Title: A Comparison of Immediate Release and Delayed Release Cysteamine in 17 Patients with Nephropathic Cystinosis
Abstract: Abstract Background Nephropathic cystinosis is a rare and severe metabolic disease leading to an accumulation of cystine in lysosomes which especially harms kidney function. A lifelong therapy with the aminothiol cysteamine can delay the development of end-stage renal disease and the necessity of kidney transplantation. The purpose of our study was to compare the effectiveness of immediate-release and delayed-release cysteamine on cystine and cysteamine levels as well as assessing the onset of adverse effects. Methods We retrospectively analysed cystine and cysteamine levels of 17 patients after a single dose of immediate-release cysteamine (CystagonÒ , Mylan Pharmaceuticals, Canonsburg, PA and Recordati Pharma GmbH) and delayed-release cysteamine (ProcysbiÒ; Horizon Pharma USA and Chiesi Farmaceutici S.p.A., Parma, Italy), respectively. Data were collected during a period of three years in the context of optimizing the individual treatment regimens. The dose of DR-cysteamine was reduced to 70 % of the equivalent dose of IR-cysteamine. The efficacy of both formulas in depleting white blood cells’ cystine levels and their side effects were compared. Results Immediate (IR)- and delayed-release (DR) cysteamine effectively decreased intracellular cystine levels under the target value of 0,5 nmol cystine/mg protein, while fewer side effects occurred under DR-cysteamine. Mean maximum levels of cysteamine were reached after 60 minutes with IR-cysteamine and after 180 minutes with DR-cysteamine. Conclusion A therapy with DR-cysteamine is as effective as IR-cysteamine while less side effects were reported. Our data show that DR-cysteamine should be dosed higher than 70% of the equivalent dose of IR-cysteamine in order to decrease cystine levels over an extended period of time. Moreover, our data suggest to increase the dosing scheme of ProcysbiÒ to three times daily to prevent a rapid decrease and achieve a more steady decline in cystine levels. Due to the more convenient dosing scheme, DR-cysteamine might ameliorate therapy adherence and improve patients’ quality of life.