Validation of a liquid chromatographic-tandem mass spectrometric method for the measurement of (R)-1-[2,3-dihydro-2-oxo-1-pivaloylmethyl-5-(2-pyridyl)-1H-1,4-benzodiazepin-3-yl]-3-(3-methylaminophenyl)urea (YF476) in human plasma

Randomised trial of the effect of a gastrin/CCK2 receptor antagonist on esomeprazole-induced hypergastrinaemia: evidence against rebound hyperacidity

PURPOSE

Hypergastrinaemia induced by proton pump inhibitor (PPI) therapy may cause ECL-cell and parietal-cell hyperplasia and rebound hyperacidity and dyspepsia after PPI withdrawal. The aim of the study was to assess the effect of different dosage-regimens of netazepide, a gastrin/CCK₂ receptor antagonist, on PPI-induced hypergastrinaemia and elevated chromogranin A (CgA).

METHODS

Six groups of eight healthy subjects participated in a randomised, double-blind study of esomeprazole 40 mg daily for 28 days, in combination with netazepide 1, 5 or 25 mg or placebo, daily, during the last 14 days of esomeprazole or during 14 days after treatment withdrawal. Fasting serum gastrin and plasma CgA were measured during treatment and after withdrawal, as biomarkers of acid suppression and ECL-cell activity, respectively. Dyspepsia was monitored throughout the study.

RESULTS

Esomeprazole increased gastrin and CgA. Netazepide increased gastrin, but not CgA, and inhibited dose dependently the CgA response to esomeprazole. Gastrin and CgA returned to baseline within 2-3 days of esomeprazole withdrawal; netazepide did not shorten that time. There was no rebound dyspepsia after esomeprazole withdrawal.

CONCLUSIONS

Esomeprazole and netazepide each increase gastrin, consistent with a secondary effect of gastric acid suppression, but by different mechanisms. Esomeprazole-induced hypergastrinaemia stimulates ECL cells and thereby increases CgA. Netazepide-induced hypergastrinaemia does not increase CgA, because netazepide blocks gastrin/CCK₂ receptors on ECL cells. Co-administration of netazepide 5 mg abolishes the effect of esomeprazole-induced hypergastrinaemia on ECL cells. The quick return to baseline of gastrin and CgA and absence of dyspepsia after esomeprazole withdrawal do not support the concept of rebound hyperacidity.

Effect of netazepide, a gastrin/CCK2 receptor antagonist, on gastric acid secretion and rabeprazole-induced hypergastrinaemia in healthy subjects

AIMS

To compare gastric acid suppression by netazepide, a gastrin/CCK2 receptor antagonist, with that by a proton pump inhibitor (PPI), and to determine if netazepide can prevent the trophic effects of PPI-induced hypergastrinaemia.

METHODS

Thirty healthy subjects completed a double-blind, randomized, parallel group trial of oral netazepide and rabeprazole, alone and combined, once daily for 6 weeks. Primary end points were: basal and pentagastrin-stimulated gastric acid and 24 h circulating gastrin and chromogranin A (CgA) at baseline, start and end of treatment, gastric biopsies at baseline and end of treatment and basal and pentagastrin-stimulated gastric acid and dyspepsia questionnaire after treatment withdrawal.

RESULTS

All treatments similarly inhibited pentagastrin-stimulated gastric acid secretion. All treatments increased serum gastrin, but the combination and rabeprazole did so more than netazepide alone. The combination also reduced basal acid secretion. Rabeprazole increased plasma CgA, whereas netazepide and the combination reduced it. None of the biopsies showed enterochromaffin-like (ECL) cell hyperplasia. Withdrawal of treatments led neither to rebound hyperacidity nor dyspepsia.

CONCLUSIONS

Netazepide suppressed pentagastrin-stimulated gastric acid secretion as effectively as did rabeprazole. The reduction in basal acid secretion and greater increase in serum gastrin by the combination is consistent with more effective acid suppression. Despite our failure to show rabeprazole-induced ECL cell hyperplasia and rebound hyperacidity, the increase in plasma CgA after rabeprazole is consistent with a trophic effect on ECL cells, which netazepide prevented. Thus, netazepide is a potential treatment for the trophic effects of hypergastrinaemia and, with or without a PPI, is a potential treatment for acid-related conditions.

Netazepide, a gastrin/CCK2 receptor antagonist, causes dose-dependent, persistent inhibition of the responses to pentagastrin in healthy subjects

AIMS

To confirm by means of pentagastrin, a synthetic gastrin agonist, that netazepide is a gastrin/CCK2 receptor antagonist in healthy subjects, and that antagonism persists during repeated dosing.

METHODS

We did two studies in which we infused pentagastrin (0.6 μg kg(-1)  h(-1) intravenously), aspirated gastric secretion and measured the volume, pH and H(+) secretion rate of the gastric aspirate. First, we did a double-blind, five-way crossover study (n = 10) to assess the effect of single oral doses of netazepide (1, 5, 25 and 100 mg) and placebo on the response to pentagastrin. Then, we did a single-blind, placebo-controlled study (n = 8) to assess the effect of the first and last oral doses of netazepide (100 mg) twice daily for 13 doses on the response to pentagastrin.

RESULTS

Netazepide was well tolerated. After placebo, pentagastrin increased the volume and H(+) secretion rate and reduced the pH of gastric aspirate. Compared with placebo, single doses of netazepide caused dose-dependent inhibition of the pentagastrin response (P < 0.02); netazepide (100 mg) abolished the response. After 13 doses, the reduction in volume and H(+) secretion rate persisted (P < 0.001), but the pH effect was mostly lost.

CONCLUSIONS

Netazepide is an orally active, potent, competitive antagonist of human gastrin/CCK2 receptors. Antagonism is dose dependent and persists during repeated dosing, despite tolerance to the effect on pH. Further studies are required to explain that tolerance. Netazepide is a tool to study the physiology and pharmacology of gastrin, and merits studies in patients to assess its potential to treat gastric acid-related conditions and the trophic effects of hypergastrinaemia.

Effect of repeated doses of netazepide, a gastrin receptor antagonist, omeprazole and placebo on 24 h gastric acidity and gastrin in healthy subjects

AIM

To administer repeated oral doses of netazepide to healthy subjects for the first time, to assess safety, tolerability, pharmacokinetics and effect on 24 h gastric pH and plasma gastrin.

METHOD

We did two randomized, double-blind, parallel group studies. The first compared netazepide 25 and 100 mg 12 hourly, omeprazole 20 mg once daily and placebo for 7 days. On day 7 only, we measured pH and assayed plasma gastrin. The second study compared netazepide 5, 10 and 25 mg and placebo once daily for 14 days. We measured pH on days 1, 7 and 14 and assayed plasma gastrin on days 1 and 14. We compared treatments by time gastric pH ≥ 4 during 0-4, 4-9, 9-13 and 13-24 h after the morning dose, and by plasma gastrin. P < 0.05 was significant.

RESULTS

Netazepide was well tolerated. On day 7 of the first study, netazepide increased pH significantly only during 9-13 h after the 100 mg dose, whereas omeprazole raised pH significantly during all periods. Both netazepide and omeprazole increased plasma gastrin significantly. Netazepide had linear pharmacokinetics. In the second study, netazepide caused dose-dependent, sustained increases in pH on day 1, but as in the first study, netazepide had little effect on pH on days 7 and 14. Again, netazepide increased plasma gastrin significantly.

CONCLUSION

Although repeated doses of netazepide led to tolerance to its effect on pH, the accompanying increase in plasma gastrin is consistent with continued inhibition of acid secretion, via gastrin receptor antagonism and gene up-regulation.

Netazepide, a gastrin receptor antagonist, normalises tumour biomarkers and causes regression of type 1 gastric neuroendocrine tumours in a nonrandomised trial of patients with chronic atrophic gastritis

INTRODUCTION

Autoimmune chronic atrophic gastritis (CAG) causes hypochlorhydria and hypergastrinaemia, which can lead to enterochromaffin-like (ECL) cell hyperplasia and gastric neuroendocrine tumours (type 1 gastric NETs). Most behave indolently, but some larger tumours metastasise. Antrectomy, which removes the source of the hypergastrinaemia, usually causes tumour regression. Non-clinical and healthy-subject studies have shown that netazepide (YF476) is a potent, highly selective and orally-active gastrin/CCK-2 receptor antagonist. Also, it is effective in animal models of ECL-cell tumours induced by hypergastrinaemia.

AIM

To assess the effect of netazepide on tumour biomarkers, number and size in patients with type I gastric NETs.

METHODS

We studied 8 patients with multiple tumours and raised circulating gastrin and chromogranin A (CgA) concentrations in an open trial of oral netazepide for 12 weeks, with follow-up 12 weeks later. At 0, 6, 12 and 24 weeks, we carried out gastroscopy, counted and measured tumours, and took biopsies to assess abundances of several ECL-cell constituents. At 0, 3, 6, 9, 12 and 24 weeks, we measured circulating gastrin and CgA and assessed safety and tolerability.

RESULTS

Netazepide was safe and well tolerated. Abundances of CgA (p<0.05), histidine decarboxylase (p<0.05) and matrix metalloproteinase-7(p<0.10) were reduced at 6 and 12 weeks, but were raised again at follow-up. Likewise, plasma CgA was reduced at 3 weeks (p<0.01), remained so until 12 weeks, but was raised again at follow-up. Tumours were fewer and the size of the largest one was smaller (p<0.05) at 12 weeks, and remained so at follow-up. Serum gastrin was unaffected.

CONCLUSION

The reduction in abundances, plasma CgA, and tumour number and size by netazepide show that type 1 NETs are gastrin-dependent tumours. Failure of netazepide to increase serum gastrin further is consistent with achlorhydria. Netazepide is a potential new treatment for type 1 NETs. Longer, controlled trials are justified.

TRIAL REGISTRATION

European Union EudraCT database 2007-002916-24 https://www.clinicaltrialsregister.eu/ctr-search/search?query=2007-002916-24ClinicalTrials.gov NCT01339169 http://clinicaltrials.gov/ct2/show/NCT01339169?term=yf476&rank=5.

Treatment of gastric carcinoids type 1 with the gastrin receptor antagonist netazepide (YF476) results in regression of tumours and normalisation of serum chromogranin A

BACKGROUND

Patients with chronic atrophic gastritis have long-term gastric hypoacidity, and secondary hypergastrinaemia. Some also develop gastric ECL cells carcinoids (type 1 GC). Most type 1 GC remain indolent, but some metastasise. Patients undergo surveillance, and some are treated with somatostatin analogues, endoscopic resection or surgery. Netazepide (YF476) is a highly selective, potent and orally active gastrin receptor antagonist, which has anti-tumour activity in various rodent models of gastric neoplasia driven by hypergastrinaemia. Netazepide has been studied in healthy volunteers.

AIM

To assess the effect of netazepide on type 1 GC.

METHODS

Eight patients with multiple type 1 GC received oral netazepide once daily for 12 weeks, with follow-up at 12 weeks in an open-label, pilot trial. Upper endoscopy was performed at 0, 6, 12 and 24 weeks, and carcinoids were counted and measured. Fasting serum gastrin and chromogranin A (CgA) and safety and tolerability were assessed at 0, 3, 6, 9, 12 and 24 weeks.

RESULTS

Netazepide was well tolerated. All patients had a reduction in the number and size of their largest carcinoid. CgA was reduced to normal levels at 3 weeks and remained so until 12 weeks, but had returned to pre-treatment levels at 24 weeks. Gastrin remained unchanged throughout treatment.

CONCLUSIONS

The gastrin receptor antagonist netazepide is a promising new medical treatment for type 1 gastric carcinoids, which appear to be gastrin-dependent. Controlled studies and long-term treatment are justified to find out whether netazepide treatment can eradicate type 1 gastric carcinoids.

Single oral doses of netazepide (YF476), a gastrin receptor antagonist, cause dose-dependent, sustained increases in gastric pH compared with placebo and ranitidine in healthy subjects

BACKGROUND

Nonclinical studies have shown netazepide (YF476) to be a potent, selective, competitive and orally active gastrin receptor antagonist.

AIM

To administer to humans for the first time single oral doses of netazepide, to assess their tolerability, safety, pharmacokinetics and effect on 24-h gastric pH.

METHODS

We did two randomised double-blind single-dose studies in healthy subjects. The first (n = 12) was a six-way incomplete crossover pilot study of rising doses of netazepide (range 0.5-100 mg) and placebo. The second (n = 20) was a five-way complete crossover study of netazepide 5, 25 and 100 mg, ranitidine 150 mg and placebo. In both trials we collected frequent blood samples, measured plasma netazepide and calculated pharmacokinetic parameters. In the comparative trial we measured gastric pH continuously for 24 h and compared treatments by percentage time gastric pH ≥4.

RESULTS

Netazepide was well tolerated. Median t (max) and t (½) for the 100 mg dose were about 1 and 7 h, respectively, and the pharmacokinetics were dose-proportional. Netazepide and ranitidine each increased gastric pH. Onset of activity was similarly rapid for both. All netazepide doses were more effective than placebo (P ≤ 0.023). Compared with ranitidine, netazepide 5 mg was as effective, and netazepide 25 and 100 mg were much more effective (P ≤ 0.010), over the 24 h after dosing. Activity of ranitidine lasted about 12 h, whereas that of netazepide exceeded 24 h.

CONCLUSIONS

In human: netazepide is an orally active gastrin antagonist, and gastrin has a major role in controlling gastric acidity. Repeated-dose studies are justified. NCT01538784 and NCT01538797.

On-Line Solid-Phase Extraction Coupled With High-Performance Liquid Chromatography and Tandem Mass Spectrometry (SPE-HPLC-MS-MS) for Quantification of Bromazepam in Human Plasma

A validated method for on-line solid-phase extraction coupled with high-performance liquid chromatography tandem mass spectrometry (SPE-HPLC-MS-MS) is described for the quantification of bromazepam in human plasma. The method involves a dilution of 300 muL of plasma with 100 muL of carbamazepine (2.5 ng/mL), used as internal standard, vortex-mixing, centrifugation, and injection of 100 muL of the supernate. The analytes were ionized using positive electrospray mass spectrometry then detected by multiple reaction monitoring (MRM). The m/z transitions 316-->182 (bromazepam) and 237-->194 (carbamazepine) were used for quantification. The calibration curve was linear from 1 ng/mL (limit of quantification) to 200 ng/mL. The retention times of bromazepam and carbamazepine were 2.6 and 3.2 minutes, respectively. The intraday and interday precisions were 3.43%-15.45% and 5.2%-17%, respectively. The intraday and interday accuracy was 94.00%-103.94%. This new automated method has been successfully applied in a bioequivalence study of 2 tablet formulations of 6 mg bromazepam: Lexotan(R) from Produtos Roche Químicos e Farmacêuticos SA, Rio de Janeiro, Brazil (reference) and test formulation from Laboratórios Biosintética Ltda, São Paulo, Brazil. Because the 90% CI of geometric mean ratios between reference and test were completely included in the 80%-125% interval, the 2 formulations were considered bioequivalent. The comparison of different experimental conditions for establishing a dissolution profile in vitro along with our bioavailability data further allowed us to propose rationally based experimental conditions for a dissolution test of bromazepam tablets, actually lacking a pharmacopeial monograph.