CYSTAGON is a medicine containing the active ingredient cysteamine bitartrate (also known as mercaptamine bitartrate). It is available as capsules (50 and 150 mg).
|Table of Contents|
|What is it used for?|
|How is it used?|
|How does it work?|
|How has it been studied?|
|What benefits has it shown during the studies?|
|What is the risk associated?|
|Why has it been approved?|
CYSTAGON is used to manage patients who have nephropathic (kidney) cystinosis. Cystinosis is a rare inherited disorder where cystine builds up within body cells, preventing them from working correctly. This leads to kidney problems and spreads to other parts of the body, including the eyes, some glands (thyroid, gonads, pancreas), the central nervous system, muscles and the liver. Stunted growth is a symptom of the condition.
The medicine can only be obtained with a prescription.
CYSTAGON treatment should be started by a doctor who has experience in the treatment of cystinosis.
Cystine levels in white blood cells should be monitored to adjust the dose.
For children up to the age of 12 years, the recommended dose is 1.30 g/m 2/day divided into 4 daily doses.
For patients over the age of 12 and over 50 kg in weight, the recommended dose is 2 g/day, divided into 4 daily doses. Starting doses should be one quarter to one sixth of the final expected doses. The starting dose should be increased gradually over 4-6 weeks.
CYSTAGON reacts with cystine to form cysteine and a cysteine-cysteamine salt (mixed disulfide). This salt is then removed from the cells by a system that transports another amino acid (lysine). The amount of cystine in the organs is reduced and this limits the damage to these organs.
CYSTAGON has been investigated in three clinical studies including 234 patients over a 12-year period. These studies included children and newly recruited patients in whom two different doses were tested. Because the disease is very serious, it was not possible for ethical reasons to compare CYSTAGON directly to a dummy treatment. The comparison was done instead with a group of patients who had been treated with a dummy treatment as part of another, unrelated trial. The studies looked at the kidney function, the survival and the growth rate of the patients.
The three studies have shown that CYSTAGON delays kidney problems, and the need for dialysis or renal transplantation when treatment is started at an early age in patients with good kidney function. It also improves survival and growth rate in the children treated.
The side effects of CYSTAGON are mainly connected with the digestive system. The most common side effects (seen in more than 1 patient in 10) are anorexia (loss of appetite), vomiting, nausea (feeling sick), diarrhoea, lethargy (lack of energy) and pyrexia (fever). For the full list of all side effects reported with CYSTAGON, see the Package Leaflet.
CYSTAGON should not be used in people who may be hypersensitive (allergic) to cysteamine or any of the other ingredients, or to penicillamine. It should also not be used in women who are breast-feeding, or who are or may be pregnant (particularly during the first three months) unless it is clearly necessary.
Cystinosis is a rare, fatal disease, and CYSTAGON is considered a useful medicine for this disease, for which no alternative treatments are available. The Committee for Medicinal products for Human Use (CHMP) decided that CYSTAGON?s benefits are greater than its risks and recommended that CYSTAGON be given marketing authorisation.
CYSTAGON was originally authorised under "Exceptional Circumstances", because, as the disease is rare, limited information was available at the time of approval. As the company had supplied the additional information requested, the "Exceptional Circumstances" ended on 17 April 2007.