Determination of R(+)- and S(-)-lansoprazole using chiral stationary-phase liquid chromatography and their enantioselective pharmacokinetics in humans

Enzalutamide: Understanding and Managing Drug Interactions to Improve Patient Safety and Drug Efficacy

Enzalutamide is an oral androgen receptor signaling inhibitor utilized in the treatment of men with prostate cancer. It is a moderate inducer of the cytochrome P450 (CYP) enzymes CYP2C9 and CYP2C19, and a strong inducer of CYP3A4. It was also shown to be a mild inhibitor of the efflux transporter P-glycoprotein in patients with prostate cancer. Enzalutamide is primarily metabolized by CYP3A4 and CYP2C8. The risk of enzalutamide drug interactions arises primarily when it is coadministered with other drugs that interact with these CYPs, including CYP3A4. In this review, we begin by providing an overview of enzalutamide including its dosing, use in special populations, pharmacokinetics, changes to its prescribing information, and potential for interaction with coadministered drugs. Enzalutamide interactions with drugs from a wide range of medication classes commonly prescribed to patients with prostate cancer are described, including oral androgen deprivation therapy, agents used to treat a range of cardiovascular diseases, antidiabetic drugs, antidepressants, anti-seizure medications, common urology medications, analgesics, proton pump inhibitors, immunosuppressants, and antigout drugs. Enzalutamide interactions with common vitamins and supplements are also briefly discussed. This review provides a resource for healthcare practitioners and patients that will help provide a basis for the understanding and management of enzalutamide drug-drug interactions to inform decision making, improve patient safety, and optimize drug efficacy.

Chirality Sensing of N-Heterocycles via 19F NMR

Methods to rapidly detect and differentiate chiral N-heterocyclic compounds become increasingly important owing to the widespread application of N-heterocycles in drug discovery and materials science. We herein report a ¹⁹F NMR-based chemosensing approach for the prompt enantioanalysis of various N-heterocycles, where the dynamic binding between the analytes and a chiral ¹⁹F-labeled palladium probe create characteristic ¹⁹F NMR signals assignable to each enantiomer. The open binding site of the probe allows the effective recognition of bulky analytes that are otherwise difficult to detect. The chirality center distal to the binding site is found sufficient for the probe to discriminate the stereoconfiguration of the analyte. The utility of the method in the screening of reaction conditions for the asymmetric synthesis of lansoprazole is demonstrated.

Chiral separation in the class of proton pump inhibitors by chromatographic and electromigration techniques: An overview

Proton pump inhibitors (PPIs) are benzimidazole-derivative chiral sulfoxides, frequently used in the treatment of gastric hyperacidity-related disorders. Due to their stereoselective metabolism, the eutomeric forms of PPIs can present a more advantageous pharmacokinetic profile by comparison with the distomers or racemates. Moreover, two representatives of the class are used in therapy both as racemates and as pure enantiomers (esomeprazole, dexlansoprazole). A relatively large number of enantioseparation methods employed for the stereoselective determination of PPIs from pharmaceutical, biological, and environmental matrices were published in the past three decades. The purpose of the current overview is to provide a systematic survey of the available chiral separation methods published since the introduction of PPIs in the therapy up to the present. Analytical and bioanalytical methods using different chromatographic and electromigration techniques reported for the enantioseparation of omeprazole, lansoprazole, pantoprazole, rabeprazole, ilaprazole, and tenatoprazole are included. The analytical conditions of the presented methods are summarized in three comprehensive tables, while a critical discussion of the applied techniques, possible mechanism of enantiorecognition, and future perspectives on the topic are also presented.

Comparison of the effect of clarithromycin triple therapy with or without N-acetylcysteine in the eradication of Helicobacter pylori: a randomized controlled trial

BACKGROUND

Whether adjunctive N-acetylcysteine (NAC) may improve the efficacy of triple therapy in the first-line treatment of Helicobacter pylori infection remains unknown. Our aim was to compare the efficacy of 14-day triple therapy with or without NAC for the first-line treatment of H. pylori.

MATERIAL AND METHODS

Between 1 January 2014 and 30 June 2018, 680 patients with H. pylori infection naïve to treatment were enrolled in this multicenter, open-label, randomized trial. Patients were randomly assigned to receive triple therapy with NAC [NAC-T14, dexlansoprazole 60 mg four times daily (q.d.); amoxicillin 1 g twice daily (b.i.d.), clarithromycin 500 mg b.i.d., NAC 600 mg b.i.d.] for 14 days, or triple therapy alone (T14, dexlansoprazole 60 mg q.d.; amoxicillin 1 g b.i.d., clarithromycin 500 mg b.i.d.) for 14 days. Our primary outcome was the eradication rates by intention to treat (ITT). Antibiotic resistance and CYP2C19 gene polymorphism were determined.

RESULTS

The ITT analysis demonstrated H. pylori eradication rates in NAC-T14 and T14 were 81.7% [276/338, 95% confidence interval (CI): 77.5-85.8%] and 84.3% (285/338, 95% CI 80.4-88.2%), respectively. In 646 participants who adhered to their assigned therapy, the eradication rates were 85.7% and 88.0% with NAC-T14 and T14 therapies, respectively. There were no differences in compliance or adverse effects. The eradication rates in subjects with clarithromycin-resistant, amoxicillin-resistant, or either clarithromycin/amoxicillin resistant strains were 45.2%, 57.9%, and 52.2%, respectively, for NAC-T14, and were 66.7%, 76.9%, and 70.0%, respectively, for T14. The efficacy of NAC-T14 and T14 was not affected by CYP2C19 polymorphism.

CONCLUSION

Add-on NAC to triple therapy was not superior to triple therapy alone for first-line H. pylori eradication [ClinicalTrials.gov identifier: NCT02249546].

The aryl hydrocarbon receptor (AhR) as a breast cancer drug target

Breast cancer is the most common cancer in women, with more than 1.7 million diagnoses worldwide per annum. Metastatic breast cancer remains incurable, and the presence of triple-negative phenotypes makes targeted treatment impossible. The aryl hydrocarbon receptor (AhR), most commonly associated with the metabolism of xenobiotic ligands, has emerged as a promising biological target for the treatment of this deadly disease. Ligands for the AhR can be classed as exogenous or endogenous and may have agonistic or antagonistic activity. It has been well reported that agonistic ligands may have potent and selective growth inhibition activity in a number of oncogenic cell lines, and one (aminoflavone) has progressed to phase I clinical trials for breast cancer sufferers. In this study, we examine the current state of the literature in this area and elucidate the promising advances that are being made in hijacking the cytosolic-to-nuclear pathway of the AhR for the possible future treatment of breast cancer.

A comparison between dexlansoprazole modified release-based and lansoprazole-based nonbismuth quadruple (concomitant) therapy for first-line Helicobacter pylori eradication: a prospective randomized trial

Purpose

Steadily maintaining high intra-gastric PH is the major factor for successful Helicobacter pylori (H.pylori) eradication. It is important to search for a stronger PPI. Dexlansoprazole MR is a dual delayed release formulation PPI taken once daily which is capable of maintaining longer duration of high intra-gastric PH. It is very effective in treating gastroesophageal disease but reports on H, pylori eradication is very rare. This study sought to compare dexlansoprazole MR-based concomitant treatment and lansoprazole-based concomitant treatment in H. pylori infection and to investigate the factors that affect the eradication rates.

Methods

Two hundred two participants with H. pylori infection were included and randomly assigned to seven days of dexlansoprazole MR-based concomitant therapy (dexlansoprazole MR 60 mg once daily, clarithromycin 500 mg twice daily, amoxicillin 1 g twice daily and metronidazole 500 mg twice daily; DACM group) or a seven days of lansoprazole-based concomitant therapy (lansoprazole 30 mg twice daily, clarithromycin 500 mg twice daily, amoxicillin 1 g twice daily, and metronidazole 500 mg twice daily; LACM group). The participants were asked to perform urea breath tests eight weeks later.

Results

The eradication rates in the DACM group were 86.1% [95% confidence interval (CI): 77.8%–92.2%] in the ITT analysis and 90.6% (95% CI: 82.9%–95.6%) in the PP analysis, respectively, as compared with 90.1% (95% CI: 82.6%–95.2%) and 92.6% (95% CI: 85.5%–96.9%) (p=0.384 and p=0.572, respectively) in the LACM group for the same analyses. The adverse event rates were 11.5% in the DACM group and 10.2% in the LACM group (p=0.779).

Conclusion

As a first-line H. pylori treatment regimen, dexlansoprazole MR-based concomitant therapy attained a successful eradication rate of 90%, which was non inferior to that of lansoprazole-based concomitant treatment.

ClinicalTrials.gov identifier

NCT03829150.

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Development of Dexlansoprazole Delayed-Release Capsules, a Dual Delayed-Release Proton Pump Inhibitor

Proton pump inhibitors (PPIs) are widely used for treating acid-related disorders. For an "ideal PPI," achieving maximal absorption and sustaining pharmacodynamic effects through the 24-h dosing cycle are critical features. Dexlansoprazole offers a relevant case study on how an improved PPI was developed capitalizing on the rational optimization of a precursor molecule-in this case, using lansoprazole as a starting point, leveraging its chemical properties on pharmacokinetics, and exploring optimized formulations. Dexlansoprazole is the R(+)-enantiomer of lansoprazole and shows stereoselective differences in absorption and metabolism compared with the racemic mixture of lansoprazole. The formulation was further refined to use pulsate-type granules with enteric coating to withstand acidic gastric conditions, while allowing prolonged absorption in the proximal and distal small intestine. As a result, the dual delayed-release formulation of dexlansoprazole has a plasma concentration-time profile characterized by 2 distinct peaks, leading to an extended duration of therapeutic plasma drug concentrations compared with the conventional delayed-release lansoprazole formulation. The dual delayed-release formulation maintains plasma drug concentrations longer than the lansoprazole delayed-release formulation at all doses.

In search of the grail: A race for acid suppression

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.

Enantioseparation, Stereochemical Assignment and Chiral Recognition Mechanism of Sulfoxide-Containing Drugs

The distinct pharmacodynamic and pharmacokinetic properties of enantiopure sulfoxide drugs have stimulated us to systematically investigate their chiral separation, stereochemical assignment, and chiral recognition mechanism. Herein, four clinically widely-used sulfoxide drugs were chosen and optically resolved on various chiral stationary phases (CSPs). Theoretical simulations including electronic circular dichroism (ECD) calculation and molecular docking were adopted to assign the stereochemistry and reveal the underlying chiral recognition mechanism. Our results showed that the sequence of calculated mean binding energies between each pair of enantiomers and CSP matched exactly with experimentally observed enantiomeric elution order (EEO). It was also found that the length of hydrogen bond might contribute dominantly the interaction between two enantiomers and CSP. We hope our study could provide a fresh perspective to explore the stereochemistry and chiral recognition mechanism of chiral drugs.

Stereoselective Inhibition of Renal Basolateral Human Organic Anion Transporter 3 by Lansoprazole Enantiomers

Lansoprazole, a proton pump inhibitor, potently inhibits human organic anion transporter, hOAT3 (SLC22A8). Lansoprazole has an asymmetric atom in its structure and is clinically administered as a racemic mixture of (R)-and (S)-enantiomers. However, little is known about the stereoselective inhibitory potencies of lansoprazole against hOAT3 and its homolog, hOAT1. In the present study, the stereoselective inhibitory effect of lansoprazole was evaluated using hOAT1-and hOAT3-expressing cultured cells. hOAT1 and hOAT3 transported [14C]p-aminohippurate and [3H]estrone-3-sulfate (ES) with Michaelis-Menten constants of 29.8 ± 4.0 and 30.1 ± 9.0 µmol/L respectively. Lansoprazole enantiomers inhibited hOAT1- and hOAT3-mediated transport of each substrate in a concentration-dependent manner. The IC50 value of (S)-lansoprazole against hOAT3-mediated transport of [3H]ES (0.61 ± 0.08 µmol/L) was significantly lower than that of (R)-lansoprazole (1.75 ± 0.31 µmol/L). In contrast, stereoselectivity was not demonstrated for the inhibition of hOAT1. Furthermore, (S)-lansoprazole inhibited hOAT3-mediated transport of pemetrexed and methotrexate (hOAT3 substrates) more strongly than the corresponding (R)-lansoprazole. This study is the first to demonstrate that the stereoselective inhibitory potency of (S)-lansoprazole against hOAT3 is greater than that of (R)-lansoprazole. The present findings provide novel information about the drug interactions associated with lansoprazole.

Impact of Gastric H+/K+-ATPase rs2733743 on the Intragastric pH-Values of Dexlansoprazole Injection in Chinese Subjects

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.

The role of dexlansoprazole modified-release in the management of gastroesophageal reflux disease

Dexlansoprazole modified-release (MR) is the R-enantiomer of lansoprazole and is currently the only proton-pump inhibitor (PPI) with a novel dual delayed release (DDR) formulation. Overall, dexlansoprazole MR demonstrates a similar safety and side-effect profile as lansoprazole. Dexlansoprazole MR has been shown to be highly efficacious in healing erosive esophagitis, maintaining healed esophageal mucosa in patients with erosive esophagitis and controlling symptoms of patients with nonerosive reflux disease (NERD). Recent studies have also demonstrated that dexlansoprazole MR is highly effective in improving nocturnal heartburn, gastroesophageal reflux disease (GERD) related sleep disturbances and bothersome regurgitation. Dexlansoprazole MR is well tolerated and can be taken without regard to food.

Dexlansoprazole: delayed-release orally disintegrating tablets for the treatment of heartburn associated with non-erosive gastroesophageal reflux disease and the maintenance of erosive esophagitis

Gastroesophageal reflux disease (GERD) is a common condition afflicting millions of patients, whose prevalence continues to rise owing to the aging population and increasing burden of comorbid conditions, such as obesity. Currently, the mainstay of therapy for GERD is treatment with proton pump inhibitors (PPIs), which have proven efficacy, safety, and tolerability. Despite this, a considerable number of patients have refractory symptoms to PPI therapy. Dexlansoprazole is a new addition to the class of PPIs, which has a unique dual delayed drug release system, which aims to address the current limitations of acid suppressive therapy by offering extended acid suppression and improved ease of administration. Areas covered: This manuscript covers the pharmacokinetics, pharmacodynamics, clinical efficacy, and regulatory approval of dexlansoprazole. Additionally, there is further discussion concerning the current market settings and the potential future impact of dexlansoprazole. Expert commentary: Overall, dexlansoprazole offers benefits in its ease of administration and proven efficacy in the healing, maintenance of erosive esophagitis, and symptomatic non-erosive GERD. Long-term, dexlansoprazole will likely find a niche market among patients who fail other acid suppressive therapy or who desire simplified administration for compliance concerns, but will likely come at a higher out of pocket expense than comparable generic PPIs.

Proton pump inhibitors for the treatment of patients with erosive esophagitis and gastroesophageal reflux disease: current evidence and safety of dexlansoprazole

Gastroesophageal reflux disease is the most common upper gastroenterology disorder in the US. It is associated with a variety of complications and significantly impacts quality of life. Proton pump inhibitors are the most effective treatment. Dexlansoprazole modified release (MR) is a proton pump inhibitor that employs a novel release formulation that prolongs its absorption and allows for more flexibility in dosing. Dexlansoprazole MR can be dosed without regard to food intake or time of day, and once-daily dosing may replace twice-daily dosing of other agents. Dexlansoprazole MR is effective for healing and maintenance of erosive esophagitis, and for the treatment of nonerosive disease, including nocturnal gastroesophageal reflux disease. Dexlansoprazole MR is safe and well tolerated, and can improve quality of life.

Pharmacological and Safety Profile of Dexlansoprazole: A New Proton Pump Inhibitor - Implications for Treatment of Gastroesophageal Reflux Disease in the Asia Pacific Region

Although gastroesophageal reflux disease is not as common in Asia as in western countries, the prevalence has increased substantially during the past decade. Gastroesophageal reflux disease is associated with considerable reductions in subjective well-being and work productivity, as well as increased healthcare use. Proton pump inhibitors (PPIs) are currently the most effective treatment for gastroesophageal reflux disease. However, there are limitations associated with these drugs in terms of partial and non-response. Dexlansoprazole is the first PPI with a dual delayed release formulation designed to provide 2 separate releases of medication to extend the duration of effective plasma drug concentration. Dexlansoprazole has been shown to be effective for healing of erosive esophagitis, and to improve subjective well-being by controlling 24-hour symptoms. Dexlansoprazole has also been shown to achieve good plasma concentration regardless of administration with food, providing flexible dosing. Studies in healthy volunteers showed no clinically important effects on exposure to the active metabolite of clopidogrel or clopidogrel-induced platelet inhibition, with no dose adjustment of clopidogrel necessary when coprescribed. This review discusses the role of the new generation PPI, dexlansoprazole, in the treatment of gastroesophageal reflux disease in Asia.

A Pilot Randomized Controlled Study of Dexlansoprazole MR-Based Triple Therapy for Helicobacter Pylori Infection

Dexlansoprazole MR is the R-enantiomer of lansoprazole that is delivered by a dual delayed release formulation. It is effective for symptom control of patients with gastroesophageal reflux disease. However, its efficacy in the treatment of Helicobacter pylori infection remains unclear. This pilot, randomized, controlled, head-to-head study was conducted to investigate whether the efficacy of single-dose dexlansoprazole MR-based triple therapy was noninferior to double-dose rabeprazole-based triple therapy in the treatment of H pylori infection. Consecutive H pylori-infected subjects were randomly allocated to either 7-day dexlansoprazole MR-based standard triple therapy (dexlansoprazole MR 60 mg once daily, clarithromycin 500 mg twice daily, and amoxicillin 1 g twice daily) or rabeprazole-based triple therapy (rabeprazole 20 mg twice daily, clarithromycin 500 mg twice daily, and amoxicillin 1 g twice daily). H pylori status was assessed 6 weeks after the end of treatment. A total of 177 H pylori-infected patients were randomized to receive dexlansoprazole MR-based (n = 90) or rabeprazole-based (n = 87) triple therapy. Intention-to-treat analysis demonstrated no differences between eradication rates of the 2 study groups (83.3% vs 81.6%; P = 0.736). Per-protocol analysis yielded comparable results (85.1% vs 81.2%; P = 0.497). Both groups exhibited similar frequencies of adverse events (7.8% vs 4.6%; P = 0.536) and drug compliance (98.9% vs 97.7%; P = 0.496). Multivariate analysis disclosed that the presence of clarithromycin resistance was the only independent factors predictive of treatment failure with an odds ratio of 6.8 (95% confidence interval: 1.2-37.6). This work demonstrates that single-dose dexlansoprazole MR-based triple therapy yields a similar eradication rate as double-dose rabeprazole-based therapy. Since the pharmaceutical cost of the single-dose dexlansoprazole MR regime is lower than that of the double-dose rabeprazole regimen, dexlansoprazole-based therapy can reasonably be recommended in the first-line treatment of H pylori infection.

Dexlansoprazole - a new-generation proton pump inhibitor

Dexlansoprazole modified release (MR) is an R-enantiomer of lansoprazole and a new-generation proton pump inhibitor exhibiting high efficacy in the treatment of symptoms and lesions associated with erosive oesophagitis caused by gastroesophageal reflux disease (GERD). The dual release of the active ingredient - in the duodenum and the small intestine - makes it possible to achieve two peak concentrations at various times, within two and five hours of administration. Dexlansoprazole MR ensures the longest maintenance of drug concentration in the plasma of all known proton pump inhibitors, and the longest proton pump inhibitory effect. The basic indications for the drug include all forms of gastroesophageal reflux disease, especially with night-time heartburn and sleep disorders resulting from GERD. Dexlansoprazole can be taken regardless of meal times. It has a good safety profile and carries a low risk of adverse interactions with other drugs.

Managing gastroesophageal reflux disease - comparative efficacy and outcomes of dexlansoprazole MR

The management of gastroesophageal reflux disease (GERD) has been revolutionized with the development of proton pump inhibitors (PPIs). Unfortunately, due to the inherent pharmacokinetic and pharmacodynamic profiles of conventional PPIs, many patients continue to suffer from symptoms related to GERD despite appropriate use of PPIs. Dexlansoprazole MR is a PPI with a unique dual delayed-release delivery system that has been designed to address the unmet needs in GERD management. Specifically, dexlansoprazole MR addresses limitations with short plasma half-life and need for meal-associated dosing, characteristic of conventional PPIs. In addition, dexlansoprazole MR has been shown to be effective in several specific clinical situations. These include coadministration with clopidogrel, healing of all grades of erosive esophagitis, improvement in reflux-related quality of life, step down to once-per-day dosing, and treatment of Helicobacter pylori infections. Furthermore, dexlansoprazole MR has been found to induce symptom improvement in patients with nonerosive esophageal reflux disease, nocturnal heartburn and GERD-related sleep disturbance, and regurgitation. Overall, dexlansoprazole MR is a unique and useful tool in the management of GERD.

Omeprazole and lansoprazole enantiomers induce CYP3A4 in human hepatocytes and cell lines via glucocorticoid receptor and pregnane X receptor axis

Benzimidazole drugs lansoprazole and omeprazole are used for treatment of various gastrointestinal pathologies. Both compounds cause drug-drug interactions because they activate aryl hydrocarbon receptor and induce CYP1A genes. In the current paper, we examined the effects of lansoprazole and omeprazole enantiomers on the expression of key drug-metabolizing enzyme CYP3A4 in human hepatocytes and human cancer cell lines. Lansoprazole enantiomers, but not omeprazole, were equipotent inducers of CYP3A4 mRNA in HepG2 cells. All forms (S-, R-, rac-) of lansoprazole and omeprazole induced CYP3A4 mRNA and protein in human hepatocytes. The quantitative profiles of CYP3A4 induction by individual forms of lansoprazole and omeprazole exerted enantiospecific patterns. Lansoprazole dose-dependently activated pregnane X receptor PXR in gene reporter assays, and slightly modulated rifampicin-inducible PXR activity, with similar potency for each enantiomer. Omeprazole dose-dependently activated PXR and inhibited rifampicin-inducible PXR activity. The effects of S-omeprazole were much stronger as compared to those of R-omeprazole. All forms of lansoprazole, but not omeprazole, slightly activated glucocorticoid receptor and augmented dexamethasone-induced GR transcriptional activity. Omeprazole and lansoprazole influenced basal and ligand inducible expression of tyrosine aminotransferase, a GR-target gene, in HepG2 cells and human hepatocytes. Overall, we demonstrate here that omeprazole and lansoprazole enantiomers induce CYP3A4 in HepG2 cells and human hepatocytes. The induction comprises differential interactions of omeprazole and lansoprazole with transcriptional regulators PXR and GR, and some of the effects were enantiospecific. The data presented here might be of toxicological and clinical importance, since the effects occurred in therapeutically relevant concentrations.

Differential effects of omeprazole and lansoprazole enantiomers on aryl hydrocarbon receptor in human hepatocytes and cell lines

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.

Absorption, distribution, metabolism and excretion of [14C]dexlansoprazole in healthy male subjects

BACKGROUND AND OBJECTIVE

The proton pump inhibitor dexlansoprazole is a modified-release formulation of dexlansoprazole, an enantiomer of lansoprazole, which employs a Dual Delayed Release™ (DDR) delivery system. This study was conducted in healthy subjects to assess the absorption, distribution, metabolism and excretion of a 60 mg dose of [14C]dexlansoprazole.

METHODS

After multiple daily doses of dexlansoprazole DDR for 4 days followed by a single dose of [14C]dexlansoprazole on day 5, absorption, distribution, metabolism and elimination of [14C]dexlansoprazole were assessed in six healthy male subjects whose CYP (cytochrome P450) 2C19 metabolizer status was also determined.

RESULTS

Five subjects were phenotyped as extensive metabolizers (EMs) and one subject was a poor metabolizer (PM). Recovery of radioactivity in urine and faeces averaged 98% after 7 days (51% in urine and 48% in faeces) post-14C dosing. In plasma, dexlansoprazole was the largest component detected, with the main metabolites in the EM subjects being 5-glucuronyloxy dexlansoprazole and 5-hydroxy dexlansoprazole (CYP2C19 mediated), whereas the PM subject had greater amounts of dexlansoprazole sulfone (CYP3A mediated). Dexlansoprazole was not detected in urine; six metabolites were identified accounting for an average of 86% of the urinary radioactivity, with 5-glucuronyloxy dexlansoprazole, 5-glucuronyloxy dexlansoprazole sulfide, 2-S-N-acetylcysteinyl benzimidazole and 5-sulfonyloxy dexlansoprazole sulfide being the primary metabolites. In faeces, parent drug and six identified metabolites accounted for 23% and 72%, respectively, of the faecal radioactivity, with 5-hydroxy dexlansoprazole sulfide and dexlansoprazole sulfide being predominant.

CONCLUSION

Overall, the results indicate that [14C]dexlansoprazole was well absorbed and extensively metabolized by oxidation, reduction and conjugation to 13 identified metabolites.

Pharmacokinetics and safety of dexlansoprazole MR in adolescents with symptomatic GERD

OBJECTIVES

Dexlansoprazole MR 30  mg once daily (QD) is approved in adults for the treatment of symptomatic nonerosive gastroesophageal reflux disease (GERD) and maintenance of healed erosive esophagitis (EE); 60  mg is approved for healing EE. The present study assesses the pharmacokinetic (PK) profile and safety of dexlansoprazole MR in adolescent patients.

PATIENTS AND METHODS

Phase 1, open-label, parallel-group, multicenter study in male and female adolescents (12-17 years) with GERD. Patients were randomized to receive dexlansoprazole MR (30 or 60  mg, QD) for 7 days. Blood samples to determine dexlansoprazole plasma concentrations were drawn over a 24-hour period after dosing on day 7. Dexlansoprazole plasma concentrations and PK parameters were summarized by dose group. Safety assessments included monitoring of adverse events (AEs).

RESULTS

Thirty-six patients (mean age 14.6 years), 14 boys and 22 girls, were randomized, with PK data available for 35 patients. The overall exposure of dexlansoprazole after administration of the 60-mg capsule was slightly less than double the exposure from the 30-mg capsule. Cmax (691 and 1136  ng/mL) and area under the plasma concentration time curve (2886 and 5120  ng · h/mL) values for the 30- and 60-mg doses, respectively, were similar to results from previous phase 1 studies in healthy adults. Twelve of 36 patients (33.3%) experienced a total of 21 treatment-emergent AEs. All of the AEs were considered to be of mild severity.

CONCLUSIONS

The PK data for dexlansoprazole MR 30- and 60-mg capsules in adolescent patients with symptomatic GERD were similar to those in healthy adults. Both doses were well tolerated.

Dexlansoprazole MR: a review

Dexlansoprazole MR is the R-enantiomer of lansoprazole that is delivered by a novel system, the dual delayed release formulation. The drug has been shown to be efficacious in healing erosive esophagitis as compared with lansoprazole. When compared to placebo, dexlansoprazole provided significantly higher maintenance rates for healed esophageal mucosa in patients with erosive esophagitis and symptom control in patients with non-erosive reflux disease. Dexlansoprazole could be taken without regard to food. Overall, dexlansoprazole is well tolerated and has a comparable side-effect profile to lansoprazole.

The 12-month safety profile of dexlansoprazole, a proton pump inhibitor with a dual delayed release formulation, in patients with gastro-oesophageal reflux disease

BACKGROUND

Dexlansoprazole MR is a Dual Delayed Release formulation of dexlansoprazole, an enantiomer of lansoprazole, designed to extend the duration of acid suppression.

AIM

To assess the 12-month safety of dexlansoprazole MR in patients with symptomatic gastro-oesophageal reflux disease (GERD).

METHODS

In this randomised open-label study, patients received dexlansoprazole MR 60 or 90 mg once-daily for 12 months. Safety was evaluated at months 1, 3, 6, 9 and 12/final visit through physical examinations, laboratory evaluations, endoscopies, gastric biopsies, fasting serum gastrin values and adverse events (AEs).

RESULTS

Of 591 patients receiving dexlansoprazole MR 60 and 90 mg, 71% and 65%, respectively, experienced ≥1 treatment-emergent AE; the most frequent AE was upper respiratory infection (14% and 13% in the 60- and 90-mg groups). Thirty patients experienced ≥1 serious AE; a majority of serious AEs were unrelated to study drug. No clinically meaningful change in any clinical laboratory parameters was noted. As expected, serum gastrin values rose with dexlansoprazole therapy; increases were not dose related. No clinically concerning trends were identified in gastric pathology results; no endocrine cell hyperplasia, adenocarcinoma, or lymphoma were observed.

CONCLUSIONS

Twelve-month treatment with dexlansoprazole MR 60 and 90 mg was well tolerated by GERD patients in this study (Clinicaltrials.gov identifier NCT00255190).

Delayed release dexlansoprazole in the treatment of GERD and erosive esophagitis

Although proton pump inhibitors (PPI) have a record of remarkable effectiveness and safety in the management of gastroesophageal reflux disease (GERD), several treatment challenges with PPI have emerged. Dexlansoprazole MR is the (R)-enantiomer of lansoprazole contained in a formulation that produces two distinct releases of drug and significantly extends the duration of active plasma concentrations and % time pH > 4 beyond that of conventional single-release PPI. Dexlansoprazole MR can be administered without regard to meals or the timing of meals in most patients. Dexlansoprazole MR 60 mg demonstrated similar efficacy for healing of erosive esophagitis at 8 weeks compared with lansoprazole 30 mg, and dexlansoprazole MR 30 mg was superior to placebo for maintenance of healed erosive esophagitis at 6 months with 99% of nights and 96% of days heartburn-free over 6 months in patients taking dexlansoprazole MR 30 mg. Superior relief of heartburn occurred in patients taking dexlansoprazole MR 30 mg (55% heartburn-free 24-hour periods) vs placebo (14%) for symptomatic nonerosive GERD. The safety profile of dexlansoprazole MR is similar to that of lansoprazole. The extended pharmacodynamic effects, added convenience, and efficacy and safety of dexlansoprazole MR offer a novel approach to gastric pH control in patients with acid-related disorders.

Clinical trial: the effects of the proton pump inhibitor dexlansoprazole MR on daytime and nighttime heartburn in patients with non-erosive reflux disease

BACKGROUND

The proportion of patients who respond to proton pump inhibitor (PPI) therapy is about 20% lower in those with non-erosive reflux disease (NERD) than in those with erosive oesophagitis.

AIM

To assess efficacy and safety of dexlansoprazole MR, a PPI using Dual Delayed Release technology, in NERD patients.

METHODS

In this 4-week, double-blind, placebo-controlled study, 947 NERD patients randomly received dexlansoprazole MR 30 mg, 60 mg or placebo once daily (QD). The percentages of 24-h heartburn-free days (primary) and nights without heartburn (secondary) were assessed from patients' daily diaries. Investigators also assessed symptoms. Patients completed validated quality of life and symptom severity questionnaires.

RESULTS

Dexlansoprazole MR provided significantly greater median percentages of 24-h heartburn-free days (54.9% and 50.0% for the 30- and 60-mg doses vs. 17.5% for placebo, P < 0.00001) and nights without heartburn (80.8% and 76.9% vs. 51.7%, P < 0.00001 vs. placebo). Dexlansoprazole MR also reduced symptom severity. Quality of life improvements in patients receiving dexlansoprazole MR were consistent with clinical efficacy endpoints. Percentages of patients experiencing treatment-emergent adverse events were similar among groups.

CONCLUSIONS

Dexlansoprazole MR 30 and 60 mg were superior to placebo in providing 24-h heartburn-free days and nights in NERD patients. Treatment was well tolerated.

Review article: dual delayed release formulation of dexlansoprazole MR, a novel approach to overcome the limitations of conventional single release proton pump inhibitor therapy

BACKGROUND

Proton pump inhibitors (PPIs) provide the most effective pharmacotherapy for treating acid-related disorders. However, PPIs do not completely control acid over 24 h with once-daily dosing.

AIMS

To discuss limitations inherent in the pharmacokinetics (PK) and pharmacodynamics of conventional PPI formulations, which provide a single drug release. Also, to consider approaches to extending the duration of acid suppression focusing on dexlansoprazole MR, a PPI with a novel Dual Delayed Release (DDR) formulation.

METHOD

We reviewed the available literature regarding marketed and investigational PPIs.

RESULTS

Non-standard dosing of currently marketed PPIs has produced incremental advances in acid control. Multiple approaches are being evaluated to enhance acid suppression with PPIs. Dexlansoprazole MR is a DDR formulation of dexlansoprazole, an enantiomer of lansoprazole, with two distinct drug release periods to prolong the plasma dexlansoprazole concentration-time profile and extend duration of acid suppression. Clinical studies show that dexlansoprazole MR produces a dual-peak PK profile that maintains therapeutic plasma drug concentrations longer than lansoprazole, with a single-peak PK profile, and increases the percentage of time that intragastric pH >4.

CONCLUSIONS

Novel drug delivery platforms, including the dexlansoprazole MR DDR formulation, may improve acid suppression and offer benefits over conventional single release PPI formulations.

Clinical trials: healing of erosive oesophagitis with dexlansoprazole MR, a proton pump inhibitor with a novel dual delayed-release formulation--results from two randomized controlled studies

BACKGROUND

Dexlansoprazole MR employs a dual delayed-release delivery system that extends drug exposure and prolongs pH control compared with lansoprazole.

AIM

To assess the efficacy and safety of dexlansoprazole MR in healing erosive oesophagitis (EO).

METHODS

Patients in two identical double-blind, randomized controlled trials (n = 4092) received dexlansoprazole MR 60 or 90 mg or lansoprazole 30 mg once daily. Week 8 healing was assessed using a closed testing procedure--first for non-inferiority, then superiority, vs. lansoprazole. Secondary endpoints included week 4 healing and week 8 healing in patients with moderate-to-severe disease (Los Angeles Classification grades C and D). Life-table and crude rate analyses were performed. Symptoms and tolerability were assessed.

RESULTS

Dexlansoprazole MR achieved non-inferiority to lansoprazole, allowing testing for superiority. Using life-table analysis, dexlansoprazole MR healed 92-95% of patients in individual studies vs. 86-92% for lansoprazole; the differences were not statistically significant (P > 0.025). Using crude rate analysis, dexlansoprazole MR 90 mg was superior to lansoprazole in both studies and 60 mg was superior in one study. Week 4 healing was > 64% with all treatments in both studies. In an integrated analysis of 8-week healing in patients with moderate-to-severe EO, dexlansoprazole MR 90 mg was superior to lansoprazole. All treatments effectively relieved symptoms and were well tolerated.

CONCLUSION

Dexlansoprazole MR is highly effective in healing EO and offers benefits over lansoprazole, particularly in moderate-to-severe disease.

Pharmacokinetics and pharmacodynamics of a known active PPI with a novel Dual Delayed Release technology, dexlansoprazole MR: a combined analysis of randomized controlled clinical trials

BACKGROUND

Dexlansoprazole MR is a novel Dual Delayed Release formulation of dexlansoprazole, an enantiomer of lansoprazole, designed to prolong the plasma concentration-time profile of dexlansoprazole and extend duration of acid suppression with once-daily (QD) dosing.

OBJECTIVES

To assess the pharmacokinetics and pharmacodynamics of dexlansoprazole at different doses of dexlansoprazole MR and delineate the exposure-response relationship following oral administration of dexlansoprazole MR.

METHODS

Dexlansoprazole MR was evaluated in two prospective randomized studies in healthy subjects. In study 1 (n = 40), subjects received dexlansoprazole MR 60, 90, and 120 mg and lansoprazole 30 mg QD. In study 2 (n = 45), subjects received dexlansoprazole MR 30 and 60 mg and lansoprazole 15 mg QD. Data from these trials were pooled and analyzed to describe the relationship between intragastric pH and dexlansoprazole systemic exposure.

RESULTS

Data from 83 subjects were analyzed. The dexlansoprazole plasma concentration-time profile following administration of dexlansoprazole MR was characterized by two distinct peaks and a prolonged drug exposure during the 24-h dosing interval. Approximate dose proportionality was observed for mean peak plasma concentration and area under the plasma-concentration time curve after administration of dexlansoprazole MR. In each study, doses of dexlansoprazole MR generally produced greater gastric acid suppression than lansoprazole. Based on the exposure-response analysis using combined data from these two trials, the predicted mean 24-h intragastric pH values were 4.06 and 4.35 for the dexlansoprazole MR 30- and 90-mg doses, respectively. The percent of time pH > 4 over 24 h values were 59.2% and 66.7% for dexlansoprazole MR 30 and 90 mg, respectively. No appreciable additional gain in the pharmacodynamic response was predicted for dexlansoprazole MR 120 mg. Despite combining data from two studies to evaluate a broader dose range, this analysis provided a reasonable estimate of the pharmacodynamic parameters and a good characterization of the dexlansoprazole MR exposure-response relationship.

CONCLUSIONS

Dexlansoprazole MR, a proton pump inhibitor that uses Dual Delayed Release technology, produced a pharmacokinetic profile with a plasma concentration-time curve characterized by two distinct peaks and an extended duration of pharmacologically active dexlansoprazole concentration in plasma. Exposure-response analysis indicated a progressive increase in the pharmacodynamic response as dexlansoprazole MR doses increased from 30 to 90 mg.

Stereoselective disposition of proton pump inhibitors

It is estimated that about half of all therapeutic agents are chiral, but most of these drugs are administered in the form of the racemic mixture, i.e. a 50/50 mixture of its enantiomers. However, chirality is one of the main features of biology, and many of the processes essential for life are stereoselective, implying that two enantiomers may work differently from each other in a physiological environment. Thus, receptors or metabolizing enzymes would recognize one of the ligand enantiomers in favour of the other. With one exception, all presently marketed proton pump inhibitors (PPIs)--omeprazole, lansoprazole, pantoprazole and rabeprazole--used for the treatment of gastric acid-related diseases are racemic mixtures. The exception is esomeprazole, the S-enantiomer of omeprazole, which is the only PPI developed as a single enantiomer drug. The development of esomeprazole (an alkaline salt thereof, e.g. magnesium or sodium) was based on unique metabolic properties that clearly differentiated esomeprazole from omeprazole, the racemate. At comparable doses, these properties led to several clinical advantages, for example higher bioavailability in the majority of patients, i.e. the extensive metabolizers (EMs; 97% in Caucasian and 80-85% in Asian populations), lower exposure in poor metabolizers (PMs; 3% in Caucasian and 15-20% in Asian populations) and lower interindividual variation. For the other, i.e. racemic, PPIs there are some data available on the characteristics of the individual enantiomers, and we have therefore undertaken to analyse the current literature with the purpose of evaluating the potential benefits of developing single enantiomer drugs from lansoprazole, pantoprazole and rabeprazole. For lansoprazole, the plasma concentrations of the S-enantiomer are lower than those of the R-enantiomer in both EMs and PMs, and, consequently, the variability in the population or between EMs and PMs is not likely to decrease with either of the lansoprazole enantiomers. Furthermore, plasma protein binding differs between the two lansoprazole enantiomers, in that the amount of the free S-enantiomer is two-fold higher than that of the R-enantiomer. This will counteract the difference seen in total plasma concentrations of the enantiomers. Also, studies using expressed human cytochrome P450 isoenzymes show that the metabolism of one enantiomer is significantly affected by the presence of the other, which is likely to result in different pharmacokinetics when administering a single enantiomer. For pantoprazole, there is a negligible difference in plasma concentrations between the two enantiomers in EMs, while the difference is substantial in PMs. The difference in AUC between PMs and EMs would decrease to some extent, but in the majority of the population the variability and efficacy would not be altered with a single enantiomer of pantoprazole. The metabolism of the enantiomers of rabeprazole displays stereoselectivity comparable to that of lansoprazole, i.e. the exposure of the R-enantiomer is higher than that of the S-enantiomer in EMs as well as in PMs, which, by analogy to lansoprazole, makes them less suitable for development of a single enantiomer drug. Furthermore, the chiral stability of the rabeprazole enantiomers may be an issue because of significant degradation of rabeprazole to its sulfide analogue, which is subject to non-stereoselective metabolic regeneration of a mixture of the two enantiomers. In conclusion, in contrast to esomeprazole, the S-enantiomer of omeprazole, minimal if any clinical advantages would be expected in developing any of the enantiomers of lansoprazole, pantoprazole, or rabeprazole as compared with their racemates.

Preparative chiral chromatography and chiroptical characterization of enantiomers of omeprazole and related benzimidazoles

To chiroptically characterize the enantiomers of omeprazole and some structurally related benzimidazoles with circular dichroism (CD), preparative chiral liquid chromatography was utilized for the isolation of the pure enantiomers. A limited analytical column screen was performed identifying Kromasil-CHI-TBB and the amylose-based phases Chiralpak AD and AS as possible chiral stationary phases (CSPs) for the preparative scale separation of the enantiomers of the different benzimidazoles. Optimization of the chromatographic conditions with respect to retention, enantioseparation, and resolution was achieved by variation of the mobile phase constituents as well as of temperature. Because of the lability of the compound in slightly acidic media, supercritical fluid chromatography (SFC) could not be applied for a preparative scale separation of the enantiomers. The separation of omeprazole was optimized to give high throughput (2.6 kg racemate/kg CSP/day) and high enantiomeric excess of the obtained isomers. The absolute configurations of the pure enantiomers of rabeprazole, lansoprazole, and pantoprazole were determined from the strong correlation to the CD spectrum of (+)-(R)-omeprazole. For all the compounds, the (+)-enantiomers displayed similar chiroptical features as (+)-(R)-omeprazole and were thus assigned the (R)- configuration. Elution order of the optical isomers was monitored by injecting racemic solutions spiked with one of the isomers and also by an on-line laser polarimeter. Both the type of CSP and also the mobile phase constituents had a strong effect on elution order of the enantiomers.

Enantioselective Disposition of Lansoprazole and Rabeprazole in Human Plasma

Lansoprazole is extensively metabolized by CYP2C19 and CYP3A4 in the liver, whereas rabeprazole is primarily converted non-enzymatically to rabeprazole-thioether, with only some being oxidized by CYP2C19 and CYP3A4. Lansoprazole and rabeprazole possess asymmetric sulfur in their chemical structure and have typically been used clinically as a racemic mixture. This article reviews the pharmacokinetic differences between enantiomers of lansoprazole and rabeprazole in relation to the CYP2C19 genotypes. In our studies in healthy Japanese subjects, the magnitude of contribution of each lansoprazole enantiomer for CYP2C19 was greater than that for CYP3A4. CYP2C19 influenced the disposition of (S)-lansoprazole to a greater extent than the (R)-enantiomer. The R/S ratios for the AUC of lansoprazole in CYP2C19 homEMs, hetEMs and PMs was 12.7, 8.5 and 5.8, respectively. On the other hand, (R)-rabeprazole disposition was influenced to a greater degree by CYP2C19 genetic polymorphisms than (S)-rabeprazole. However, the R/S ratios for the AUC of rabeprazole in CYP2C19 homEMs, hetEMs and PMs was only 1.8, 2.2 and 2.4, respectively, suggesting a lesser effect of CYP2C19 polymorphisms on the stereoselective disposition of rabeprazole compared to lansoprazole. Such a difference in the AUC between rabeprazole enantiomers is likely to be dependent on stereoselectivity in the CYP3A4-mediated metabolic conversion from rabeprazole-thioether to rabeprazole. Both enantiomers of these PPIs have been reported to possess equal potency. Therefore, particularly with lansoprazole, the use of (R)-lansoprazole alone would be highly desirable for use in clinical applications.

Pharmacodynamic comparison of pantoprazole enantiomers: inhibition of acid-related lesions and acid secretion in rats and guinea-pigs

Pantoprazole is an irreversible proton pump inhibitor that is administered as a racemic mixture clinically. The effects of pantoprazole sodium (PAN.Na) enantiomers on acid-related lesions were compared using models of pylorus ligation induced ulcer, histamine induced ulcer and reflux oesophagitis in rats and guinea-pigs. Compared with (+)-PAN.Na and (+/-)-PAN.Na, (-)-PAN.Na showed much stronger inhibitory effects on pylorus ligation induced and histamine induced ulcers, but similar effects on reflux oesophagitis. The doses of (-)-PAN.Na, (+)-PAN.Na and (+/-)-PAN.Na required for 50% inhibition (ID50) of acid-related lesions were 1.28, 5.03 and 3.40 mg kg(-1) against pylorus ligation induced ulcer, 1.20, 4.28 and 3.15 mg kg(-1) against histamine induced ulcer, and 2.92, 3.56 and 3.70 mg kg(-1) against reflux oesophagitis, respectively. The inhibitory effects of PAN.Na enantiomers on basal gastric acid output were compared in rats with acute fistula. In contrast to inhibitory rates of 89.3% and 83.6% on gastric acid output by (-)-PAN.Na and (+/-)-PAN.Na at 1.5 mg kg(-1), (+)-PAN.Na had an inhibitory rate of only 24.7% at the same dose. The above results indicate that (-)-PAN.Na is more potent than (+)-PAN.Na at inhibiting acid-related lesions owing to its stronger inhibition of acid secretion.