Colloidal bismuth subcitrate, a new agent for the scintigraphy of inflammatory bowel diseases

A correct diagnosis and adequate assessment of disease activity is crucial in the management and surveillance of inflammatory bowel diseases (IBDs). However, in certain occasions the obtained results by traditional techniques are not correlated specifically with the mucosal wall inflammatory state, mainly in case of the small bowel, due to its no accessibility. On the order hand, some of them such as the endoscopy and the histopatological studies have the inconvenience of being bloody and traumatic for the patient. Radioactive isotopes techniques have been used with advantageous in relationship with conventional ones. They are able to detect inflammations along the whole gastrointestinal tract; radiation level is low and tolerated by extreme care patient and children. One of these techniques relates the inflamed state of the mucous with the 111In-leukocytes uptake level of the injured area. Another radioisotopic technique developed by Vazquez et al., consists on detecting the gastric lesion by means of the use of a local action anti ulcerous agent labelled with Tc-99m. This one is simple, cheap and its results are similar to those of conventional techniques. Taking into account that the inflammatory intestinal illnesses develop inflamed and ulcerated areas in the mucous and that Colloidal Bismuth Subcitrate (CBS) K55(NH4)36(C6H7O7)22 [Bi30(OH)55(C6H5O7)20] possesses the capacity to form with the mucus a complex that adheres on ulcerated mucous through a reaction with the detritus derivate from the tissue necrosis. The present work has been proposed as a method to assess disease activity in patients with inflammatory diseases along the entire alimentary tract. This investigation constituted a multicentric clinical trial phase I-II. Forty-four patients were prospectively evaluated with the objective of determining the validity of the scintigraphy with 99mTc-Sn-CBS for the diagnosis of illnesses with ulcerations of the intestinal tube. Of the evaluated patients, 20 presented Cohn's Disease (in 1 of them the scintigraphy was not useful), 1 Idiopatic Ulcerative Colitis, 3 gastric ulcer and 20 patients were seemingly healthy, conformed the control group. Five hundred mgs of CBS were labelled with 370 MBq (10 mCi) of 99mTc and administered via oral as unique dose. The formulation of the freeze-dried kit was previously adjusted in pre-clinical studies, where ph and the NH4+ ions played an important role in the complex stability. The diagnostic test had three days duration for each patient: first day for the patient's preparation with soft diet and mannitol 20%, in order to clean intestine and the next two days for the drug administration and image registrations. The images were carried out at 2, 4, 6 and 24 h post administered the product. Shown is a) Patient 10, control group, where no defined uptake is observed and b) Patient 42 with Cohn's Disease more than 5 year evolution, several gastric and small bowel lesions including terminal ileum are observed. All procedures were performed by experienced examiners, who were blinded to the clinical data and other results. It was determined the sensibility and specificity of this technique taking colonoscopy, gastroduodenoscopy, intestinal transit and/or biopsy as reference test, achieving a 91,3% sensibility and 90% specificity. The EPIDAT test (version 3.0) was used for statistical analysis. During the whole study an adverse event appeared, which had not probable causation with drug administration according to Karch and Lasagna scale. It can be concluded that the diagnostic criteria established in this study can be useful for the evaluation of inflammatory bowel diseases by scintigraphy with 99mTc-Sn-CBS