Drug-induced disorders of the stomach and duodenum

Drug-induced enterocolitis: Prevention and management in primary care

Drug-induced enterocolitis is a condition diagnosed with increasing frequency. It includes a variety of morphological and functional alterations of the small and large intestine as a consequence of exposure to pharmacological active compounds. A number of factors play a key role in this condition or participate in the onset of enterocolitis, which is the result of an interplay between the effect of the drug molecule and the tolerance of the bowel to damaging insults. The patient's age, gender, dose of drug, time of exposure, pharmaceutical preparation, drug-drug and drug-food interactions, gut barrier integrity, underlying intestinal conditions, and gut microbiota composition are all involved in the occurrence and extent of the injury. This review approaches the topic from the viewpoint of primary care, and focuses on epidemiology, mechanisms of damage, protective systems and diagnostic tools. Although the first-line therapeutic measure is the discontinuation of the drug, some options for prevention and treatment are discussed.

Gastrointestinal Safety Pharmacology in Drug Discovery and Development

Although the basic structure of the gastrointestinal tract (GIT) is similar across species, there are significant differences in the anatomy, physiology, and biochemistry between humans and laboratory animals, which should be taken into account when conducting a gastrointestinal (GI) assessment. Historically, the percentage of cases of drug attrition associated with GI-related adverse effects is small; however, this incidence has increased over the last few years. Drug-related GI effects are very diverse, usually functional in nature, and not limited to a single pharmacological class. The most common GI signs are nausea and vomiting, diarrhea, constipation, and gastric ulceration. Despite being generally not life-threatening, they can greatly affect patient compliance and quality of life. There is therefore a real need for improved and/or more extensive GI screening of candidate drugs in preclinical development, which may help to better predict clinical effects. Models to identify drug effects on GI function cover GI motility, nausea and emesis liability, secretory function (mainly gastric secretion), and absorption aspects. Both in vitro and in vivo assessments are described in this chapter. Drug-induced effects on GI function can be assessed in stand-alone safety pharmacology studies or as endpoints integrated into toxicology studies. In silico approaches are also being developed, such as the gut-on-a-chip model, but await further optimization and validation before routine use in drug development. GI injuries are still in their infancy with regard to biomarkers, probably due to their greater diversity. Nevertheless, several potential blood, stool, and breath biomarkers have been investigated. However, additional validation studies are necessary to assess the relevance of these biomarkers and their predictive value for GI injuries.

Endoscopic management of nonvariceal, nonulcer upper gastrointestinal bleeding

Upper gastrointestinal bleeding (UGIB) is the most common emergency condition in gastroenterology. Although peptic ulcer and esophagogastric varices are the predominant causes, other conditions account for up to 50% of UGIBs. These conditions, among others, include angiodysplasia, Dieulafoy and Mallory-Weiss lesions, gastric antral vascular ectasia, and Cameron lesions. Upper GI cancer as well as lesions of the biliary tract and pancreas may also result in severe UGIB. This article provides an overview of the endoscopic management of these lesions, including the role of novel therapeutic modalities such as hemostatic powder and over-the-scope-clips.

Translational potential of a mouse in vitro bioassay in predicting gastrointestinal adverse drug reactions in Phase I clinical trials

BACKGROUND

Motility-related gastrointestinal (GI) adverse drug reactions (GADRs) such as diarrhea and constipation are a common and deleterious feature associated with drug development. Novel biomarkers of GI function are therefore required to aid decision making on the GI liability of compounds in development.

METHODS

Fifteen compounds associated with or without clinical GADRs were used to assess the ability of an in vitro colonic motility bioassay to predict motility-related GADRs. Compounds were examined in a blinded fashion for their effects on mouse colonic peristaltic motor complexes in vitro. For each compound concentration-response relationships were determined and the results compared to clinical data. Compounds were also assessed using GI transit measurements obtained using an in vivo rat charcoal meal model.

KEY RESULTS

Within a clinically relevant dosing range, the in vitro assay identified five true and three false positives, four true and three false negatives, which gave a predictive capacity of 60%. The in vivo assay detected four true and four false positives, four false and three true negatives, giving rise to a predictive capacity for this model of 47%.

CONCLUSIONS & INFERENCES

Overall these results imply that both assays are poor predictors of GADRs. Further analysis would benefit from a larger compound set, but the data show a clear need for improved models for use in safety pharmacology assessment of GI motility.