Effects of the new H2-receptor antagonist 3-amino-4-[4- [4- (1-piperidinomethyl)-2-pyridyloxy]-cis-2-butenylamino]-3-cyclobutene-1, 2- dione hydrochloride on gastric acid secretion and ulceration

The effect of 3-amino-4-[4-[4-(1-piperidinomethyl)-2-pyridyloxy]-cis- 2-butenylamino]-3-cyclobutene-1,2-dione hydrochloride (IT-066), a new H2-receptor antagonist, on gastric acid secretion and on various experimental ulcers was investigated. IT-066 showed very potent and long lasting antisecretory action in pylorus ligated rats. The inhibitory potency of IT-066 given subcutaneously for gastric acid secretion was 1285 and 44 times higher than for cimetidine and famotidine, respectively. The duration of the inhibitory action of IT-066 was significantly longer than that of famotidine and cimetidine. In pylorus ligated rats, IT-066 showed almost 20 times higher potency than omeprazole with intraduodenal administration, and almost the same duration of action as omeprazole with one tenth the dose in oral administration. IT-066 showed a powerful protective effect on various experimental ulcer models. The potency of IT-066 administered subcutaneously was significantly higher compared with that of cimetidine, famotidine and omeprazole. IT-066 given orally also showed a more powerful antiulcer effect than cimetidine and omeprazole, and was comparable with that of famotidine in restraint and water immersion stress and cold-stress plus indometacin induced ulcer models in rats. These results suggest that IT-066 has powerful and long lasting antisecretory and antiulcer effects and is a useful antisecretory drug for treatment of peptic ulcer diseases.     

Gastric antisecretory and antiulcer/cytoprotective effects of 2-cyano-3-(ethylthio-3-methylthio)-2-propenoic acid methyl ester

AY-28,200 (2-cyano-3-(ethylthio-3-methylthio)-2-propenoic acid methyl ester), a new gastric antisecretory/antiulcer agent, inhibited basal and pentagastrin-stimulated gastric acid secretion in the conscious rat (ED50 = 7.6 and 1.9 mg/kg i.g., respectively). For inhibition of basal secretion, peak activity was attained in 5 to 6 h after dosing and was maintained for more than 10 h, with no gastric antisecretory activity occurring at 24 h. The K+ stimulated H+-K+ ATPase activity from rabbit gastric microsomes was inhibited by AY-28,200 (IC50 = 22 mumol/l). AY-28,200 inhibited ethanol-induced gastric lesions, at 3 mg/kg p.o. AY-28,200's cytoprotective effects against ethanol lasted for more than 4 h. AY-28,200 blocked acetylsalicylic acid and stress-induced gastric ulcers but was inactive against indomethacin-induced gastric ulcers. These results suggest that AY-28,200 is a parietal cell proton pump inhibitor with cytoprotective properties, and may produce its cytoprotective effect by stimulating the formation of endogenous prostaglandins.     

Gastric cytoprotective, antisecretory and antiulcer activities of (E)-4-oxo-4-(3,4,5-trimethoxyphenyl)-2-butenoic acid (RU 38086)

As a result of trials of a large series of compounds, RU 38086 (E)-4-oxo-4-(3,4,5-trimethoxyphenyl)-2-butenoic acid) was selected because of its cytoprotective, antisecretory and antiulcer properties. In pylorus-ligated rats, RU 38086 dose-dependently decreased the total acid output, at 2.5, 5 and 10 mg/kg orally and at 10 and 50 mg/kg intraduodenally. In the perfused rat stomach, 1.2 mg/kg RU 38086 in situ inhibited acid secretion stimulated by histamine or pentagastrin but was inactive against carbachol. In the same test 5 mg/kg intravenously did not antagonize pentagastrin-induced acid secretion. In the cat Heidenhain pouch, 0.6 mg/kg RU 38086 was also antisecretory, reducing the acid concentration when in contact with the mucosa of the pouch. In ulcers induced in rats by ligature of the pylorus plus acetylsalicylic acid, RU 38086 at 2.5 and 5 mg/kg demonstrated much more striking activity after oral than after intraduodenal administration. It also had antiulcer activity against stress ulcers (restraint plus cold), starting at a dose of 5 mg/kg orally. RU 38086 had marked gastric cytoprotective activity in rats against the necrotizing effects of ethanol from the low dose of 0.3 mg/kg orally. This cytoprotective activity was not significantly affected by indomethacin pre-treatment. At 4 and 20 mg/kg orally, RU 38086 strongly increased prostaglandin E2 levels in gastric juice of pylorus-ligated rats and in stomach tissue of normal rats. These data indicate that RU 38086 is an orally effective cytoprotective, antisecretory and antiulcer agent.     

Effect of metiamide, a histamine H2-receptor antagonist on reserpine-induced gastric ulcers and acid secretion

The effect of metiamide on reserpine-induced gastric ulcers and on gastric secretion during 6 h after ip administration was investigated in conscious intact rats and in rats with chronic gastric fistula. Reserpine, 3 mg/kg ip increased substantially the concentration of gastric acid in the first 4 h. Metiamide given every 3 h in a low dose (0.01 mumol/kg) intensified reserpine-induced gastric ulcers and also significantly increased the reserpine-induced acid concentration and output. In larger doses, (50-100 mumol/kg) metiamide considerably diminished gastric ulcer development and decreased gastric acid concentration. Given every 2 h metiamide in doses of 50-100 mumol/kg almost completely abolished gastric ulcer formation and markedly reduced the secretion of gastric acid in reserpinized rats. Anti-ulcer effect of metiamide was stronger than its antisecretory action, suggesting also the antiulcer action of metiamide other than inhibition of acid secretion. The results suggest that in conscious rats histamine H2-receptors are involved in reserpine-induced gastric ulcer development and gastric acid secretion. The antiulcer effect of metiamide may in part depend on its antisecretory action.     

A new class of antiulcer drugs. I. Antiulcer effect of AN5, a 4-phenyl-tetrahydroisoquinoline derivative, on different experimental models of ulcer in rats

The action of AN5 on experimental models of gastric ulcers induced by water-immersion stress, indomethacin and reserpine, or by pylorus ligation in rats has been studied. AN5 supresses the formation of ulcers in all experimental models. The strongest antiulcer effect is shown in relation to water-immersion stress-induced ulcers. From the broad pharmacological studies of AN5 on this model it can be seen that even a dose of 0.100 mg/kg has a high antiulcer activity. The increase of the dose leads to a regular increase of the antiulcer activity, the highest suppression of the ulcer index being reached at a dose of 1 mg/kg (86.15%). The comparative studies with ranitidine and cimetidine on the same experimental models of gastric ulcers show that AN5 possesses an antiulcer activity many times higher than that of the above-mentioned drugs.     

Antiulcer effects of 3-[[[2-(3,4-dimethoxyphenyl)ethyl] carbamoyl]methyl]-amino-N-methylbenzamide in experimental gastric and duodenal ulcers

Effects of 3-[[[2-(3,4-dimethoxyphenyl)ethyl]carbamoyl] methyl]-amino-N-methylbenzamide (DQ-2511), a newly synthesized compound, were evaluated using various types of experimental gastric and duodenal ulcers in rats. Pretreatment with DQ-2511, over the dose range 30-300 mg/kg p.o., resulted in a dose-related inhibition of water-immersion stress-, serotonin-, acetylsalicylic acid (ASA)-, indometacin-, ethanol-, and 2-deoxy-D-glucose(2DG) plus indometacin-induced gastric ulcers as well as cysteamine-induced duodenal ulcers. The antiulcer potencies of DQ-2511 were equal to or greater than those of H2-receptor antagonist cimetidine in these ulcer models except for ASA- and 2DG plus indometacin-induced ulcers. The rate of healing of chronic gastric ulcers induced by acetic acid was significantly accelerated by DQ-2511 (100 and 300 mg/kg p.o.) but not by the same doses of cimetidine. DQ-2511, at doses of 30 mg/kg p.o. and above, produced a significant decrease in gastric acid and pepsin output in pylorus-ligated rats. In anesthetized rats with acute gastric fistulae, 30 mg/kg i.v. of DQ-2511 significantly inhibited gastric acid secretion stimulated by 2DG, whereas it did not affect gastric hyperacidity evoked by either carbachol, histamine or pentagastrin. At effective antiulcer doses, this compound produced a sustained increase in gastric mucosal blood flow in conscious, restrained rats. Based on these observations, DQ-2511 is characterized as a new antiulcer compound with beneficial effects on both gastric aggressive and defensive factors. Furthermore, these results indicate a possible superiority of DQ2511 over cimetidine in regard to its antiulcer potency and spectrum.     

Effects of a gastric antisecretory-cytoprotectant 2-methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine-3-acetonitrile (Sch 28 080) on cysteamine, reserpine and stress ulcers in rats

Prostaglandin E2 and carbenoxolone, putative cytoprotective agents, were tested in cysteamine, reserpine and stress ulcers in rats. In cysteamine-induced duodenal ulcer, PGE2 was inactive at 0.1 and 0.5 mg/kg p.o.; carbenoxolone at 100 mg/kg p.o. decreased the incidence but not the severity of the ulcer. PGE2 at 5.0 mg/kg p.o. and carbenoxolone at 300 mg/kg p.o. showed moderate effects, but the dosage also inhibited cysteamine-stimulated acid secretion. PGE2 (0.1 and 0.3 mg/kg p.o.) was inactive and carbenoxolone (100 and 300 mg/kg p.o.) further aggravated the gastric ulceration caused by reserpine or cold-restraint stress. In contrast, atropine (3 and 10 mg/kg p.o.) and cimetidine (30, 100 and 300 mg/kg p.o.) were active in all three ulcer models. But the results with cimetidine in stress ulcer were somewhat variable. 2-methyl-8-(phenylmethoxy) imidazo [1,2-a] pyridine-3-acetonitrile (Sch 28 080), a novel structure with both cytoprotective and antisecretory activity, was highly efficacious in cysteamine, reserpine and stress ulcers (1-30 mg/kg p.o.), which was presumably adequately accounted for by its potent antisecretory activity. It is concluded that cysteamine, reserpine and stress ulcers may not be appropriate models for testing the potential antiulcer effect of primarily cytoprotective compounds.     

Effect of OPC-12759, a novel antiulcer agent, on chronic and acute experimental gastric ulcer, and gastric secretion in rats

The antiulcer effects of OPC-12759, a novel antiulcer agent were compared with those of cetraxate in various experimental ulcer models and on gastric secretion in rats. OPC-12759 (0.3-30 mg/kg, b.i.d., p.o.) significantly accelerated the healing rate of acetic acid-induced gastric ulcer in a dose-dependent manner, while cetraxate did not. When administered orally at 0.3-30 mg/kg, b.i.d., for 7 days, pretreatment with OPC-12759 (0.3-30 mg/kg, b.i.d., p.o.) prevented the formation of acute gastric ulcers, induced by: restraint water immersion stress, aspirin, indomethacin, histamine, serotonin, platelet activating factor (PAF) and DDC. Cetraxate showed antiulcer activity against a part of the OPC-12759-positive gastric ulcer models. Given intraperitoneally at the single dosing range of 10-100 mg/kg, OPC-12759 inhibited the formation of these acute gastric ulcer models. OPC-12759 administered orally at 0.3-30 mg/kg, b.i.d., for 7 days did not inhibit basal gastric secretion in pylorus ligated rats. The results indicated that OPC-12759 possesses wide spectrum antiulcer activity as compared with cetraxate.     

Gastroprotective Effect of Oxalis corniculata (Whole Plant) on Experimentally Induced Gastric Ulceration in Wistar Rats

The objective of the present study was to investigate the antiulcer activity of methanol extract of Oxalis corniculata (whole plant) using pylorus ligation and indomethacin-induced gastric ulceration in Wistar rats. The extract was preliminary evaluated for acute oral toxicity test using Organisation for Economic Co-operation and Development guidelines 423. Further, it was studied for antiulcer potential at the dose levels of 125, 250 and 500 mg/kg. Ranitidine was used as a standard drug (100 mg/kg). Acid secretory parameters like gastric volume, pH, total acidity and free acidity were measured in pylorus ligation model, whereas numbers of ulcers, ulcers score and ulcer index was measured in pylorus ligated and indomethacin treated rats. Pretreatment of test extract significantly (p<0.05) decreased the gastric volume, total acidity, free acidity and increase in the pH of the gastric fluid in pylorus-ligated rats. It also showed significant (p<0.05) decrease in number of ulcers, ulcers score and ulcer index in pylorus ligated and indomethacin treated rats. Results of the study suggest that, the methanol extract of Oxalis corniculata possesses significant antisecretory and antiulcer effects and justify the traditional usage of this herb to treat peptic ulcers.     

BAY P 1455, a thiazolylaminobenzimidazole derivative with gastroprotective properties in the rat

The antiulcer activity of BAY P 14551 a thiazolylaminobenzimidazole derivative, was evaluated in different experimental ulcer models and its antiulcer activity was compared to that of different reference drugs. The overall activity of the compound was equal to or more potent than that of reference antiulcer drugs, such as pirenzepine, cimetidine and carbenoxolone, but it was not as potent as rioprostil. The ED50 values (expressed as mumol/kg p.o.) were 68 (confidence limits: 51-91) for indomethacin-induced ulcers, 21 (confidence limits: 13-31) for stress-induced ulcers and 1260 mumol/kg p.o. (confidence limits: 412-3800) for ulcers induced by absolute ethanol. The compound had no activity against cysteamine-induced duodenal ulcers and lost its cytoprotective activity in adrenalectomised rats. Since inhibition of gastric acid secretion was seen, if at all, only with the higher doses, the gastro-protective action of BAY P 1455 seemed not to be due to an antisecretory effect, but more likely to a gastroprotective action as hypothesised for prostaglandins.     

Effects of 5-acetylspiro[benzofuran-2(3H),1'-cyclopropan]-3-one, a new anti-ulcer agent, on experimental acute and chronic ulcers

The effects of 5-acetylspiro[benzofuran-2(3H),1'-cyclopropan]-3-one (AG 629), a newly synthesized compound, on various experimentally induced ulcers were investigated. Oral or intraduodenal administration of AG 629 in a dose range of 25-100 mg/kg inhibited water-immersion stress ulcer, exertion ulcer, Shay ulcer, indometacin- and acetylsalicylic acid (ASA)-induced gastric ulcer, and indomethacin-induced small intestinal ulcer in rats, histamine-induced gastric ulcer in guinea pigs, and ASA-induced gastric ulcer in dogs, though it was not effective against cysteamine-induced duodenal ulcer in rats. AG 629 in doses of 6.3-25 mg/kg p.o. twice a day significantly promoted the healing of acetic acid- or thermal-cortisone-induced gastric ulcers and acetic acid-induced duodenal ulcers in rats. AG 629 (25-100 mg/kg i.d.) inhibited the secretion of gastric acid and pepsin in pylorus-ligated rats and the acid secretion stimulated by distension of the rat stomach with air, whereas this compound did not affect acid secretion stimulated by histamine, pentagastrin, carbachol or 2-deoxy-D-glucose. This study shows that AG 629 has both prophylactic and curative effects on various ulcers. The anti-ulcer effect of this agent seems to be mediated primarily by increasing mucosal resistance and secondarily by an antisecretory activity.     

Ulcer formation and cytoprotection by acetazolamide

Acetazolamide, a carbonic anhydrase inhibitor, was administered orally and subcutaneously to rats. Acetazolamide increased the gastric ulcerogenicity of indomethacin, but inhibited gastric ulcers produced by acidified aspirin. When administered alone to fasted rats, it did not produce gastric ulcers. Acetazolamide was also cytoprotective for the stomach (it reduced dose dependently the number of gastric necrotic lesions caused by absolute ethanol given orally) and for the small intestine (it prevented dose dependently intestinal lesions produced by administration of a high dose of indomethacin). Acetazolamide did not prevent the antiulcer effect of PGE2 (against aspirin-induced ulcers) nor the cytoprotective effect of 16,16-dimethyl PGE2 (against ethanol-induced gastric lesions). The degree of gastric cytoprotection increased with time after a single administration of acetazolamide; the optimal effect occurred 60 and 90 min after oral and subcutaneous administration, respectively. Pretreatment with indomethacin completely prevented the cytoprotective effect of acetazolamide; this suggests that the cytoprotective effect may be mediated by endogenous release of prostaglandins by the stomach. All the effects of acetazolamide reported here were observed after either oral or subcutaneous administration. The mechanism by which acetazolamide influences ulcer formation and is cytoprotective is unknown.     

Effect of Bromazepam on stress-induced gastric ulcer in rats and its relation to brain neurotransmitters

The possible antiulcer potential of bromazepam was investigated in relation to its effect on the levels of central neurotransmitters in rats. Peptic ulcer was induced by cold-restraint stress, by immobilizing the animals in open wire restraint cages placed for 2 h at 4 degrees C. Bromazepam (1 and 2 mg x kg(-1), i.p.) was given as prophylactic regimens, either as a single (2 h before ulcer induction) or repeated (twice daily for 15 days) administration. Results revealed that single (1 mg x kg(-1)) and repeated (1 and 2 mg x kg(-1)) dose regimens of bromazepam succeeded in preventing gastric ulceration, without significant effects on the protein-bound hexose content of gastric mucus. Increases in gamma-aminobutyric acid (GABA) concentrations in almost all tested brain regions were observed in bromazepam-treated groups, as compared to the control stressed group. Cortical dopamine (D) concentrations were reduced following single (2 mg x kg(-1)) as well as repeated administration of bromazepam. Similarly, norepinephrine (NE) concentrations were decreased in the cerebral cortex and thalamus/hypothalamus by repeated doses of bromazepam. Cortical 5-hydroxytryptamine (5-HT) was elevated by single (1 mg x kg(-1)) and repeated (1 mg x kg(-1)) doses of the drug. It could be concluded that bromazepam affords a good gastroprotective potential against cold-restraint stress-induced gastric ulceration and the possible mechanisms might involve an increase in the inhibitory GABA and a suppression of the stimulatory NE and D in central regions, especially the cerebral cortex and/or thalamus/hypothalamus.     

1H-2-Benzopyran-1-one derivatives, microbial products with pharmacological activity. Conversion into orally active derivatives with antiinflammatory and antiulcer activities

A novel gastroprotective substance, 6-[[1(S)-[3(S),4-dihydro-8-hydroxy-1-oxo-1H-2-benzopyran-3-yl] -3-methylbutyl]amino]-4(S),5(S)-dihydroxy-6-oxo-3(S)-ammoniohexanoate (AI-77-B, 1), isolated from a culture broth of Bacillus pumilus AI-77, was chemically modified to prodrugs that are active by oral dosing. Compound 1 was lactonized and then monoalkylated at the primary amine position. Six N-alkylated gamma-lactone derivatives of 1 (with alkyl chains being methyl 5a, ethyl 5b, n-propyl 5c, n-butyl 5d, n-pentyl 5e, or n-hexyl 5f) were synthesized and eight compounds including 1 and gamma-lactone derivative 2 were compared for their gastroprotective activities and blood levels after oral administration in rats. Further, chloroform-water partition coefficients of 5a-f were also compared as a measure of lipid solubility. The protective effects of these compounds on stress ulcers were mutually related to blood levels of dealkylated compounds (1 and 2). Parent compound 1 was detected in blood at 1 h after each of 5a-d was administered. When 5b or 5c was administered, high activity and high blood levels of 1 were observed in comparison with those levels obtained with 5a or 5d. Neither 5e nor 5f were detected in any amount in blood by oral administration without special formulation due to extremely low solubilities and agglutinative properties in intestinal fluid. Interestingly, 5b and 5c were found to have antiinflammatory activities in addition to potent antiulcerogenicity action.     

Antiulcer activity of an anthocyanidin from Vaccinium myrtillus

The antiulcer effects of 3,5,7-trihydroxy-2-(3,4-dihydroxyphenyl)-1-benzopyrylium chloride (IdB 1027) were assessed in various experimental models. Given orally, IdB 1027 antagonized gastric ulcerations induced by pylorus ligation, stress, nonsteroidal antiinflammatory drugs, ethanol, reserpine, histamine and duodenal ulceration induced by mercaptamine (cysteamine). Moreover it antagonized chronic gastric ulcers induced by acetic acid. Given intraperitoneally, it was more potent than after oral administration. IdB 1027 did not affect gastric secretion in pylorus-ligated rats and increased gastric mucus in normal animals both in the absence and in the presence of indometacin treatment. Tolerability was very good. These results indicate that IdB 1027 possesses a promising antiulcer activity, probably by potentiating the defensive barriers of the gastrointestinal mucosa.     

Effects of verapamil, carbenoxolone and N-acetylcysteine on gastric wall mucus and ulceration in stressed rats

The effects of verapamil on gastric wall mucus and ulceration were studied in rats which were restrained and exposed to 4 degrees C (stress). Stress for 2 h significantly depleted stomach wall mucus and produced marked gastric glandular ulcers. Verapamil pretreatment (2, 4, 8 or 16 mg/kg), injected intraperitoneally 30 min before experimentation, significantly prevented stress-induced mucus depletion and gastric ulceration; however, it did not itself influence stomach wall mucus levels in nonstressed animals. Intragastric administration of carbenoxolone (100 or 200 mg/kg), also given 30 min before stress, exhibited similar actions as verapamil. A 15% solution of N-acetylcysteine (10 ml/kg), given orally, strongly decreased the mucus content in both nonstress and stress conditions; it induced ulcers in nonstressed rats, and worsened stress ulceration. These effects were not reversed by verapamil pretreatment. The influence of multiple-dose pretreatment with verapamil or carbenoxolone on mucus content and ulceration in the gastric glandular mucosa during stress is also discussed. It is concluded that gastric wall mucus depletion is likely to play an important role in stress ulcer formation; the antiulcer action of verapamil could partly be due to the preservation of mucus.     

Effect of SR 58611A,a beta-3 receptor agonist,against experimental gastro-duodenal ulcers

The present study was designed to study the effect of SR 58611A, a selective beta 3-adrenoceptor agonist against gastric ulcers: pylorus ligation, water immersion plus restraint stress (WIRS), ethanol, aspirin-induced and on cysteamine-induced duodenal ulcers, in rats. SR 58611A (10 mg/kg, p.o.) was found to be effective in attenuating gastric ulceration and the results were comparable with those from standard cimetidine-treated group. Apart from reducing ulcer index, SR 58611A significantly decreased total acidity and thereby exhibited antisecretory activity in pylorus ligation model. SR 58611A showed significant reduction in ulcer index alongwith significant rise in the gastric wall mucus content in WIRS model. Further it showed significant cytoprotective activity against ethanol insult, that was evident from significant reduction in ulcer index. It showed significant reduction in gastric ulceration in aspirin-treated rats. The drug was found to be ineffective in inhibiting the cysteamine-induced duodenal ulcers as evident from the ulcer index and total lesion area parameters. It is concluded that SR 586111A possesses significant gastroprotective activity. This activity could be attributed to the inhibition of gastric acidity, increase in gastric wall mucus content and the reversal of gastric microvascular injury resulting into protection of the vascular integrity.     

Healing-promoting action of rhinax with dual action on chronic gastric and duodenal ulcers induced by acetic acid in rats

Healing promoting actions of Rhinax, a multiconstituent herbal preparation, was investigated in chronic gastric and duodenal ulcer models induced by acetic acid in rats and the effects were compared with those of famotidine by gross of histological evaluation. Rhinax markedly promoted the well balanced healing of gastric ulcer at oral does of 25-100 mg/kg x 2 /day, as evidenced by the reduction of ulcer, regeneration of mucosa and proliferation of connecitve tissue. Rhinax caused an increase in gastric mucosa secretion in all the regenerated mucosa around the gastric ulcers. Famotidine failed to promote the healing of gastric ulcers at 100 mg/kg x 2/ day p.o. Rhinax also significantly accelerated the healing of acetic acid -induced duodenal ulcers as well famotidine. These results indicate that Rhinax is characterised by a potent promoting action on the healing of chronic ulcers, suggesting that the increase in gastric mucus secretion might be associated with the antiulcer action of Rhinax in rats.     

Misoprostol. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in the treatment of peptic ulcer disease

Misoprostol is an analogue of prostaglandin E1 and is the first synthetic prostaglandin analogue to be made available for the treatment of peptic ulcer disease. It inhibits gastric acid secretion in man, and there is also some evidence that it limits the extent of gastrointestinal damage induced by ulcerogenic agents in animals and healthy volunteers at doses lower than those required to inhibit acid secretion. This 'cytoprotective' activity has been explained by several mechanisms, but its contribution to the clinical efficacy of misoprostol in healing established ulcers is doubtful since the drug does not appear to be effective in healing peptic ulcers at non-antisecretory dosages. In clinical trials, ulcer healing has been reported in 60 to 85% of patients with duodenal ulcers and 32 to 54% with gastric ulcers receiving misoprostol 200 micrograms 4 times daily for 4 weeks--the recommended dosage. In comparative studies, the percentage of patients with healed ulcers after misoprostol (800 micrograms daily) was not significantly different from that with cimetidine (1200 mg daily), although there was greater pain relief with cimetidine. No study has yet been published concerning the use of misoprostol as maintenance therapy for the prevention of ulcer recurrence, and no long term tolerability data are available. However, in acute ulcer healing studies (2 to 12 weeks in duration) misoprostol has been well tolerated. Diarrhoea was the most commonly reported symptom, and this was only rarely of sufficient severity to interfere with treatment. No evidence of histopathological changes in the gastric mucosa induced by misoprostol have been reported in man. Evidence of uterine stimulant effects in women receiving misoprostol during the first trimester of pregnancy has resulted in the drug being contraindicated during pregnancy. Thus, misoprostol is a new type of antiulcer drug, providing an alternative approach to the therapy of peptic ulcer disease. It has been shown to be effective and well tolerated in the healing of both gastric and duodenal ulcers. Future studies need to identify the specific types of patients likely to obtain most benefit from treatment, in order to define more clearly the place of misoprostol in the treatment of these indications, as well as addressing the possibility of ulcer prevention with lower doses of misoprostol.     

Effects of 3-hydroxymethyl-2-methylimidazo [2, 1-b] benzothiazole (NIK-228) on gastric acid secretion and various experimental peptic ulcers in rats

We examined the antisecretory and antiulcer activities of NIK-228 in rats. Male Wistar rats (200 to 250 g) were used under 24 to 48 hr fasted (without water) conditions. NIK-228 and famotidine were administered orally 1 hr before pylorus ligation, stress or each ulceration inducer. Both NIK-228 (10 to 100 mg/kg) and famotidine (0.3 to 3 mg/kg) dose-dependently inhibited gastric secretion in pylorus ligated rats. Water-immersion stress-, indomethacin- or pylorus ligation (Shay)-induced gastric ulcers were dose-dependently inhibited by NIK-228 (10 to 100 mg/kg), but only water-immersion stress and indomethacin induced ulcers were dose-dependently inhibited by famotidine (0.03 to 3 mg/kg). Ethanol- and 0.6 N HCl-induced gastric lesions were remarkably inhibited by NIK-228 (ED50 = 2.7 and 5.6 mg/kg), but tended to be inhibited also by famotidine (0.3 to 3 mg/kg). Cysteamine-induced duodenal ulcer was inhibited significantly by NIK-228 (30, 100 mg/kg) or famotidine (3 mg/kg). NIK-228 may produce its antiulcer effects via antisecretory and cytoprotective effects. These results suggest that NIK-228 has antisecretory and antiulcer activities.