1-[5-(2-Fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl]-N-methylmethanamine monofumarate (TAK-438), a novel and potent potassium-competitive acid blocker for the treatment of acid-related diseases

Study on pharmacokinetics and bioequivalence of Vonoprazan pyroglutamate in rats by liquid chromatography with tandem mass spectrometry

Vonoprazan Fumarate (TAK-438F) is a new and effective drug approved in Japan in 2014 for treatment and prevention of acid-related diseases (ARDs), which exhibits many advantages compared with traditional proton-pump inhibitors (PPIs). However, the clinical applications of TAK0-438F suffers limitation due to the lack of injection dosage form. Efforts to overcome this limitation lead to the systhesis of Vonoprazan pyroglutamate (TAK-438P) for its high water solubility and more potent antisecretory effect. This was the first report to establish and validate a reliable and sensitive LC-MS/MS method for the quantification of TAK-438P in rat plasma and tissues (heart, liver, spleen, liver, kidney, rain, stomach and small intestine). All the features of the developed method suggested it was within bioanalytical criteria recommended by regulatory authorities. Furthermore, the developed method was applied to the exploration of the bioequivalence between TAK-438P and TAK-438F, as well as the pharmacokinetics and tissue distribution of TAK-438P. The results showed that there was no significant differences between TAK-438P and TAK-438F after oral administration of the same dose. Besides, TAK-438P was rapidly absorbed and eliminated in rat plasma. And it was widely distributed and there was no long-term accumulation in most tissues. Notably, more than 2000ng/mL was observed in stomach 12h after oral administration. The high accumulation revealed that stomach was likely to be the target organs of TAK-438P.

Novel and Effective Therapeutic Regimens for Helicobacter pylori in an Era of Increasing Antibiotic Resistance

Helicobacter pylori (H. pylori) is a common gastrointestinal bacterial strain closely associated with the incidence of chronic gastritis, peptic ulcers, gastric mucosa-associated lymphoid tissue lymphoma, and gastric cancer. A current research and clinical challenge is the increased rate of antibiotic resistance in H. pylori, which has led to a decreased H. pylori eradication rate. In this article, we review recent H. pylori infection and reinfection rates and H. pylori resistance to antibiotics, and we discuss the pertinent treatments. A PubMed literature search was performed using the following keywords: Helicobacter pylori, infection, reinfection, antibiotic resistance, bismuth, proton pump inhibitors, vonoprazan, susceptibility, quintuple therapy, dual therapy, and probiotic. The prevalence of H. pylori has remained high in some areas despite the decreasing trend of H. pylori prevalence observed over time. Additionally, the H. pylori reinfection rate has varied in different countries due to socioeconomic and hygienic conditions. Helicobacter pylori monoresistance to clarithromycin, metronidazole or levofloxacin was common in most countries. However, the prevalence of amoxicillin and tetracycline resistance has remained low. Because H. pylori infection and reinfection present serious challenges and because H. pylori resistance to clarithromycin, metronidazole or levofloxacin remains high in most countries, the selection of an efficient regimen to eradicate H. pylori is critical. Currently, bismuth-containing quadruple therapies still achieve high eradication rates. Moreover, susceptibility-based therapies are alternatives because they may avoid the use of unnecessary antibiotics. Novel regimens, e.g., vonoprazan-containing triple therapies, quintuple therapies, high-dose dual therapies, and standard triple therapies with probiotics, require further studies concerning their efficiency and safety for treating H. pylori.

Effect of Therapeutic and Supratherapeutic Doses of Vonoprazan on the QT/QTc Interval in a Phase I Randomized Study in Healthy Subjects

This phase I, randomized, 4-period, 4-sequence, double-blind, active- and placebo-controlled, crossover study assessed the effects of vonoprazan on the QT/QTc interval in healthy subjects. Subjects received single oral doses of vonoprazan 40 mg, vonoprazan 120 mg, moxifloxacin 400 mg (positive control/open label), and placebo. The primary end point was time-matched, placebo-corrected, baseline-adjusted mean Fridericia-corrected QT interval (ddQTcF). Of 64 subjects (mean age, 37.8 years; 50% male), 63 received all four regimens. One subject discontinued due to nondrug-related adverse event of tonsillitis. Assay sensitivity was established; lower bound of the one-sided 95% confidence interval (CI) for ddQTcF was >5 ms between 1.5 and 12 h following moxifloxacin administration. For both doses of vonoprazan, the one-sided upper 95% CI ddQTcF did not exceed 10 ms. There was no correlation between plasma vonoprazan concentrations and increases in ddQTcF. Vonoprazan was well tolerated. No severe adverse events/deaths were reported. (European Clinical Trials Database Registry: 2011-004003-20.).

Pharmacokinetic Drug-Drug Interactions Between Vonoprazan and Low-Dose Aspirin or Nonsteroidal Anti-inflammatory Drugs: A Phase 2, Open-Label, Study in Healthy Japanese Men

Background

Gastroprotective agents are recommended for patients receiving low-dose aspirin (LDA) or nonsteroidal anti-inflammatory drugs (NSAIDs). Vonoprazan is a potassium-competitive acid blocker recently approved for the prevention of peptic ulcer recurrence in patients receiving LDA or NSAIDs.

Methods

This phase 2, open-label, single-center study in healthy Japanese males evaluated drug–drug interactions between vonoprazan 40 mg and LDA (100 mg) or NSAIDs [loxoprofen sodium (60 mg), diclofenac sodium (25 mg), or meloxicam (10 mg)] and vice versa. Subjects were allocated to one of eight cohorts and received their orally administered treatment regimen (to assess the effect of vonoprazan vs. NSAID or LDA, or vice versa) once daily. Endpoints were the pharmacokinetics of plasma concentrations of the study drugs alone and in combination (primary), safety (secondary), and vonoprazan effects on aspirin-mediated inhibition of platelet-aggregation.

Results

Of 109 subjects screened, 64 were assigned to one of eight cohorts (n = 8 per cohort) and received treatment, one subject discontinued due to a treatment-emergent adverse event (TEAE), and 63 completed the study. There were few differences in the pharmacokinetics of vonoprazan when administered with LDA or NSAIDs, and few differences in the pharmacokinetics of LDA or NSAIDs when administered with vonoprazan. The differences were small and not clinically meaningful. Inhibition of arachidonic-induced platelet aggregation by LDA was not influenced by vonoprazan. Six patients experienced a TEAE, all were mild and were deemed unrelated to study drugs. One subject withdrew due to infection (tonsillitis).

Conclusions

No clinically meaningful drug–drug interactions were observed and vonoprazan was well tolerated when administered with LDA or NSAIDs.

Study registration

JapicCTI-153100

Electronic supplementary material

The online version of this article (doi:10.1007/s40261-016-0455-2) contains supplementary material, which is available to authorized users.

Effect of Vonoprazan, a Potassium-Competitive Acid Blocker, on the 13C-Urea Breath Test in Helicobacter pylori-Positive Patients

BACKGROUND AND AIM

Vonoprazan (VPZ) is a new oral potassium-competitive acid blocker that has recently become available. The aim of this study was to investigate the effects of VPZ on the urease activity of H. pylori as measured by the ¹³C-urea breath test (¹³C-UBT).

PATIENTS AND METHODS

A total of 60 patients (26 men, 34 women; mean age 53.2 ± 13.6 years) who were diagnosed as H. pylori-positive were recruited. The patients were randomly allocated to three treatment groups: lansoprazole (LPZ) 30 mg (n = 20), VPZ 20 mg (n = 20) once daily for 3 weeks, or the control group (n = 20). The ¹³C-UBT was carried out at baseline and after 3 weeks of treatment, and the baseline and after treatment results then compared. Δ¹³C‰ ≥ 2.5‰ was considered H. pylori-positive.

RESULTS

Four patients failed to complete the medication and were omitted from the analysis; data from the LPZ group (n = 18), VPZ group (n = 18), and control group (n = 20) were analyzed. The control group showed no significant change in ¹³C-UBT data between baseline and the completion of 3-week treatment (baseline: 26.6 ± 23.0‰, completion: 21.1 ± 13.1‰). The ¹³C-UBT data at week 3 were significantly decreased in both the VPZ group (baseline: 32.8 ± 22.7‰, completion: 7.6 ± 9.2‰, p = 0.0002) and the LPZ group (baseline: 41.8 ± 33.4‰; completion: 9.6 ± 8.8‰, p = 0.0006) compared to baseline.

CONCLUSIONS

VPZ treatment reduced the value of UBT, warning that UBT for patients with VPZ treatment should be evaluated carefully.

Randomised clinical trial: efficacy and safety of vonoprazan vs. lansoprazole in patients with gastric or duodenal ulcers - results from two phase 3, non-inferiority randomised controlled trials

BACKGROUND

Vonoprazan is a new potassium-competitive acid blocker for treatment of acid-related diseases.

AIM

To conduct two randomised-controlled trials, to evaluate the non-inferiority of vonoprazan vs. lansoprazole, a proton pump inhibitor, for treatment of gastric ulcer (GU) or duodenal ulcer (DU).

METHODS

Patients aged ≥20 years with ≥1 endoscopically-confirmed GU or DU (≥5 mm white coating) were randomised 1:1 using double-dummy blinding to receive lansoprazole (30 mg) or vonoprazan (20 mg) for 8 (GU study) or 6 (DU study) weeks. The primary endpoint was the proportion of patients with endoscopically confirmed healed GU or DU.

RESULTS

For GU, 93.5% (216/231) of vonoprazan-treated patients and 93.8% (211/225) of lansoprazole-treated patients achieved healed GU; non-inferiority of vonoprazan to lansoprazole was confirmed [difference = -0.3% (95% CI -4.750, 4.208); P = 0.0011]. For DU, 95.5% (170/178) of vonoprazan-treated patients and 98.3% (177/180) of lansoprazole-treated patients achieved healed DU; non-inferiority to lansoprazole was not confirmed [difference = -2.8% (95% CI -6.400, 0.745); P = 0.0654]. The incidences of treatment-emergent adverse events were slightly lower for GU and slightly higher for DU with vonoprazan than with lansoprazole. There was one death (subarachnoid haemorrhage) in the vonoprazan group (DU). The possibility of a relationship between this unexpected patient death and the study drug could not be ruled out. In both studies, increases in serum gastrin levels were greater in vonoprazan-treated vs. lansoprazole-treated patients; levels returned to baseline after treatment in both groups.

CONCLUSIONS

Vonoprazan 20 mg has a similar tolerability profile to lansoprazole 30 mg and is non-inferior with respect to GU healing and has similar efficacy for DU healing.

Vonoprazan is superior to proton pump inhibitors in healing artificial ulcers of the stomach post-endoscopic submucosal dissection: A propensity score-matching analysis

BACKGROUND AND AIM

Proton pump inhibitors (PPI) are effective at healing artificial ulcers after endoscopic submucosal dissection (ESD) for gastric neoplasms; however, the efficacy of vonoprazan is not completely understood. The aim of the present study was to determine the healing effect of vonoprazan on artificial ulcers post-gastric ESD relative to PPI.

METHODS

Thirty-five patients who underwent gastric ESD between April and November 2015 were treated with vonoprazan 20 mg/day for 4 weeks and subsequently underwent endoscopy for evaluation of ulcer size (V group). Ulcer contraction rate was determined by the following formula: ([ESD specimen size] - [ulcer size at 4 weeks after ESD])/(ESD specimen size) × 100%. We compared the results with those of a historical control group treated with esomeprazole 20 mg/day for 4 weeks after gastric ESD and subsequently measured their ulcer size (33 patients, E group) by propensity score-matching methods.

RESULTS

Sixty-two subjects were enrolled after propensity score-matching. Ulcer contraction rate at 4 weeks after ESD in the V group was significantly higher than that of the E group (97.7 ± 3.2% vs 94.5 ± 6.7%, respectively, P = 0.025). Number of subjects with a scar-stage ulcer (100% contraction rate) tended to be higher in the V group relative to the E group (32% [10 of 31] vs 13% [4 of 31], respectively, P = 0.070, McNemar's chi-squared test).

CONCLUSION

Vonoprazan has a faster post-gastric ESD artificial ulcer contraction rate than esomeprazole. Vonoprazan may supersede PPI in treating post-ESD artificial ulcers of the stomach.

The Superiority of Vonoprazan-based First-line Triple Therapy with Clarithromycin: A Prospective Multi-center Cohort Study on Helicobacter pylori Eradication

Objective We evaluated the safety and efficacy of vonoprazan-based amoxicillin and clarithromycin 7-day triple therapy (VAC) in comparison to proton pump inhibitor (PPI)-based (PAC) as a first-line treatment and vonoprazan-based amoxicillin and metronidazole 7-day triple therapy (VAM) in comparison to PPI-based (PAM) as a second-line treatment for the eradication of Helicobacter pylori in Japan. Methods We performed a non-randomized, multi-center, parallel-group study to compare first-line VAC to PAC and second-line VAM to PAM. A pre-planned subgroup analysis on CAM resistance was also performed. Safety was evaluated with an adverse effects questionnaire (AEQ), which was completed by patients during therapy. Results The first-line eradication rates (ER) in the intention-to-treat (ITT) and per protocol (PP) analyses were 84.9% (95% CI: 81.9-87.6%, n=623) and 86.4% (83.5-89.1%, n=612), respectively, for VAC and 78.8% (75.3-82.0%, n=608) and 79.4% (76.0-82.6%, n=603), respectively, for PAC. The ER of VAC was higher than that of PAC in the ITT (p=0.0061) and PP analyses (p=0.0013). The ERs for VAC in patients with CAM-resistant and CAM-susceptible bacteria were 73.2% (59.7-84.2%, n=56) and 88.9% (83.4-93.1%, n=180), respectively. PAC was associated with higher AEQ scores for diarrhea, nausea, headache, and general malaise. In the second-line ITT and PP analyses VAM achieved ERs of 80.5% (74.6-85.6%, n=216) and 82.4% (76.6-87.3%, n=211), respectively, while PAM achieved ERs of 81.5% (74.2-87.4%, n=146) and 82.1% (74.8-87.9%, n=145), respectively. No significant differences were observed in the ITT (p=0.89) or PP (p=1.0) analyses. Conclusion The ER of first-line VAC was higher than that of PAC, but still <90%. No difference was observed between second-line VAM and PAM. Vonoprazan-based triple therapy was safe and well tolerated.

Vonoprazan-Based Regimen Is More Useful than PPI-Based One as a First-Line Helicobacter pylori Eradication: A Randomized Controlled Trial

Background. A new agent, potassium-competitive acid blocker vonoprazan (VPZ) has potent acid-inhibitory effects and may offer advantages over conventional H. pylori eradication therapies. We aimed to compare the eradication rate between VPZ-based treatment and PPI-based one. Methods. This randomized controlled trial was designed to assign 141 patients with H. pylori-positive gastritis to VPZ group (VPZ 20 mg, amoxicillin 750 mg, and clarithromycin 200 or 400 mg twice daily for 7 days) or PPI group (rabeprazole 20 mg or lansoprazole 30 mg, amoxicillin 750 mg, and clarithromycin 200 or 400 mg twice daily for 7 days). Primary endpoints were eradication rates and adverse events. Results. Seventy of 72 patients in VPZ group and 63 of 69 patients in PPI group completed the treatment after 7 days. The eradication rate was significantly higher in VPZ group than PPI group by intention-to-treat analysis (95.8% versus 69.6%, P = 0.00003, 95% confidence interval [CI] 88.3-99.1% versus 57.3-80.1%) and per-protocol analysis (95.7% versus 71.4%, P = 0.0002, 95% CI 88.0-99.1% versus 58.7-82.1%). The incidence of adverse events was not different between the groups (26.3% in VPZ group versus 37.7% in PPI group, P = 0.15). Conclusion. VPZ-based regimen is more useful than that PPI-based regimen as a first-line H. pylori eradication therapy.

Evaluation of the Efficacy and Safety of Vonoprazan in Patients with Nonerosive Gastroesophageal Reflux Disease: A Phase III, Randomized, Double-Blind, Placebo-Controlled, Multicenter Study

BACKGROUND

For many patients, current treatments do not adequately resolve heartburn in nonerosive reflux disease (NERD).

OBJECTIVE

To compare vonoprazan and placebo with respect to the frequency and severity of heartburn in patients with NERD.

METHODS

This Phase III, double-blind, placebo-controlled, parallel-group, multicenter study included patients in Japan aged ≥20 years with Grade N or M NERD and recurrent acid reflux symptoms. Patients were blinded and randomized 1:1:1 to receive placebo or vonoprazan 10 mg or 20 mg. The primary efficacy outcome was the proportion of days without heartburn measured by patient scores during the 4-week treatment period.

RESULTS

Eight hundred twenty-seven patients were randomized (placebo: n = 278, vonoprazan 10 mg: n = 278, and vonoprazan 20 mg: n = 271). Median proportion of days without heartburn was 7.4% (placebo), 10.3% (vonoprazan 10 mg), and 12.0% (vonoprazan 20 mg). Proportion of days without heartburn was not statistically significant between the vonoprazan and placebo groups (P = 0.2310 [10 mg] and P = 0.0504 [20 mg]). Mean severity of heartburn was significantly higher with placebo (median score = 1.070) than with vonoprazan 10 mg (median score = 0.990; P = 0.0440) and 20 mg (median score = 0.960; P = 0.0139). Patients whose symptoms improved at Week 2 experienced significantly increased proportion of days without heartburn and reduced mean severity of heartburn at Week 4 with vonoprazan compared with placebo (proportion of days without heartburn: P = 0.0004 [10 mg] and P = 0.0001 [20 mg] and mean severity: P < 0.0001 [10 mg] and P < 0.0001 [20 mg]). A significant difference in median proportion of days without heartburn was observed for vonoprazan 20 mg compared with placebo in patients with Grade M NERD. Incidence of treatment-emergent adverse events was 32.7% (placebo), 27.7% (vonoprazan 10 mg), and 28.0% (vonoprazan 20 mg).

CONCLUSIONS

Vonoprazan at doses of 10 mg and 20 mg are not superior to placebo with respect to proportion of days without heartburn, whereas the mean severity of heartburn is lower with vonoprazan compared with placebo in patients with NERD. ClinicalTrials.gov identifier: NCT01474369.

The First-in-Class Potassium-Competitive Acid Blocker, Vonoprazan Fumarate: Pharmacokinetic and Pharmacodynamic Considerations

Vonoprazan fumarate (Takecab) is a first-in-class potassium-competitive acid blocker that has been available in the market in Japan since February 2015. Vonoprazan is administered orally at 20 mg once daily for the treatment of gastroduodenal ulcer, at 20 and 10 mg once daily for the treatment and secondary prevention of reflux esophagitis, respectively, at 10 mg once daily for the secondary prevention of low-dose aspirin- or non-steroidal anti-inflammatory drug-induced peptic ulcer, and at 20 mg twice daily in combination with clarithromycin and amoxicillin for the eradication of Helicobacter pylori. It inhibits H(+),K(+)-ATPase activities in a reversible and potassium-competitive manner with a potency of inhibition approximately 350 times higher than the proton pump inhibitor, lansoprazole. Vonoprazan is absorbed rapidly and reaches maximum plasma concentration at 1.5-2.0 h after oral administration. Food has minimal effect on its intestinal absorption. Oral bioavailability in humans remains unknown. The plasma protein binding of vonoprazan is 80% in healthy subjects. It distributes extensively into tissues with a mean apparent volume of distribution of 1050 L. Being a base with pKa of 9.6 and with acid-resistant properties, vonoprazan is highly concentrated in the acidic canaliculi of the gastric parietal cells and elicited an acid suppression effect for longer than 24 h after the administration of 20 mg. The mean apparent terminal half-life of the drug is approximately 7.7 h in healthy adults. Vonoprazan is metabolized to inactive metabolites mainly by cytochrome P450 (CYP)3A4 and to some extent by CYP2B6, CYP2C19, CYP2D6, and SULT2A1. A mass balance study showed that 59 and 8% of the orally administered radioactivity was recovered in urine as metabolites and in an unchanged form, respectively, indicating extensive metabolism. Genetic polymorphism of CYP2C19 may influence drug exposure but only to a clinically insignificant extent (15-29%), according to the population pharmacokinetic study performed in Japanese patients. When vonoprazan was co-administered with clarithromycin, the mean AUC from time 0 to time of the next dose (dosing interval) of vonoprazan and clarithromycin were increased by 1.8 and 1.5 times, respectively, compared with the corresponding control values, indicating mutual metabolic inhibition. The mean area under the curve from time zero to infinity obtained from patients with severe liver and renal dysfunction were elevated by 2.6 and 2.4 times, respectively, compared with healthy subjects, with no significant changes in plasma protein binding. Vonoprazan increases intragastric pH above 4.0 as early as 4 h after an oral dose of 20 mg, and the extensive anti-secretory effect is maintained up to 24 h post-dose. During repeated dosing of 20 mg once daily, the 24-h intragastric pH >4 holding time ratios were 63 and 83 % on days 1 and 7, respectively. Because vonoprazan elicited a more extensive gastric acid suppression than the proton pump inhibitor, lansoprazole, it also gave rise to two to three times greater serum gastrin concentrations as compared with lansoprazole. In pre-approval clinical studies for the treatment of acid-related disorders, mild to moderate adverse drug reactions (mostly constipation or diarrhea) occurred at frequencies of 8-17%. Neither severe liver toxicity nor neuroendocrine tumor has been reported in patients receiving vonoprazan.

Efficacy of a potassium-competitive acid blocker for improving symptoms in patients with reflux esophagitis, non-erosive reflux disease, and functional dyspepsia

The aim of the present study was to investigate the efficacy of a potassium-competitive acid blocker (PCAB) named vonoprazan (VPZ) for improving symptoms in patients with reflux esophagitis (RE), non-erosive reflux disease (NERD), and functional dyspepsia (FD). A hospital-based, retrospective study of outpatients in our department (Department of Gastroenterology, University of Juntendo, Tokyo, Japan) between March 2015 and August 2016 was performed. The patients who were experiencing heartburn, acid regurgitation, gastric pain, and/or a heavy feeling in the stomach of at least moderate severity at baseline were treated with 20 mg VPZ once daily for 4 weeks. The patients completed the global overall symptom (GOS) scale to determine their symptom severity at baseline and after the 4 week treatment period. The proportions of patients with RE, NERD, and FD achieving improvement of their symptoms, defined as a GOS scale score of 1 ('no problem') or 2 ('minimal problem'), were evaluated. During 4 weeks of VPZ therapy, changes in the gastroesophageal reflux disease (GERD) score, which was defined as the total points for heartburn and acid regurgitation on the GOS scale in patients with RE and NERD, and in the FD score, which was defined as the total points for gastric pain and a heavy feeling in the stomach on the GOS scale in patients with FD, were also evaluated. A total of 88 eligible cases were included in the present study, comprising 20 patients with RE, 25 patients with NERD, and 43 patients with FD. The rates of symptomatic improvement in patients with RE, NERD, and FD were 75.0, 60.0, and 48.8%, respectively. For the patients who were first administered VPZ, the rates of symptomatic improvement were 90.9, 66.7, and 58.8% in patients with RE, NERD, and FD, respectively. For those patients who were resistant to 8 weeks of proton pump inhibitor therapy, the rates of symptomatic improvement were 55.6, 53.8, and 42.3% in patients with RE, NERD, and FD, respectively. The GERD score in patients with RE and NERD, and the FD score in FD patients, were decreased after 4 weeks of VPZ therapy (P<0.01). In patients with RE, NERD and FD, the possibility that PCAB may be used as a novel therapeutic drug was suggested. However, the number of study subjects was small; therefore, further, larger and prospective studies are required.

Inhibiting the proton pump: mechanisms, benefits, harms, and questions

Inhibition of the H⁺/K⁺-adenosine triphosphatase (the proton pump) is the final common mechanistic pathway in reducing gastric acid secretion pharmacologically. Proton pump inhibitors are widely used in upper gastrointestinal diseases, including gastric and duodenal ulcers, eradication of Helicobacter pylori in combination with antibiotics, gastroesophageal reflux disease, Zollinger-Ellison syndrome, eosinophilic esophagitis, and prevention of non-steroidal anti-inflammatory drug-induced peptic ulceration. Reviewing their benefits and harms in BMC Medicine, Scarpignato et al. report effectiveness in these conditions, and harms that are generally mild and uncommon (1-3 %). Serious adverse reactions, such as tubulointerstitial nephritis, are rare. However, the risks of gastric and pancreatic cancer are unclear. Drug-drug interactions can occur through effects on P glycoprotein and cytochrome P450 (CYP) isoenzymes. Several questions remain. Do all proton pump inhibitors carry the same risks of serious adverse reactions? Which individuals are most susceptible? What are the time courses of individual reactions? What monitoring strategies are best? New drugs for the same indications continue to emerge, including potassium-competitive acid blockers, inhibitors of transient lower esophageal sphincter relaxation, serotonergic agents/prokinetics, mucosal protectants, histamine H₃ receptor agonists, anti-gastrin agents, and esophageal pain modulators. Their benefit to harm balance remains to be discovered.Please see related article: https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-016-0718-z.

Usefulness of vonoprazan, a potassium ion-competitive acid blocker, for primary eradication of Helicobacter pylori

AIM

To investigate usefulness of triple therapy with vonoprazan, a potassium ion-competitive acid blocker and antibiotics, for Helicobacter pylori (H. pylori) eradication.

METHODS

The H. pylori eradication rate was examined in 2507 patients (2055 undergoing primary eradication and 452 undergoing secondary eradication, excluding patients with subtotal gastrectomy) at the Japanese Red Cross Kyoto Daiichi Hospital from March 2013 to September 2015. For patients treated from March 2013 to February 2015, a proton pump inhibitor (PPI) was used to reduce acid secretion, while vonoprazan was used after March 2015. The success rates of the 2 regimens (PPI + amoxicillin + clarithromycin/metronidazole, or vonoprazan + amoxicillin + clarithromycin/metronidazole) were compared.

RESULTS

The success rate of primary H. pylori eradication was significantly higher in the vonoprazan group. When stratified by the underlying disease, a significant increase of the H. pylori eradication rate was observed in patients with chronic gastritis. A significantly lower H. pylori eradication rate was observed in younger patients compared to older patients in the PPI group, but there was no difference according to age in the vonoprazan group. On the other hand, the success rate of secondary eradication was similar at approximately 90% in both groups.

CONCLUSION

Vonoprazan is very useful for primary eradication of H. pylori, and may become a first-line acid secretion inhibitor instead of PPIs.

Vonoprazan-based therapy for Helicobacter pylori eradication: experience and clinical evidence

Stable suppression of gastric acid secretion is a crucial factor in Helicobacter pylori eradication. Vonoprazan is a potassium-competitive acid blocker recently approved for use in Japan. As vonoprazan has a long duration of action and causes rapid and strong inhibition of gastric acid secretion, it has gained clinical attention for treating erosive oesophagitis, peptic ulcers, and H. pylori infection. In this review, we discuss the recent knowledge regarding the safety and efficacy of vonoprazan, focusing on its use in H. pylori eradication. The latest literature and our clinical experience have shown that vonoprazan-based therapies have satisfactory eradication rates. Additionally, vonoprazan-based therapies are associated with similar rates of adverse events as standard triple therapies with conventional proton-pump inhibitors.

Helicobacter pylori Eradication with Proton Pump Inhibitors or Potassium-Competitive Acid Blockers: The Effect of Clarithromycin Resistance

BACKGROUND

Vonoprazan is a novel potassium-competitive acid blocker (P-CAB) recently approved for Helicobacter pylori eradication therapy in Japan.

AIMS

To compare PPI- and P-CAP-containing triple therapy and vonoprazan-based triple therapy.

METHODS

Two hundred ninety-five initial subjects received a PPI-containing triple therapy; the next 125 subjects received vonoprazan-containing triple therapy. Two sequential groups received 7-day eradication regimens consisting of amoxicillin 750 mg, clarithromycin 200 mg both twice a day with standard dose PPI or vonoprazan (20 mg) each twice daily. H. pylori eradication was confirmed by a 13C-UBT. Clarithromycin susceptibility was evaluated by 23S rRNA PCR.

RESULTS

Population cure rates with clarithromycin susceptible strains were 89.6 versus 100 % for PPI and vonoprazan therapies, respectively. Cure rates with resistant strains were 40.2 % with PPI therapy versus 76.1 % with vonoprazan triple therapy. There was no difference in side effects.

CONCLUSIONS

Although 7-day P-CAB triple therapy was superior to 7-day PPI triple therapy, neither was highly effective, or can be recommended, in the presence of clarithromycin-resistant infections.

Pharmacokinetics and Safety of Triple Therapy with Vonoprazan, Amoxicillin, and Clarithromycin or Metronidazole: A Phase 1, Open-Label, Randomized, Crossover Study

INTRODUCTION

Vonoprazan (TAK-438) is a novel potassium-competitive acid blocker that inhibits gastric H(+), K(+)-ATPase. The objectives of this study were to evaluate the influence of triple therapy with vonoprazan-amoxicillin-clarithromycin or vonoprazan-amoxicillin-metronidazole on the pharmacokinetics of each component of the triple therapies (primary) and to evaluate the safety and tolerability of vonoprazan-based triple therapies (secondary) in healthy adults.

METHODS

In this single-center, phase 1, open-label, randomized, four-way crossover study, Helicobacter pylori-negative, healthy Japanese male subjects were randomly assigned to 1 of 4 treatment sequences in two cohorts (12 subjects per cohort). Each treatment sequence comprised four treatment periods separated by a washout period of 7 or 14 days. Pharmacokinetic parameters for vonoprazan, amoxicillin, clarithromycin and metronidazole in single therapy or triple therapies were assessed. All adverse events were recorded.

RESULTS

Compared with single therapy, triple therapy with vonoprazan-amoxicillin-clarithromycin increased the area under the plasma concentration-time curve from time 0-12 h (AUC0-12) and maximum plasma concentration (C max) of plasma vonoprazan free base by 1.846- and 1.868-fold, respectively, and increased the AUC0-12 and C max of plasma clarithromycin by 1.450- and 1.635-fold, respectively. Triple therapy with vonoprazan-amoxicillin-metronidazole had no influence on the pharmacokinetics of vonoprazan or metronidazole. The pharmacokinetics of amoxicillin was not influenced by vonoprazan-based triple therapies. Seven adverse events were reported. Two subjects discontinued because of an adverse event (rash, liver function test abnormal); both events were considered to be study drug-related.

CONCLUSION

In healthy Japanese male subjects, triple therapy with vonoprazan-amoxicillin-clarithromycin increased vonoprazan and clarithromycin exposure. The safety and tolerability profile of triple therapy with vonoprazan-amoxicillin-clarithromycin or vonoprazan-amoxicillin-metronidazole was favorable in this population.

FUNDING

Takeda Pharmaceutical Company Ltd.

TRIAL REGISTRATION

JapicCTI-153102.

Vonoprazan, a novel potassium-competitive acid blocker, as a component of first-line and second-line triple therapy for Helicobacter pylori eradication: a phase III, randomised, double-blind study

OBJECTIVE

The objective of this study was to assess the efficacy, safety and tolerability of vonoprazan, a novel potassium-competitive acid blocker, as a component of Helicobacter pylori eradication therapy.

DESIGN

A randomised, double-blind, multicentre, parallel-group study was conducted to verify the non-inferiority of vonoprazan 20 mg to lansoprazole 30 mg as part of first-line triple therapy (with amoxicillin 750 mg and clarithromycin 200 or 400 mg) in H pylori-positive patients with gastric or duodenal ulcer history. The first 50 patients failing first-line therapy with good compliance also received second-line vonoprazan-based triple therapy (with amoxicillin 750 mg and metronidazole 250 mg) as an open-label treatment.

RESULTS

Of the 650 subjects randomly allocated to either first-line triple therapy, 641 subjects completed first-line therapy and 50 subjects completed second-line therapy. The first-line eradication rate (primary end point) was 92.6% (95% CI 89.2% to 95.2%) with vonoprazan versus 75.9% (95% CI 70.9% to 80.5%) with lansoprazole, with the difference being 16.7% (95% CI 11.2% to 22.1%) in favour of vonoprazan, thus confirming the non-inferiority of vonoprazan (p<0.0001). The second-line eradication rate (secondary end point) was also high (98.0%; 95% CI 89.4% to 99.9%) in those who received second-line therapy (n=50). Both first-line triple therapies were well tolerated with no notable differences. Second-line triple therapy was also well tolerated.

CONCLUSION

Vonoprazan is effective as part of first-line triple therapy and as part of second-line triple therapy in H pylori-positive patients with a history of gastric or duodenal ulcer.

TRIAL REGISTRATION NUMBER

NCT01505127.

Potassium-competitive acid blockers: Advanced therapeutic option for acid-related diseases

Acid-related diseases (ARDs), such as peptic ulcers and gastroesophageal reflux disease, represent a major health-care concern. Some major milestones in our understanding of gastric acid secretion and ARD treatment reached during the last 50years include 1) discovery of histamine H₂-receptors and development of H₂-receptor antagonists, 2) identification of H⁺,K⁺-ATPase as the parietal cell proton pump and development of proton pump inhibitors (PPIs), and 3) identification of Helicobacter pylori (H. pylori) as the major cause of peptic ulcers and development of effective eradication regimens. Although PPI treatments have been effective and successful, there are limitations to their efficacy and usage, i.e. short half-life, insufficient acid suppression, slow onset of action, and large variation in efficacy among patients due to CYP2C19 metabolism. Potassium-competitive acid blockers (P-CABs) inhibit H⁺,K⁺-ATPase in a reversible and K⁺-competitive manner, and exhibit almost complete inhibition of gastric acid secretion from the first dose. Many pharmaceutical companies have tried to develop P-CABs, but most of their clinical development has been discontinued due to safety concerns or a similar efficacy to PPIs. Revaprazan was developed in Korea and was the first P-CAB approved for sale. Vonoprazan, approved in 2014 in Japan, has a completely different chemical structure and higher pKa value compared to other P-CABs, and exhibits rapid onset of action and prolonged control of intragastric acidity. Vonoprazan is an effective treatment for ARDs that is especially effective in healing reflux esophagitis and for H. pylori eradication. P-CABs, such as vonoprazan, promise to further improve the management of ARDs.

The Efficacy and Tolerability of a Triple Therapy Containing a Potassium-Competitive Acid Blocker Compared With a 7-Day PPI-Based Low-Dose Clarithromycin Triple Therapy

OBJECTIVES

This study evaluated the efficacy and tolerability of potassium-competitive acid blocker (P-CAB), a new class of gastric acid inhibitory agents, as first-line H. pylori eradication treatment compared with 7-day proton pump inhibitor (PPI)-based triple therapy.

METHODS

We retrospectively reviewed the medical records of 661 consecutive patients who received first-line H. pylori eradication treatment between January 2013 and October 2015. Patients who received 7-day P-CAB therapy (vonoprazan 20 mg+amoxicillin 750 mg+clarithromycin 200 mg twice/day; n=181) were compared with those who received 7-day PPI therapy (lansoprazole 30 mg/rabeprazole 20 mg+amoxicillin 750 mg+clarithromycin 200 mg twice/day; n=480) using propensity score matching analysis. The successful eradication and adverse event rates were compared between the two groups.

RESULTS

The propensity score matching analysis yielded 175 matched pairs. Adjusted comparisons between the two groups showed a significantly higher eradication rate for the P-CAB than the PPI group in both intention-to-treat (89.1 vs. 70.9%; P<0.001) and per-protocol analyses (91.2 vs. 71.7%; P<0.001). There was no significant difference in the incidence of adverse events between the two therapies except skin rash. No patients discontinued H. pylori eradication treatment because of adverse events.

CONCLUSIONS

Seven-day P-CAB-based triple therapy was more effective than 7-day PPI-based triple therapy as a first-line H. pylori eradication treatment. Seven-day P-CAB-based triple therapy was generally well-tolerated.

Radiographic Localization Study of a Novel Potassium-Competitive Acid Blocker, Vonoprazan, in the Rat Gastric Mucosa

BACKGROUND

Vonoprazan fumarate (TAK-438) is a novel potassium-competitive acid blocker that appears to exert a longer/more potent antisecretory effect than lansoprazole due to high accumulation/slow clearance from the gastric glands. However, there is no direct evidence that vonoprazan selectively accumulates in gastric parietal cells of gastric glands.

AIM

To investigate the distribution of radioactivity in the rat stomach after single intravenous administration of [(3)H]-labeled vonoprazan.

METHODS/RESULTS

Autoradioluminography of the stomach revealed that at 5 h after administration, radioactivity levels in the corpus mucosal layer was higher than radioactivity levels in the muscular layer, pylorus, and forestomach. At 24 h, although overall radioactivity was significantly decreased, the highest radioactivity was still observed in the mucosal layer. Accumulation of radioactivity in gastric parietal cells was quantitatively analyzed using microautoradiography. The number of silver granules in parietal cells from vonoprazan-injected rats was higher than in cells from a saline-injected rat. At 24 h, the number of granules was approximately at 20 % of the number of granules at 5 h. There was no clear deposition of granules in other components. At 5 h, radioactivity was measured at 1.799 µg Eq/g in the stomach and 0.172 µg Eq/mL in plasma. After 24 h, radioactivity had decreased to 0.584 µg Eq/g in the stomach and 0.078 µg Eq/mL in plasma.

CONCLUSIONS

Vonoprazan selectively accumulates in gastric parietal cells in the mucosal layer of the rat stomach after intravenous administration.

Potent acid inhibition by vonoprazan in comparison with esomeprazole, with reference to CYP2C19 genotype

BACKGROUND

Acid inhibitory effects of proton pump inhibitors (PPIs) are influenced by CYP2C19 genotype. In contrast, the potent acid inhibition of vonoprazan is not influenced by CYP2C19 genotype.

AIM

To compare the acid inhibitory effects of vonoprazan and esomeprazole in relation to CYP2C19 genotype.

METHODS

Twenty-eight healthy Japanese volunteers [7 CYP2C19 poor metabolisers (PMs), 11 intermediate metabolisers (IMs) and 10 rapid metabolisers (RMs)] received four different regimens in a randomised crossover manner: (i) vonoprazan 20 mg twice daily (b.d.), (ii) vonoprazan 20 mg daily, (iii) esomeprazole 20 mg b.d. and (iv) esomeprazole 20 mg daily. The timing of each dosing was 1 h before a meal. Twenty-four-hour intragastric pH monitoring was performed on day 7 on each regimen.

RESULTS

In the overall genotype group, pH ≥4 holding time ratios (pH 4 HTRs) with vonoprazan b.d., vonoprazan daily, esomeprazole b.d. and esomeprazole daily were 100%, 95%, 91%, and 68% respectively. pH 5 HTRs were 99%, 91%, 84% and 54% respectively. Vonoprazan b.d. potently suppressed acid for 24 h, and was significantly superior to other regimens irrespective of CYP2C19 genotype. Vonoprazan daily was equivalent to esomeprazole b.d. in IMs and PMs, but superior in RMs. CYP2C19 genotype-dependent differences were observed in esomeprazole daily but not in vonoprazan b.d. or daily.

CONCLUSION

Vonoprazan 20 mg b.d. inhibits acid irrespective of CYP2C19 genotype, more potently than esomeprazole 20 mg b.d., pH 4 and 5 holding time ratios reached 100% and 99%, respectively.

Factors associated with healing of artificial ulcer after endoscopic submucosal dissection with reference to Helicobacter pylori infection, CYP2C19 genotype, and tumor location: Multicenter randomized trial

BACKGROUND AND AIM

Healing speed of peptic ulcer is affected by a number of factors, including Helicobacter pylori (H. pylori) infection and intragastric pH. Acid inhibition exerted by proton pump inhibitors differs by CYP2C19 genotype. Herein, we investigated whether healing speed of artificial ulcers formed after endoscopic submucosal dissection (ESD) was influenced by H. pylori infection, CYP2C19 genotype, or other factors.

METHODS

A total of 96 H. pylori-positive patients with gastric tumors scheduled for ESD were randomly assigned to receive eradication therapy for H. pylori before ESD (pre-ESD eradication) (n = 44) or after (post-ESD eradication) (n = 52). Patients received eradication therapy consisting of lansoprazole 30 mg, amoxicillin 750 mg, and clarithromycin 200 mg twice daily for 1 week. After ESD, lansoprazole 30 mg was given once daily for 8 weeks. Ulcer size was endoscopically measured on the next day and at 4 and 8 weeks after ESD.

RESULTS

Mean reduction rate of artificial ulcer area in the pre-ESD eradication group was 94.7% ± 5.5% at 4 weeks, which was similar to that in the post-ESD eradication group (94.7% ± 6.7%, P = 0.987), irrespective of CYP2C19 genotype. In multivariate analyses, location of gastric tumor (middle and upper, odds ratio: 4.05, 95% CI: 1.620-10.230, P = 0.003) was a factor for 97% reduction of artificial ulcer area at 4 weeks post-ESD, but CYP2C19 genotype and H. pylori infection were not.

CONCLUSION

Healing speed of ESD-induced artificial ulcer was affected by tumor location, but not by time of H. pylori eradication, resected size, or CYP2C19 genotype.

A validated simultaneous quantification method for vonoprazan (TAK-438F) and its 4 metabolites in human plasma by the liquid chromatography-tandem mass spectrometry

Vonoprazan fumarate (TAK-438) is a potassium-competitive acid blocker which was approved in Japan for a treatment of acid-related diseases. In this study a simple and validated bioanalytical method, which can simultaneously determine vonoprazan (TAK-438F) and its four metabolites (M-I, M-II, M-III and M-IV-Sul) in human plasma, was developed. The method is based on protein precipitation and subsequent ultra-high performance liquid chromatography separation followed by tandem mass spectrometry detection. The mass spectrometric parameters for detection of TAK-438F, M-I, M-III and M-IV-Sul were modified from their optimum values in order to achieve a simultaneous quantification while retaining enough sensitivity and wide dynamic ranges for all the target analytes. The validity and robustness of the method was verified through a validation study as per the regulatory guidance on bioanalytical method validation. The calibration ranges are 0.1-100 ng/mL for TAK-438F and M-III, and 1-1000 ng/mL for M-I, M-II and M-IV-Sul using the 100 μL of human plasma. The total run time per sample is 5 min. The working solution for M-III was recommended to be prepared separately, especially for the long-term use, in order to avoid the instability of M-III in the mixed working solutions, which could cause the high consumption of reference standards. The established method was applied to clinical pharmacokinetic studies and concentrations of all the analytes in human plasma were successfully determined with high reproducibility ensured by incurred sample reanalysis, indicating the suitableness of the established method.

Randomised clinical trial: vonoprazan, a novel potassium-competitive acid blocker, vs. lansoprazole for the healing of erosive oesophagitis

BACKGROUND

Vonoprazan is a novel potassium-competitive acid blocker which may provide clinical benefit in acid-related disorders.

AIM

To verify the non-inferiority of vonoprazan vs. lansoprazole in patients with erosive oesophagitis (EE), and to establish its long-term safety and efficacy as maintenance therapy.

METHODS

In this multicentre, randomised, double-blind, parallel-group comparison study, patients with endoscopically confirmed EE (LA Classification Grades A-D) were randomly allocated to receive vonoprazan 20 mg or lansoprazole 30 mg once daily after breakfast. The primary endpoint was the proportion of patients with healed EE confirmed by endoscopy up to week 8. In addition, subjects who achieved healed EE in the comparison study were re-randomised into a long-term study to investigate the safety and efficacy of vonoprazan 10 or 20 mg as maintenance therapy for 52 weeks.

RESULTS

Of the 409 eligible subjects randomised, 401 completed the comparison study, and 305 entered the long-term maintenance study. The proportion of patients with healed EE up to week 8 was 99.0% for vonoprazan (203/205) and 95.5% for lansoprazole (190/199), thus verifying the non-inferiority of vonoprazan (P < 0.0001). Vonoprazan was also effective in patients with more severe EE (LA Classification Grades C/D) and CYP2C19 extensive metabolisers. In the long-term maintenance study, there were few recurrences (<10%) of EE in patients treated with vonoprazan 10 or 20 mg. Overall, vonoprazan was well-tolerated.

CONCLUSIONS

The non-inferiority of vonoprazan to lansoprazole in EE was verified in the comparison study, and vonoprazan was well-tolerated and effective during the long-term maintenance study.

The binding selectivity of vonoprazan (TAK-438) to the gastric H+, K+ -ATPase

BACKGROUND

The gastric H(+) ,K(+) -ATPase is the preferred target for acid suppression. Until recently, the only drugs that effectively inhibited this ATPase were the proton pump inhibitors (PPIs). PPIs are acid-activated prodrugs that require acid protection. Once acid-activated, PPIs bind to cysteines of the ATPase, resulting in covalent, long-lasting inhibition. The short plasma half-life of PPIs and continual de novo synthesis of the H(+) ,K(+) -ATPase result in difficulty controlling night-time acid secretion. A new alternative to PPIs is the pyrrolo-pyridine, vonoprazan (TAK-438), a potassium-competitive acid blocker (PCAB) that does not require acid protection. In contrast to other PCABs, vonoprazan has a long duration of action, resulting in 24-h control of acid secretion, a high pKa of 9.37 and high affinity (Ki = 3.0 ηmol/L).

AIM

To determine binding selectivity of vonoprazan for the gastric H(+) ,K(+) -ATPase and to explain its slow dissociation.

METHODS

Gastric gland and parietal cell binding of vonoprazan was determined radiometrically. Molecular modelling explained the slow dissociation of vonoprazan from the H(+) ,K(+) -ATPase.

RESULTS

Vonoprazan binds selectively to the parietal cell, independent of acid secretion. Vonoprazan binds in a luminal vestibule between the surfaces of membrane helices 4, 5 and 6. Exit of the drug to the lumen is hindered by asp137 and asn138 in the loop between TM1 and TM2, which presents an electrostatic barrier to movement of the sulfonyl group of vonoprazan. This may explain its slow dissociation from the H(+) ,K(+) -ATPase and long-lasting inhibition.

CONCLUSION

The binding model provides a template for design of novel potassium-competitive acid blockers.

Randomised clinical trial: a dose-ranging study of vonoprazan, a novel potassium-competitive acid blocker, vs. lansoprazole for the treatment of erosive oesophagitis

BACKGROUND

The potassium-competitive acid blocker vonoprazan (VPZ) has potent acid-inhibitory effects and may offer clinical advantages over conventional therapy for acid-related disorders.

AIM

To investigate the efficacy and safety of VPZ in patients with erosive oesophagitis (EO).

METHODS

In this multicentre, randomised, double-blind, parallel-group, dose-ranging study, patients ≥20 years with endoscopically confirmed EO [Los Angeles (LA) grades A-D] received VPZ 5, 10, 20 or 40 mg, or lansoprazole (LPZ) 30 mg once daily for 8 weeks. The primary endpoint was the proportion of healed EO subjects as shown by endoscopy at week 4.

RESULTS

A total of 732 subjects received VPZ or LPZ. The proportion of healed EO subjects at week 4 was 92.3%, 92.5%, 94.4%, 97.0% and 93.2%, respectively, with VPZ 5, 10, 20 and 40 mg and LPZ 30 mg. All VPZ doses were non-inferior to LPZ when adjusted for baseline LA grades A/B and C/D. Among those with LA grades C/D, the proportions of healed EO subjects were 87.3%, 86.4%, 100%, 96.0% and 87.0%, respectively, with VPZ 5, 10, 20 and 40 mg and LPZ 30 mg. The incidence of adverse events was similar across the groups.

CONCLUSIONS

Vonoprazan was effective and non-inferior to LPZ in healing EO. VPZ 20 mg or higher was highly efficacious for severe EO (LA grades C/D). VPZ was associated with no safety concern during this 8-week study, while there was a dose-dependent increase in serum gastrin. Once-daily VPZ 20 mg is the recommended clinical dose for treating EO.

Acid-inhibitory effects of vonoprazan 20 mg compared with esomeprazole 20 mg or rabeprazole 10 mg in healthy adult male subjects--a randomised open-label cross-over study

BACKGROUND

Proton pump inhibitors (PPIs) are widely used for the treatment of acid-related diseases. Vonoprazan is a member of a new class of acid suppressants; potassium-competitive acid blockers. Vonoprazan may thus be an alternative to PPIs.

AIM

To evaluate efficacy, rapidity and duration of acid-inhibitory effects of vonoprazan vs. two control PPIs, esomeprazole and rabeprazole, in 20 healthy Japanese adult male volunteers with CYP2C19 extensive metaboliser genotype.

METHODS

In this randomised, open-label, two-period cross-over study, vonoprazan 20 mg and esomeprazole 20 mg (Study V vs. E) or rabeprazole 10 mg (Study V vs. R) were orally administered daily for 7 days. Primary pharmacodynamic endpoint was gastric pH over 24 h measured as percentage of time pH ≥3, ≥4 and ≥5 (pH holding time ratios; HTRs) and mean gastric pH.

RESULTS

Acid-inhibitory effect (pH4 HTR) of vonoprazan was significantly greater than that of esomeprazole or rabeprazole on both Days 1 and 7; Day 7 difference in pH4 HTR for vonoprazan vs. esomeprazole was 24.6% [95% confidence interval (CI): 16.2-33.1] and for vonoprazan vs. rabeprazole 28.8% [95% CI: 17.2-40.4]. The Day 1 to Day 7 ratio of 24-h pH4 HTRs was >0.8 for vonoprazan, compared with 0.370 for esomeprazole and 0.393 for rabeprazole. Vonoprazan was generally well tolerated. One vonoprazan subject withdrew due to a rash which resolved after discontinuation.

CONCLUSIONS

This study demonstrated a more rapid and sustained acid-inhibitory effect of vonoprazan 20 mg vs. esomeprazole 20 mg or rabeprazole 10 mg. Therefore, vonoprazan may be a potentially new treatment for acid-related diseases.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single Rising TAK-438 (Vonoprazan) Doses in Healthy Male Japanese/non-Japanese Subjects

OBJECTIVES:

To evaluate safety, tolerability, pharmacokinetics, and pharmacodynamics of TAK-438 (vonoprazan, a potassium-competitive acid blocker) in healthy male subjects.

METHODS:

In two phase I, randomized, double-blind, placebo-controlled, single rising-dose studies, healthy male subjects (Japan N=84; UK N=63) received a single TAK-438 dose (1–120 mg in Japan and 1–40 mg in the UK). Assessments included safety, tolerability, pharmacokinetics, and pharmacodynamics (intragastric pH).

RESULTS:

Plasma concentration–time profiles of TAK-438 at all dose levels showed rapid absorption (median T_max up to 2 h). Estimated mean elimination half-life was up to 9 h. Exposure was slightly greater than dose proportional. No clear difference in TAK-438 pharmacokinetics was observed between Japanese and non-Japanese subjects. Acid suppression was dose dependent and similar in both studies. The 24-h intragastric pH ≥4 holding time ratio with 40 mg TAK-438 was 92% in Japan and 87% in the UK. TAK-438 was well tolerated, with no adverse events reported in Japanese subjects; 10 of 63 UK subjects experienced 12 treatment-emergent adverse events (non-serious). Increases in serum gastrin and pepsinogen I and II concentrations were observed at doses ≥10 mg, but there were no changes in alanine aminotransferase concentrations.

CONCLUSIONS:

Single oral doses of TAK-438 20–120 mg caused rapid, profound, and 24-h suppression of gastric acid secretion in healthy male subjects, regardless of geographical region, and TAK-438 was well tolerated at all doses studied, making it a potential alternative to proton pump inhibitors for the treatment of acid-related disorders.

Randomised clinical trial: safety, tolerability, pharmacokinetics and pharmacodynamics of repeated doses of TAK-438 (vonoprazan), a novel potassium-competitive acid blocker, in healthy male subjects

BACKGROUND

TAK-438 (vonoprazan) is a potassium-competitive acid blocker that reversibly inhibits gastric H(+) , K(+) -ATPase.

AIM

To evaluate the safety, tolerability, pharmacokinetics and pharmacodynamics of TAK-438 in healthy Japanese and non-Japanese men.

METHODS

In two Phase I, randomised, double-blind, placebo-controlled studies, healthy men (Japan N = 60; UK N = 48) received TAK-438 10-40 mg once daily at a fixed dose level for 7 consecutive days. Assessments included safety, tolerability, pharmacokinetics and pharmacodynamics (intragastric pH).

RESULTS

Plasma concentration-time profiles of TAK-438 at all dose levels showed rapid absorption (median Tmax ≤2 h). Mean elimination half-life was up to 9 h. Exposure was slightly greater than dose proportional, with no apparent time-dependent inhibition of metabolism. There was no important difference between the two studies in AUC0-tau on Day 7. TAK-438 caused dose-dependent acid suppression. On Day 7, mean 24-h intragastric pH>4 holding time ratio (HTR) with 40 mg TAK-438 was 100% (Japan) and 93.2% (UK), and mean night-time pH>4 HTR was 100% (Japan) and 90.4% (UK). TAK-438 was well tolerated. The frequency of adverse events was similar at all dose levels and there were no serious adverse events. There were no important increases in serum alanine transaminase activity. Serum gastrin and pepsinogen I and II concentrations increased with TAK-438 dose.

CONCLUSIONS

TAK-438 in multiple rising oral dose levels of 10-40 mg once daily for 7 days was safe and well tolerated in healthy men and caused rapid, profound and sustained suppression of gastric acid secretion throughout each 24-h dosing interval. Clinicaltrials.gov identifiers: NCT02123953 and NCT02141711.

Protonated form: the potent form of potassium-competitive acid blockers

Potassium-competitive acid blockers (P-CABs) are highly safe and active drugs targeting H+,K+-ATPase to cure acid-related gastric diseases. In this study, we for the first time investigate the interaction mechanism between the protonated form of P-CABs and human H+,K+-ATPase using homology modeling, molecular docking, molecular dynamics and binding free energy calculation methods. The results explain why P-CABs have higher activities with higher pKa values or at lower pH. With positive charge, the protonated forms of P-CABs have more competitive advantage to block potassium ion into luminal channel and to bind with H+,K+-ATPase via electrostatic interactions. The binding affinity of the protonated form is more favorable than that of the neutral P-CABs. In particular, Asp139 should be a very important binding site for the protonated form of P-CABs through hydrogen bonds and electrostatic interactions. These findings could promote the rational design of novel P-CABs.

Gastric H+,K+-ATPase

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.

Proton pump inhibitors

Proton pump inhibitors (PPIs) can bind to the proton pump and inhibit it to secrete hydrogen ions. Since currently used PPIs have a short plasma half-life and can interact with other drugs, there is still an urgent need to develop new and interesting PPIs that can overcome these problems. This review summarizes the latest progress in research of PPIs with regard to the mechanism of action, side effects, and interactions with other drugs and provides an update of the status of acid-suppression therapy.

Discovery of a novel pyrrole derivative 1-[5-(2-fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl]-N-methylmethanamine fumarate (TAK-438) as a potassium-competitive acid blocker (P-CAB)

In our pursuit of developing a novel and potent potassium-competitive acid blocker (P-CAB), we synthesized pyrrole derivatives focusing on compounds with low log D and high ligand-lipophilicity efficiency (LLE) values. Among the compounds synthesized, the compound 13e exhibited potent H(+),K(+)-ATPase inhibitory activity and potent gastric acid secretion inhibitory action in vivo. Its maximum efficacy was more potent and its duration of action was much longer than those of proton pump inhibitors (PPIs). Therefore, compound 13e (1-[5-(2-fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl]-N-methylmethanamine fumarate, TAK-438) was selected as a drug candidate for the treatment of gastroesophageal reflux disease (GERD), peptic ulcer, and other acid-related diseases.

Barrett's esophagus: proton pump inhibitors and chemoprevention II

The following on proton pump inhibitors (PPIs) and chemoprevention in relation to Barrett's esophagus includes commentaries on 48-h pH monitoring, pH-impedence, bile acid testing, dyspepsia, long/short segment Barrett's esophagus, nonerosive reflux disease (NERD), functional heartburn, dual-release delivery PPIs, immediate-release PPIs, long-term PPI use, prokinetic agents, obesity, baclofen, nocturnal acid breakthrough, nonsteroidal anti-inflammatory drugs (NSAIDs), and new PPIs.

High-throughput screening of potassium-competitive acid blockers

H(+),K(+)-ATPase is a key enzyme in the process of gastric acid secretion, and proton pump inhibitors (PPIs) have been accepted as one of the most effective treatments for peptic ulcer and gastroesophageal reflux disease. To discover a novel class of PPIs, the authors screened a low-molecular-weight compound library and identified two prospective acid blockers that were pyrrole derivatives. Both compounds inhibited H(+),K(+)-ATPase in a reversible and potassium-competitive manner. These compounds led to the development of TAK-438 (1-[5-(2-fluorophenyl)-1-(pyridin-3-ylsulfonyl)-1H-pyrrol-3-yl]-N-methylmethanamine monofumarate), which is currently undergoing clinical trials as a novel potassium-competitive acid blocker for the treatment of acid-related diseases.