Lafutidine, a novel histamine H2-receptor antagonist, increases serum calcitonin gene-related peptide in rats after water immersion-restraint stress

Randomized study of lafutidine vs lansoprazole in patients with mild gastroesophageal reflux disease

AIM: To compare the clinical efficacy of the second-generation H2RA lafutidine with that of lansoprazole in Japanese patients with mild gastroesophageal reflux disease (GERD).

METHODS: Patients with symptoms of GERD and a diagnosis of grade A reflux esophagitis (according to the Los Angeles classification) were randomized to receive lafutidine (10 mg, twice daily) or lansoprazole (30 mg, once daily) for an initial 8 wk, followed by maintenance treatment comprising half-doses of the assigned drug for 24 wk. The primary endpoint was the frequency and severity of heartburn during initial and maintenance treatment. The secondary endpoints were the sum score of questions 2 and 3 in the Gastrointestinal Symptom Rating Scale (GSRS), and the satisfaction score.

RESULTS: Between April 2012 and March 2013, a total of 53 patients were enrolled, of whom 24 and 29 received lafutidine and lansoprazole, respectively. After 8 wk, the frequency and severity of heartburn was significantly reduced in both groups. However, lafutidine was significantly inferior to lansoprazole with regard to the severity of heartburn during initial and maintenance treatment (P = 0.016). The sum score of questions 2 and 3 in the GSRS, and satisfaction scores were also significantly worse in the lafutidine group than the lansoprazole group (P = 0.0068 and P = 0.0048, respectively).

CONCLUSION: The clinical efficacy of lafutidine was inferior to that of lansoprazole, even in Japanese patients with mild GERD.

Stimulation of calcitonin gene-related peptide release through targeting capsaicin receptor: a potential strategy for gastric mucosal protection

Calcitonin gene-related peptide (CGRP) is a predominant neurotransmitter from capsaicin-sensitive sensory nerves, which are widely distributed in the gastrointestinal system. These sensory nerves are reported to be involved in the protection of gastric mucosa against damage by various stimuli, and CGRP is a potential mediator in this process. In addition to increase in gastric mucosal blood flow, the beneficial effects of CGRP on gastric mucosa include inhibition of gastric acid secretion, prevention of cellular apoptosis and oxidative injury. The synthesis and release of CGRP is regulated by the capsaicin receptor which is known as transient receptor potential vanilloid subfamily member 1 (TRPV1) and the agonists of TRPV1 have the potential for gastric mucosal protection. So far, multiple TRPV1 agonists, including capsaicin, capsiate, anandamide and rutaecarpine are reported to exert beneficial effects on gastric mucosal injury induced by various stimuli. Therefore, the TRPV1/CGRP pathway represents a novel target for therapeutic intervention in human gastric mucosal injury.

Lafutidine prevents low-dose aspirin and loxoprofen induced gastric injury: a randomized, double-blinded, placebo controlled study

BACKGROUND AND AIM

The concomitant use of non-steroidal anti-inflammatory drugs is a risk factor for low-dose aspirin (LDA)-associated upper gastrointestinal toxicity. Lafutidine is an H2-receptor antagonist with gastroprotective activity, produced by acting on capsaicin-sensitive afferent neurons. To evaluate the preventive effect of lafutidine on gastric damage caused by LDA alone and by the combination of both LDA and loxoprofen, we conducted a clinical study using healthy volunteers.

METHODS

A randomized, double-blinded, placebo-controlled, crossover study was carried out. Sixteen healthy volunteers without Helicobacter pylori infection were randomly assigned to two groups. Both groups received 81 mg of aspirin once daily for 14 days (on days 1 to 14) and 60 mg of loxoprofen three times daily for the last 7 days (on days 8 to 14). Placebo or 10 mg of lafutidine was administered twice daily for 14 days in each group. After a 2-week washout period, placebo and lafutidine were crossed over. Endoscopic findings of gastric mucosal damage were evaluated according to the modified Lanza score.

RESULTS

The mean modified Lanza score was 2.19 ± 1.06 (SD) for aspirin plus placebo as compared with 0.50 ± 0.77 for aspirin plus lafutidine (P < 0.001), and 3.00 ± 1.56 for aspirin plus loxoprofen and placebo as compared with 1.25 ± 1.37 for aspirin plus loxoprofen and lafutidine (P < 0.01).

CONCLUSIONS

The addition of loxoprofen to LDA increases gastric mucosal damage. Standard-dose lafutidine significantly prevents gastric mucosal damage induced by LDA alone or LDA plus loxoprofen in H. pylori-negative volunteers. Larger controlled studies are needed to strengthen these findings.

Effects of a novel histamine H2-receptor antagonist, lafutidine, on the mucus barrier of human gastric mucosa

BACKGROUND AND AIM

Lafutidine is a novel histamine H(2)-receptor antagonist used primarily as an antisecretory agent in Japan. Previous human studies have not assessed its gastroprotective effects. The purpose of the present study was to determine the effects of lafutidine on the human gastric mucus layer using both histological and biochemical methods.

METHODS

Of the 14 patients scheduled for gastrectomy who consented to participate, seven were given 14 days of lafutidine 20 mg/day (lafutidine group) and the others received no medication (control group). The surface mucus gel layer in Carnoy-fixed tissue sections was examined immunohistochemically. Both the thickness of the mucus layer and its mucin content were measured in gastric corpus mucosa.

RESULTS

There was no detectable difference between the groups in the grade of gastritis or the immunohistochemical staining characteristics. The laminated structure of the surface mucus gel layer was retained after administration of lafutidine and it was thicker than the layer in the control group. The surface layer in the lafutidine group had three-fold more mucin than that in the control group. There was no difference between the two groups in the mucin content of the deep mucosa.

CONCLUSION

Lafutidine, given at clinical dosages, not only inhibits acid secretion but also strengthens the mucus barrier of the human gastric mucosa.

Inhibition of neutrophil activation by lafutidine, an H2-receptor antagonist, through enhancement of sensory neuron activation contributes to the reduction of stress-induced gastric mucosal injury in rats

Sensory neuron activation reduces water-immersion restraint stress (WIR)-induced gastric mucosal injury by inhibiting neutrophil activation through increase in endothelial production of prostacyclin. This study was designed to examine whether lafutidine, which is an H(2)-receptor antagonist and activates sensory neurons, inhibits neutrophil activation, thereby reducing WIR-induced gastric mucosal injury. Lafutidine enhanced WIR-induced increases in gastric tissue levels of calcitonin gene-related peptide (CGRP) and 6-keto-PGF(1alpha), a stable metabolite of prostacyclin, whereas famotidine, another H(2)-receptor antagonist, did not. Such lafutidine-induced increases in gastric tissue levels of 6-keto-PGF(1alpha) were reversed by pretreatment with capsazepine, an inhibitor of sensory neuron activation, CGRP(8-37), a CGRP antagonist, and indomethacin. Lafutidine inhibited acid-induced exacerbation of gastric mucosal injury in animals subjected to WIR by inhibiting neutrophil activation, whereas famotidine did not. Lafutidine synergistically increased CGRP release from isolated rat dorsal root ganglion neurons in the presence of anandamide, but famotidine did not. These observations suggest that lafutidine might reduce WIR-induced gastric mucosal injury not only by inhibiting acid secretion but also by inhibiting neutrophil activation through enhancement of sensory neuron activation.

Calcitonin gene-related peptide and somatostatin releases correlated with the area under the lafutidine concentration–time curve in human plasma

OBJECTIVE

To examine the effects of the histamine H(2)-receptor antagonist, lafutidine, at clinical dosage (10 mg tablet after a standardized meal) on plasma levels of the gastrointestinal peptides, calcitonin gene-related peptide (CGRP), somatostatin and gastrin.

METHODS

Six healthy male volunteers ate a standardized meal, and received either lafutidine orally at a dose of 10 mg or water only (control). Blood samples were taken before and up to 4 h after the drug administration. Plasma lafutidine concentrations were determined by high pressure liquid chromatography. Pharmacokinetic analysis of lafutidine was performed using one-compartmental model. The levels of immunoreactive substances of plasma CGRP, somatostatin and gastrin were measured by enzyme immunoassay, and the amount of peptide release was calculated by the trapezoidal method. Lafutidine significantly increased plasma CGRP levels at 1, 1.5, 2.5 and 4 h and the total amount of CGRP release (192 +/- 14.0 pg.h/mL) compared with the control group (128 +/- 21.5 pg.h/mL).

RESULTS

Lafutidine significantly increased the plasma somatostatin levels at 1 and 1.5 h, and the total amount of somatostatin released (107 +/- 18.2 pg.h/mL) compared with the control (78.4 +/- 7.70 pg.h/mL). The area under the drug concentration-time curve (AUC) from 0 to 4 h after administration correlated well with the Delta-CGRP and Delta-somatostatin release but not with total amount of gastrin released. However, plasma gastrin levels were significantly elevated at 1.5 h after drug administration.

CONCLUSION

Lafutidine at clinical dosage increases plasma CGRP and the somatostatin. The amounts released correlated with the AUC of lafutidine in humans. These results suggest that the increased release of CGRP and somatostatin may contribute to its gastroprotective and anti-acid secretory effect.

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.

Roles of histamine and its receptors in allergic and inflammatory bowel diseases

Mast cell has a long history of being recognized as an important mediator-secreting cell in allergic diseases, and has been discovered to be involved in IBD in last two decades. Histamine is a major mediator in allergic diseases, and has multiple effects that are mediated by specific surface receptors on target cells. Four types of histamine receptors have now been recognized pharmacologically and the first three are located in the gut. The ability of histamine receptor antagonists to inhibit mast cell degranulation suggests that they might be developed as a group of mast cell stabilizers. Recently, a series of experiments with dispersed colon mast cells suggested that there should be at least two pathways in man for mast cells to amplify their own activation-degranulation signals in an autocrine or paracrine manner. In a word, histamine is an important mediator in allergic diseases and IBD, its antagonists may be developed as a group of mast cell stabilizers to treat these diseases.

Helicobacter pylori infection prevents the occurrence of the tolerance phenomenon of histamine H2 receptor antagonists

BACKGROUND

The attenuated anti-secretory activity of H2 receptor antagonists (H2RA) during continuous administration is referred to as the tolerance phenomenon. However, it is not clarified whether Helicobacter pylori infection affects the occurrence of tolerance to H2RA. It is also not clarified whether the tolerance phenomenon occurs to a new H2RA, lafutidine.

AIM

To investigate the occurrence of the tolerance phenomenon in subjects with and without H. pylori infection during the continuous administration of lafutidine and famotidine.

SUBJECTS AND METHODS

Subjects were 20 healthy male volunteers (seven H. pylori positive and 13 H. pylori negative cases). All subjects were examined by ambulatory intragastric pH monitoring five times without medication, on the first and 15th day of the administration of 20 mg b.d. famotidine and 10 mg b.d. lafutidine in a cross-over fashion.

RESULTS

The tolerance phenomenon was not observed in H. pylori-positive subjects during the 15-day-long administration of both H2RAs. In contrast, the tolerance phenomenon was observed in H. pylori negative subjects, which has been previously reported.

CONCLUSIONS

This study demonstrated that H. pylori infection affects the tolerance phenomenon during continuous administration of H2RAs.