CYSTAGON® is indicated for the management of nephropathic cystinosis in children and adults.

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Fanconi Syndrome -- A hereditary or acquired form of generalized dysfunction of the PROXIMAL KIDNEY TUBULE without primary involvement of the KIDNEY GLOMERULUS. It is usually characterized by the tubular wasting of nutrients and salts (GLUCOSE; AMINO ACIDS; PHOSPHATES; and BICARBONATES) resulting in HYPOKALEMIA; ACIDOSIS; HYPERCALCIURIA; and PROTEINURIA.

CYSTAGON® is contraindicated in patients who have developed hypersensitivity to it or to cysteamine or penicillamine.

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Hypersensitivity -- Altered reactivity to an antigen, which can result in pathologic reactions upon subsequent exposure to that particular antigen.

If a skin rash develops, CYSTAGON® should be withheld until the rash clears.

CYSTAGON® may be restarted at a lower dose under close supervision, then slowly titrated to the therapeutic dose.

If a severe skin rash develops such as erythema multiforme bullosa or toxic epidermal necrolysis, CYSTAGON® should not be readministered.CNS symptoms such as seizures, lethargy, somnolence, depression, and encephalopathy have been associated with cysteamine.

If CNS symptoms develop, the patient should be carefully evaluated and the dose adjusted as necessary.

Neurological complications have been described in some cystinotic patients not on cysteamine treatment.

This may be a manifestation of the primary disorder.

Patients should not engage in hazardous activities until the effects of CYSTAGON® on mental performance are known.Gastrointestinal ulceration and bleeding have been reported in patients receiving cysteamine bitartrate.

Physicians should remain alert for signs of ulceration and bleeding and should inform patients and/or guardians about the signs and symptoms of serious G.I.

toxicity and what steps to take if they occur.Post marketing reports include one report of interstitial nephritis with early renal failure.

A causal relationship between this event and cysteamine bitartrate therapy has not been established.