 2014; 90:554-9. [PMID: 24646079 DOI: 10.3109/09553002.2014.905727] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PURPOSE Pantoprazole sodium (Protonix) is a proton pump inhibitor (PPI) widely used to treat peptic ulcer and gastroesophageal reflux due to its ability to inhibit gastric acid secretion. Therefore, a large group of the population exposed to total body irradiation (TBI) in the event of a nuclear disaster would be on this or similar medications. We investigated the effect of pantoprazole on TBI-induced lethality in mice. METHODS AND MATERIALS Male CD2F1 mice were exposed to various doses of uniform TBI using a (137)Cs irradiator. Pantoprazole was administered by twice daily subcutaneous injection in saline from 4 days before to 5 days after irradiation. Effects on gastric pH, and gastrointestinal (GI) and hematopoietic toxicity were evaluated. RESULTS Pantoprazole administration significantly exacerbated 30 day lethality and gastrointestinal toxicity. Median survival after 9.0 Gy TBI was reduced from 22 days to 12 days (p = 0.006). Pantoprazole adversely effected intestinal crypt survival and mucosal surface area. In contrast, equivalent doses of a histamine type-2(H2) receptor blocker (cimetidine) did not alter TBI-induced lethality. CONCLUSION The adverse effect of pantoprazole on TBI-induced lethality is highly important because of the widespread use of PPI in the general population, as well as use of these drugs for acid suppression in individuals exposed to radiation. Further studies of the mechanisms underlying the adverse effect of PPI after exposure to TBI are clearly warranted. Until results from such studies are available, other acid-suppressing strategies should be preferred in the context of radiation exposure.
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Novotna A, Srovnalova A, Svecarova M, Korhonova M, Bartonkova I, Dvorak Z. Differential effects of omeprazole and lansoprazole enantiomers on aryl hydrocarbon receptor in human hepatocytes and cell lines. PLoS One 2014; 9:e98711. [PMID: 24887303 PMCID: PMC4041848 DOI: 10.1371/journal.pone.0098711] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 05/07/2014] [Indexed: 11/22/2022] Open
Abstract
Proton pump inhibitors omeprazole and lansoprazole contain chiral sulfur atom and they are administered as a racemate, i.e. equimolar mixture of S- and R-enantiomers. The enantiopure drugs esomeprazole and dexlansoprazole have been developed and introduced to clinical practice due to their improved clinical and therapeutic properties. Since omeprazole and lansoprazole are activators of aryl hydrocarbon receptor (AhR) and inducers of CYP1A genes, we examined their enantiospecific effects on AhR-CYP1A pathway in human cancer cells and primary human hepatocytes. We performed gene reporter assays for transcriptional activity of AhR, RT-PCR analyses for CYP1A1/2 mRNAs, western blots for CYP1A1/2 proteins and EROD assay for CYP1A1/2 catalytic activity. Lansoprazole and omeprazole enantiomers displayed differential effects on AhR-CYP1A1/2 pathway. In general, S-enantiomers were stronger activators of AhR and inducers of CYP1A genes as compared to R-enantiomers in lower concentrations, i.e. 1–10 µM for lansoprazole and 10–100 µM for omeprazole. In contrast, R-enantiomers were stronger AhR activators and CYP1A inducers than S-enantiomers in higher concentrations, i.e. 100 µM for lansoprazole and 250 µM for omeprazole. In conclusion, we provide the first evidence of enantiospecific effects of omeprazole and lansoprazole on AhR signaling pathway.
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Affiliation(s)
- Aneta Novotna
- Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Olomouc, Czech Republic
| | - Alzbeta Srovnalova
- Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Olomouc, Czech Republic
| | - Michaela Svecarova
- Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Olomouc, Czech Republic
| | - Martina Korhonova
- Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Olomouc, Czech Republic
| | - Iveta Bartonkova
- Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Olomouc, Czech Republic
| | - Zdenek Dvorak
- Department of Cell Biology and Genetics, Faculty of Science, Palacky University, Olomouc, Czech Republic
- * E-mail:
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Watson C, Zhu L, Guan S, Machen TE, Forte JG. Reaction of proton pump inhibitors with model peptides results in novel products. J Pharmacol Sci 2014; 122:213-22. [PMID: 23877017 DOI: 10.1254/jphs.13058fp] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The proposed mechanism for proton pump inhibitors (PPIs) is that PPIs are activated at low pH to the sulfenamide form, which reacts with the sulfhydryl group of cysteine(s) at the active site of the proton pump, to produce reducible disulfide-bonded PPI-proton pump conjugates. However, this mechanism cannot explain the observations that some PPI-protein conjugates are irreducible. This study was designed to investigate the chemistry of the irreducible conjugates by mass spectrometry, using three PPIs and 17 cysteine-containing peptides. While some peptides favored the formation of reducible PPI-peptide adduct, the other peptides mainly produced irreducible adducts. Characterization of the irreducible adduct revealed that the irreducible bonding required the participation of both a sulfhydryl group and a nearby primary amino group. High resolution mass spectrometry suggested a molecular structure of the irreducible adduct. These results suggested a reaction mechanism in which the PPI pyridone form reacted with an amino group and a sulfhydryl group to form an irreducible adduct. The irreducible adduct becomes the dominant product over time because of the irreversible nature of the pyridone-mediated reaction. These findings may explain the irreducible inhibition of H/K-ATPase by PPIs and their relatively slow biological turnover in vivo. [Supplementary materials: available only at http://dx.doi.org/10.1254/jphs.13058FP].
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Affiliation(s)
- Charles Watson
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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18
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Abstract
The gastric H(+),K(+)-ATPase is responsible for gastric acid secretion. This ATPase is composed of two subunits, the catalytic α subunit and the structural β subunit. The α subunit with molecular mass of about 100 kDa has 10 transmembrane domains and is strongly associated with the β subunit with a single transmembrane segment and a peptide mass of 35 kDa. Its three-dimensional structure is based on homology modeling and site-directed mutagenesis resulting in a proton extrusion and K(+) reabsorption model. There are three conserved H3O(+)-binding sites in the middle of the membrane domain and H3O(+) secretion depends on a conformational change involving Lys(791) insertion into the second H3O(+) site enclosed by E795, E820, and D824 that allows export of protons at a concentration of 160 mM. K(+) countertransport involves binding to this site after the release of protons with retrograde displacement of Lys(791) and then K(+) transfer to E343 and exit to the cytoplasm. This ATPase is the major therapeutic target in treatment of acid-related diseases and there are several known luminal inhibitors allowing analysis of the luminal vestibule. One class contains the acid-activated covalent, thiophilic proton pump inhibitors, the most effective of current acid-suppressive drugs. Their binding sites and trypsinolysis allowed identification of all ten transmembrane segments of the ATPase. In addition, various K(+)-competitive inhibitors of the ATPase are being developed, with the advantage of complete and rapid inhibition of acid secretion independent of pump activity and allowing further refinement of the structure of the luminal vestibule of the E2 form of this ATPase.
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Affiliation(s)
- Jai Moo Shin
- Department of Physiology and Medicine, University of California at Los Angeles, and VA Greater Los Angeles Healthcare System, Los Angeles, California, USA.
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19
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Shin JM, Kim N. Pharmacokinetics and pharmacodynamics of the proton pump inhibitors. J Neurogastroenterol Motil 2013; 19:25-35. [PMID: 23350044 PMCID: PMC3548122 DOI: 10.5056/jnm.2013.19.1.25] [Citation(s) in RCA: 251] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 12/20/2012] [Accepted: 12/21/2012] [Indexed: 12/13/2022] Open
Abstract
Proton pump inhibitor (PPI) is a prodrug which is activated by acid. Activated PPI binds covalently to the gastric H+, K+-ATPase via disulfide bond. Cys813 is the primary site responsible for the inhibition of acid pump enzyme, where PPIs bind. Omeprazole was the first PPI introduced in market, followed by pantoprazole, lansoprazole and rabeprazole. Though these PPIs share the core structures benzimidazole and pyridine, their pharmacokinetics and pharmacodynamics are a little different. Several factors must be considered in understanding the pharmacodynamics of PPIs, including: accumulation of PPI in the parietal cell, the proportion of the pump enzyme located at the canaliculus, de novo synthesis of new pump enzyme, metabolism of PPI, amounts of covalent binding of PPI in the parietal cell, and the stability of PPI binding. PPIs have about 1hour of elimination half-life. Area under the plasmic concentration curve and the intragastric pH profile are very good indicators for evaluating PPI efficacy. Though CYP2C19 and CYP3A4 polymorphism are major components of PPI metabolism, the pharmacokinetics and pharmacodynamics of racemic mixture of PPIs depend on the CYP2C19 genotype status. S-omeprazole is relatively insensitive to CYP2C19, so better control of the intragastric pH is achieved. Similarly, R-lansoprazole was developed in order to increase the drug activity. Delayed-release formulation resulted in a longer duration of effective concentration of R-lansoprazole in blood, in addition to metabolic advantage. Thus, dexlansoprazole showed best control of the intragastric pH among the present PPIs. Overall, PPIs made significant progress in the management of acid-related diseases and improved health-related quality of life.
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20
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Naven RT, Kantesaria S, Nadanaciva S, Schroeter T, Leach KL. High throughput glutathione and Nrf2 assays to assess chemical and biological reactivity of cysteine-reactive compounds. Toxicol Res (Camb) 2013. [DOI: 10.1039/c3tx50027f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
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21
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Chourasia M, Sastry GN. The nucleotide, inhibitor, and cation binding sites of P-type II ATPases. Chem Biol Drug Des 2012; 79:617-27. [PMID: 22260628 DOI: 10.1111/j.1747-0285.2012.01334.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
P-type ATPases constitute a ubiquitous superfamily of cation transport enzymes, responsible for carrying out actions of paramount importance in biology such as ion transport and expulsion of toxic ions from cells. The harmonized toggling of gates in the extra- and intracellular domains explain the phenomenon of specific cation binding in selective physiological states. A quantitative understanding of the fundamental aspects of ion transport mechanism and regulation of P-type ATPases requires detailed knowledge of thermodynamical, structural, and functional properties. Computational studies have made significant contributions to our understanding of biological ion pumps. Various 3D structures of Ca(2+) -ATPase between E1 and E2 transition states have given a impetus to the theorists to work on the Na(+) K(+) - and H(+) K(+) -ATPase to address important questions about their function. The current review delineates the importance of cation, nucleotide, and inhibitor binding domains, with a focus on the therapeutic potential and biological relevance of the three P-type II ATPases. This will give an insight into the ion selectivity and their conduction across the transmembrane helices of P-type II ATPases, which may pave the way to a range of fundamental questions about the mechanism and aid in the efforts of structure- and analog-based drug design.
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Affiliation(s)
- Mukesh Chourasia
- Molecular Modeling Group, Indian Institute of Chemical Technology, Hyderabad, India
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22
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Abstract
The gastric H,K-adenosine triphosphatase (ATPase) is the primary target for treatment of acid-related diseases. Proton pump inhibitors (PPIs) are weak bases composed of two moieties, a substituted pyridine with a primary pK(a) of about 4.0 that allows selective accumulation in the secretory canaliculus of the parietal cell, and a benzimidazole with a second pK(a) of about 1.0. Protonation of this benzimidazole activates these prodrugs, converting them to sulfenic acids and/or sulfenamides that react covalently with one or more cysteines accessible from the luminal surface of the ATPase. The maximal pharmacodynamic effect of PPIs as a group relies on cyclic adenosine monophosphate-driven H,K-ATPase translocation from the cytoplasm to the canalicular membrane of the parietal cell. At present, this effect can only be achieved with protein meal stimulation. Because of covalent binding, inhibitory effects last much longer than their plasma half-life. However, the short dwell-time of the drug in the blood and the requirement for acid activation impair their efficacy in acid suppression, particularly at night. All PPIs give excellent healing of peptic ulcer and produce good, but less than satisfactory, results in reflux esophagitis. PPIs combined with antibiotics eradicate Helicobacter pylori, but success has fallen to less than 80%. Longer dwell-time PPIs promise to improve acid suppression and hence clinical outcome. Potassium-competitive acid blockers (P-CABs) are another class of ATPase inhibitors, and at least one is in development. The P-CAB under development has a long duration of action even though its binding is not covalent. PPIs with a longer dwell time or P-CABs with long duration promise to address unmet clinical needs arising from an inability to inhibit nighttime acid secretion, with continued symptoms, delayed healing, and growth suppression of H. pylori reducing susceptibility to clarithromycin and amoxicillin. Thus, novel and more effective suppression of acid secretion would benefit those who suffer from acid-related morbidity, continuing esophageal damage and pain, nonsteroidal anti-inflammatory drug-induced ulcers, and nonresponders to H. pylori eradication.
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Affiliation(s)
- George Sachs
- Department of Physiology and Medicine, David Geffen School of Medicine, University of California at Los Angeles, VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA.
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Bardou M, Martin J, Barkun A. Intravenous proton pump inhibitors: an evidence-based review of their use in gastrointestinal disorders. Drugs 2009; 69:435-48. [PMID: 19323587 DOI: 10.2165/00003495-200969040-00004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Conditions requiring inhibition of acid secretion, such as gastro-oesophageal reflux disease or peptic ulcers, are very common and their prevalence is expected to rise as they are seen predominantly in the elderly. The general basis of treatment with antisecretory agents is to maintain gastric pH >4 for a substantial proportion of the 24-hour cycle. Among the drugs available to inhibit acid secretion, proton pump inhibitors (PPIs) have been shown to have the best benefit-risk ratio and have been used widely. Intravenous administration of a PPI provides gastric acid suppression faster than oral administration does. Whereas some indications for the use of intravenous PPIs are widely known, mostly for acute management of peptic ulcer bleeding, there are some controversies surrounding their use in other conditions such as stress-induced mucosal damage. There is still a need to define the best schedule for intravenous PPI administration (i.e. bolus infusion or constant infusion), the optimal time to switch from intravenous to oral administration and the choice of which agent is best. In most of the clinical scenarios where PPIs are recommended, they can be administered via either oral or enteral routes, unless the patient is nil by mouth. Since there are no head-to-head comparisons of the different intravenous PPIs available worldwide (omeprazole, lansoprazole, pantoprazole and esomeprazole), the rule might be to choose the drug with the best proven efficacy in each specific condition. Indeed, the key difference between them, the ability to reach and to maintain a threshold gastric pH, might not necessarily translate into clinically significant differences.
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Affiliation(s)
- Marc Bardou
- INSERM-Centre d'Investigations Cliniques Plurithématique 803 (CIC-P 803), Dijon Cedex, France.
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Abstract
The gastric H,K-ATPase is the primary target for the treatment of acid-related diseases. Proton pump inhibitors (PPIs) are weak bases composed of two moieties, a substituted pyridine with a primary pK(a) of about 4.0, which allows selective accumulation in the secretory canaliculus of the parietal cell, and a benzimidazole with a second pK(a) of about 1.0. PPIs are acid-activated prodrugs that convert to sulfenic acids or sulfenamides that react covalently with one or more cysteines accessible from the luminal surface of the ATPase. Because of covalent binding, their inhibitory effects last much longer than their plasma half-life. However, the short half-life of the drug in the blood and the requirement for acid activation impair their efficacy in acid suppression, particularly at night. PPIs with longer half-life promise to improve acid suppression. All PPIs give excellent healing of peptic ulcers and produce good results in reflux esophagitis. PPIs combined with antibiotics eradicate Helicobacter pylori.
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Affiliation(s)
- Jai Moo Shin
- Membrane Biology, David Geffen School of Medicine, University of California at Los Angeles, Room 324, Building 113, 11301 Wilshire Boulevard, Los Angeles, CA 90073, USA
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25
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Comoglu T, Gonul N, Dogan A, Basci N. Development and In Vitro Evaluation of Pantoprazole-Loaded Microspheres. Drug Deliv 2008; 15:295-302. [DOI: 10.1080/10717540802006864] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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26
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Sripathi S, Bojja RR, Karnati VR, Raju VVNKVP, Khunt MD. An Improved Synthesis of Antiulcerative Drug: Tenatoprazole. Org Process Res Dev 2008. [DOI: 10.1021/op800173u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Somaiah Sripathi
- Department of Research and Development, Srini Pharmaceuticals Ltd., Plot No. 10, Type-C, Road No. 8, Film Nagar, Jubilee Hills, Hyderabad-500033, Andhra Pradesh, India, Department of Chemistry, Osmania University, Tarnaka, Hyderabad-500007, Andhra Pradesh, India and Research and Development, Integrated Product Development Organization, Innovation Plaza, Dr. Reddy’s Laboratories Ltd., Bachupally, Qutubullapur, R. R. Dist. 500 072, Andhra Pradesh, India
| | - Ramachandra Reddy Bojja
- Department of Research and Development, Srini Pharmaceuticals Ltd., Plot No. 10, Type-C, Road No. 8, Film Nagar, Jubilee Hills, Hyderabad-500033, Andhra Pradesh, India, Department of Chemistry, Osmania University, Tarnaka, Hyderabad-500007, Andhra Pradesh, India and Research and Development, Integrated Product Development Organization, Innovation Plaza, Dr. Reddy’s Laboratories Ltd., Bachupally, Qutubullapur, R. R. Dist. 500 072, Andhra Pradesh, India
| | - Venugopal Reddy Karnati
- Department of Research and Development, Srini Pharmaceuticals Ltd., Plot No. 10, Type-C, Road No. 8, Film Nagar, Jubilee Hills, Hyderabad-500033, Andhra Pradesh, India, Department of Chemistry, Osmania University, Tarnaka, Hyderabad-500007, Andhra Pradesh, India and Research and Development, Integrated Product Development Organization, Innovation Plaza, Dr. Reddy’s Laboratories Ltd., Bachupally, Qutubullapur, R. R. Dist. 500 072, Andhra Pradesh, India
| | - V. V. N. K. V. Prasada Raju
- Department of Research and Development, Srini Pharmaceuticals Ltd., Plot No. 10, Type-C, Road No. 8, Film Nagar, Jubilee Hills, Hyderabad-500033, Andhra Pradesh, India, Department of Chemistry, Osmania University, Tarnaka, Hyderabad-500007, Andhra Pradesh, India and Research and Development, Integrated Product Development Organization, Innovation Plaza, Dr. Reddy’s Laboratories Ltd., Bachupally, Qutubullapur, R. R. Dist. 500 072, Andhra Pradesh, India
| | - Mayur D. Khunt
- Department of Research and Development, Srini Pharmaceuticals Ltd., Plot No. 10, Type-C, Road No. 8, Film Nagar, Jubilee Hills, Hyderabad-500033, Andhra Pradesh, India, Department of Chemistry, Osmania University, Tarnaka, Hyderabad-500007, Andhra Pradesh, India and Research and Development, Integrated Product Development Organization, Innovation Plaza, Dr. Reddy’s Laboratories Ltd., Bachupally, Qutubullapur, R. R. Dist. 500 072, Andhra Pradesh, India
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27
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Shin JM, Munson K, Vagin O, Sachs G. The gastric HK-ATPase: structure, function, and inhibition. Pflugers Arch 2008; 457:609-22. [PMID: 18536934 DOI: 10.1007/s00424-008-0495-4] [Citation(s) in RCA: 167] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2008] [Revised: 03/07/2008] [Accepted: 03/11/2008] [Indexed: 02/06/2023]
Abstract
The gastric H,K-ATPase, a member of the P(2)-type ATPase family, is the integral membrane protein responsible for gastric acid secretion. It is an alpha,beta-heterodimeric enzyme that exchanges cytoplasmic hydronium with extracellular potassium. The catalytic alpha subunit has ten transmembrane segments with a cluster of intramembranal carboxylic amino acids located in the middle of the transmembrane segments TM4, TM5,TM6, and TM8. Comparison to the known structure of the SERCA pump, mutagenesis, and molecular modeling has identified these as constituents of the ion binding domain. The beta subunit has one transmembrane segment with N terminus in cytoplasmic region. The extracellular domain of the beta subunit contains six or seven N-linked glycosylation sites. N-glycosylation is important for the enzyme assembly, maturation, and sorting. The enzyme pumps acid by a series of conformational changes from an E(1) (ion site in) to an E(2) (ion site out) configuration following binding of MgATP and phosphorylation. Several experimental observations support the hypothesis that expulsion of the proton at 160 mM (pH 0.8) results from movement of lysine 791 into the ion binding site in the E(2)P configuration. Potassium access from the lumen depends on activation of a K and Cl conductance via a KCNQ1/KCNE2 complex and Clic6. K movement through the luminal channel in E(2)P is proposed to displace the lysine along with dephosphorylation to return the enzyme to the E(1) configuration. This enzyme is inhibited by the unique proton pump inhibitor class of drug, allowing therapy of acid-related diseases.
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Affiliation(s)
- Jai Moo Shin
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles and VA Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
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Bardou M, Martin J. Pantoprazole: from drug metabolism to clinical relevance. Expert Opin Drug Metab Toxicol 2008; 4:471-83. [DOI: 10.1517/17425255.4.4.471] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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29
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Shin JM, Vagin O, Munson K, Kidd M, Modlin IM, Sachs G. Molecular mechanisms in therapy of acid-related diseases. Cell Mol Life Sci 2008; 65:264-81. [PMID: 17928953 PMCID: PMC3081136 DOI: 10.1007/s00018-007-7249-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Inhibition of gastric acid secretion is the mainstay of the treatment of gastroesophageal reflux disease and peptic ulceration; therapies to inhibit acid are among the best-selling drugs worldwide. Highly effective agents targeting the histamine H2 receptor were first identified in the 1970s. These were followed by the development of irreversible inhibitors of the parietal cell hydrogen-potassium ATPase (the proton pump inhibitors) that inhibit acid secretion much more effectively. Reviewed here are the chemistry, biological targets and pharmacology of these drugs, with reference to their current and evolving clinical utilities. Future directions in the development of acid inhibitory drugs include modifications of current agents and the emergence of a novel class of agents, the acid pump antagonists.
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Affiliation(s)
- J. M. Shin
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California USA
- VA Greater Los Angeles Healthcare System, West LA Medical Center, 11301 Wilshire Boulevard, Building 113, Los Angeles, California 90073 USA
| | - O. Vagin
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California USA
- VA Greater Los Angeles Healthcare System, West LA Medical Center, 11301 Wilshire Boulevard, Building 113, Los Angeles, California 90073 USA
| | - K. Munson
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California USA
- VA Greater Los Angeles Healthcare System, West LA Medical Center, 11301 Wilshire Boulevard, Building 113, Los Angeles, California 90073 USA
| | - M. Kidd
- Department of Surgery, Yale University School of Medicine, TMP202, 333 Cedar Street, New Haven Connecticut, 06520-8062 USA
| | - I. M. Modlin
- Department of Surgery, Yale University School of Medicine, TMP202, 333 Cedar Street, New Haven Connecticut, 06520-8062 USA
| | - G. Sachs
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, California USA
- VA Greater Los Angeles Healthcare System, West LA Medical Center, 11301 Wilshire Boulevard, Building 113, Los Angeles, California 90073 USA
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Herrmann M, Selige J, Raffael S, Sachs G, Brambilla A, Klein T. Systematic expression profiling of the gastric H+/K+ ATPase in human tissue. Scand J Gastroenterol 2007; 42:1275-88. [PMID: 17852870 DOI: 10.1080/00365520701405579] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
OBJECTIVE The potassium-competitive acid blockers (P-CABs), comprise a new, innovative group of competitive and reversible inhibitors of the gastric H+/K+ ATPase. Our aim was to identify sites of expression of the H+/K+ ATPase that are potential targets of these compounds by examining the expression profile of the gastric H+/K+ ATPase in the human body from a broad range of tissues. MATERIAL AND METHODS Expression profiling was done by quantitative mRNA analysis (TaqMan PCR). Tissues that were mRNA-positive for the alpha subunit were investigated further by Western blot and immunohistochemistry (IHC) for the presence of gastric H+/K+ ATPase protein. RESULTS In addition to the very high expression levels in the stomach, the adrenal gland, cerebellum and pancreas gave unexpectedly positive mRNA signals for the alpha subunit of gastric H +/K+ ATPase. However, they were negative for mRNA of the beta subunit, and Western blot and IHC were negative for alpha and beta subunit protein. Another group of tissues with low alpha subunit mRNA expression including the frontal cortex, cortex grey matter, testis, thymus and larynx submucosa were also found negative for both alpha and beta subunit protein. In contrast to mouse kidney, no gastric H+/K+ ATPase could be detected in human kidney. CONCLUSIONS We therefore conclude that the only organ in humans expressing significant levels of the P-CAB target gastric H+/K+ ATPase is the stomach.
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Affiliation(s)
- Michael Herrmann
- Department of Biochemistry Gastroenterology, ALTANA Pharma AG, Konstanz, Germany
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Sachs G, Shin JM, Vagin O, Lambrecht N, Yakubov I, Munson K. The gastric H,K ATPase as a drug target: past, present, and future. J Clin Gastroenterol 2007; 41 Suppl 2:S226-42. [PMID: 17575528 PMCID: PMC2860960 DOI: 10.1097/mcg.0b013e31803233b7] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The recent progress in therapy if acid disease has relied heavily on the performance of drugs targeted against the H,K ATPase of the stomach and the H2 receptor antagonists. It has become apparent in the last decade that the proton pump is the target that has the likelihood of being the most sustainable area of therapeutic application in the regulation of acid suppression. The process of activation of acid secretion requires a change in location of the ATPase from cytoplasmic tubules into the microvilli of the secretory canaliculus of the parietal cell. Stimulation of the resting parietal cell, with involvement of F-actin and ezrin does not use significant numbers of SNARE proteins, because their message is depleted in the pure parietal cell transcriptome. The cell morphology and gene expression suggest a tubule fusion-eversion event. As the active H,K ATPase requires efflux of KCl for activity we have, using the transcriptome derived from 99% pure parietal cells and immunocytochemistry, provided evidence that the KCl pathway is mediated by a KCQ1/KCNE2 complex for supplying K and CLIC6 for supplying the accompanying Cl. The pump has been modeled on the basis of the structures of different conformations of the sr Ca ATPase related to the catalytic cycle. These models use the effects of site directed mutations and identification of the binding domain of the K competitive acid pump antagonists or the defined site of binding for the covalent class of proton pump inhibitors. The pump undergoes conformational changes associated with phosphorylation to allow the ion binding site to change exposure from cytoplasmic to luminal exposure. We have been able to postulate that the very low gastric pH is achieved by lysine 791 motion extruding the hydronium ion bound to carboxylates in the middle of the membrane domain. These models also allow description of the K entry to form the K liganded form of the enzyme and the reformation of the ion site inward conformation thus relating the catalytic cycle of the pump to conformational models. The mechanism of action of the proton pump inhibitor class of drug is discussed along with the cysteines covalently bound with these inhibitors. The review concludes with a discussion of the mechanism of action and binding regions of a possible new class of drug for acid control, the K competitive acid pump antagonists.
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Affiliation(s)
- George Sachs
- Department of Physiology, David Geffen School of Medicine, University of California at Los Angeles, CA, USA.
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Abstract
Proton pump inhibitors inhibit the gastric H+/K+-ATPase via covalent binding to cysteine residues of the proton pump. All proton pump inhibitors must undergo acid accumulation in the parietal cell through protonation, followed by activation mediated by a second protonation at the active secretory canaliculus of the parietal cell. The relative ease with which these steps occur with different proton pump inhibitors underlies differences in their rates of activation, which in turn influence the location of covalent binding and the stability of inhibition. Slow activation is associated with binding to a cysteine residue involved in proton transport that is located deep in the membrane. However, this is inaccessible to the endogenous reducing agents responsible for restoring H+/K+-ATPase activity, favouring a longer duration of gastric acid inhibition. Pantoprazole and tenatoprazole, a novel proton pump inhibitor which has an imidazopyridine ring in place of the benzimidazole moiety found in other proton pump inhibitors, are activated more slowly than other proton pump inhibitors but their inhibition is resistant to reversal. In addition, tenatoprazole has a greatly extended plasma half-life in comparison with all other proton pump inhibitors. The chemical and pharmacological characteristics of tenatoprazole give it theoretical advantages over benzimidazole-based proton pump inhibitors that should translate into improved acid control, particularly during the night.
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Affiliation(s)
- G Sachs
- Department of Physiology and Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA.
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Affiliation(s)
- Jai Moo Shin
- Department of Physiology and Medicine, University of California at Los Angeles, and VA Greater Los Angeles Healthcare System, Los Angeles, California 90073, USA
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Lehmann FS, Beglinger C. Role of pantoprazole in the treatment of gastro-oesophageal reflux disease. Expert Opin Pharmacother 2006; 6:93-104. [PMID: 15709887 DOI: 10.1517/14656566.6.1.93] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The diagnosis and treatment of gastro-oesophageal reflux disease (GERD) presents many problems, despite the fact that significant advances have been made in recent years in the understanding of its pathogenesis and symptomatology. GERD affects many people and has a significant negative impact on patient quality of life. Heartburn is the most common symptom of GERD which occurs with and without oesophagitis. The predominant causative factor for symptoms is prolonged contact of oesophageal mucosa with refluxed acid and pepsin. Proton pump inhibitors (PPIs) are the most effective treatment for GERD: overall proportions of patients with healing and complete heartburn relief are markedly higher with PPIs than with alternative treatment strategies. Furthermore, the speed of healing and heartburn relief with PPIs is almost twice as rapid as with any other form of therapy. The present review focuses on the effectiveness and safety of the PPI, pantoprazole. The data show that the compound is highly effective in GERD patients with and without oesophagitis. Pantoprazole has an excellent safety record and shows only minor interaction with other drugs.
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Affiliation(s)
- Frank Serge Lehmann
- University Hospital of Basel, Division of Gastroenterology, 4031 Basel, Switzerland
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Shin JM, Homerin M, Domagala F, Ficheux H, Sachs G. Characterization of the inhibitory activity of tenatoprazole on the gastric H+,K+ -ATPase in vitro and in vivo. Biochem Pharmacol 2006; 71:837-49. [PMID: 16405921 DOI: 10.1016/j.bcp.2005.11.030] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 11/24/2005] [Accepted: 11/28/2005] [Indexed: 01/12/2023]
Abstract
Tenatoprazole is a prodrug of the proton pump inhibitor (PPI) class, which is converted to the active sulfenamide or sulfenic acid by acid in the secretory canaliculus of the stimulated parietal cell of the stomach. This active species binds to luminally accessible cysteines of the gastric H+,K+ -ATPase resulting in disulfide formation and acid secretion inhibition. Tenatoprazole binds at the catalytic subunit of the gastric acid pump with a stoichiometry of 2.6 nmol mg(-1) of the enzyme in vitro. In vivo, maximum binding of tenatoprazole was 2.9 nmol mg(-1) of the enzyme at 2 h after IV administration. The binding sites of tenatoprazole were in the TM5/6 region at Cys813 and Cys822 as shown by tryptic and thermolysin digestion of the ATPase labeled by tenatoprazole. Decay of tenatoprazole binding on the gastric H+,K+ -ATPase consisted of two components. One was relatively fast, with a half-life 3.9 h due to reversal of binding at cysteine 813, and the other was a plateau phase corresponding to ATPase turnover reflecting binding at cysteine 822 that also results in sustained inhibition in the presence of reducing agents in vitro. The stability of inhibition and the long plasma half-life of tenatoprazole should result in prolonged inhibition of acid secretion as compared to omeprazole. Further, the bioavailability of tenatoprazole was two-fold greater in the (S)-tenatoprazole sodium salt hydrate form as compared to the free form in dogs which is due to differences in the crystal structure and hydrophobic nature of the two forms.
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Affiliation(s)
- Jai Moo Shin
- Department of Physiology and Medicine, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA.
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Téllez E, Ocampo L, Bernad M, Sumano H. Pharmacodynamic study of a long-acting parenteral formulation of omeprazole in horses. J Vet Pharmacol Ther 2005; 28:587-9. [PMID: 16343293 DOI: 10.1111/j.1365-2885.2005.00690.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- E Téllez
- Department of Physiology & Pharmacology, Veterinary School, Chemistry School, University of Mexico (UNAM), Mexico City, Mexico
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Abstract
PURPOSE OF REVIEW The purpose of this review is to summarize the pertinent literature published in the past year regarding the regulation of gastric exocrine and endocrine secretion. RECENT FINDINGS Gastric acid aids protein digestion; facilitates the absorption of iron, calcium, and vitamin B12; thwarts enteric infection; and prevents bacterial overgrowth. When levels of acid and proteolytic enzymes overwhelm the mucosal defense mechanisms, ulcers occur. To avoid damage under these harsh conditions, gastric acid must be finely regulated by overlapping neural (e.g. orexin, pituitary adenylate cyclase-activating polypeptide, nitric oxide, and galanin), hormonal (e.g. gastrin, cholecystokinin, and ghrelin), paracrine (e.g. histamine and somatostatin), and autocrine (e.g. transforming growth factor-alpha) pathways. The precise mechanisms whereby Helicobacter pylori induces perturbations in acid secretion are not known, but they seem to involve changes in somatostatin and perhaps ghrelin secretion. Acid secretion by parietal cells involves intracellular elevation of calcium and/or cyclic AMP, followed by a cascade that triggers translocation of the proton pump, HK-adenosine triphosphatase, from cytoplasmic tubulovesicles to the secretory canaliculi. SUMMARY An improved understanding of the pathways and mechanisms regulating gastric acid secretion may lead to the development of new strategies to prevent and treat acid peptic disorders as well as circumvent the adverse effects of currently prescribed antisecretory medications.
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