Antisecretory and mucosal protective actions of misoprostol. Potential role in the treatment of peptic ulcer disease

Turn over the new leaf of the treatment in peptic ulcer bleeding: a review of the literature

Peptic ulcer bleeding is the most common cause of upper gastrointestinal bleeding, which has a high mortality risk. The standard therapy for acute peptic ulcer bleeding combines medication administration and endoscopic therapies. Both pharmacologic and endoscopic therapies have developed continuously in the past few decades. Proton pump inhibitors (PPIs) already reached a high efficacy in ulcer healing and have been widely used in the past few decades. Endoscopic hemostasis, which includes local epinephrine injection, heater probe coagulation, use of hemostatic clips, and/or band ligation, is highly effective with an overall hemostatic success rate of 85%-90%. However, 10%-20% of patients could not be cured by the current standard combination treatment. Recurrent ulcer bleeding, despite an initial successful hemostasis, is also a big problem for longer hospitalization stays, higher mortality, and higher complication rates, especially for malignant ulcer bleeding. How to manage all types of peptic ulcer bleeding and how to prevent early recurrent peptic ulcer bleeding remain unresolved clinical problems. Recently, several novel medications and endoscopic methods have been developed. Potassium competitive acid blockers have shown a stronger and longer acid suppression than PPI. Hemostatic powder spray and hemostatic gel emulsion are novel hemostatic weapons with emerging evidence, which are potential missing pieces of the puzzle. This literature review will go through the development of endoscopic hemostasis to the prospects of novel endoscopic treatments.

Stress ulcer prophylaxis in the intensive care unit: is it indicated? A topical systematic review

Stress ulcer prophylaxis (SUP) is regarded as standard of care in the intensive care unit (ICU). However, recent randomized, clinical trials (RCTs) and meta-analyses have questioned the rationale and level of evidence for this recommendation. The aim of the present systematic review was to evaluate if SUP in the critically ill patients is indicated.

DATA SOURCES

 MEDLINE including MeSH, EMBASE, and the Cochrane Library.

PARTICIPANTS

patients in the ICU.

INTERVENTIONS

pharmacological and non-pharmacological SUP.

STUDY APPRAISAL AND SYNTHESIS METHODS

Risk of bias was assessed according to Grading of Recommendations Assessment, Development, and Evaluation, and risk of random errors in cumulative meta-analyses was assessed with trial sequential analysis. A total of 57 studies were included in the review. The literature on SUP in the ICU includes limited trial data and methodological weak studies. The reported incidence of gastrointestinal (GI) bleeding varies considerably. Data on the incidence and severity of GI bleeding in general ICUs in the developed world as of today are lacking. The best intervention for SUP is yet to be settled by balancing efficacy and harm. In essence, it is unresolved if intensive care patients benefit overall from SUP. The following clinically research questions are unanswered: (1) What is the incidence of GI bleeding, and which interventions are used for SUP in general ICUs today?; (2) Which criteria are used to prescribe SUP?; (3) What is the best SUP intervention?; (4) Do intensive care patients benefit from SUP with proton pump inhibitors as compared with other SUP interventions? Systematic reviews of possible interventions and well-powered observational studies and RCTs are needed.

NSAIDs: take with food or after fasting?

OBJECTIVE

Published and regulatory advice is to take NSAIDs with fluids and/or food irrespective whether NSAIDs are taken over the counter or long-term. The basis for this recommendation is not clear and we sought to establish the reasons for it through a search of published literature and personal files.

RESULTS

Results from experimental animals show that fasting increases the gastric side effects of NSAIDs while food increases small bowel damage, but this has not been tested in humans. The possible effects of food in modifying the gastric damage caused by NSAIDs are complex, as food quantity and composition modify the responses substantially. Food usually delays peak levels of NSAIDs (and hence onset of action) without affecting total bioavailability. This may not be important when a steady state is achieved, but rapid onset of action is highly relevant for over-the-counter use of NSAIDs. The safety of over-the-counter use of ibuprofen and naproxen appears to be excellent and comparable with paracetamol.

CONCLUSION

The rapid onset of action of NSAIDs is most important during over-the-counter use, in which case it may be more appropriate to take the drugs on a fasting stomach.

Nonsteroidal antiinflammatory drug-related injury to the gastrointestinal tract: clinical picture, pathogenesis, and prevention

Increasing life expectancy in developed countries has led to a growing prevalence of arthritic disorders, which has been accompanied by increasing prescriptions for nonsteroidal antiinflammatory drugs (NSAIDs). These are the most widely used agents for musculoskeletal and arthritic conditions. Although NSAIDs are effective, their use is associated with a broad spectrum of adverse reactions in the liver, kidney, cardiovascular system, skin, and gut. Gastrointestinal (GI) side effects are the most common. The dilemma for the physician prescribing NSAIDs is, therefore, to maintain the antiinflammatory and analgesic benefits, while reducing or preventing GI side effects. The challenge is to develop safer NSAIDs by shifting from a focus on GI toxicity to the increasingly more appreciated cardiovascular toxicity.

Canadian consensus guidelines on long-term nonsteroidal anti-inflammatory drug therapy and the need for gastroprotection: benefits versus risks

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used, but are not without risks.

AIM

To provide evidence-based management recommendations to help clinicians determine optimal long-term NSAID therapy and the need for gastroprotective strategies based on an assessment of both gastrointestinal (GI) and cardiovascular (CV) risks.

METHODS

A multidisciplinary group of 21 voting participants revised and voted on the statements and the strength of evidence (assessed according to GRADE) at a consensus meeting.

RESULTS

An algorithmic approach was developed to help manage patients who require long-term NSAID therapy. The use of low-dose acetylsalicylic acid in patients with high CV risk was assumed. For patients at low GI and CV risk, a traditional NSAID alone may be acceptable. For patients with low GI risk and high CV risk, full-dose naproxen may have a lower potential for CV risk than other NSAIDs. In patients with high GI and low CV risk, a COX-2 inhibitor plus a proton pump inhibitor (PPI) may offer the best GI safety profile. When both GI and CV risks are high and NSAID therapy is absolutely necessary, risk should be prioritized. If the primary concern is GI risk, a COX-2 inhibitor plus a PPI is recommended; if CV risk, naproxen 500 mg b.d. plus a PPI would be preferred. NSAIDs should be used at the lowest effective dose for the shortest possible duration.

CONCLUSION

More large, long-term trials that examine clinical outcomes of complicated and symptomatic upper and lower GI ulcers are needed.

Pharmacokinetics of oral omeprazole in llamas

Gastrogard, an oral formulation of omeprazole, was given to six llamas at a dose of 4 mg/kg once a day for 6 days. Plasma samples were collected at 0, 15, 30, 45, and 60 min and 2, 3, 4, 6, 8, 12, and 24 h on days 1 and 6. Plasma omeprazole concentrations were measured by high-pressure liquid chromatography with ultraviolet detection. Pharmacokinetic parameters calculated included the area under the curve (AUC(0-infinity)), peak plasma concentration (Cmax), time of peak plasma concentration (Tmax), and terminal half-life (t(1/2)). On day 6, plasma omeprazole concentrations reached a Cmax of 0.12 microg/mL at a Tmax of 45 min. The t(1/2) of omeprazole was 2.3 h and the AUC(0-infinity) was 0.38 h x microg/mL. Plasma concentrations remained above the minimum concentration for inhibition of gastric acid secretion projected from other studies on day 6 in all the llamas for approximately 6 h. However, the AUC(0-infinity) was below the concentrations associated with clinical efficacy. It was not possible to measure oral systemic bioavailability because there was no i.v. data collected from these animals. However, using data published on the i.v. pharmacokinetics of omeprazole in llamas, oral absorption was estimated to be only 2.95%. Due to low absorption the oral dose was increased to 8 and 12 mg/kg and studies were repeated. There were no significant differences in Cmax, Tmax, or AUC(0-infinity) for either of the increased doses. These results indicate that after 6 days of treatment with doses up to 12 mg/kg, oral omeprazole produced plasma drug concentrations which are not likely to be associated with clinical efficacy in camelids.

GI complications in patients receiving mechanical ventilation

Mechanical ventilation (MV) can be lifesaving by maintaining gas exchange until the underlying disorders are corrected, but it is associated with numerous organ-system complications, which can significantly affect the outcome of critically ill patients. Like other organ systems, GI complications may be directly attributable to MV, but most are a reflection of the severity of the underlying disease that required intensive care. The interactions of the underlying critical illness and MV with the GI tract are complex and can manifest in a variety of clinical pictures. Incorporated in this review are discussions of the most prevalent GI complications associated with MV, and current diagnosis and management of these problems.

Gastrointestinal problems in the chronically critically ill patient

In summary, a variety of gastrointestinal processes may occur in the chronically critically ill patient population, usually as consequence of the primary systemic process. The clinical presentation is frequently nonclassic and there often is a substantial delay in diagnosis, resulting in increased morbidity and mortality.

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.

Misoprostol coadministered with diclofenac for prevention of gastroduodenal ulcers. A one-year study

The objective of this study was to determine the long-term efficacy of misoprostol in preventing diclofenac-induced gastroduodenal ulcers in rheumatoid arthritis and osteoarthritis patients. Three hundred eighty-four patients who had an endoscopically confirmed gastric or duodenal lesion that had healed with misoprostol therapy were randomized to receive misoprostol or placebo coadministered with diclofenac for up to 52 weeks. Endoscopic examinations were repeated at weeks 12, 24, and 52. The development of a gastric and/or duodenal ulcer was considered a prophylaxis failure. Results in the evaluable cohort of patients demonstrated that gastroduodenal ulcer incidences were lower with misoprostol than placebo for all study periods (0-12 weeks, 7% vs 23%; 0-24 weeks, 11% vs 26%; and 0-52 weeks, 15% vs 31%). Misoprostol did not interfere with the antiarthritic effects of diclofenac. In conclusion, misoprostol coadministered with diclofenac for 12 months to patients with rheumatoid arthritis or osteoarthritis significantly reduced the incidence of diclofenac-induced gastroduodenal ulcers (P < or = 0.018).

Helicobacter pylori infection, ABO blood group, and effect of misoprostol on gastroduodenal mucosa in NSAID-treated patients with rheumatoid arthritis

Our aim was to investigate the effect of misoprostol on NSAID-induced gastroduodenal mucosal damage in patients with rheumatoid arthritis. The study included 40 patients, and it was designed as a double-blind, placebo-controlled trial. Misoprostol significantly reduced the gastroduodenal mucosal lesions found at endoscopy (P < 0.05) and prevented the development of ulcers. The cumulative incidence of ulcers at four weeks was 5% in the placebo group and 0% in the misoprostol group. The basal and pentagastrin-stimulated acid output as evaluated after 23 days of treatment with misoprostol was not significantly affected. Forty-one percent of the patients had signs of current Helicobacter pylori infection, 33% had positive serology only, and 26% had no evidence of infection. Most of the patients with current infection belonged to blood group O (P < 0.05). Misoprostol treatment did not affect the occurrence of Helicobacter pylori or the rheumatic disease activity. It is concluded that the protective actions of misoprostol on the gastroduodenal mucosa of NSAID-treated patients are largely mediated by mechanisms other than inhibition of acid secretion. The relationship among active Helicobacter pylori infection, blood group O, and peptic ulcer may be helpful to identify a subpopulation of patients taking NSAIDs at risk of developing peptic ulcers.

Management of gastroduodenopathy associated with use of nonsteroidal anti-inflammatory drugs

Adverse events associated with the use of nonsteroidal anti-inflammatory drugs (NSAIDs) are reported more frequently to the Food and Drug Administration than are those associated with any other group of drugs. The absolute risk for serious gastrointestinal events--in particular, ulcer bleeding, perforation, and death--is controversial; some investigators believe that an epidemic of NSAID-related complications is being experienced, whereas others suggest that the risks are being overemphasized. The management of patients who take NSAIDs regularly also remains controversial. Key unresolved issues include how best to identify those patients at particularly high risk for the development of ulcer complications and whether such patients should receive prophylactic therapy in an attempt to prevent such problems. In this review, we critically evaluate the currently available literature and present a management algorithm for the treatment and prevention of NSAID-associated gastroduodenopathy.

Nonsteroidal anti-inflammatory drugs and peptic ulcer disease. An overview

Evidence is accumulating that use of nonsteroidal anti-inflammatory drugs (NSAIDs) is linked to ulceration of the stomach and duodenum and can cause significant, life-threatening ulcer complications. The mechanism of action seems to be both topical damage to the mucosal barrier and the systemic effect of a reduction in levels of mucosal prostaglandins. Patients especially at risk are the elderly, those with concomitant debilitating disease, those with a history of ulcers, and those taking corticosteroids. Histamine2 blockers are reported to significantly reduce the incidence of NSAID-induced duodenal ulcer, and misoprostol (Cytotec) has been shown to significantly reduce the incidence of NSAID-induced gastric ulcer. Prophylaxis with these agents should be considered for high-risk patients who need NSAID therapy to maintain a reasonable life-style.

Mechanisms of nonsteroidal anti-inflammatory drug-induced gastric damage

The effects of nonsteroidal anti-inflammatory drugs (NSAIDs) on the gastric mucosa are well documented. The complex mechanisms of gastric damage, however, are not fully understood. This review examines current knowledge about the normal function of the gastric mucosal barrier; the role of prostaglandins in cytoprotection and repair; the mechanisms by which aspirin and other weak organic acids are absorbed by the stomach; and the subsequent cascade of events--including ion trapping and back diffusion of hydrogen ions--that leads to gastric erosion and bleeding. A hypothesis describing NSAIDs' dual insult on the stomach is advanced.

The effects of E series prostaglandins on blastogenic responses in vitro and graft vs. host responses in vivo

In this study the ability of prostaglandin E1 (PGE1), Misoprostol (a stable analog of PGE1), and 16,16-dimethyl PGE2 (a stable analog of PGE2) to suppress immune responses in vitro and in vivo was determined. All of the compounds caused a titratable (10(-6) to 10(-9) M) suppression of Con A blastogenesis and the mixed lymphocyte response whereas there was only slight inhibition of the LPS response. When either 16,16-dimethyl PGE2 (30 ug/mouse) or Misoprostol (60 ug/mouse) was administered daily in vivo, there was a significant suppression of splenomegaly in F1 mice (C57Bl/6 x CBA) which had been injected with parental (C57Bl/6) spleen cells. We conclude that prostaglandins of the E series can function as immunosuppressive reagents both in vitro and in vivo. In the future they may serve to augment existing forms of immunosuppressive therapy.