Cystadrops® (cysteamine hydrochloride 0.55% viscous eye-drops solution) in treating corneal cystine crystal deposits in patients with cystinosis: a profile of its use

Abstract

Published online: 31 March 2017 © Springer International Publishing Switzerland 2017 Abstract Cystadrops® (viscous cysteamine hydrochloride 0.55% eye-drops solution) is the first orphan drug approved in the EU for the treatment of corneal crystal deposits in adults and children aged >2 years with cystinosis. Relative to extemporaneously prepared formulations of cysteamine hydrochloride eye drops, Cystadrops® requires less frequent administration (relieving treatment burden), displays better stability (making storage, distribution and use by patients less difficult) and provides reliable standardization and availability. Following oral administration of cysteamine bitartrate, free-base cysteamine interacts with lysosomal cystine to form cysteine and cysteine-cysteamine mixed disulphide, neither of which require the cystinosin transporter to move from the lysosome into the cytoplasm [8, 9]. [...]the use of such eye drops is hampered by their rapid clearing from the ocular surface, leading to the need to instill the drops frequently while awake (e.g. generally every 1 [14, 16] or 2 h [21] or at least six times daily [17]), which may lead to poor treatment adherence and poor ocular outcomes [1, 4, 19]. [...]aqueous formulations of cysteamine hydrochloride are unstable at room temperature, with rapid oxidization to inactive cystamine disulphide in the presence of heat or atmospheric oxygen [1, 4, 18, 19], making eye-drops solutions difficult to package, distribute and store. Cysteamine hydrochloride 0.55% viscous eye-drops solution (Cystadrops®) was approved as the first orphan drug for the treatment of corneal crystal deposits in patients with cystinosis in the EU in early 2017 [23]. The article reviews the clinical evidence...