Long-term treatment of cystinosis in children with twice-daily cysteamine.
OBJECTIVE
Cystinosis causes renal and other organ failure. Treatment with 6-hourly cysteamine bitartrate (Cystagon, Mylan, Morgantown, West Virginia) reduces intracellular cystine and the rate of organ deterioration. A recent study showed that an enteric-release cysteamine required less frequent daily dosing. This report describes the long-term use of enteric-coated (EC) cysteamine bitartrate (Cystagon) in children with cystinosis.


METHODS
After a pharmacokinetic and pharmacodynamic study of EC-cysteamine in children with cystinosis, 5 patients remained on twice-daily treatment. White blood cell cystine levels were measured 12 hours after ingestion every 4 to 8 weeks. These levels were then compared with the patient's previous 6-h post-dose levels taken while on regular cysteamine bitartrate before entering the study. Blood chemistry was also measured.


RESULTS
Five children with cystinosis (mean age, 9 years; range, 8 to 17 years) who previously took cysteamine bitartrate (mean dose, 47 mg/kg body wt), received EC-cysteamine for 10 to 27 months (mean dose, 25 mg/kg body wt) and had mean white blood cell cystine levels of 0.77 and 0.71 nmol half-cystine/mg protein, respectively. During the study period, patients maintained adequate growth and there was no significant deterioration in renal or thyroid function. Two children were required to restart acid suppression after 6 months on EC-cysteamine therapy.


CONCLUSIONS
Long-term, twice-daily EC-cysteamine, given at approximately 60% of the previous daily dose of cysteamine bitartrate, was effective at maintaining white blood cell cystine levels within a satisfactory range. There was no significant deterioration in renal or thyroid function.
Department of Pediatrics, University of California, San Diego, La Jolla, CA, USA. rdohil@ucsd.edu
Ranjan
R
Dohil
Jon A
JA
Gangoiti
Betty L
BL
Cabrera
Meredith
M
Fidler
Jerry A
JA
Schneider
Bruce A
BA
Barshop
D000293:Adolescent; D002648:Child; D003404:Creatinine / Q000097:blood; D003543:Cysteamine / Q000008:administration & dosage*; D003553:Cystine / Q000097:blood; D003554:Cystinosis / Q000097:blood / Q000188:drug therapy*; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007962:Leukocytes / Q000378:metabolism; D008297:Male; D013608:Tablets, Enteric-Coated
D013608:Tablets, Enteric-Coated; D003553:Cystine; D003543:Cysteamine; D003404:Creatinine