Understanding intestinal cysteamine bitartrate absorption

Objectives To test the hypothesis that a controlled-release preparation of cysteamine, with fewer daily administrations, would improve the quality of fife for patients with cystinosis. Study design A specifically designed nasoenteric tube was used to administer cysteamine directly into the stomach, small intestine (Sl) and colon and serial plasma eysteamine, serum gastrin and leukocyte eystine levels were measured. Results Eight control subjects (mean age 23.2 years) and 6 subjects with eystinosis (mean age 15.2 years) were studied. Cysteamine absorption (maximum concentration and area under the curve of the concentration-time gradient) was greater from the Sl than stomach or cecum (P <.01). Leukocyte eystine depletion was greater after delivery of eysteamine into the Sl than stomach or cecum; this effect was associated with the plasma eysteamine maximum concentration and area under the curve (P <.001 and <.02, respectively). Gastrin levels were not affected by site of drug delivery and were elevated only in patients with eystinosis with gastrointestinal symptoms. Conclusions The absorption of eysteamine and the effect of this agent on leukoeyte cystine depletion are more profound after Sl administration. Enteric-coated eysteamine, targeted for Sl release, may require fewer daily dosages. Not all patients with eystinosis require acid-suppression therapy.