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

Acid-catalyzed allenylation of pyrazolones with propargyl alcohols

A TsOH-catalyzed allenylation of pyrazolones with propargylic alcohols has been developed. The established reaction system is well tolerated by a wide scope of pyrazolones and propargylic alcohols. The process has the salient features of operational simplicity, facile scale-up and high yield. In particular, the integration of the pharmaceutical-related pyrazolone skeleton and the allenyl group into a single molecule not only enriches the structural diversity of the pyrazolone scaffold, but potentially also contributes to a broader spectrum of biological activity. Furthermore, it is easy to synthesize 3aa in gram-scale with the yield and efficiency basically maintained, making the practical application of this process more prominent.

Protective effect of a cysteine prodrug and antioxidant, L-2-oxothiazolidine-4-carboxylate, against ethanol-induced gastric lesions in rats

Earlier studies have suggested an important role of glutathione (GSH) in cytoprotection against free radicals induced oxidative damage. This study reports gastroprotective effects of a cysteine precursor, L-2-oxothiazolidine-4-carboxylate (OTC), in experimental models of gastric secretion and ulceration. Acid secretion studies (volume and acidity) were undertaken in pylorus-ligated rats whereas the gastric lesions were induced by ethanol. Different groups of animals were treated with OTC (0, 100, 200 and 400 mg/kg). The levels of gastric wall mucus, nonprotein sulfhydryls (NP-SH) and myeloperoxidase (MPO) were measured in the glandular stomach of rats following ethanol-induced gastric lesions. Both medium and high doses of OTC significantly reduced the volume and acidity of gastric secretion in pylorus-ligated rats. Pretreatment with OTC significantly and dose-dependently attenuated the formation of ethanol-induced gastric lesion. OTC significantly protected the gastric mucosa against ethanol-induced depletion of gastric wall mucus, NP-SH and MPO. The gastroprotective effects of OTC may be attributed to its ability to inhibit neutrophils activity and replenish GSH demand.

Allenic and cumulenic lipids

Nowadays, about 200 natural allenic metabolites, more than 2700 synthetic allenic compounds, and about 1300 cumulenic structures are known. The present review describes research on natural as well as some biological active allenic and cumulenic lipids and related compounds isolated from different sources. Intensive searches for new classes of pharmacologically potent agents produced by living organisms have resulted in the discovery of dozens of such compounds possessing high anticancer, cytotoxic, antibacterial, antiviral, and other activities. Known allenic and cumulenic compounds can be subdivided on several structural classes: fatty acids, hydrocarbons, terpenes, steroids, carotenoids, marine bromoallenes, peptides, aromatic, cumulenic, and miscellaneous compounds. This review emphasizes the role of natural and synthetic allenic and cumulenic lipids and other related compounds as an important source of leads for drug discovery.

Bromophenacyl bromide, a phospholipase A2 inhibitor attenuates chemically induced gastroduodenal ulcers in rats

AIM

To study the effect of bromophenacyl bromide (BPB), a phospholipase A2 inhibitor on gastric secretion and to protect chemically induced gastric and duodenal ulcers in rats.

METHODS

Acid secretion studies were undertaken in pylorus-ligated rats with BPB treatment (0, 5, 15 and 45 mg/kg). Gastric and duodenal lesions in the rats were induced by ethanol and cysteamine respectively. The levels of gastric wall mucus, nonprotein sulfhydryls (NP-SH) and myeloperoxidase (MPO) were also measured in the glandular stomach of rats following ethanol induced gastric lesions.

RESULTS

BPB produced a dose-dependent inhibition of gastric acid secretion and acidity in rats. Pretreatment with BPB significantly attenuated the formation of ethanol induced gastric lesion. BPB also protected intestinal mucosa against cysteamine-induced duodenal ulcers. The antiulcer activity of BPB was associated with significant inhibition of ethanol-induced depletion of gastric wall mucus, NP-SH and MPO. These findings pointed towards the mediation of sulfhydryls in BPB induced gastrointestinal cytoprotection.

CONCLUSION

BPB possesses significant antiulcer and cytoprotective activity against experimentally induced gastroduodenal lesions.

Effect of Commiphora opobalsamum (L.) Engl. (Balessan) on experimental gastric ulcers and secretion in rats

The ulcer protective potential of an ethanol extract of Commiphora opobalsamum (L.) Engl. (Burseraceae) 'Balessan' was assessed against different acute gastric ulcer models in rats induced by necrotizing agents (80% ethanol, 0.2M NaOH and 25% NaCl), hypothermic restraint stress, pyloric ligation (Shay) and indomethacin. Balessan, 250 and 500 mg/kg administered orally (intraperitoneally in Shay rat model) showed a dose-dependent ulcer protective effects in all the above ulcer models. Besides, the extract offered protection against ethanol-induced depletion of stomach wall mucus and reduction in nonprotein sulfhydryl (NP-SH) concentration. Ethanol treatment also caused histopathological lesions of the stomach wall. Pretreatment with Balessan extract provided a complete protection of gastric mucosa through supporting both the offensive and defensive factors. Balessan extract was also showed a large margin of safety without any apparent adverse effects in rats.

Gastric Antiulcer Activity of Syngonanthus arthrotrichus SILVEIRA

Syngonanthus arthrotrichus SILVEIRA, popularly known as "sempre-vivas mini-saia," is found in mountains of the Espinhaço range in the Brazilian states of Bahia and Minas Gerais. Extracts of this species contain several constituents, including flavonoids which may have antiulcerogenic activity. An ethanolic extract (EEOH), and flavonoid-rich (FRF) and flavonoid-deficient (FDF) fractions obtained from the scapes of S. arthrotrichus were investigated for their ability to prevent ulceration of the gastric mucosa in mice and rats. In the ethanol/HCl-induced ulcer model, lansoprazole (30 mg/kg), EEOH (50, 100, 250 mg/kg) given orally protected the gastric mucosal against injury in mice by 79%, 78%, 73%, and 64% respectively. In the ethanol-induced gastric ulcer model in rats, the lansoprazole (30 mg/kg), FRF and FDF (100 mg/kg) significantly protected the gastric mucosal of rats by 65%, 38% and 25% respectively when compared with the negative control group. In indomethacin/bethanechol-induced gastric ulcers, cimetidine (100 mg/kg) and the EEOH (100, 250 mg/kg) inhibited gastric ulcer formation by 73%, 55% and 32% respectively. In this exactly model other treatments as cimetidine, FRF and FDF (100 mg/kg) each caused 54%, 36% and 45% inhibition, respectively. In the stress-induced gastric ulcer model, cimetidine (100 mg/kg) and the EEOH (50, 100, 250 mg/kg), inhibited gastric ulcer formation by 63%, 73%, 68% and 69% respectively. In the same model, cimetidine, FRF and FDF (100 mg/kg) significantly protected the gastric mucosal of the mice by 60%, 51% and 47% when compared to the control group. In pylorus-ligated mice, cimetidine (positive control) and FRF significantly decreased gastric acid secretion, increased gastric pH and reduced the acid output when compared to the negative control. FDF had no significant effect on these parameters. The protection provided by FRF probably involved an antisecretory mechanism mediated by flavonoids which were absent in FDF. The amount of adherent mucous in the stomach contents was also evaluated with the treatments carbenoxolone (200 mg/kg), FRF and FDF (100 mg/kg) treatment. Each treatments significantly increased the amount of adherent mucous in the gastric juice (8.67+/-1.73, 3.35+/-1.59, 2.1+/-0.41 mg/g of wet tissue, respectively) compared to the control group, indicating a cytoprotective action on the gastric mucosa. Treatment with FRF plus indomethacin and FDF plus indomethacin reduced the prostaglandin biosyntesis (13.6+/-6.5, 27+/-5.5 pg/well) by the mucosa, indicating that the cytoprotective action on the gastric mucosa was not related to the level of prostaglandins. Only FDF (38+/-17 pg/well) maintained the level of prostaglandins and guaranteed the integrity of the mucosa. The results indicate that the EEOH, FRF and FDF have antisecretory and cytoprotective actions, that may be related to the presence of luteoline in the extract and active fractions.

Comparison of the gastroprotective effect of a diterpene lactone isolated from Croton cajucara with its synthetic derivatives

The effect of three new derivatives from dehydrocrotonin (DHC-compound I) on gastric damage in different animal models including gastric ulceration induced by a necrotic agent and hypothermic restrained-stress was studied: compound II (produced by reducing the cyclohexenone moiety of DHC with NaBH(4)); compound III (produced by reducing the carbonyls with LiAlH(4)); and compound IV (produced by transforming the lactone moiety into an amide). Their structures were confirmed on the basis of chemical and physicochemical evidence. When previously administered (p.o.) at a dose of 100mg/kg, compound II significantly (P<0.01) reduced gastric injury induced by HCl/ethanol (78%) and indomethacin (88%) better than did reference compound I (48 and 43%, respectively). But the anti-ulcerogenic activity of compound II was completely abolished by the stress-induced ulcer. Reduction of carbonyls with LiAlH(4) (compound III) caused decreased activity, markedly when no protective effect in any of the models was applied (P>0.05). However, compound IV, in which the lactone moiety was changed into an amide, when administered at the same dose (100mg/kg, p.o.), was more effective. The presence of a lactone moiety or Michael acceptor is probably essential for the anti-ulcerogenic effect of these compounds.

Evaluation of the antiulcerogenic activity of violacein and its modulation by the inclusion complexation with beta-cyclodextrin

The effects of beta-cyclodextrin (betaCD) inclusion complexation on the ability of violacein to prevent gastric ulceration in mice were studied. Violacein-betaCD inclusion complexes were prepared in 1:1 and 1:2 molar ratios and analysed by differential scanning calorimetry and powder X-ray diffractometry. Violacein previously administered orally at 10 mg/kg significantly reduced indomethacin-induced gastric lesions, as well as 100 mg/kg of cimetidine (positive control). However, betaCD complexation in both molar ratios significantly potentiated the protective action of violacein. In the HCl--ethanol-induced gastric ulcer model, violacein and the 1:2 inclusion complex (10 mg/kg, p.o.) inhibited gastric damage by almost 85%, whereas a 63% reduction was observed for the positive control, lansoprazole, at 30 mg/kg. In contrast, treatment with the 1:1 inclusion complex resulted in almost total disappearance of the antiulcer activity in this model. No significant changes in stress-induced gastric injury were found. In addition, the 1:2 inclusion complex improved the antilipoperoxidant activity of violacein in rat liver cells exposed to t-butyl hydroperoxide, whereas the 1:1 complex was less active than violacein. In summary, the 1:2 betaCD inclusion complex has gastroprotective properties similar to or higher than that of violacein. An increase in mucosal defensive mechanisms and protection against peroxidative damage might be involved.

Methimazole prevents stress and chemical induced gastropathy in rats

This investigation was undertaken to study the effect of methimazole (MMI) on gastric acid secretion and stress and chemically induced gastric ulcer in rats. Acid secretion studies were undertaken using pylorus-ligated rats pretreated with MMI (10-100 mg/kg, i.p.). The effect of orally administered MMI on water-immersion restraint (WIR) stress, indomethacin and ethanol-induced gastric ulcers was also tested. The level of myeloperoxidase (MPO), non-protein sulfhydryls (NP-SH) and gastric wall mucus was measured in the glandular stomach of rats following ethanol-induced gastric lesions. There was a dose-dependent inhibition of gastric acid secretion and ulcerogen induced gastric lesion formation in the MMI treated rats. Our morphological and histological studies showed a complete prevention of ethanol-induced lesions in the rats treated with high dose (100 mg/kg) of MMI. A significant attenuation of ethanol-induced increase in gastric MPO activity, depletion of NP-SH and reduction of gastric wall mucus was also observed in MMI treated rats. These findings clearly suggest the involvement of endogenous pro-inflammatory agents and oxidative stress in mediating the gastroprotective effect of MMI.

Gastroprotective effect of aparisthman, a diterpene isolated from Aparisthmium cordatum, on experimental gastric ulcer models in rats and mice

Aparisthmium cordatum (Juss.) Bail. (Euphorbiaceae), known in the State of Pará, Brazil as "ariquena queimosa", is a medium-sized tree which is native to the North Brazilian coastal region. Previous phytochemical studies of the bark of A. cordatum yielded a furan diterpenoid with a clerodane skeleton, called aparisthman. Recently, we reported the antiulcerogenic activity of trans-dehydrocrotonin (DHC), a furan diterpene isolated from Croton cajucara bark, in different ulcerogenic models in mice and rats. The aim of the present study was to assess the possible antiulcerogenic activity of aparisthman. When previously administered (p.o.) at the dose of 100 mg/kg(-1), aparisthman reduced significantly (p < 0.01) gastric injury induced by the indomethacin/bethanechol (71%), ethanol (71%), pylorus ligature, (59%) and hypothermic restraint-stress models (50%), in mice and rats. In the HCl/ethanol-induced gastric ulcer model in mice, at oral doses of 100 and 250 mg/kg(-1), aparisthman from A. cordatum reduced significantly (p < 0.001) the formation of gastric lesions by 59% and 66%, respectively, as compared with control. In the pylorus-ligature model, aparisthman (p.o.) decreased the volume of gastric juice as compared with control (p < 0.001). When aparisthman (100 mg/kg(-1)) was administered intraduodenally to mice, significant modifications were found, such as a decrease in gastric acidity as compared with control. In the animals pre-treated with aparisthman, free mucus production increased by 19% in the gastric mucosa (p < 0.05). The results suggest that aparisthman from A. cordatum presents a significant anti-ulcer effect when assessed in these induced ulcer models. Although the mechanism underlying this antiulcerogenic effect remains unknown, it seems to be related to an increase of the defensive mechanisms of the stomach such as prostaglandin synthesis and mucus production. The good yield of aparisthman obtained from A. cordatum, as well as its antiulcerogenic activity, suggest that this compound should be submitted to pharmacological research as a potential new antiulcerogenic drug.

Antiulcerogenic effect of a hydroalcoholic extract and its organic fractions of Neurolaena lobata (L.) R.BR

Neurolaena lobata is a species used widely in Caribbean folk medicine to treat gastric pain and ulcers. The hexane (HxF), chloroform (ClF) and aqueous (H2OF) fractions of a hydroalcoholic extract (HE) of N. lobata aerial parts were investigated for their ability to prevent ulceration of the gastric mucosa. In the stress-induced gastric model the HE, HxF and ClF fractions produced a significant reduction of gastric lesion formation by 48, 70 and 52%, respectively. HE, HxF and ClF fractions (41, 57 and 51%, respectively) also reduced significantly the gastric lesions induced by the combination of indomethacin and bethanechol, and the ulcers induced by HCl/ethanol solution by 77, 86 and 83%, respectively (P < 0.05). The pylorus-ligature experiment demonstrated that the HE, HxF and ClF fractions changed significantly the gastric juice parameters, such as pH values (increases to 5.4, 4.9 and 4.8, respectively) and acid output (decreased by 4.6, 5.8 and 6.2 mEq mL(-1) 4h respectively) and gastric content (increased by 400, 410 and 390 mg, respectively) in animals. In the animals pre-treated orally with the HxF fraction, prostaglandin synthesis was increased significantly, by 104%, and free mucus production was increased by 54 % in the gastric mucosa (P < 0.001). The H2OF did not exhibit activity in any of the experimental models assayed. The data suggest that the HE and mainly the HxF of fractions from N. lobata present a significant anti-ulcer effect when assessed in these ulcer-induced models. Although the mechanism underlying this antiulcerogenic effect remains unknown, it seems to be related to an increased activity of the defensive mechanisms of the stomach, such as prostaglandin synthesis and mucus production.

Inhibition of gastric mucosal damage by methylglyoxal pretreatment in rats

The effect of methylglyoxal pretreatment on gastric mucosal injuries caused by 80% ethanol, 25% NaCl and 0.2 M NaOH, was investigated in rats. The effects caused by pylorous ligation accumulated gastric acid secretions and ethanol-induced changes in gastric mucus secretions, levels of proteins, nucleic acid, malondialdehyde (MDA) and non-protein sulfhydryl groups were also investigated. Methylglyoxal pretreatment at oral doses of 50, 100 and 200 mg/kg body weight was found to provide a dose-dependent protection against the ulcerogenic effects of different necrotizing agents used. With the same dose regimen methylglyoxal offered significant protection against ethanol-induced damage on the parameters evaluated for histopathology. Furthermore, the pretreatment afforded a dose-dependent inhibition of pylorous ligated accumulation of gastric acid secretions and ethanol-induced depletion of stomach wall mucus, proteins, nucleic acids, NP-SH contents and an increase in the MDA levels in gastric tissue. The protective effect of methylglyoxal against ethanol-induced damage to the gastric wall mucosa may be mediated through its effect on mucous production, proteins, nucleic acids, NP-SH groups and its free-radical scavenging property under the influence of polyamines stimulated by ornithine decarboxylase activity (ODC).

Gastroprotective effect of essential oil from Croton cajucara Benth. (Euphorbiaceae)

The gastroprotective activity of the essential oil from the bark of Croton cajucara Benth (Euphorbiaceae) was assessed in three different models of experimentally induced gastric ulcer in mice. At oral dose of 100 mg/kg the essential oil reduced gastric lesions induced by hypothermic restraint stress and HCl/ethanol significantly. In the HCl/ethanol model a dose-dependent gastroprotective effect was found. Moreover, significant changes in gastric parameters such as pH, secretion rate and total gastric acid were found after intraduodenal administration of essential oil under ligated pylorus (Shay) conditions. The acute toxicity of essential oil was assessed in mice. The LD50 values were 9.3 and 680 mg/kg for oral and intraperitoneal administrations, respectively. The cytotoxicity of essential oil was studied also. A dose-dependent cell viability inhibition was found in V79 fibroblast cell cultures with an IC50 of 22.9 microg/ml. Our results support the pharmacological study of this essential oil.

Effects of an essential oil from the bark of Croton cajucara Benth. on experimental gastric ulcer models in rats and mice

Croton cajucara Benth. (Euphorbiaceae) is widely used in Amazonian folk medicine for the treatment of a wide range of gastrointestinal symptoms. The essential oil from its bark was investigated for acute toxicity in mice and for its ability to prevent the formation of ulceration of the gastric mucosa in different models of experimentally induced gastric ulcer in mice and rats. When previously administered orally at a dose of 100 mg kg(-1), the essential oil significantly reduced (P < 0.01) the gastric injury induced by hypothermic restraint stress (48%), indomethacin (47%), ethanol (86%) and pylorus ligature models (87%) in rats. In the HCl/ethanol-induced gastric ulcer model in mice, at oral doses of 100 and 200 mg kg(-1), the essential oil from C. cajucara significantly reduced (P < 0.01) the formation of gastric lesions by 52% and 67%, respectively, when compared with the control group. In rats submitted to pylorus ligature, the essential oil given orally increased the volume of gastric juice when compared with the control group (P < 0.01). When the essential oil (100 mg kg(-1)) was administered intraduodenally to mice, significant modifications were found in gastric parameters such as pH and total acid content after oil treatment. We observed significant changes (P < 0.01) in gastric juice parameters such as an increase in volume and a decrease in gastric acidity (pH and total acid content). The acute toxicologic effects of the essential oil from C. cajucara were assessed in mice. The LD50 values were 9.3 g kg(-1) by the oral route and 680 mg kg(-1) by the intraperitoneal route. The good yield of essential oil obtained from dried C. cajucara bark (1%) as well as its anti-ulcerogenic activity and low toxicity suggest that pharmacological studies of this substance as a potential new anti-ulcerogenic drug are warranted.

A comparison of two prostaglandin analogues (enprostil vs misoprostol) in the treatment of acute duodenal ulcer disease

We conducted a clinical trial to compare the efficacy and safety profile of two prostaglandin analogues, enprostil (35 micrograms twice daily) and misoprostol (200 micrograms four times daily) in the treatment of acute duodenal ulcers in 214 patients. The two agents healed approximately 80% and in excess of 90% of duodenal ulcers after 4 and 6 weeks' therapy, respectively. There was a significantly lower ulcer healing rate in both treatment groups in smokers compared with non-smokers (P < 0.05). However, daytime and nighttime ulcer pain relief was achieved in fewer than 50% of patients by either agent. Diarrhea, which occurred in more than 40% of patients, was the predominant side effect, and occurred mainly during the first 2 weeks of therapy with either agent. Nevertheless, this side effect was mild and self-limiting in the majority of patients. Both agents were found to be safe and well tolerated by the majority of patients. We conclude that these prostaglandin analogues are safe and effective duodenal ulcer healing agents. Furthermore, there was very little difference between enprostil and misoprostol. The limiting factors, however, for their routine use as ulcer healing agents are their low efficacy with regard to ulcer pain relief and the high incidence of diarrhea.

Pharmacokinetics of nocloprost in human volunteers and its relation to dose

The pharmacokinetics and absolute bioavailability of nocloprost, a synthetic PGE2-analogue with cytoprotective properties, was investigated in human volunteers as a function of the dose. Ten young male volunteers received nocloprost 5 micrograms i.v. and 100, 200 and 400 micrograms p.o. in random order at weekly intervals. Serum nocloprost levels were monitored for up to 12 h after each dose, using a specific, validated assay. After nocloprost 5 micrograms i.v. the highest serum level of 373 pg.ml-1 was found in the first sample 5 min after injection, and the subsequent decline showed one or two phases, with half-lives of 4 and 49 min. The AUC was 89 pg.h.ml-1, the total plasma clearance was 13.2 ml.min-1.kg-1, and the volume of distribution at steady state was 0.16 l.kg-1. After oral administration the maximum serum level and AUC increased in proportion to the dose. tmax showed a wide scatter, with an average value of about 30 min independent of the dose. Although not detectable in every subject, post maximum serum levels declined biphasically, with half-lives of ca 10 and 35-40 min. The absolute bioavailability after oral administration averaged about 2% and was independent of the dose.

Central and peripheral effects of prostaglandin E2 and enprostil on gastric acid secretion in the rat

The intracerebroventricular (i.c.v.) administration of prostaglandin E2 (PGE2) inhibits gastric secretion at doses that are inactive by i.v. administration in the rat. The present study was undertaken to examine the central and peripheral effects of enprostil, a potent synthetic PGE2 analogue, on gastric acid secretion as compared to those of PGE2. We used conscious rats equipped with a chronic gastric fistula and a cannula to allow injection into the third ventricle of the brain. Gastric acid output was measured under basal interdigestive conditions and during stimulation with submaximal doses of pentagastrin and histamine. Total inhibition of basal and stimulated gastric acid output was obtained after i.c.v. PGE2 and after i.c.v. or i.v. enprostil administration. After i.v. PGE2, the maximal observed inhibition was not greater than 50%. The ratio of ED50 values for i.v. administered to i.c.v. administered PGE2 was 64 or more, whereas the ratio of ED50 values for i.v. enprostil to i.c.v. enprostil was 9 to 13. Under all conditions studied, enprostil was more potent than PGE2 and this greater potency was more prominent after i.v. administration (ratio 250 to 2500) than after i.c.v. administration (ratio 10 to 400). The blockade of alpha 2-adrenoceptors by idazoxan did not suppress the inhibition of gastric secretion produced by i.c.v. PGE2 or enprostil. It is concluded that low doses of PGE2 inhibit gastric acid output mainly through a central mechanism, whereas low doses of enprostil potently inhibit gastric acid output through both a central and a peripheral mechanism. alpha 2-Adrenoceptors are not essential for the effect of i.c.v. prostanoids on gastric acid secretion.

[Comparative effects of diazepam, ranitidine , sodium citrate and enprostil on pH and gastric volume in preanesthetic medication]

A study was designed to assess the efficacy of oral premedication with diazepam or enprostil in preventing the gastric aspiration syndrome in fasted patients scheduled for elective surgery, and to compare the results with those obtained with ranitidine and sodium citrate. The study included 120 consecutive patients undergoing urological or plastic surgery, randomly assigned to four groups of 30. Two hours before anaesthesia, the patients from three groups were given, with 30 ml of water, either 10 mg diazepam, or 150 mg ranitidine, or 35 micrograms enprostil. Those in the fourth group were given 30 ml of 0.5 M sodium citrate, ten minutes before induction. Anaesthesia consisted in the administration of thiopentone, fentanyl, vecuronium and nitrous oxide in oxygen. After endotracheal intubation, a gastric tube was inserted. The stomach fluid content was completely aspirated, and then again 60 and 120 min after induction, as well as at the end of surgery. Age, weight and duration of surgery were comparable in the four groups. Mean pH in the diazepam group was much lower than that in the other groups, both just after induction (2.3 +/- 1.54; p less than 0.001 vs. ranitidine and sodium citrate; p less than 0.01 vs. enprostil) and at the end of surgery (3.2 +/- 2.03; p less than 0.01 vs. ranitidine and sodium citrate; p less than 0.05 vs. enprostil). There was more than 0.4 ml.kg-1 gastric juice in the sodium citrate group.(ABSTRACT TRUNCATED AT 250 WORDS)

A synthetic prostaglandin E2 analogue, enprostil, hastens gastric emptying of solids in patients with an active duodenal ulcer

The effect of gastric emptying of two doses (35 and 70 micrograms) of enprostil given orally was evaluated in eight patients with endoscopically confirmed duodenal ulcer. Gastric emptying of a radiolabelled solid meal was assessed with the use of a gamma camera. Enprostil dose-dependently accelerated gastric emptying of solids; the gastric emptying index, Ix, increased from 1.62 +/- 0.38 min-1.10(-2) after placebo to 2.77 +/- 0.56 min-1.10(-2) after 35 micrograms enprostil (p less than 0.05 versus placebo) and to 3.65 +/- 0.64 min-1.10(-2) after 70 micrograms enprostil (p less than 0.005 versus placebo). The fraction of the radiolabelled food retained in the stomach at the end of the gastric emptying examination (that is, after 90 min) amounted to 50.5 +/- 6.9% after placebo, 35.2 +/- 7.4% after 35 micrograms enprostil, and 24.1 +/- 8.4% after 70 micrograms enprostil. It is concluded that enprostil elicits a significant speeding up of solid-phase gastric emptying in duodenal ulcer patients.

Human antral damage induced by alcohol is potentiated by enprostil

Enprostil, a synthetic analogue of prostaglandin E2, has been shown to protect the human gastroduodenal mucosa from aspirin injury. This study was designed to determine if enprostil protected against alcohol damage. A double-blind, randomized, cross-over study was performed on eight healthy adult men. After an overnight fast, a gastroscope was inserted and the antral mucosa was sprayed with a 10-mL test solution containing either enprostil (70 micrograms) or its vehicle (control). After 15 minutes, mucosal injury was scored (0-5), and the mucosa was sprayed with 100 mL 80% ethanol. Mucosal injury was scored after a further 15, 20, 25, and 30 minutes. The entire experiment was recorded on video film, which a second endoscopist used to score the damage independently. The two experiments were separated by an interval of 1 week. There was close agreement between the two endoscopists (r = 0.9385), and their scores were averaged. Using Friedman's two-way analysis of variance, a highly significant (P less than 0.00004) increase in injury was demonstrated following enprostil pretreatment. The Wilcoxin signed rank test showed the differences to be significant (P less than 0.05) at every time point. We conclude that enprostil, rather than protecting the human antral mucosa from alcohol injury, appears to potentiate this injury and may itself be damaging in therapeutic concentrations. This unexpected result cannot yet be explained but demands caution in the clinical use of enprostil.

Oral prostaglandin E analogues induce intestinal migrating motor complexes after a meal in dogs. Evidence for a central mechanism

The effects of oral, intravenous, and intracerebroventricular administration of synthetic derivatives of prostaglandins E1 (misoprostol) and E2 (enprostil) on postprandial gastrointestinal motility were investigated in dogs chronically fitted with strain gauge transducers on the antrum and the proximal and middle jejunum. Synthetic prostaglandin E analogues administered orally at a dose of 20-50 micrograms/kg 15 min before the meal did not modify the postprandial pattern of gastric contractions but suppressed the spontaneous postprandial irregular activity on the jejunum and induced a cyclic pattern of migrating motor complexes for 4-6 h after the meal. These postprandial migrating motor complexes induced by prostaglandin E were propagated between the two recording sites and had a period similar to that observed in the fasted state. However, the duration of phase 2 was significantly increased and the amplitude of the phase 3 decreased. This jejunal cyclic motor pattern was reproduced by administration of synthetic prostaglandin E derivatives either intravenously (4-10 micrograms/kg) 15 min before the meal or intracerebroventricularly (50 ng/kg) 1 h after the meal. The intestinal migrating motor complex activity observed after oral administration of synthetic prostaglandin E derivatives was abolished by the previous intracerebroventricular (40 micrograms/kg) but not intravenous (200 micrograms/kg) administration of SC-19220, a receptor antagonist of prostaglandin E. These results suggest that oral administration of synthetic prostaglandin E1 (misoprostol) or prostaglandin E2 (enprostil) analogues before a meal induces postprandial migrating motor complexes on the jejunum in dogs through a mechanism involving central prostaglandin receptors.

Ranitidine compared with the dimethylprostaglandin E2 analogue enprostil as adjunct to pancreatic enzyme replacement in adult cystic fibrosis

In a double-blind cross-over randomized study adjunct therapy with ranitidine (2 x 150 mg) was compared with enprostil (2 x 35 micrograms) in eight adult cystic fibrosis (CF) patients receiving a fixed dose of enteric-coated microsphere capsules of pancreatin (Pancrease). The study consisted of two consecutive 14-day treatment periods. All patients kept a fixed daily fat intake during the last 5 days of each treatment period and performed 72-h faecal collections during the last 3 days of each treatment period. Gastrointestinal complaints were scored at the end of each treatment period. During treatment with ranitidine there was less faecal fat excretion (18.9% versus 25.1%; NS), less faecal weight (263 versus 303 g/day; NS), and a lower gastrointestinal complaints score (5.3 versus 3.1; P less than 0.05) compared with the treatment with enprostil. One patient dropped out during the treatment period with enprostil because of very severe diarrhoea and abdominal discomfort. We conclude from this study that adjunct therapy with ranitidine has significantly less side effects and may give a better reduction of faecal fat excretion and daily faecal weight in CF.

Treatment of peptic ulcer disease in the arthritic patient

Dyspepsia associated with arthritis and non-steroidal anti-inflammatory drugs (NSAIDs) is a common clinical problem. Up to 80% of deaths attributable to peptic ulceration may be associated with NSAID usage. The problem is foremost in the elderly population, in which there has been an increase both in the incidence of peptic ulcers and in the use of NSAIDs. Although the development of duodenal ulceration is not clearly associated with NSAIDs, it is accepted that these drugs increase the risk of gastric ulceration and the occurrence of peptic ulcer complications. Asymptomatic peptic ulceration is common, and patients taking NSAIDs are often asymptomatic prior to presentation with life-threatening complications. The key principle in management of this problem is prevention through careful selection of patients for NSAID use, adequate treatment of peptic ulceration and maintenance of remission. A variety of effective drugs are available for the treatment of peptic ulcers, including H2-receptor antagonists, pirenzepine, sucralfate and colloidal bismuth subcitrate. However, it is recognised that peptic ulceration is a chronic disease with a relapsing-remitting course, often with asymptomatic ulcer episodes. The knowledge that current ulcer-healing strategies do not significantly alter this natural history has lead to increasing efforts to prevent relapse with effective 'maintenance' therapy.

Rioprostil and ranitidine in the treatment of prepyloric gastric ulcer. A double-blind comparative trial

Rioprostil, a synthetic 16-methylprostaglandin E1, combines antisecretory with cytoprotective properties, the latter being active even at doses below those required for acid inhibition. To test whether rioprostil given in antisecretory doses would heal prepyloric ulcers rapidly, we assigned patients with endoscopically proved ulcers randomly to double-blind treatment with 100 micrograms rioprostil twice daily or 150 mg ranitidine twice daily for up to 8 weeks. Recruitment was terminated at the time point of planned interim analysis because the total healing rate was markedly lower than expected. Thirty patients were allocated to each treatment group. The cumulative healing rates at 4 and 8 weeks were 40% and 60%, respectively, in the rioprostil group versus 70% and 90%, respectively, in the ranitidine group (p less than 0.01). Pain relief occurred simultaneously in the two groups. No major adverse effects were noted. These findings question the clinical relevance of using 'cytoprotection' by prostaglandin analogues as treatment for prepyloric ulcer disease in the short term.

Enprostil inhibits post-prandial gastrin release: a dose-response study

In a double-blind placebo-controlled study in nine healthy volunteers, the effects of single doses of oral enprostil (8.75, 17.5, 35 and 70 micrograms), taken before a standard breakfast, were assessed on the post-prandial release of gastrin into the plasma. All doses of enprostil caused a significant dose-related decrease in median post-prandial plasma gastrin concentration (range from -29 to -44%). In the same subjects, two doses of 25 mg indomethacin caused a significant (38%) increase in median post-prandial plasma gastrin concentration.