RECENT ADVANCES IN THE TREATMENT OF CYSTINOSIS

Cysteamine bitartrate capsules (Cystagon) have been approved by the US Food and Drug Administration for use in patients with nephropathic cy stinosis. Plasma cysteamine concentrations were virtually identical at various times following ingestion of either cysteamine hydrochloride or Cystagon capsules in 24 normal control subjects. A transfer study w as done with eight cystinosis patients who had been receiving either c ysteamine hydrochloride or phosphocysteamine for many years. The plasm a cysteamine concentration was significantly higher 2h after Cystagon and the leukocyte cystine content was significantly lower at all times after Cystagon compared to older forms of the drug. These differences are probably the result of greater patient compliance in taking the c apsules compared to the older, liquid forms of the drug. A new method for following the course of renal, glomerular deterioration in disease s such as cystinosis has been published recently. This method was used to re-analyse data on the efficacy of cysteamine treatment and to re- analyse new data on treating cystinosis patients with either of two do ses of cysteamine (1.30g/m(2) per day and 1.95 g/m(2) per day). This n ew method agrees well with other methods and shows that both doses of drug are equally effective in maintaining glomerular function.