Cysteamine bitartrate capsules (
Cystagon) have been approved by the US Food and Drug Administration for use in patients with
nephropathic cystinosis. 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 was done with eight
cystinosis patients who had been receiving either
cysteamine hydrochloride or
phosphocysteamine for many years. The plasma
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 capsules compared to the older, liquid forms of the
drug. A new method for following the course of renal glomerular deterioration in diseases 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 doses of
cysteamine (1.30 g/m2 per day and 1.95 g/m2 per day). This new method agrees well with other methods and shows that both doses of
drug are equally effective in maintaining glomerular function.