Absorption of Cysteamine Study

The purpose of our study was to determine where cysteamine was absorbed within the intestinal tract. Our longer term aim is to identify an alternative way of delivering cysteamine so that it (1) as effective or more effective than our current regimens, (2) can be administered less often through the day, (3) may cause less unwanted effects such as bad odor and gastrointestinal symptoms. Our study is going well; we are close to completion and, have so far enrolled 9 adult control subjects, and 6 children with cystinosis. Each subject is asked to stay in hospital for 6-8 days during which time a specially designed tube, which is passed through the nose, is allowed to pass all the way down to the large bowel. At different points during its descent, cysteamine is injected into the tube. By taking serial blood samples, we then measure how well cysteamine is absorbed from these different sites and how effective it is at controlling the cystine deposition in the tissues. The theory behind the study is simple, but in reality this was a complicated undertaking. The tube that we used to perform this study did not already exist; we had to design the tube specifically and had it made in Australia.

Our preliminary data demonstrates best absorption of cysteamine in the small intestine (SI), particularly within the lower SI. We are still analyzing the data regarding efficacy of cysteamine when it is administered at different sites in intestinal tract. The data so far does suggest that a sustained-release or enteric-coated dosage form of cysteamine is feasible. There still, however, remains a considerable amount of work.

Once our data is fully analyzed we will be hoping to talk with appropriate pharmaceutical companies to discuss future options.

 Ranjan Dohil, M.D.
Associate Clinical Professor
Division of Pediatric Gastroenterology and Hepatology
University of California, San Diego
La Jolla, CA

Dr. Dohil was awarded a two-year grant to study the absorption of cysteamine in the intestinal system.   Data collected is necessary to understand the possibilities for a time-release medication.  Currently, medications must be taken every six hours.  A time-release medication would dramatically improve the quality of life for children and adults with Cystinosis.