Effect of sucralfate on human gastric bicarbonate secretion and local prostaglandin E2 metabolism

Chemotherapy-induced gastrointestinal toxicity: Pathogenesis and current management

Chemotherapy is the most common treatment for malignant tumors. However, chemotherapy-induced gastrointestinal toxicity (CIGT) has been a major concern for cancer patients, which reduces their quality of life and leads to treatment intolerance and even cessation. Nevertheless, prevention and treatment for CIGT are challenging, due to the prevalence and complexity of the condition. Chemotherapeutic drugs directly damage gastrointestinal mucosa to induce CIGT, including nausea, vomiting, anorexia, gastrointestinal mucositis, and diarrhea, etc. The pathogenesis of CIGT involves multiple factors, such as gut microbiota disorders, inflammatory responses and abnormal neurotransmitter levels, that synergistically contribute to its occurrence and development. In particular, the dysbiosis of gut microbiota is usually linked to abnormal immune responses that increases inflammatory cytokines' expression, which is a common characteristic of many types of CIGT. Chemotherapy-induced intestinal neurotoxicity is also a vital concern in CIGT. Currently, modern medicine is the dominant treatment of CIGT, however, traditional Chinese medicine (TCM) has attracted interest as a complementary and alternative therapy that can greatly alleviate CIGT. Accordingly, this review aimed to comprehensively summarize the pathogenesis and current management of CIGT using PubMed and Google Scholar databases, and proposed that future research for CIGT should focus on the gut microbiota, intestinal neurotoxicity, and promising TCM therapies, which may help to develop more effective interventions and optimize managements of CIGT.

Gastroprotective Therapy

A range of gastroprotective drugs are available for the treatment of esophagitis and gastroduodenal mucosal injury including acid suppressants (ie, histamine-2 receptor antagonists, proton pump inhibitors), coating agents, prostaglandin analogs, and antacids. Of these, the proton pump inhibitors are the most effective drugs for the medical treatment of upper gastrointestinal injury. However, proton pump inhibitors are not effective for all causes of upper gastrointestinal injury. The choice of gastroprotective drug should be guided by the cause and location of gastrointestinal injury and the potential for adverse effects.

Equine glandular gastric disease: prevalence, impact and management strategies

Equine glandular gastric disease (EGGD) is an increasingly recognized disease of the glandular mucosa of the equine stomach. Diagnosis is confirmed by gastric endoscopy and scored based upon one of several different endoscopic scoring systems. Prevalence appears to be variable, depending upon breed and discipline. Primary identified risk factors include exercise frequency, and stress; therefore, management strategies are focused on reducing exercise and stress. Limiting grain intake and increasing pasture turnout may also be helpful preventative measures. Pharmacologic treatment consists primarily of an approved omeprazole product with or without misoprostol or sucralfate. Further research into the pathophysiology of EGGD may allow for identification of other targeted treatments.

Effect of sucralfate on gastric permeability in an ex vivo model of stress-related mucosal disease in dogs

BACKGROUND

Sucralfate is a gastroprotectant with no known systemic effects. The efficacy of sucralfate for prevention and treatment of stress-related mucosal diseases (SRMD) in dogs is unknown.

HYPOTHESIS/OBJECTIVES

To develop a canine ex vivo model of SRMD and to determine the effect of sucralfate on mucosal barrier function in this model.

ANIMALS

Gastric antral mucosa was collected immediately postmortem from 29 random-source apparently healthy dogs euthanized at a local animal control facility.

METHODS

Randomized experimental trial. Sucralfate (100 mg/mL) was applied to ex vivo canine gastric mucosa concurrent with and after acid injury. Barrier function was assessed by measurement of transepithelial electrical resistance (TER) and radiolabeled mannitol flux.

RESULTS

Application of acidified Ringers solution to the mucosal side of gastric antrum caused a reduction in gastric barrier function, and washout of acidified Ringers solution allowed recovery of barrier function (TER: 34.0 ± 2.8% of control at maximum injury, 71.3 ± 5.5% at recovery, P < .001). Sucralfate application at the time of injury or after injury significantly hastened recovery of barrier function (TER: 118.0 ± 15.2% of control at maximum injury, P < .001 and 111.0 ± 15.5% at recovery, P = .35).

CONCLUSIONS AND CLINICAL IMPORTANCE

Sucralfate appeared effective at restoring defects in gastric barrier function induced by acid and accelerating repair of tissues subjected to acid in this model, suggesting that sucralfate could have utility for the treatment and prevention of SRMD in dogs.

Alcohol intake and its effect on some appetite-regulating hormones in man: influence of gastroprotection with sucralfate

BACKGROUND

Alcohol stimulates appetite. Ghrelin, obestatin, glucagon-like peptide 1 and leptin are putative mediators.

OBJECTIVE

We studied whether alcohol ingestion affects serum levels of these peripheral hormones, and if gastroprotective sucralfate prevents such an effect.

MATERIALS AND METHODS

Ten participants were investigated on four occasions. On one alcohol was ingested; on another alcohol was given after pretreatment with sucralfate; on a third water was ingested; and on a fourth sucralfate was ingested followed by water. Serum hormones and ethanol concentrations were determined.

RESULTS

The ghrelin and leptin levels fell after ingestion of alcohol, whereas the obestatin and GLP-1 levels remained unchanged. Sucralfate did not affect any of the basal four hormone levels, nor the ghrelin or leptin responses to alcohol.

CONCLUSIONS

An appetite-stimulating effect of alcohol is hardly mediated by any of the hormones studied in this investigation, as the GLP-1 and obestatin levels were unaffected by alcohol, the ghelin level decreased, and leptin - although declining after alcohol - has not previously been found to have short-term inhibitory effect on hunger.

Pharmacologic considerations in the treatment of neonatal septicemia and its complications

This article focuses on the pharmacologic properties of drugs commonly used in the treatment of neonatal septicemia and its complications. Rational therapy demands an awareness of not only the pharmacology of individual drugs but also the interactions and anticipated fate of such drugs in the rapidly changing physiologic environment of the neonate. Further research in the area of equine neonatal pharmacology should greatly assist our understanding of the impact of the disease state on the unique physiology of the newborn and should allow us to better predict the ultimate fate of drugs commonly used for such purposes. Careful dosing and close monitoring of pharmacologic effects are critical for a successful outcome. In the future, newer therapeutic strategies that are safe and efficacious may provide a means to circumvent many of the problems currently encountered with treating the septicemic newborn foal.

Short-term sucralfate administration alters potassium diclofenac absorption in healthy male volunteers

AIMS

Since patients who regularly take NSAIDS may use sucralfate because of its cytoprotective properties, we examined the influence of this compound on the pharmacokinetics of diclofenac.

METHODS

Potassium diclofenac (105 mg) was administered orally to eighteen healthy male volunteers with or without a 5-day pre-treatment with sucralfate (2000 mg twice daily). Blood samples were collected at intervals post-dose and serum concentrations of diclofenac were determined by reverse-phase h.p.l.c.

RESULTS

Pre-treatment with sucralfate significantly decreased both the AUC(0,8 h) [2265 ng h ml-1 (geometric mean) (range 1815-2827) vs 1821 ng h ml-1 (1295-2562)] and the Cmax [1135 ng ml-1 (geometric mean) (range 898-1436) 701 ng ml-1 (501-981)] with no significant delay in absorption [tmax 1.0 h (median) (range 0.5-2.0) vs 1.0 h (0.5-4.0)].

CONCLUSIONS

The short-term treatment of healthy male volunteers with sucralfate decreases potassium diclofenac bioavailability. These findings suggest that either an appropriate increase in the diclofenac intake or the use of another gastric mucosa protector must be adopted.

Effect of sucralfate on components of mucosal barrier produced by cultured canine epithelial cells in vitro

The mucous gel maintains a neutral microclimate at the epithelial cell surface, which may play a role in both the prevention of gastroduodenal injury and the provision of an environment essential for epithelial restitution and regeneration after injury. Enhancement of the components of the mucous barrier by sucralfate may explain its therapeutic efficacy for upper gastrointestinal tract protection, repair, and healing. We studied the effect of sucralfate and its major soluble component, sucrose octasulfate (SOS), on the synthesis and release of gastric mucin and surface active phospholipid, utilizing an isolated canine gastric mucous cells in culture. We correlated these results with the effect of the agents on mucin synthesis and secretion utilizing explants of canine fundus in vitro. Sucralfate and SOS significantly stimulated phospholipid secretion by isolated canine mucous cells in culture (123% and 112% of control, respectively). Indomethacin pretreatment significantly inhibited the effect of sucralfate, but not SOS, on the stimulation of phospholipid release. Administration of either sucralfate or SOS to the isolated canine mucous cells had no effect upon mucin synthesis or secretion using a sensitive immunoassay. Sucralfate and SOS did not stimulate mucin release in the canine explants; sucralfate significantly stimulated the synthesis of mucin, but only to 108% of that observed in untreated explants. No increase in PGE2 release was observed after sucralfate or SOS exposure to the isolated canine mucous cells. Our results suggest sucralfate affects the mucous barrier largely in a qualitative manner. No increase in mucin secretion or major effect on synthesis was noted, although a significant increase in surface active phospholipid release was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Pathogenesis of gastroduodenal injury due to nonsteroidal antiinflammatory drugs: implications for prevention and therapy

Nonsteroidal antiinflammatory drugs (NSAIDs) initiate gastroduodenal ulceration and promote complications such as bleeding and perforation by interfering with the ability of the proximal gastrointestinal tract to maintain its defensive capabilities. Mucosal defense is composed of three critical components: preepithelial, epithelial, and postepithelial. Preepithelial defense is composed of the mucous gel containing mucin, bicarbonate, and surface-active phospholipids. The epithelial component includes the surface cells, their apical tight junctions, and membrane transporters. Postepithelial defense is maintained by mucosal blood flow, which is essential for both defense and repair. NSAIDs interfere with each component of mucosal defense via direct toxic effects along with cyclooxygenase inhibition and depletion of endogenous prostaglandins. Although NSAID injury is dependent on luminal acid, attempts to prevent NSAID injury by acid suppression using H2-receptor antagonists in humans have had limited success, whereas complete inhibition of acid secretion with proton pump inhibition may have promise. Prostaglandins appear most effective for prevention of NSAID injury, sucralfate appears ineffective, and bismuth compounds have not been studied extensively. Recent evidence suggests that NSAID ulcers heal quickly with proton pump inhibitors compared with H2-receptor antagonists in patients who continue NSAID therapy.

Effects of sucralfate, lansoprazole, and cimetidine on the delayed healing by hydrocortisone sodium phosphate of chronic gastric ulcers in the rat

We have previously shown that chronic sucralfate ingestion stimulates gastric epithelial proliferation in rats, which may explain one of the beneficial effects of sucralfate in healing of peptic ulcers. In a separate study, we have found that chronic steroid administration delays the healing of experimental gastric ulcers in rats. This study was designed to test the beneficial effects of sucralfate, cimetidine, and lansoprazole (AG-1749, a new proton pump inhibitor), on the delayed healing by steroids in rat chronic gastric ulcers. Chronic gastric ulcers were produced in male Wistar rats, weighing 180 g, by the application of 100% acetic acid. The rats were randomly divided into five groups; (1) control, (2) vehicle alone, (3) 10 mg/kg lansoprazole, (4) 500 mg/kg sucralfate, and (5) 100 mg/kg cimetidine. Except for controls, all rats received daily intraperitoneal injections of 2.5 mg/kg hydrocortisone sodium phosphate. Tested drugs were administered intragastrically (lansoprazole and sucralfate) or intraperitoneally (cimetidine) twice a day for 2 weeks. Rats were sacrificed 14 days later and ulcer size was measured. Chronic administration of hydrocortisone sodium phosphate resulted in a significant delay of ulcer healing induced by acetic acid. Treatment with either lansoprazole or sucralfate abolished the deleterious effect of steroids, whereas cimetidine had no effect. These results indicate that lansoprazole and sucralfate overcome the delayed healing by steroids of chronic gastric ulcers in the rat.

The effects of sucralfate and luminal stasis on recovery of the chambered rat gastric mucosa from taurocholate-induced damage

We have previously shown, using a gastric chamber model, that both sucralfate and luminal stasis protected the rat gastric mucosa against the development of hemorrhagic erosions produced by subsequent exposure for 10 minutes to acidified (50 mM HCl) 80 mM sodium taurocholate (NaT). The protection afforded by sucralfate was abolished by inhibition of cyclooxygenase activity but restored by sucralfate. In this study we demonstrate that indomethacin pretreatment decreases both the depth (in microns) and magnitude (in pH units) of the juxtamucosal pH gradient, but that sucralfate restores these parameters to levels characteristic of normal mucosae. The cytoprotective effect of sucralfate is thus prostaglandin-independent and, at least in part, a consequence of sucralfate-induced increases in the thickness of the juxtamucosal pH gradient/unstirred layer. We have also examined the ability of sucralfate to prevent the otherwise inevitable development of hemorrhagic erosions when it was applied after the gastric mucosa was exposed to NaT. When 100 mg sucralfate in 50 mM HCl was applied for 10 minutes, without stirring, subsequent to a 10-minute exposure of the mucosa to NaT, the average lesion area was reduced from about 15% to less than 3%. Unlike its cytoprotective property, the ability of sucralfate to accelerate the recovery process after damage was abolished by indomethacin pretreatment. Studies using antimony microelectrodes revealed that indomethacin pretreatment resulted in reductions in both the depth and magnitude of the pH gradient that resulted from plasma efflux from the mucosa after exposure to the acidified bile salt. These studies demonstrate that sucralfate is capable not only of prevention or attenuation of acute damage when administered prior to damaging agents, but is also capable of arresting the sequence of events that produces hemorrhage in the previously inflamed or damaged stomach.

Effect of sucralfate and its components on taurocholate-induced damage to rat gastric mucosal cells in tissue culture

The present study evaluated the effect of sucralfate and its components, sucrose octasulfate and aluminum hydroxide, on: (1) damage to rat cultured gastric mucosal cells induced by sodium taurocholate in a neutral environment and in conditions independent of systemic factors, (2) prostaglandin E2 and on 6-keto prostaglandin F1 alpha release by cultured cells, and (3) sulfhydryl content of cultured cells. Cell damage was quantitated by chromium-51 release assay. Prostaglandin E2 and 6-keto prostaglandin F1 alpha were measured by radioimmunoassay. Total sulfhydryl content of cultured cells was determined calorimetrically. Microscopically, sucralfate was found to adhere tightly to epithelial cell surfaces despite frequent washings. Sucralfate 2 mg/ml and 5 mg/ml significantly decreased taurocholate-induced damage, reducing taurocholate-induced specific 51Cr release by 11.8 points (equal to 29% decrease in cell damage, P less than 0.01) and 22.9 points (equal to 56% decrease in cell damage, P less than 0.001), respectively. Sucrose octasulfate and aluminum hydroxide did not exert significant protection against damage induced by sodium taurocholate. The protective effect of sucralfate was not prevented by indomethacin, nor was it counteracted by the sulfhydryl blocker, iodoacetamide. Sucralfate, but not its components, significantly and dose-dependently stimulated prostaglandin E2 (r = 0.94, P less than 0.05) and 6-keto prostaglandin F1 alpha (r = 0.89, P less than 0.05) production by cultured cells. Neither sucralfate nor its components affected sulfhydryl content of cultured cells. In conclusion, sucralfate, but not its components, (1) protects rat gastric mucosal cells against taurocholate-induced damage in conditions independent of systemic factors and in a neutral environment and (2) significantly stimulates prostaglandin production by cultured cells. (3) The protection by sucralfate in vitro does not seem to depend on its stimulatory effect on endogenous prostaglandin synthesis.

The protective and therapeutic mechanisms of sucralfate

Sucralfate is a nonsystemic agent that is effective in protecting the gastroduodenal mucosa against injury. In addition, sucralfate is effective in the healing of acute duodenal and gastric ulceration, the therapy of esophagitis, and the prevention of ulcer recurrence. The mechanisms responsible for sucralfate's successful protective and therapeutic actions include the adsorption of pepsin and bile acids, the stimulation of bicarbonate and mucus secretion, and stimulation of endogenous synthesis of prostaglandins. When sucralfate is given to experimental animals or humans, it stimulates endogenous synthesis and release of prostaglandin E2 and inhibits thromboxane release. Pretreatment of animals with the cyclooxygenase inhibitor indomethacin results in a marked decrease in the protective effect of sucralfate against alcohol injury. Sucralfate also increases epidermal growth factor binding to ulcerated areas and stimulates macrophage activity. In addition, sucralfate stimulates endogenous sulfhydryl compounds. At the microscopic level sucralfate protects the vascular integrity of the mucosa and the mucosal proliferative zone. It also stimulates epithelial cell restitution and stimulates cell proliferation. The administration of sucralfate before acute injury results in decreased depth and extent of injury and in acceleration of healing. Because of sucralfate's ability to stimulate the protective and reparative mechanisms of the gastric and duodenal mucosa, it is an important nonsystemic agent for the therapy and prevention of peptic ulceration.