Whole-bowel transit in patients with the irritable bowel syndrome

A novel method for real-time magnetic marker monitoring in the gastrointestinal tract

In internal medicine, a simple method for the functional examination of the gastrointestinal tract without the risk of radiation exposure is required. We describe a novel principle based on the monitoring of magnetic markers which meets these demands. Our method employs a special permanent magnet which is repeatedly aligned by a vertically oriented pulsed magnetic field. Due to this alignment, the marker position can be derived from the stray field components measured by commercial field sensors. Our method was evaluated by means of a 3D intestinal phantom. The monitoring procedure yielded the time course of the marker position as a 3D plot either in real-time or as a time-lapse movie. The spatial resolution, expressed by the mean square deviation, was better than 10 mm and is thus sufficiently high to distinguish between adjacent loops of the gut. The temporal resolution, i.e. the minimum time between two successive measurements, was about 1 s. The presented method has very moderate technical demands and allows us to monitor magnetic markers in real-time. The technique may be useful with respect to functional examination of the gastrointestinal tract. In pharmaceutical research, our method offers the opportunity for remote drug release at any position of the gut.

Gastrointestinal motility in patients with irritable bowel syndrome studied by using radiopaque markers

BACKGROUND

Irritable bowel syndrome (IBS) has been identified as a physiologic abnormality, but no test has been established as a diagnostic standard for gastrointestinal dyskinesia in IBS patients. The aim of this study was to investigate gastrointestinal motility in patients with IBS by using radiopaque markers.

METHODS

Gastrointestinal motility was studied in IBS patients (n = 72), constipation patients (n = 19), diarrhoea patients (n = 9), and healthy controls (n = 23). Using three types of radiopaque markers, analysis was performed to establish the transit time and a new indicator, the 'scattering index'.

RESULTS

Transit times were not characteristic in IBS. The patients with IBS had significantly higher scattering indexes in the colon and total gut than the healthy controls and the patients with constipation and diarrhoea. The transit time and scattering index of the colon were linearly correlated in the healthy controls and the constipation and diarrhoea patients but were not correlated in the IBS patients. Using transit time and scattering index was a reliable means of evaluating gastrointestinal motility in IBS patients, with a sensitivity of 65% and a specificity of 96%.

CONCLUSION

Three days' use of the radiopaque marker method was useful for providing an objective means of detecting gastrointestinal dysmotility in IBS patients.

Colon transit scintigraphy using oral indium-111-labeled DTPA. Can scan pattern predict final diagnosis?

Colon transit scintigraphy (CTS) was performed in 100 consecutive patients with idiopathic constipation using oral indium-111-labeled DTPA. Criteria were defined to allow classification of studies as normal, slow transit constipation (STC), or obstructed defecation (OD). Results were compared with final clinical diagnosis in 100 and findings of defecating proctography in 70. Of those with a scintigraphic diagnosis of STC, this was also the final diagnosis in 75% (33 of 44), and the scintigraphic diagnosis of OD was confirmed in 61% (17 of 28). Of 28 normal or equivocal scans, the final diagnosis was STC in only two (4%) but OD in 10 (21%). Fifty-four percent of patients with STC and 71% with OD had abnormal proctograms. The correlation between CTS and proctography was mediocre, occurring in 54% of patients. CTS has a valuable role in the diagnostic work-up of patients with idiopathic constipation.

Influence of antidepressants on whole gut and orocaecal transit times in health and irritable bowel syndrome

BACKGROUND

Antidepressants are used in the treatment of irritable bowel syndrome but it is unclear whether any symptomatic improvement is due solely to correction of an associated affective disorder, or whether these drugs have effects on bowel function which may be of therapeutic benefit. Intestinal transit is known to be abnormal in some irritable bowel syndrome patients.

METHODS

We have studied the effects of imipramine, a tricyclic antidepressant with mixed pharmacological properties, and paroxetine, a selective 5-hydroxytryptamine re-uptake inhibitor, on intestinal transit times.

RESULTS

Median (range) whole gut transit time was lower in 10 diarrhoea-predominant irritable bowel syndrome patients, 22.2 (3.6-51.6) h, compared to 28 control subjects 39.6 (7.2-68.4) h, (P < 0.05). Similarly, orocaecal transit time was shorter at 55 (30-90) min in diarrhoea-predominant irritable bowel syndrome patients compared to 75 (40-150) min in controls, (P < 0.05). Four days' administration of imipramine increasing to a daily dose of 100 mg prolonged both orocaecal and whole gut transit times in 12 control subjects and six diarrhoea-predominant irritable bowel syndrome patients. In contrast, 30 mg paroxetine daily for 4 days reduced orocaecal transit time in ten controls and eight irritable bowel syndrome patients, but had no effect on whole gut transit time.

CONCLUSION

Short-term administration of antidepressants alters intestinal transit, but the selective 5-hydroxytryptamine re-uptake inhibitor, paroxetine, has different effects to the tricyclic drug, imipramine. These effects on transit precede any effects on mood. Although there is a high prevalence of affective disorder in irritable bowel syndrome clinic patients, these drugs may have additional therapeutic actions on the gut. These actions might be taken into account when prescribing antidepressants in irritable bowel syndrome.

Transit through the proximal colon influences stool weight in the irritable bowel syndrome

The inherent variability of symptoms and motor abnormalities in patients with the irritable bowel syndrome has hampered the demonstration of motor abnormalities that could underlie symptoms. The aim in the current study was to evaluate whether altered regional capacitance or transit of solid residue through the unprepared human gut were factors in the diarrhea of patients with the irritable bowel syndrome. In 10 such patients and in 5 healthy controls, gastric and small bowel transits were evaluated scintigraphically by means of a mixed meal containing 99mTc-labeled resin pellets. Regional colonic transit was quantitated by 111In-labeled pellets delivered to the ileocecal region by a pH-sensitive, methacrylate-coated capsule. Symptomatic patients did not have significantly altered gastric or small bowel transits, but colonic transit was accelerated in 7 of 10 persons with the irritable bowel syndrome (P less than 0.02), in the proximal colon of five patients and in the left colon of two patients. The 24-hour stool weight was positively correlated with the rate at which solid residue emptied from the ascending and transverse colons (r = 0.78; P less than 0.01). There was also an inverse relationship between emptying rates and maximal volumes accommodated by the proximal colon (r = -0.58; P less than 0.05), although the maximum volume of the proximal colon was not significantly different in patients and healthy subjects. Thus, accelerated transit through the proximal colon is a factor in the pathophysiology of the irritable bowel syndrome and influences the stool weight of such patients. The capacitance of the proximal colon presumably influences its storage capacity and, hence, the rate at which it empties.

The effect of capsule size and density on transit through the proximal colon

Colonic transit of radiolabelled capsules has been monitored in 18 healthy subjects using gamma scintigraphy. The capsules ranged in volume from 0.3-1.8 cm3 and in density from 0.7-1.5 gcm-3. The capsules were administered after an overnight fast and entered the colon, on average, 5 h after dosing. Transit rates through the proximal colon were independent of capsule density. Any effect due to capsule volume was small when compared with intersubject variations in transit rates. Within 10 h of entering the colon 80% of the units had reached the splenic flexure. These findings have implications in the design of non-disintegrating, sustained release dosage forms.

Evaluation of an enteric-coated delayed-release 5-aminosalicylic acid tablet in patients with inflammatory bowel disease

Gastrointestinal transit of an enteric coated delayed release 5-aminosalicylic acid tablet radiolabelled with 111indium has been monitored in a total of 13 patients with Crohn's disease and ulcerative colitis. More than 70% of the tablets disintegrated in the small intestine, on average 3.2 hours after emptying from the stomach. Dispersed preparation was detected in the proximal colon of all the patients, except one with an ileostomy. Mean peak plasma concentrations of 5-aminosalicylic acid and its metabolite acetyl-5-aminosalicylic acid occurred 3-4 hours after gastric emptying. The tablets provide a reliable means of drug delivery to the ileum and proximal colon.

Gastrointestinal transit of an enteric-coated delayed-release 5-aminosalicylic acid tablet

Gastrointestinal transit of an enteric-coated, delayed-release 5-aminosalicylic acid tablet radiolabelled with indium-111 has been monitored in a preliminary study with eight healthy subjects using gamma scintigraphy. Gastric emptying of the tablet was delayed by the presence of food in the stomach. Disintegration occurred about 5 hours after the tablet left the stomach. There was close agreement between the tablet disintegration times and the initial detection of drug in the blood. The site of disintegration could be established in most instances; approximately 80% of the doses resulted in drug dispersion within the ascending colon. The coated tablets provide an effective means of drug delivery to the proximal colon.