Nizatidine and cisapride increase salivary secretion in rats

Acid Suppressive Drugs

Histamine H₂ receptor antagonists (H₂RAs) suppress gastric acid production by blocking H₂ receptors in parietal cells. Studies have shown that proton pump inhibitors (PPIs) are superior to H₂RAs as a treatment for acid-related disorders, such as peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD). PPIs reduce gastric acid production by irreversibly inhibiting the H⁺/K⁺ ATPase pump, and they also increase gastric emptying. Although PPIs have differing pharmacokinetic properties, each PPI is effective in managing GERD and PUDs. However, PPIs have some limitations, including short plasma half-lives, breakthrough symptoms (especially at night), meal-associated dosing, and concerns associated with long-term PPI use. Potassium-competitive acid blockers (P-CABs) provide more rapid and profound suppression of intragastric acidity than PPIs. P-CABs are non-inferior to lansoprazole in healing erosive esophagitis and peptic ulcers, and may also be effective in improving symptoms in patients with non-erosive reflux disease. Acid suppressive drugs are the most commonly used drugs in clinical practice, and it is necessary to understand the pharmacological properties and adverse effects of each drug.

Glutaraldehyde-crosslinked chitosan-polyethylene oxide nanofibers as a potential gastroretentive delivery system of nizatidine for augmented gastroprotective activity

Nizatidine (NIZ), a histamine H₂-receptor antagonist, is soluble and stable in the stomach, however, it exhibits a short half-life and a rapid clearance. Therefore, chitosan (CS) and polyethylene oxide (PEO) nanofibers (NFs) at different weight ratios were prepared by electrospinning and characterized. The selected uncrosslinked and glutaraldehyde-crosslinked NFs were investigated regarding floating, solid-state characteristics, in vitro release, and in vitro cytotoxicity. The cytoprotective activity against ethanol-induced gastric injury in rats was evaluated through macroscopical, histopathological, immunohistochemical, and oxidative stress examinations. NFs based on 8:2 CS:PEO exhibited the smallest diameter (119.17 ± 22.05 nm) and the greatest mucoadhesion (22.82 ± 3.21 g/cm²), so they were crosslinked with glutaraldehyde. Solid-state characterization indicated polymers interaction, a successful crosslinking, and NIZ dispersion in NFs. Crosslinking maintained swollen mats at pH 1.2 (swelling% = 29.47 ± 3.50% at 24 h), retarded their erosion at pH 6.8 (swelling%= 84.64 ± 4.91% vs. 25.40 ± 0.79% for the uncrosslinked NFs at 24 h), augmented the floating up to 24 h vs. 10 min for the uncrosslinked NFs at pH 1.2 and prolonged the drug release (%drug released ≥ 93% at 24 h vs. 4 and 5 h for the uncrosslinked NFs at pHs 1.2 and 6.8, respectively). The viability of Caco-2 cells ≥ 86.87 ± 6.86% revealed NFs biocompatibility and unreacted glutaraldehyde removal. Crosslinking of 8:2 CS:PEO NFs potentiated the antiulcer activity (38.98 vs. 8.67 for the uncrosslinked NFs) as well as it preserved the gastric wall architecture, COX-2 expression, and oxidative stress markers levels of the normal rats.

The Effect of H2 Receptor Antagonist in Acid Inhibition and Its Clinical Efficacy

The first histamine H₂ receptor antagonists (H₂RAs) were developed in the early 1970s. They played a dominant role in treating peptic ulcer disease and gastroesophageal reflux disease (GERD). H₂RAs block the production of acid by H⁺, K⁺-ATPase at the parietal cells and produce gastric luminal anacidity for varying periods. H₂RAs are highly selective, and they do not affect H1 receptors. Moreover, they are not anticholinergic agents. Sequential development of H₂RAs, proton pump inhibitors (PPIs), and discovery of Helicobacter pylori infection changed the paradigm of peptic ulcer disease with marked decrease of morbidity and mortality. PPIs are known to be the most effective drugs that are currently available for suppressing gastric acid secretion. Many studies have shown its superiority over H₂RAs as a treatment for acid-related disorders, such as peptic ulcer disease, GERD, and Zollinger-Ellison syndrome. However, other studies have reported that PPIs may not be able to render stomach achlorhydric and have identified a phenomenon of increasing gastric acidity at night in individuals receiving a PPI twice daily. These nocturnal acid breakthrough episodes can be eliminated with an addition of H₂RAs at night. The effectiveness of nighttime dose of H₂RA suggests a major role of histamine in nocturnal acid secretion. H₂RAs reduce secretion of gastric acid, and each H₂RA also has specific effects. For instance, nizitidine alleviates not only symptoms of GERD, but also provokes gastric emptying, resulting in clinical symptom improvement of functional dyspepsia. The aim of this paper was to review the characteristics and role of H₂RAs and assess the future strategy and treatment of upper gastrointestinal disease, including acid related disorders.

Effects of mosapride on esophageal functions and gastroesophageal reflux

BACKGROUND AND AIM

A substantial number of patients with gastroesophageal reflux disease show symptomatic resistance to high-dose proton pump inhibitors. In those cases, prokinetics are possible candidates for treatment. The aim of the present study was to determine whether mosapride, a prokinetic agent, stimulates esophageal functions, and prevents acidic and non-acidic gastroesophageal reflux.

METHODS

Normal volunteers (nine and 13 for two experiments, respectively) were enrolled. Salivary secretion, esophageal peristaltic contractions, and resting lower esophageal sphincter pressure with and without mosapride administration were recorded using a cross-over protocol. Post-prandial acidic and non-acidic reflux levels were also recorded.

RESULTS

Mosapride at a standard dose of 15 mg/day did not stimulate salivary secretion or any esophageal motor functions. It also failed to prevent acidic and non-acidic post-prandial gastroesophageal reflux.

CONCLUSIONS

Mosapride at 15 mg/day, a standard dose in Japan, did not change the esophageal motility and salivary secretion in healthy volunteers. Future study on a larger number of individuals with higher dose of mosapride is worthwhile.

Lafutidine, a newly developed antiulcer drug, elevates postprandial intragastric pH and increases plasma calcitonin gene-related peptide and somatostatin concentrations in humans: comparisons with famotidine

Lafutidine, a newly developed histamine H(2)-receptor antagonist, inhibits daytime (i.e., postprandial) as well as nighttime gastric acid secretion in clinical studies. It also has gastroprotective activity that particularly affects mucosal blood flow in rats. This study focused on the efficacy of lafutidine on plasma concentrations of gastrointestinal peptides in humans. Six healthy male volunteers aged 23-32 years without Helicobacter pylori infection were orally administered either 10 mg lafutidine, 20 mg famotidine, or water only (control) 30 min after a standard meal (650 kcal). Plasma concentrations of lafutidine and famotidine were highest from 90 to 150 min after administration. Intragastric pH was elevated after both lafutidine and famotidine compared with the control. Plasma concentrations of calcitonin gene-related peptide (CGRP) and somatostatin were significantly increased after lafutidine at 60 and 90 min. We concluded that lafutidine increases plasma concentrations of CGRP and somatostatin in humans, which may result in inhibition of postprandial acid secretion and gastroprotective activity.

Comparative study of nizatidine and famotidine for maintenance therapy of erosive esophagitis

BACKGROUND

The therapeutic effect of combined administration of prokinetics and histamine H2 receptor antagonists (H2RA) in gastroesophageal reflux disease is reported to be superior to that of monotherapy with H2RA alone. In addition to its acid-suppressing effect, the H2RA nizatidine also has a prokinetic action by suppressing acetylcholine esterase. The present multicenter, randomized controlled study was performed to investigate whether nizatidine is superior to famotidine, which does not suppress acetylcholine esterase activity, in maintenance therapy for erosive esophagitis. In addition, the question as to whether the grade of erosive esophagitis affects the non-recurrence rate during the maintenance therapy with H2RA was also investigated.

METHODS

Seventy-two patients with endoscopically healed erosive esophagitis after 8 weeks of initial treatment with proton pump inhibitors were randomly divided into two groups. Patients in the nizatidine group were treated with 150 mg nizatidine twice a day (b.i.d.), while patients in the famotidine group were treated with 20 mg famotidine b.i.d. for 6 months. At the end of therapy, and at the time when patients complained of symptoms, endoscopic investigations were repeated to find out whether the esophagitis had recurred.

RESULTS

Nizatidine produced a significantly higher non-recurrence rate than famotidine (P = 0.049 in intention-to-treat [ITT] analysis). This difference of remission rate between nizatidine and famotidine was observed mainly in grade B esophagitis (P = 0.016 in ITT analysis).

CONCLUSION

Nizatidine is a more effective H2RA than famotidine in the maintenance therapy of patients with reflux esophagitis.