Long-term clinical benefits of delayed-release cysteamine bitartrate capsules in patients with nephropathic cystinosis (response to “A comparison of immediate release and delayed release cysteamine in 17 patients with nephropathic cystinosis”)

The aim of this letter to the editor is to summarize the results from three clinical trial programs evaluating delayed-release cysteamine bitartrate (DR-CYS), which demonstrated the long-term clinical benefits in patients with nephropathic cystinosis when dosed every 12 h. The authors of “A comparison of immediate release and delayed release cysteamine in 17 patients with nephropathic cystinosis” presented recommendations altering the dosage and dosing scheme from what has been previously approved by the FDA for DR-CYS. In this letter to the editor, we critique the authors’ aforementioned article as it is a retrospective analysis of a small number of patients and does not follow the dosing recommendation by the FDA for equivalent dosing of DR-CYS to immediate-release cysteamine bitartrate (IR-CYS). In addition, the article does not include study data to properly support the authors’ suggestion of increased dosing effects and benefits. We present a summary of the results from the DR-CYS clinical trial program and evidence of the rigor from which the clinical data for DR-CYS were generated and recommendation for usage as prescribed.