The Effect of Food on Cysteamine Bitartrate Absorption in Healthy Participants

Objectives: Treatment with cysteamine reduces the rate of progression to end-stage kidney disease in cystinosis. Although food is often taken with cysteamine to reduce associated gastrointestinal symptoms, this may alter the bioavailability of cysteamine. Methods: This is a prospective, randomized, 3-treatment study to determine the effects of fasting and high-fat/calorie and high-protein meals on cysteamine absorption in healthy adult controls. On 3 separate days, serial plasma cysteamine levels were measured after cysteamine bitartrate 500 mg was ingested while fasting and also 30 minutes after high-fat/calorie and high-protein diets. Gastrointestinal (GI) symptoms were also monitored. Results: Eight participants (5 men) were enrolled. Cysteamine absorption, as measured by area under the cysteamine concentration-time curve (AUC(0-infinity)) while fasted and following high-fat/calorie and high-protein meals, was 3618 +/- 372 min.mu M, 2799 +/- 405 min.mu M (P = .04 vs fasted), and 2457 +/- 353 min.mu M (P = .005), respectively, and the mean C-max values for participants were 26.3 +/- 3.5 mu M, 22.4 +/- 5.6 mu M (P = .16 vs fasted), and 17.2 +/- 2.6 mu M (P = .036 vs fasted), respectively. Mild GI symptoms were reported in 3 participants. Conclusions: Cysteamine absorption may be decreased by 30% when taken with food as compared with the fasting state. Food causes wide variation in t(max) and C-max for cysteamine.