Dropcys

Dropcys is a medicine that contains the active substance mercaptamine hydrochloride (also known as cysteamine hydrochloride). It was to be available as a powder and a solvent, to make a solution for eye drops.

Dropcys was expected to be used to prevent and treat cystinosis affecting the cornea. Cystinosis is a rare inherited disease caused by the accumulation of a substance called cystine, which forms crystals inside cells, particularly cells in the cornea and kidneys.
Dropcys was designated an ‘orphan medicine’ (a medicine to be used in rare diseases) on 15 October 2014 for the treatment of cystinosis.

Medicines containing mercaptamine hydrochloride are authorised in the EU for use by mouth in the treatment of cystinosis. Ophthalmic (eye) formulations of mercaptamine are made up locally and used for the management of eye symptoms.

The build-up of cystine crystals inside corneal cells can damage the eyes and cause serious vision problems. The active substance in Dropcys, mercaptamine hydrochloride, was expected to react with cystine to dissolve it and to form substances that could be removed from the cells. When the medicine is applied to the eye, the amount of cystine in the cells of the cornea was expected to be reduced, limiting the amount of eye damage.

Because mercaptamine has been used for many years to treat cystinosis and its use is well established, the applicant presented data from the medical literature to support its application for Dropcys.

The CHMP considered that the studies from the medical literature presented to support the application were insufficient. Although the role of mercaptamine eye drops in the treatment of corneal deposits appears sufficiently supported by the literature, current clinical recommendations and its routine use in hospital preparations, there were few data supporting the effectiveness of the concentration of mercaptamine used in Dropcys (0.1% solution). In addition, the CHMP had concerns regarding other ingredients of the medicine, their impact on long-term safety, particularly in children, and how stable and sterile the solution would be once prepared.

Therefore, the CHMP was of the opinion that the benefits of Dropcys did not outweigh its risks and recommended that it be refused marketing authorisation.

During the re-examination, the CHMP looked again at the data from the company. The Committee confirmed the opinion that the effectiveness of Dropcys in the treatment of corneal deposits had not been sufficiently demonstrated and that there were unresolved issues regarding the formulation and long-term safety and sterility of the medicine. Thus, the CHMP reaffirmed its previous recommendation that the medicine be refused marketing authorisation.

The company informed the CHMP that there are no ongoing clinical trials or compassionate use programmes with Dropcys.