General Information

Cystaran (cysteamine hydrochloride) is a cystine-depleting agent which lowers the cystine content of cells in patients with cystinosis, a rare genetic disorder. Cystine is a naturally occuring amino acid. Cystinosis causes an accumulation cystine within cells; the cystine eventually forms crystals that build up and damage the cells.

Cystaran is specifically approved for the treatment of corneal cystine crystal accumulation in adults and children with cystinosis.

Cystaran is supplied as an ophthalmic solution for topical administration. The recommended dose one drop in each eye, every waking hour. The solution should be discarded after one week of use.

Mechanism of Action

Cystaran (cysteamine hydrochloride) acts as a cystine-depleting agent by converting cystine to cysteine and cysteine-cysteamine mixed disulfides and reduces corneal cystine crystal accumulation.

Side Effects

Adverse effects associated with the use of Cystaran may include, but are not limited to, the following:

• sensitivity to light
• redness
• eye pain and irritation
• headache
• visual field defects

Clinical Trial Results

The FDA approval of Cystaran was based on on three controlled clinical trials conducted by the NIH, in approximately 300 subjects. The primary efficacy endpoint was the response rate of eyes that had a reduction of at least 1 unit in the photo-rated Corneal Cystine Crystal Score (CCCS) at some time point during the study when baseline CCCS >1, or a lack of an increase of more than 1 unit in CCCS throughout the study when baseline CCCS <1. Study 1 combined the data from three smaller studies. For eyes with a lower baseline of CCCS <1, the response rate was 13%. For eyes with a higher baseline of CCCS >1, the response rate was 32%. Study 2 evaluated ocular cystinosis patients who had a baseline of CCCS >1. The response rate was 67%. Study 3 also evaluated ocular cystinosis patients who had a baseline of CCCS >1, the response rate was 33%.