Abstract
BackgroundNephropathic 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.MethodsWe retrospectively analysed cystine and cysteamine levels of 17 patients after a single dose of immediate-release cysteamine (Cystagon®, Mylan Pharmaceuticals, Canonsburg, PA and Recordati Pharma GmbH) as well as a single dose of delayed-release cysteamine (Procysbi®; 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.ResultsImmediate (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 min with IR-cysteamine and after 180 min with DR-cysteamine.ConclusionA 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 increasing the dosing scheme of Procysbi® to three times daily, to prevent a rapid decrease and achieve a steadier decline in cystine levels. Due to the more convenient dosing scheme, DR-cysteamine might ameliorate therapy adherence and improve patients’ quality of life.
Highlights
Nephropathic cystinosis is a rare and severe metabolic disease leading to an accumulation of cystine in lysosomes which especially harms kidney function
Data collection Data had been collected during a period of three years in the context of a standard operating procedure: at the department of General Pediatrics at the University Hospital Muenster, patients with nephropathic cystinosis receive one-time measurements of their cysteamine and cystine levels with IR-cysteamine as well as DR-cysteamine, aiming to assess the optimal therapy for each patient, regarding effectiveness on white blood cells (WBC) cystine levels, as well as the occurrence of side effects
All 17 patients were under a regular therapy with cysteamine since they were diagnosed with nephropathic cystinosis in early childhood
Summary
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. Nephropathic cystinosis is a lysosomal storage disease which is inherited in an autosomal-recessive manner. Cystine accumulates in the lysosomes, harming various organs, primarily the kidneys [3]. End-stage renal disease occurs on average at the age of 9 years [4]. The two other less common allelic forms of nephropathic cystinosis are the ocular form with an involvement of the eyes only [5] and the intermediate form, which shows less severe clinical symptoms [6]
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