Reviews in gastroenterological disorders最新文献

Chronic hepatitis B virus (HBV) infection is a significant public health problem in the United States, with 1.25 million people infected with the virus. The long-term risks of chronic HBV infection include cirrhosis and hepatocellular carcinoma, which occur in 15% to 30% of those infected at birth or early in life and may lead to liver transplantation or death. During the past few years, the development and increased availability of oral antiviral agents have made treatment simpler, safer, and more tolerable for these patients. This article focuses on 3 of these drugs--lamivudine, adefovir, and entecavir--and their use in patients with chronic HBV infection and advanced hepatic fibrosis or cirrhosis.

The currently available endoscopic treatment modalities for the palliation of malignant dysphagia outside of self-expandable stent placement are, as yet, not optimal for achieving rapid and sustained dysphagia relief with minimal morbidity and mortality. Self-expanding stents are effective in improving dysphagia; however, the number of re-interventions needed for management of recurrent dysphagia remains higher than initially anticipated. The introduction of newer-generation stents may reduce stent migration and nontumoral tissue overgrowth and result in a decrease in the need for re-intervention. The use of self-expandable stents for benign esophageal disease has shown promising results for the treatment of anastomotic leaks and perforations. However, the data on benign esophageal strictures have been mixed. Multicenter, prospective studies are needed to evaluate the late complication rate and long-term effectiveness in this difficult-to-treat patient population with refractory esophageal strictures. Future developments in stent design include biodegradable stents, stents with a radioactive coating, and drug-eluting stents.

Lubiprostone offers an additional alternative for patients with chronic idiopathic constipation. Lubiprostone is more efficacious than placebo in the treatment of chronic idiopathic constipation. In placebo-controlled clinical trials, lubiprostone therapy was generally well tolerated and was not associated with severe adverse effects; however, the high incidence of nausea may be problematic for some patients. The nausea may be alleviated or minimized by administering the dose with food, and some patients may require a dosage reduction to 24 mug once daily. The key limitations of the placebo-controlled clinical trials include the absence of information regarding the duration of the constipation and previous types of therapies that had been used to treat the constipation and the absence of an active control group. Comparative studies with other therapies (eg, saline laxatives, polyethylene glycol) used for constipation are necessary to determine the clinical and economic value of this agent relative to other forms of therapy.

This review highlights the changes recommended by Rome III to the criteria for the functional gastrointestinal disorders and summarizes the practical implications for clinical practice. The committee retained functional dyspepsia as an umbrella term but emphasized its limited utility; they concluded that those with epigastric pain or burning probably constituted a set of patients very distinct from those who reported meal-related symptoms. Rome III added cyclic vomiting syndrome to the adult functional nausea and vomiting disorder category. The committee simplified clinical subtyping of irritable bowel syndrome. Problems remain with the Rome criteria for functional gallbladder and sphincter of Oddi disorders. Although these patients' pain is probably genuine, the exact characteristics that identify true biliary-type pain remain poorly defined from a scientific perspective. The Rome criteria have been criticized for potentially over-splitting what are truly interdependent conditions. Nevertheless, the Rome criteria remain the best standard we have for guiding diagnosis and helping choose therapy.

Loperamide is an antidiarrheal medication approved for the control of diarrhea symptoms and is available without a prescription. Loperamide works by a number of different mechanisms of action that decrease peristalsis and fluid secretion, resulting in longer gastrointestinal transit time and increased absorption of fluids and electrolytes from the gastrointestinal tract. It is a phenylpiperidine derivative with a chemical structure similar to opiate receptor agonists such as diphenoxylate and haloperidol. It was designed to maintain the antidiarrheal activity of these drugs, but minimize the negative aspects associated with their effects on the opiate receptor. Because of loperamides's low oral absorption and inability to cross the blood-brain barrier, it has minimal central nervous system effects. It also has a longer duration of action than diphenoxylate. However, it has no clinically significant analgesic activity and does not decrease the pain associated with some forms of irritable bowel syndrome and diarrhea. Loperamide is metabolized by the cytochrome P450 (CYP) system and is a substrate for the CYP3A4 isoenzyme. Concurrent administration with CYP3A4 inhibitors may elevate loperamide concentrations. Common adverse reactions to loperamide include cramps and nausea. Loperamide is an effective treatment for patients with painless diarrhea and is considered to be free of abuse potential.

Patients who respond to infliximab enjoy many benefits, including improvement in clinical symptoms, less disability, and a better quality of life. Unfortunately, many patients are unresponsive to infliximab therapy. They may be completely refractory to infliximab therapy (ie, primary nonresponders), they may have shown an initial response to therapy that subsequently diminished, or they may be hypersensitive to the drug. For these patients, second-generation tumor necrosis factor (TNF) inhibitors will soon be available; adalimumab and certolizumab pegol are the two agents most likely to gain Food and Drug Administration approval for the treatment of Crohn's disease. This article looks at recent studies using these newer TNF inhibitors in patients in whom infliximab treatment has failed as well as in those who have never received infliximab.

Conventional endoscopy can assess the location, mucosal appearance, and consistency of a gastrointestinal submucosal tumor but cannot provide enough information to differentiate the tumor from extraluminal compression by an external structure or from a neoplastic lesion or to determine whether the tumor is malignant. Therefore, endoscopic ultrasonography (EUS) has emerged as the most reliable method for evaluating submucosal tumors. EUS is very accurate in determining whether a submucosal "bump" is the result of extrinsic compression and can clearly distinguish solid from cystic structure within the submucosa, differentiate the layers of the gut wall, and define the layer of origin of the tumor. Moreover, EUS is the best way to decide whether a lesion can be resected safely and provides an indication as to whether endoscopic or surgical resection should be performed. Although various advanced EUS methods have been introduced, they require more study to determine their role in the diagnosis and staging of gastrointestinal tumors.