[Non-steroidal anti-inflammatory agents increase intestinal permeability]

Effect of glutamine on the intestinal permeability changes induced by indomethacin in humans

BACKGROUND

Long-term non-steroidal anti-inflammatory drug (NSAID) intake may induce increased intestinal permeability, eventually resulting in enteropathy. Because increased permeability might be related to cell damage resulting from energy depletion, it was hypothesized that glutamine--the major energy source of the intestinal mucosal cell--might prevent permeability changes.

METHODS

The 6-h urinary excretion of 51Cr-EDTA after an oral load of 51Cr-EDTA was used in this study as a measure for intestinal permeability. Healthy volunteers underwent a series of permeability tests: (i) basal test; (ii) test following NSAID (indomethacin); (iii) test following NSAID in combination with glutamine and/or misoprostol.

RESULTS

The NSAID induced increased permeability in all volunteers. Pre-treatment with glutamine (3x7 g daily, 1 week before NSAID-dosing) did not prevent the NSAID-induced increase in permeability. Multiple doses of glutamine close in time to NSAID-dosing resulted in significantly lower permeability compared to the NSAID without glutamine. Co-administration of misoprostol with the multiple-dose scheme of glutamine resulted in a further reduction in the NSAID-induced increase in permeability.

CONCLUSIONS

Glutamine decreases the permeability changes caused by NSAID-dosing when it is administered close in time, and misoprostol has a synergistic effect.

High frequency of silent inflammatory bowel disease in spondylarthropathy

OBJECTIVE

To search for an association between gut infection, gut inflammation, and spondylarthropathies.

METHODS

Ileocolonoscopy was performed in 118 patients with various inflammatory and noninflammatory joint diseases and in 24 patients with uncomplicated acute bacterial gastroenteritis.

RESULTS

Endoscopic lesions were more frequent in patients with spondylarthropathy (44%) compared with those with other inflammatory arthritides (6%; P = 0.001). Ileal changes were observed only in patients with spondylarthropathy (20% versus 0%; P = 0.01). Inflammatory bowel disease was the endoscopic diagnosis in 19% of the arthritis patients. Possible or definite Crohn's disease was diagnosed in 26% of patients with chronic spondylarthropathy, and ulcerative colitis in 1 patient with rheumatoid arthritis and in 1 with chronic uroarthritis. Histologic evidence of inflammation differed less distinctly than endoscopy findings between patients groups. There was no association of gut lesions with the use of nonsteroidal antiinflammatory drugs or with the presence of HLA-B27.

CONCLUSION

Gut inflammation is frequent in patients with spondylarthropathy, and one-fourth of the patients who have chronic disease have early features of Crohn's disease.

Side effects of nonsteroidal anti-inflammatory drugs on the small and large intestine in humans

BACKGROUND

It is not widely appreciated that nonsteroidal anti-inflammatory drugs (NSAIDs) may cause damage distal to the duodenum. We reviewed the adverse effects of NSAIDs on the large and small intestine, the clinical implications and pathogenesis.

METHODS

A systematic search was made through Medline and Embase to identify possible adverse effects of NSAIDs on the large and small intestine.

RESULTS

Ingested NSAIDs may cause a nonspecific colitis (in particular, fenemates), and many patients with collagenous colitis are taking NSAIDs. Large intestinal ulcers, bleeding, and perforation are occasionally due to NSAIDs. NSAIDs may cause relapse of classic inflammatory bowel disease and contribute to serious complications of diverticular disease (fistula and perforation). NSAIDs may occasionally cause small intestinal perforation, ulcers, and strictures requiring surgery. NSAIDs, however, frequently cause small intestinal inflammation, and the associated complications of blood loss and protein loss may lead to difficult management problems. The pathogenesis of NSAID enteropathy is a multistage process involving specific biochemical and subcellular organelle damage followed by a relatively nonspecific tissue reaction. The various possible treatments of NSAID-induced enteropathy (sulphasalazine, misoprostol, metronidazole) have yet to undergo rigorous trials.

CONCLUSIONS

The adverse effects of NSAIDs distal to the duodenum represent a range of pathologies that may be asymptomatic, but some are life threatening.

Glucose and citrate reduce the permeability changes caused by indomethacin in humans

Nonsteroidal anti-inflammatory drug (NSAID)-induced increased intestinal permeability appears to be a prerequisite for NSAID enteropathy. It has been suggested that early metabolic events leading to the permeability changes may involve inhibition of glycolysis and the tricarboxylic acid cycle, in which case the coadministration of glucose and citrate (the substrates for these metabolic pathways) with indomethacin may afford some protection. The present study, using a combined intestinal absorption-permeability test including 3-O-methyl-D-glucose, D-xylose, L-rhamnose, and [51Cr]ethylene-diaminetetraacetic acid (EDTA) as test probes and the differential urine excretion ratio of [51Cr]-EDTA/L-rhamnose, showed that indomethacin (50 + 75 mg) increased intestinal permeability. A formulation of indomethacin containing 15 mg glucose and 15 mg citrate to each milligram of indomethacin did not increase intestinal permeability significantly above baseline values. When given alone with indomethacin, neither glucose nor citrate (45 mg to each milligram of indomethacin) had any protective effects. Pharmokinetic studies showed that the effects of glucose and citrate cannot be explained on the basis of altered drug absorption. These results suggest a new approach to reducing the small intestinal side effects of NSAIDs.

Review article: non-steroidal, anti-inflammatory drugs--the extending scope of gastrointestinal side effects

The gastrointestinal side effects of non-steroidal, anti-inflammatory drugs extend beyond the duodenal bulb, and comprise a variety of lesions in all parts of the gut. Gastroduodenal ulceration is quantitatively dominant, although a major part of these lesions probably go unnoticed and heal spontaneously. Adaptation has been demonstrated for acetylsalicylic acid, and may be of importance for other substances as well. Non-steroidal anti-inflammatory drugs (NSAIDs) may induce relapse of inflammatory bowel disease. Permeability changes and mucosal inflammation are found in the small and large bowel in the majority of subjects taking NSAIDs, although the clinical significance is still not clear. Ulceration and perforation do, however, occur in this part of the gut as well. Treatment of NSAID-associated ulceration is similar to traditional ulcer treatment, possibly with extended treatment duration if the NSAID is continued. Prophylaxis is of some value, but is not required for every patient receiving an NSAID.

Gastroduodenal lesions induced by naproxen. An endoscopic evaluation of regional differences and natural course

Gastroduodenal endoscopic findings were studied in 65 healthy volunteers receiving 750 mg or 1000 mg naproxen for 1 or 2 weeks. Separate registration of the mid- and distal duodenum showed that mucosal toxicity can be demonstrated even distally to the duodenal bulb. The lesions were closely correlated to the findings in the stomach and duodenal bulb, though generally somewhat less extensive. Whereas a difference between 750 mg and 1000 mg naproxen was demonstrated in an intraindividual comparison (n = 26; median sum of visual analogue scale score in the stomach/duodenal bulb, 129 mm and 183 mm, respectively; p less than 0.05), no difference was seen in two parallel groups (n = 32 and 33). In the stomach and duodenal bulb, a significant aggravation of mucosal lesions was seen from 1 to 2 weeks in 16 subjects. Healing was complete in 10/12 subjects after 3 weeks, independent of the extent of the initial damage.

51Cr-ethylenediaminetetraacetic acid absorption test. Effects of naproxen, a non-steroidal, antiinflammatory drug

Eighty volunteers were studied to determine the effects of 750 or 1000 mg naproxen daily for a week on intestinal permeability, by means of the 51Cr-ethylenediaminetetraacetic acid (EDTA) absorption test. With 750 mg naproxen (n = 42) the median urinary excretion increased from 2.44% to 3.51% (p less than 0.01), and with 1000 mg (n = 38) from 2.26% to 3.39% (p less than 0.01). When the individual pretreatment absorption was included in the analysis, a statistically significant difference was found between the two doses (19% and 68% median increase as a percentage of base line, respectively (p = 0.04)). Similar results were found in 27 subjects who were given both doses of naproxen. Intraduodenal instillation of the test dose in 18 subjects showed that gastric absorption was negligible, and no correlation was found with upper endoscopy findings, changes in orocoecal transit time, or reported symptoms.

Cr-ethylenediaminetetraacetic acid absorption test. Methodologic aspects

The 51Cr-ethylenediaminetetraacetic acid (EDTA) absorption test was evaluated in 83 healthy, male volunteers. Base-line 24-h excretion after peroral administration ranged from 0.88% to 7.96%, with a higher median absorption than reported by most authors (2.45%). However, the reproducibility and stability of the method and the reproducibility of the results were satisfactory. Urinary excretion after intraduodenal instillation (n = 18) was comparable to that seen after peroral test dose administration, indicating a limited significance of gastric 51Cr-EDTA absorption under normal conditions. In 16 subjects a single intake of alcohol immediately before the test gave a modest and short-lasting increase in 51Cr-EDTA absorption. No correlation was seen to body mass index, creatinine clearance, urinary volume, or small-bowel transit time, possibly reducing the number of confounding factors in the evaluation of absorption data. A small but significant negative correlation was, however, found to body surface area and age.

Misoprostol reduces indomethacin-induced changes in human small intestinal permeability

This study examined whether indomethacin-induced increases in small intestinal permeability in man are prevented by concomitant administration of a prostaglandin analog (misoprostol). Twelve male volunteers were tested as baseline, following misoprostol alone (200 micrograms, at -16, -12, -8.5, -4, -1.5, and +4 hr); following indomethacin alone (75 mg, at -8; 50 mg, -1 hr); and following coadministration of misoprostol and indomethacin as specified above. A 100-ml test solution containing 3-O-methyl glucose (0.2 g), D-xylose (0.5 g), L-rhamnose (1.0 g), and [51Cr]EDTA (100 microCi) was ingested at 8 AM, and a 5-hr collection made for marker analysis to assess active and passive carrier-mediated transport and trans- and intercellular permeation, respectively. Indomethacin increased the permeation of [51Cr]EDTA selectively, and this increase was significantly reduced by the coadministration of misoprostol. These changes were mirrored by changes in [51Cr]EDTA-L-rhamnose urine excretion ratios, which indicates that paracellular permeability was specifically altered. This study supports the suggestion that NSAIDs alter intestinal permeability by a mechanism involving reduced prostaglandin synthesis and indicates that coadministration of misoprostol with NSAIDs may reduce the frequency and severity of NSAID-induced small intestinal inflammation.

Sucralfate for prevention of naproxen-induced mucosal lesions in the proximal and distal gastrointestinal tract

To study the protective effect of Sucralfate on Naproxen-induced mucosal lesions, 16 healthy, male volunteers were given Naproxen 500 mg b.i.d. together with Sucralfate 2 g b.i.d. or placebo in a double-blind, crossover study. Drug periods were 1 week, with a 3-week wash out in between. Mucosal lesions in stomach and duodenum were assessed by upper endoscopy before and after each drug period, using a visual analogue with separate scoring of mid- and distal duodenal lesions. 51Cr-EDTA absorption tests were performed to demonstrate possible changes in distal gut permeability. In addition, subjective symptoms were registered. Both drug periods induced significant lesions in the stomach and duodenum. Statistically speaking, fewer changes were found in the stomach and duodenal bulb after Sucralfate co-administration, whereas no significant reduction of lesions was seen in the distal duodenum. The 51Cr-EDTA absorption was increased in both periods, indicating deleterious effects to distal parts of the gut, but our results did not demonstrate Sucralfate-mediated protection from these changes. Symptoms were modest, and equal in the two periods. We conclude that Sucralfate may offer protection in the gastric and proximal duodenal mucosa, but no such protective effect was seen distally to the duodenal bulb.

Diarrhoea and constipation

Drug-induced constipation is mostly caused by changes in gut motility, whilst diarrhoea is more frequently caused by an increase in intestinal fluid secretion. In both instances the drug has to reach the enteric nervous system or the enterocyte, either via the blood or from the lumen, in sufficient concentrations to affect the mediators that regulate motility and fluid transport. Diarrhoea and constipation are frequently mentioned as side-effects of drugs, and therapeutic agents for almost all organ systems have been implicated. However, both these side-effects are usually mild or moderate, and rarely necessitate interruption of drug treatment. An exception to this rule is the antibiotic-associated colitis seen in patients treated with antibiotics such as lincomycin or clindamycin; in principle almost all antibiotics may cause this severe and potentially life-threatening complication. Other rare forms of severe, drug-induced colitis and diarrhoea result from toxic or anaphylactic reactions against gold preparations, cytostatic agents and sulphonamides. Ischaemic colitis due to vascular complications has been described in some women taking oral contraceptives, and in patients treated with vasopressin or digitalis.