POTASSIUM-INDUCED LESIONS OF THE SMALL BOWEL. II. PATHOLOGY AND PATHOGENESIS

Review article: drug-induced small bowel injury

BACKGROUND

Drug-induced gastrointestinal injury has been increasingly reported, but its exact incidence is not known. The small and large intestines represent the most affected sites of injury, accounting for 20%-40% of all gastrointestinal side effects.

AIM

To provide an updated literature review detailing medications linked to the development of small bowel injury.

METHODS

We conducted a literature search on PubMed from its inception to May 1, 2021. We included English-language original studies, meta-analyses, systematic reviews, review articles and case reports.

RESULTS

Drug-induced enteropathy can range from asymptomatic histological changes resulting in a subtle, self-limited disease to a chronic inflammatory condition mimicking inflammatory bowel disease, or bowel perforation. Endoscopy can demonstrate erythema, mucosal friability, oedema, erosions, ulcers or strictures in severe cases. Histology may include mucosal erosions and ulcerations, focal active enteritis, villous atrophy, epithelial apoptosis or necrotising enteritis. A well-established association has been found with the use of nonsteroidal anti-inflammatory drugs, immunosuppressants, chemotherapeutic agents, antibiotics, immunotherapies, etanercept and olmesartan. Possible associations have been reported with other biologic agents, medications used for glycemic control, antihypertensives, cholinesterase inhibitors, potassium and iron supplements, with conflicting data regarding contraceptives/hormonal therapy and isotretinoin.

CONCLUSION

Physicians should be aware of the manifestations of drug-induced enteropathy as early recognition can lead to prompt discontinuation of the offending therapy and, therefore, a reduced risk of future complications.

Comparison of 4 Methods to Assess the Prevalence of Use and Estimates of Nutrient Intakes from Dietary Supplements among US Adults

BACKGROUND

Accurate and reliable methods to assess prevalence of use of and nutrient intakes from dietary supplements (DSs) are critical for research, clinical practice, and public health monitoring. NHANES has been the primary source of DS usage patterns using an in-home inventory with a frequency-based DS and Prescription Medicine Questionnaire (DSMQ), but little is known regarding DS information obtained from 24-h dietary recalls (24HRs).

METHODS

The objectives of this analysis were to compare results from 4 different methods for measuring DS use constructed from two data collection instruments (i.e., DSMQ and 24HR) and to determine the most comprehensive method for measuring the prevalence of use and estimating nutrient intakes from DS for selected nutrients. NHANES 2011-2014 data from US adults (aged ≥19 y; n = 11,451) were used to examine the 4 combinations of methods constructed for measuring the prevalence of use of and amount of selected nutrients from DSs (i.e., riboflavin, vitamin D, folate, magnesium, calcium): 1) DSMQ, 2) 24HR day 1, 3) two 24HRs (i.e., mean), and 4) DSMQ or at least one 24HR.

RESULTS

Half of US adults reported DS use on the DSMQ (52%) and on two 24HRs (mean of 49%), as compared with a lower prevalence of DS use when using a single 24HR (43%) and a higher (57%) prevalence when combining the DSMQ with at least one 24HR. Mean nutrient intake estimates were highest using 24HR day 1. Mean supplemental calcium from the DSMQ or at least one 24HR was 372 mg/d, but 464 mg/d on the 24HR only. For vitamin D, the estimated intakes per consumption day were higher on the DSMQ (46 μg) and the DSMQ or at least one 24HR (44 μg) than those on the 24HR day 1 (32 μg) or the mean 24HR (31 μg). Fewer products were also classed as a default or reasonable match on the DSMQ than on the 24HR.

CONCLUSIONS

A higher prevalence of use of DSs is obtained using frequency-based methods, whereas higher amounts of nutrients are reported from a 24HR. The home inventory results in greater accuracy for products reported. Collectively, these findings suggest that combining the DSMQ with at least one 24HR (i.e., DSMQ or at least one 24HR) is the most comprehensive method for assessing the prevalence of and estimating usual intake from DSs in US adults.This trial was registered at clinicaltrials.gov as NCT03400436.

Drug-Induced Small Bowel Injury: a Challenging and Often Forgotten Clinical Condition

PURPOSE OF REVIEW

Most drugs are given by the oral route. Oral intake allows direct contact between the drug and the entire GI tract mucosa, exposing it to potential topical damage until absorption. Medication-induced GI symptoms and lesions are therefore commonly encountered in clinical practice. This review will examine the most common drugs or classes of drugs affecting small bowel function and/or structure.

RECENT FINDINGS

Since non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used medicines, NSAID enteropathy is highly prevalent and brings about considerable morbidity. Antimicrobials and proton-pump inhibitors profoundly modify intestinal microbiota, affecting gut sensory and motor functions, while other drugs (like iron and gold derivatives) impair intestinal permeability. Olmesartan (and likely ACE inhibitors) induce villous atrophy and consequent malabsorption. Mycophenolate mofetil, cancer chemotherapeutic agents, and immune checkpoint inhibitors cause intestinal inflammation, abdominal pain, and diarrhea. Potassium chloride supplements may induce small bowel ulceration, stenosis, and perforation while the cotraceptive pill and anticoagulants are associated with intestinal ischemia and spontaneous intramural hematoma, respectively. In clinical practice, a deep knowledge of clinical pharmacology and toxicology and a high degree of suspicion of drug-related adverse events are mandatory. Only then, the practicing physician will be able to diagnose medication-induced small bowel lesions correctly and will implement the best strategies to treat them.

Drug-induced esophagitis

Drug-induced esophagitis is being recognized increasingly in the past few years. Since 1970 more than 650 cases have been reported worldwide caused by 30 or more medications. We have reviewed these cases with a view to classifying this disease based on underlying pathological mechanism. Drug-induced esophageal injury tends to occur at the anatomical site of narrowing, with the middle third behind the left atrium predominating (75.6%). The disease is broadly classified into two groups. The first group being transient and self-limiting as exemplified by the tetracycline group induced injury (65.8%). The second is the persistent esophagitis group, often with stricture, with two distinct entities: (i) patients on nonsteroidal anti-inflammatory agents whose injury is aggravated by gastroesophageal reflux (21.8%) (reflux aggravated); and (ii) patients with potasium chloride and quinidine sulphate induced injury (12.4%) (persistent drug injury). Severe esophageal injury has been reported in some women taking biphosphonates as treatment for postmenopausal osteoporosis. Endoscopic findings in such patients with esophageal injury generally suggested a chemical esophagitis, with erosions or ulcerations and exudative inflammation accompanied by thickening of the esophageal wall. Most cases of medication-induced esophageal injury heal without intervention within a few days. Thus, the most important aspect of therapy is to make the correct diagnosis and then to avoid reinjury with the drug. When possible, potentially caustic oral medications should be discontinued.

Pravastatin-induced colitis

We report an unusual case of pravastatin-induced colitis in an 80-year old lady. Onset of symptoms was noted within 48 h of starting the medication. Colonoscopy revealed diffuse ulceration throughout the colon with relative sparing of the rectum, with the biopsies showing ulceration and inflammation. The patient received a short course of steroid therapy and 5 months after stopping pravastatin, there was complete macroscopic and microscopic resolution of the colonic lesions. Drug interaction of pravastatin with amitryptiline could have resulted in this uncommon complication.

Effect of potassium-magnesium citrate on upper gastrointestinal mucosa

BACKGROUND

Potassium supplements may cause mucosal damage of the gastrointestinal tract.

AIM

To evaluate the effect of a new potassium supplement, potassium-magnesium citrate (K-Mag), on upper gastrointestinal mucosa and to compare it with an older potassium supplement, potassium citrate (Urocit-K).

METHODS

A randomized and double-blind study was conducted utilizing 36 healthy adults. Subjects were randomized into three groups: K-Mag (70 mmol/day K, 35 mmol/day citrate and 17.6 mmol/day Mg); Urocit-K (70 mmol/day K and 23.4 mmol/day citrate), and placebo. All subjects took 5 tablets b.d. of the allocated drug and 2 mg t.d.s. of glycopyrrolate for 7 days. On day 8, stool was examined for occult blood, a symptom score was calculated and an oesophagogastroduodenoscopy was performed. Mucosal lesions were scored at five anatomic sites.

RESULTS

Demographic characteristics and symptom score were similar in the three groups (< 10% with more than mild symptoms). There were no significant differences in the endoscopic scores at any site examined nor in the total scores among the three groups. Erosion or ulcers were found in 180% of K-Mag, 23% of Urocit-K and 17% of the placebo group.

CONCLUSION

Short-term use of K-Mag does not appear to induce lesions in the upper gastrointestinal mucosa and its oral tolerance is similar to Urocit-K or placebo.

Small intestinal bleeding

Bleeding from the small intestine may be difficult to diagnose, because of the organ's length and free intraperitoneal location. Although there is a variety of causes of intestinal bleeding, angiodysplasia is the most common. Several different tests can be used to identify the bleeding site preoperatively or intraoperatively, including enteroscopy.

Systemic diseases affecting the mesenteric circulation

The mesenteric circulation is acutely sensitive to processes that affect the entire body. Such systemic diseases and syndromes are reviewed with particular emphasis on the mechanisms by which they influence the mesenteric vasculature and blood flow.

Environmental diseases of the digestive system

Environmental factors are important mediators of many diseases of the digestive system, defined as the alimentary tract and the accessory organs of digestion, the liver and pancreas. In this review, we principally focus on the action of chemical agents which are classified as (1) naturally occurring compounds, (2) occupational hazards, (3) therapeutic drugs, and (4) constituents of substances of abuse. In addition, the putative role of dietary habits in the pathogenesis of malignant diseases of the digestive system is discussed.

Jejunal perforation possibly induced by slow-release potassium in a patient with Crohn's disease

A case of small bowel ulceration and perforation possibly due to therapy with Klotrix in a patient with Crohn's disease is presented. Following emergent surgery with creation of a diverting loop jejunostomy, subsequent reestablishment of intestinal continuity was carried out with excellent clinical results. Gastrointestinal mucosal lesions possibly due to wax-matrix potassium chloride preparations are reviewed.

Medication-induced oesophageal injury. Survey of the literature

This is a review of the 127 cases of drug-induced oesophagitis reported in the English language literature since 1970. The most common symptoms reported were retrosternal pain, odynophagia, and dysphagia. Most cases were self-limited and symptoms resolved in 7 to 10 days with symptomatic therapy. Occasionally, severe odynophagia or dysphagia necessitated hospitalisation. Emepronium bromide, tetracycline and its derivatives, potassium chloride, and quinidine account for 89% of the reported cases of medication-induced oesophageal injury. 14 other medications have been reported to injure the oesophagus. Serious sequelae, including death, have been linked to potassium-induced oesophageal injury. With other medications, however, serious complications were rare. The diagnostic study of choice is endoscopy; an air-contrast barium swallow may also detect the often subtle mucosal abnormalities produced by medication injury. However, the diagnosis does not require confirmation by radiographical or endoscopic means in all cases, and the history alone may be sufficient to make the diagnosis in uncomplicated cases. Medication-induced oesophageal injury is preventable if pills are taken with an adequate amount of fluid and if the practice of taking medications immediately before bedtime is avoided.

Irritative properties of two clinical potassium chloride formulations on duodenal mucosa of the cat and esophageal mucosa of the opossum

The local gastrointestinal irritating properties of microencapsulated KCl (M-E), a new and unique form of KCl (8 meq potassium per capsule), were compared with a wax-matrix (W-M) KCl formulation (8 meq potassium per tablet). Normal saline in 0-size gelatin capsules was used as the control substance. The comparisons were made in two animal models that simulate the condition of partial obstruction of the gastrointestinal tract in humans. These models are the duodenum of the cat and the esophagus of the opossum, each with a surgically created partial obstruction. The tissues were exposed to two capsules or tablets of KCl or saline for 4 hr, and the extent of tissue injury assessed by using a rating scale. The irritation caused by M-E was significantly (P less than 0.05) less than that caused by W-M in both the cat and the opossum, and it was not significantly (P greater than 0.05) different from the injury caused by saline in either model. The relative lack of irritation by M-E is probably explained by the fact that there was a significantly (P less than 0.05) greater dispersion of KCl from the M-E capsule than from the W-M tablet.

Clinicopathologic study of nonspecific ulcers of the small intestine

Fifty-nine cases (31 men and 28 women) of nonspecific small bowel ulceration, representing the Mayo Clinic experience from 1956 to 1979, are reviewed. The average age was 51 years. Presenting symptoms or signs were those of intermittent small bowel obstruction (63%), blood loss (25%), and acute abdomen (12%). Whereas 78% of the ulcers were located in the ileum, 15% in the jejunum, and 7% in the jejunoileum, perforation was by far more common in the jejunum (78%) as compared with the ileum (11%). Diagnosis was rarely made preoperatively, although abnormalities were noted roentgenographically in 66%. Treatment was surgical and was usually curative. Operative mortality was 8.5%. No single cause was implicated.

Drug-induced gastrointestinal disease

The gastrointestinal tract is a common target for adverse drug reactions. The resultant changes are often nonspecific (e.g., mucosal ulceration, intestinal infarction, motility disturbance) and in many cases no radiographically detectable lesion may occur. A comprehensive review of the reported drug-induced disorders of the digestive organs is herein presented and their radiographic manifestations are described.

Benign oesophageal stricture following oral potassium chloride therapy

A patient is described who developed a benign oesophageal stricture following cardiac surgery. A brief review of the literature is given and the possible dangers of oral potassium cholride therapy in patients with dysphagia are highlighted.

Idiopathic and drug-induced ulceration of the small intestine

Ulceration of the small intestine is an uncommon lesion of multifactorial origin. The most important factor responsible for the reported increased incidence is the ingestion of enteric-coated potassium chloride. It is desirable that potassium supplements be given in another form, for example as a slow-release preparation. Other drugs which may play a part in the aetiology include corticosteroids and phenylbutazone.

Diagnosis is difficult and ulceration is usually only demonstrated after one of the complications (obstruction, perforation, or haemorrhage) has occurred. It is imperative that a full drug-taking history is obtained.

Laboratory tests are not helpful in diagnosis, but where radiological studies are carried out they often contribute useful information.

If the symptoms of such an ulcer are severe enough to warrant laparotomy, then the treatment of choice is excision of the affected segment followed by end-to-end anastomosis.

Circumferential small bowel ulcers: a report of nine cases

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