Preparation, antimicrobial evaluation, and mutagenicity of [2-hydroxyaryl]-[1-methyl-5-nitro-1H-2-imidazolyl]methanols , [5-tert-butyl-2-methylaminophenyl]-[1-methyl-5-nitro-1H-2-imidazo lyl]me thanol, and [2-hydroxyaryl]-[1-methyl-5-nitro-1H-2-imidazolyl] ketones

Efficient preparations of the titled compounds are described, their antimicrobial activity and mutagenic properties being evaluated. Some of the studied compounds are nonmutagenic and present a MIC as low as some of the usual standards in the field.

Chicken ovalbumin upstream-promoter transcription factor (COUP-TF) could act as a transcriptional activator or repressor of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase gene

The chicken ovalbumin upstream-promoter transcription factor (COUP-TF) has a dual effect on the regulation of the mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase gene. COUP-TF could act as a transcriptional activator or repressor of this gene through different DNA sequences. COUP-TF induces expression of a reporter gene linked to the mitochondrial HMG-CoA synthase gene promoter in human hepatoma HepG2 cells, but represses it in a Leydig tumour cell line (R2C); in both these cell lines the expression of the mitochondrial HMG-CoA synthase gene mimics that of liver and testis. The activation is promoted by a fragment of the gene from coordinates -62 to +28, which contains a GC box and a TATA box, and where no COUP-TF binding site was observed by in vitro DNA binding studies. On the other hand, the COUP-TF inhibitory effect is mainly due to repression of peroxisome-proliferator-activated receptor-dependent activation of the gene, interacting with the region from -104 to -92. To our knowledge this work represents the second example of a target gene for COUP-TF I that could be either activated or repressed by the action of this receptor through different DNA sequences of the same gene.

Large B-cell lymphoma of the uterine corpus: case report with immunohistochemical and molecular study

Primary lymphoma of the uterine corpus (PLUC) is an extremely rare neoplasm. We report a case of PLUC in a 78-year-old woman with vaginal bleeding without hepatosplenomegaly, adenopathies, or bone marrow infiltration, classified as stage I. A diagnosis of diffuse large B-cell lymphoma was made in endometrial curettage tissue. Immunohistochemical study showed tumoral cells of B-cell nature. Two different polymerase chain reaction (PCR) techniques showed immunoglobulin heavy chain gene rearrangement and we could not demonstrate, with PCR technique, either Epstein-Barr virus or papilloma virus infection. Total hysterectomy with bilateral salpingo-oophorectomy was carried out and adjuvant chemotherapy was given. She was alive and free of disease after a follow-up period of 7 years, and the patient has been in perfect health.

Carcinogenicity studies on ebrotidine

The results from two carcinogenicity studies on ebrotidine (N-[2-(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) conducted in mice and rats are reported. Oral doses of 50, 200 and 500 mg/kg were administered to mice for 18 months and 50, 200 (150), 300 and 500 mg/kg were administered to rats for 24 months. The study design was prepared according to EEC guidelines, and the recommendations by the International Agency for Research on Cancer were used for the statistical analysis of data. Weekly palpations were made along the course of studies and general parameters were monitored. The only effects attributed to ebrotidine administration were a slight decrease in the survival rate of female mice given the 500 mg/kg dose and a lower weight gain in rats of both sexes. The histopathological data revealed that lipoid pneumonia and kidney calculi are more frequent in rats treated with doses of 500 and 300 mg/kg. No increment in the spontaneous occurrence of tumours or significant presence of tumours in treated animals differing from that in control animals was observed, and a decrease in the time required for their onset that could be related to ebrotidine was not observed either. There were no differences in hyperplastic and/or dysplastic changes between treated and control animals. Therefore, it is deduced that ebrotidine does not induce neoplastic or preneoplastic effects in rats or mice even at doses of 500 mg/kg, at which some general toxicity effects are seen.

Subacute toxicity of ebrotidine in rats and dogs

Subacute toxicity studies of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl] thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) were performed in Spragu-Dawley rats and Beagle dogs. Both animal species were administered with the same dose levels (50, 200 and 500 mg/kg) for 4 and 7 weeks, respectively. In a previous 4-week subacute toxicity study in the rat, ranitidine and cimetidine at 500 mg/kg were used as reference drugs. The results indicated that ebrotidine was well tolerated at 50 mg/kg, while there were dose-related effects at 200 and 500 mg/kg. Probably due to its pharmacokinetics, ebrotidine was more toxic in dogs than in rats, since the most severe effects were the death or sacrifice in extremis of two dogs from the high dose group which had undergone rectal prolapse, while no deaths occurred in the rats. The changes that were very likely related to treatment (500 mg/kg) were a lower weight in both species, a slight decrease of hematocrit and red blood cells in rats, single increments of transaminases, alkaline phosphatase and lactate dehydrogenase in dogs (some animals of the 200 mg/kg dose group were also affected) and a higher liver weight. These effects with a few exceptions were found to be common to cimetidine and ranitidine.

Efficacy of ebrotidine and ranitidine in the treatment of benign gastric ulcer

This is a phase III, randomized, double-blind, clinical trial with two parallel groups of 50 patients to assess the efficacy of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio]ethyl ] amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) 800 mg and ranitidine 300 mg as a single evening dose in the treatment of benign gastric peptic ulcer. Prior to treatment, an endoscopy was performed to detect ulcer lesions and to discard malignancies. Clinical and endoscopic examinations were performed at 6, 9 and 12 weeks. Healing rates were significant for both treatments at week 6, while at week 12 there was statistical significance for ebrotidine as compared to ranitidine (96% vs 88% in the intention-to-treat analysis and 98% vs 87.5% in the per protocol analysis). Decrease in ulcer diameter was significant for both treatments at week 6, and for ebrotidine versus ranitidine at weeks 9 and 12. The overall improvement of symptoms was higher with ebrotidine, which was already significant at week 6. Safety was considered to be excellent, since no significant adverse events were reported for the patients included in the study.

Comparative study of plasma gastrin levels in rats after two months of ebrotidine administration

Four groups of male rats were orally administered for 60 days with daily doses of ebrotidine (N-[(E)-[[2-[[[2-[(diaminoethylene) amino]-4-thiazolyl]methyl]thio]ethyl]amino]methylene]-4-bromo- benzenesulfonamide, CAS 100981-43-9, FI-3542) (500 mg/kg), ranitidine (500 mg/kg), cimetidine (500 mg/kg) and omeprazole (43.5 mg/kg). A fifth group received no treatment and was used as control. The curve of gastrinemia was obtained on days 1, 15 and 60 of administration. On each of these days gastrinemia was assessed at 0, 1, 5, 8, and 24 h on day 1, and 1, 5, 8, 10 and 24 h on days 15 and 60. The purpose of this study was to compare the plasma gastrin level profile in association with the administration of test drugs on days 1, 15 and 60 of treatment. The results showed a significant difference in the duration of hypergastrinemia of H2-receptor antagonists as compared to proton pump blockers. Although peak plasma gastrin levels were attained for all products between 5 and 8 h after day 1 of administration, H2-receptor antagonists, unlike omeprazole, achieved recovery of gastrin baseline levels within 24 h. On days 15 and 60 of ebrotidine, treatment, plasma gastrin levels returned to normal range at 5 and 8 h after administration, respectively. After ranitidine and cimetidine, hypergastrinemia was still present at this time, but normal levels were attained before 24 h. With omeprazole plasma gastrin levels did not return to normal range within 24 h after each administration, and a cumulative effect occurred during treatment. The omeprazole treated group showed the highest and more sustained plasma gastrin levels. It was concluded that ebrotidine was the antisecretory agent with the lowest hypergastrinemic effect during long-term treatment. With ebrotidine daily baseline gastrin levels were more rapidly recovered after each administration.

Synthesis and assessment of formamidines as new histamine H2-receptor antagonists

Four series of compounds whose substructure contains a formamidine functionalized as a novel group in the chemistry of histamine H2-receptors have been synthesized. Series design, synthesis and pharmacological data including inhibition of histamine-stimulated acid secretion, inhibition of acid secretion p.o. and pA2 are reported. N-[(E)-[[2-[[[2](Diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide (ebrotidine, CAS 100981-43-9, FI-3542) was selected for further research.

Involvement of endogenous nitric oxide and sulfhydryl compounds in ebrotidine-induced gastroprotection

The role of endogenous nitric oxide and sulfhydryl compounds in the prevention by ebrotidine (N-[(E)- [[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio]ethyl]amino] methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) (100 mg/kg i.g.) of ethanol-induced gastric damage in rats was demonstrated. When the animals were pretreated with N-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthase, at the dose of 10 mg/kg i.v., the mucosal lesions were aggravated and the gastroprotective action of ebrotidine decreased from 85% to 24%. This decrease in ebrotidine protection was antagonized by L-arginine (200 mg/kg i.v.), the lesion inhibition rate being 69%. D-arginine (200 mg/kg i.v.) was ineffective and the inhibition afforded by ebrotidine was only 14%. Pretreatment with N-ethylmaleimide, a sulfhydryl blocker, at the dose of 50 mg/kg s.c., increased the mucosal lesion induced by ethanol, and the gastroprotective action of ebrotidine decreased from 75% to 9%. These results suggest that endogenous nitric oxide and sulfhydryl compounds play a crucial role in the gastroprotective activity of ebrotidine.

In vitro anti-Helicobacter pylori activity of ebrotidine

The in vitro anti-Helicobacter pylori (H. pylori) activity of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene) amino]-4-thiazolyl]methyl]thio]ethyl]amino]methylene]-4-bromo- benzenesulfonamide, CAS 100981-43-9, FI-3542) versus ranitidine, and their effect on the susceptibility to the antimicrobial agents used in H. pylori eradication were investigated. Assessment was performed by determining the minimum inhibitory concentrations (MIC) against 9 strains of H. pylori, 8 from clinical source and 1 from the American Type Culture Collection (ATCC 43504), in Mueller-Hinton solid media plus 7% blood. The concentration of inocula was 10(7) CFU/ml, incubation was performed at 37 degrees C in microaerophilic atmosphere, and results were read after 5 days of growth. Ebrotidine gave a mean MIC value of 75 micrograms/ml, while that for ranitidine was > 1000 micrograms/ml. Ebrotidine at 100 micrograms/ml enhanced the activity of the antimicrobials studied as follows: erythromycin 3 times, tetracycline 1.1 times, amoxicillin 3 times, metronidazole-sensitive strains 9 times and clarithromycin 5 times. Ranitidine had no effect on the MIC of the antibiotics even at 500 micrograms/ml.

Pharmacokinetics of ebrotidine in rats and dogs

The pharmacokinetics of ebrotidine (N-[(E)-[[[2-[(diaminomethylene)amino] -4-thiazolyl]methyl]thio]ethyl] amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) was studied in the rat and dog. After oral (agar suspension) and intravenous administration at 10 mg/kg to rats, ebrotidine was rapidly absorbed. Cmax values averaged 0.498 microgram/ml attained at tmax = 30 min. Distribution was fitted to a two-compartmental model with t1/2 beta = 1 h (i.v.). Clearance (Cl) was 29 ml/min.kg and volume of distribution (Vdss) was 1852 ml/kg. Absolute bioavailability was 22% of the dose administered. After oral (the same tablet formulation as that used for clinical trials) and intravenous administration at 150 mg and 25 mg, respectively, to dogs, absorption of ebrotidine was relatively rapid. Cmax values averaged 2,170 micrograms/ml attained at tmax = 2 h. Distribution was fitted to a two-compartmental model with t1/2 beta = 2.8 h (i.v.). Clearance (Cl) was 600 ml/h.kg and volume of distribution (Vdss) was 1000 ml/kg. Absolute bioavailability, which is variable in this type of drugs, ranges from 29% to 64% of the dose administered.

Toxicity of ebrotidine on reproduction. Toxicity on fertility and general reproductive performance, embryo-fetal toxicity and peri- and postnatal toxicity

Reproduction toxicity studies of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl] thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) are presented in this paper. Rats dosed with 50, 200 and 500 mg/kg p.o. of ebrotidine were used for the fertility and peri- and postnatal toxicity studies, and rabbits dosed with 25, 100 and 250 mg/kg and rats dosed with 50, 200 and 500 mg/kg of ebrotidine were used for the embryotoxicity study. The fertility study was designed in accordance with a 2-generation study protocol. The results showed that ebrotidine did not interfere with male and female gametogenesis, fertility, organogenesis, postnatal development and lactation in F0 or F1 animals. Only general or non-specific effects were attributed to treatment, such as a lower weight gain in parents or fetuses in rats, or a somewhat slower bone calcification in rats, which was shown to be recoverable and had no peri- or postnatal repercussions. Neither did the fertility study reveal a possible longer duration of gestation nor did the peri- and postnatal study show a lower weight of the F1 offspring. There was only an increase in rabbit embryonic mortality, probably related to some cases of abortion at the high dose. No potential antiandrogenic effect on the reproductive function has been found. Among the different doses used in both animal species, the maximum toxic effect-free dose was that of 25 mg/kg.

Pharmacokinetics of ebrotidine in healthy volunteers. A summary

Several clinical pharmacokinetic studies of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) administered by oral route in single and multiple doses to healthy volunteers have been performed. Dosage levels were 150, 300, 400, 500, 600 and 800 mg. Plasma concentrations of unchanged ebrotidine and its major metabolite, ebrotidine sulfoxide, excreted in the urine were determined. The main pharmacokinetic parameters were calculated from the experimental data. Absorption was relatively rapid (Imax = 2 h) and unrelated to dose. Drug behavior was considered as reasonably linear: Cmax = 364-1168 ng/ml and AUC0-12 h = 1427-5997 ng.h/ml (doses from 150 mg to 800 mg). The mean values of terminal elimination half-life (t1/2 beta) ranged from 13.9 to 20.3 h (doses of 400, 600 and 800 mg). After multiple dosing there was no drug accumulation, and no significant changes in the mean values of the main pharmacokinetic parameters were observed. The steady state was reached from the second day of administration, 10-24% of the ebrotidine administered dose was excreted in urine mainly as its major metabolite, ebrotidine sulfoxide, as well as unchanged drug and other minor metabolites. These percentages were constant and independent of the dose administered.

Comparison of the efficacy and safety of ebrotidine in the treatment of duodenal ulcer. A multicentre, double-blind, placebo-controlled phase II study

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4 -thiazoly]methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfon amide, CAS 100981-43-9, FI-3542) is a new H2-receptor antagonist characterized by its high receptor affinity and gastroprotective effect. This Phase II study has been undertaken to establish the efficacy and safety of ebrotidine, administered in four dosages as a single evening dose versus placebo in the treatment of duodenal ulcer. A total of 110 duodenal ulcer patients were studied in a randomized, double-blind, placebo-controlled, multicentre clinical trial. The patients were assigned to 5 groups: placebo, 200 mg, 400 mg, 600 mg and 800 mg of ebrotidine once daily. Controls were performed at baseline and every two weeks at four follow-up visits unless ulcer healed before. Endoscopic examination was the main parameter for the assessment of treatment efficacy and ulcer healing rate. Vital signs and blood/ urine analysis were used to establish safety. The three groups treated with higher dosages (400 to 800 mg of ebrotidine daily) showed an endoscopic ulcer healing rate of 90-95%, significantly higher than 55% achieved with placebo (p < 0.05), whilst the differences between these three dosages of ebrotidine were not statistically significant. Healing rate in the group treated with 200 mg of ebrotidine daily was not significantly different from that in the placebo group. The development of symptoms, number of episodes of ulcer-related pain, total ulcerated surface area or subjective ratings by the patients and investigators also differed significantly between ebrotidine (400, 600 and 800 mg daily) and placebo, and again, no marked differences were found between these three doses of ebrotidine. As far as tolerance is concerned, no clinically or statistically significant changes were observed in vital signs and analytical parameters. The incidence of side effects was less than that presented by the placebo group, possibly due to a greater consumption of antacids in this group. Results showed that a daily dose of 400 mg ebrotidine is effective and safe in the treatment of duodenal ulcers.

Action of ebrotidine, ranitidine and cimetidine on the specific binding to histamine H1- and H2-receptors

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)-4-thiazolyl]methyl]thio] ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542), a selective H2-receptor antagonist, has proved to competitively inhibit the positive chronotropism induced by histamine in isolated guinea pig atrium. The affinity of ebrotidine to histamine H1- and H2-receptors through the displacement of 3H-pyrilamine and 3H-thiotidine binding to guinea pig cerebellum and brain cortex membranes was investigated. Ebrotidine displaced 3H-thiotidine specific binding to histamine H2-receptors (Ki: 127.5 nmol/l), showing a higher affinity (p < 0.05) than ranitidine (Ki: 190.0 nmol/l) and cimetidine (Ki: 246.1 nmol/l). None of the three substances displaced 3H-pyrilamine binding to H1-receptors (Ki: > 5000 nmol/l). The results showed that ebrotidine is a drug with a high affinity for H2 receptors, higher than cimetidine and ranitidine.

Continuous intragastric pH monitoring in the evaluation of ebrotidine, cimetidine and placebo on gastric acidity in healthy volunteers

This study was conducted to determine the efficacy and tolerance of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl) methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43.9, FI-3542), a new H2-receptor antagonist, on reducing gastric acidity after a single 800 mg dose, compared with cimetidine 800 mg once daily and placebo by means of a continuous intragastric pH monitoring. A total of 30 healthy volunteers were allocated to receive in a double blind, parallel design the study medication. Clinical observations, physical examinations and visual analogue scales (VAS) were performed during the study to assess the tolerability of the three treatments. Ebrotidine and cimetidine caused a greater and longer-lasting gastric acid inhibition than placebo. With ebrotidine, significantly (p < 0.05) higher median pH values (and interquartile range, IQR) were reached in the post-administration (2.61, IQR 2.02-3.93), postprandial (3.38, IQR 2.82-3.91) and nocturnal (2.83, IQR 1.69-3.77) periods than with placebo: 1.82 (IQR, 1.66-2.09), 2.81 (IQR, 2.02-3.28), and 1.89 (IQR, 1.44-2.13), respectively. Cimetidine showed significant differences compared to placebo in the post-administration (2.36, IQR 1.89-3.46) and nocturnal (2.46, IQR 1.88-4.33) periods. No statistical differences were observed between the active treatments. Ebrotidine caused a significantly higher percentage of time above pH 2.0 in the post-administration and nocturnal periods compared to placebo (p < 0.05), and above pH 3.0 in the post-administration, postprandial and nocturnal periods. No serious adverse effects, or disturbances in the VAS or in the vital signs were reported, and all medications were well tolerated. It is concluded that a single dose of ebrotidine 800 mg is as effective as cimetidine 800 mg in reducing total and nocturnal intragastric acidity. The study also confirms the excellent safety profile of the new drug.

Studies on the cytoprotective and antisecretory activity of ebrotidine. A review

Gastric mucosa is exposed to various aggressive factors such as stress, ulcerogenic drugs including acetyl-salicylic acid(ASA)-like agents, ethanol, bacteria, particularly Helicobacter pylori (Hp), and various endogenous irritants such as acid-pepsin secretion and bile salts. The maintenance of the mucosal barrier depends upon the activation of the pre-epithelial (mucus-alkali secretion), epithelial (surface-active phospholipids and rapid mucosal restitution) and post-epithelial (mucosal microcirculation, sensory nerves and mast cells) components of mucosal defense. Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]- 4-thiazolyl]methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamid e, CAS 100981-43-9, FI-3542) is the first of a new generation of H2-receptor antagonists with both antisecretory and cytoprotective activities. Its inhibitory action is similar to that of ranitidine and approximately tenfold greater than cimetidine, and is accompanied by a small and transient increase in plasma gastrin levels. In contrast to ranitidine and other H2-receptor antagonists, ebrotidine exerts a unique cytoprotection against injury by various ulcerogens such as ethanol, ammonia, lipopolysaccharides (LPS), stress and ASA or acidified taurocholate. The mechanism of this protection by ebrotidine is not clear, but it has been shown to stimulate mucus secretion, to increase the quality of adherent mucus gel and to increase gastric mucosal blood flow (GBF), possibly due to enhanced mucosal formation of prostaglandin E2 (PGE2) and nitric oxide (NO). The cytoprotective effects of ebrotidine were observed in rats and confirmed also in humans with gastric lesions induced by ethanol or ASA. Ebrotidine also exerts anti-Helicobacter pylori (Hp) effects by interfering with surface receptors of epithelial cells and inhibiting urease, protease and lipase activity, and by counteracting the noxious effects of Hp-related substances such as ammonia and lipopoly-saccharides (LPS).

Histamine H2-receptor antagonist action of ebrotidine. Effects on gastric acid secretion, gastrin levels and NSAID-induced gastrotoxicity in the rat

The antagonism of histamine H2-receptors by ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio]ethyl ] amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) was assessed on isolated guinea-pig right atrium. The dose-response curves obtained by histamine on the positive chronotropic effect in guinea-pig atrium were displaced to the right in parallel depending on the concentration of ebrotidine and ranitidine without change in the maximum response with pA2 values of 7.12 and 7.26, respectively. The slope of the regression line of log (DR-1) against log ebrotidine concentration was not significantly different from unity: 0.96 (95% confidence limits: 0.89-1.03). These results indicate that ebrotidine is a competitive H2-receptor antagonist. Following intravenous administration to rats, ebrotidine inhibited histamine- and pentagastrin-stimulated acid secretion in a dose-dependent manner, ED50 being 0.21 and 0.44 mg/kg, respectively. After oral administration to fasting rats 3 h before their sacrifice, ebrotidine decreased the total acid contents of the stomach in a dose-dependent manner, ED50 being 7.5 mg/kg. After a single dose of 100 mg/kg in fasting rats, ebrotidine increased significantly serum gastrin levels within 2 and 5 h after administration, but 8 h after administration serum gastrin levels returned to normal values. In contrast, ranitidine at a single oral dose of 100 mg/kg increased serum gastrin levels more markedly within 2 and 5 h after administration, while after 8 h, this increase still persisted although without significant differences with respect to control, and after 24 h levels returned to normal values. Both ebrotidine and ranitidine were administered orally at a dose of 100 mg/kg for 26 days showing significant increments in plasma gastrin levels 5 h after administration. Such increments were not so marked after ebrotidine and normal values were attained at 24 h after administration. The results obtained after repeated oral administration for 15 days of ebrotidine and ranitidine at the doses of 15 and 50 mg/kg demonstrated that ebrotidine did not increase significantly serum gastrin levels with respect to control 2 h after administration, and no dose-related effect was observed. In contrast, ranitidine increased serum gastrin levels significantly and in a dose-dependent manner with respect to control group. ED50 values of ebrotidine obtained in the experiments on the prevention of NSAID-induced gastrotoxicity in the rat were 12.2, 12.5, 11.5 and 9.8 mg/kg against diclofenac, ketoprofen, indometacin and naproxen, respectively. ED50 values of ranitidine were of the same order: 20.6, 13.9, > 50 and 15.1 mg/kg.

Study of the population of antral G-cells and enterochromaffin-like cells in the rat and mouse gastric mucosa after long-term treatment with ebrotidine

The potential effect of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene]amino]-4-thiazolyl]methyl]thio]ethyl ] amino)methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) on two types of enteroendocrine cell populations in the gastric mucosa, antral G-cells and enterochromaffin-like cells, was investigated. The study of the population of antral G-cells was performed in a group of male rats treated with ebrotidine 500 mg/kg p.o. for 60 days; a control group receiving 10 ml/kg of an aqueous agar solution was used. A PAP (peroxidase-antiperoxidase) system-associated antigastrin immunohistochemical method was used for cell identification. The population of enterochromaffin-like cells was assessed by quantifying the density of argyrophilic cells in mouse gastric mucosa after an 18-month treatment with ebrotidine 500 mg/kg. Grimelius silver staining method was used for cell identification. In both studies, cell count was performed using a light microscope at 400 x magnification and cell density was calculated by computer-assisted image analysis. Compared to control, ebrotidine did not cause any significant differences in the cell density of the populations studied.

Ebrotidine versus ranitidine in the treatment of acute duodenal ulcer. A multicentre, randomized, double-blind, controlled clinical trial

A total of 478 patients with endoscopically confirmed duodenal ulcer entered this randomized, parallel, double-blind trial. Patients were randomly assigned to receive ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]- 4-thiazolyl]methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfona mid e, CAS 100981-43-9, FI-3542) 400 mg or ranitidine 300 mg tablets (4:1) respectively, administered in single evening doses. Endoscopy, clinical examination and symptom assessment were performed at baseline and at weeks 4 and 8. Safety evaluations including laboratory tests, treatment compliance and antacid consumption checks were conducted at the beginning and/or at the 4 and 8 week visits. Patients whose ulcer showed endoscopic healing at the 4-week control left the study. Both groups were matched in all parameters studied. The healing rates at 4 weeks were 76.4% and 75.3% for ebrotidine and ranitidine respectively, while at 8 weeks the final rates were 95% and 91.8% respectively. Accompanying symptoms disappeared rapidly and the patients returned to normal. Smoking proved to be a highly significant negative risk factor, since healing rates were 83.4% and 71.2% at 4 weeks and 97.4% and 92.3% at 8 weeks in non-smokers and smokers respectively (p = 0.0046). Smokers treated with ranitidine showed significantly lower final healing rates than non-smokers (86% vs 100%; p = 0.0358), while the healing rates among patients treated with ebrotidine were similar regardless of whether they were smokers or not (93.9% and 96.7% N.S.). Ebrotidine (94%) proved to be more effective than ranitidine (86%) in smokers with higher healing rates (p < 0.05). Alcohol intake showed no significant relationship with the healing rates. Both drugs demonstrated an excellent safety. There were no changes in blood parameters, and no significant adverse events were reported.

Studies on the protective effect of ebrotidine on experimental ulcers induced by non-steroidal anti-inflammatory drugs in healthy volunteers

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]- 4-thiazolyl]methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamid e, CAS 100981-43-9, FI-3542) is a new H2-receptor antagonist providing a new therapy for the prevention and healing of non-steroidal anti-inflammatory drugs-induced gastroduodenal lesions. Carbonic anhydrase is a zinc enzyme, and its isozyme (carbonic anhydrase II) in parietal cells plays a central role in HCl secretion. The effects of ebrotidine on carbonic anhydrase in human subjects are reported. Eighteen healthy volunteers were distributed in 3 equal subgroups and treated for 10 days as follows: ebrotidine 800 mg/d p.o. (Group A); indometacin 4 mg/kg/d p.o. in 3 divided doses (Group B); ebrotidine 800 mg/d p.o. plus indometacin 4 mg/kg/d p.o. (Group C). Assessment of the enzymatic activity of carbonic anhydrase was based on the colorimetric method of changing pH with the stopped-flow technique. In group A, ebrotidine reduced total gastric mucosal carbonic anhydrase activity by 62%; in group B, indometacin increased carbonic anhydrase activity in gastric mucosa by 138%; in group C, the combined treatment with ebrotidine plus indometacin decreased gastric mucosal carbonic anhydrase activity by 38%. The present study shows that, unlike ranitidine, ebrotidine, a competitive H2-receptor antagonist, is also a non-competitive inhibitor of carbonic anhydrase I and II. By antagonizing the activating effects of indometacin on gastric mucosal carbonic anhydrase, ebrotidine prevents mucosal lesions caused by anti-inflammatory drugs.

Efficacy of ebrotidine and ranitidine combined with amoxicillin and metronidazole in the eradication of Helicobacter pylori in patients with duodenal ulcer

This double-blind, randomized, phase III clinical trial was carried out in two parallel groups to assess the efficacy of ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene) amino]-4-thiazolyl]methyl]thio]ethyl]amino] methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) 400 mg and ranitidine 300 mg given in single evening dose, combined with amoxicillin 750 mg and metronidazole 500 mg three times daily for 14 days, in the eradication of Helicobacter pylori in patients with duodenal ulcer. Thirty patients were included, divided into two groups of 15, to whom one of the study therapies was administered based on a randomization code. Clinical and endoscopic controls were performed 4, 6 and 8 weeks after the onset of the treatment. No differences were seen between the two treatment groups with regard to demographic parameters and clinical histories. They were both perfectly homogeneous. There were no differences between the eradication of both therapies in both the antrum and gastric body samples (over 80% eradication), allowing the results to be classified as satisfactory. Moreover, perfect control was achieved through the study of clinical symptoms, which even disappeared in some cases. There were no differences in the healing rate of the duodenal ulcer after four weeks, 86.7% being achieved for both groups.

Physicochemical properties, analytical determinations and stability of ebrotidine

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl] thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) is a new H2-receptor antagonist with a potent antisecretory activity and evidenced gastroprotection. This paper describes its physicochemical properties, spectroscopy for its structural identification, detection methods for its organic and inorganic impurities, purity quantitation and stressed degradation and stability tests in solid and solution forms in order to know the behaviour of the test substance against certain experimental conditions. The results obtained indicate that ebrotidine is stable for over 3 years normal storage conditions (25 degrees C/75% RH). As ebrotidine was not found to be hygroscopic or particularly photosensitive, no special storage precautions are required.

Study on the increment of the amount of gastric mucus in rats after repeated-dose administration of ebrotidine

Ebrotidine (N-[(E)-[[2-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio]ethyl ] amino]methylene]-4-bromo-benzenesulfonamide, CAS 100981-43-9, FI-3542) is a novel H2-receptor antagonist that also exhibits a potent gastroprotective action against ethanol damage. This study was designed to ascertain under physiological conditions the effect of ebrotidine on the secretion of gastric mucus, probably the main component of the mucosal barrier. Two groups of 20 rats each were given a daily oral dose of 10 or 35 mg/kg ebrotidine, respectively, for 17 days. A third group of 20 rats was used as a control. Once the administration period had concluded, the animals were killed and their stomachs were removed and processed by the periodic acid-Schiff (PAS) histochemical method, selective for mucopolysaccharides. PAS-positive areas exhibited a characteristic carmine colour, allowing morphometric study by computerized image analysis. All the histological sections studied were from the same region of the stomach. A significant increase in the PAS-positive area corresponding to glandular mucus was found in all treated groups. This action is consistent with an increased secretion of mucopolysaccharides and represents one of the main mechanisms of the cytoprotective action of ebrotidine.