Active Substance: mercaptamine bitartrate
Common Name: mercaptamine bitartrate
ATC Code: A16AA04
Marketing Authorisation Holder: Orphan Europe S.A.R.L.
Active Substance: mercaptamine bitartrate
Authorisation Date: 1997-06-23
Therapeutic Area: Cystinosis
Pharmacotherapeutic Group: Other alimentary tract and metabolism products
Cystagon is indicated for the treatment of proven nephropathic cystinosis. Cysteamine reduces cystine accumulation in some cells (e.g. leukocytes, muscle and liver cells) of nephropathic cystinosis patients and, when treatment is started early, it delays the development of renal failure.
What is Cystagon?
Cystagon is a medicine containing the active ingredient cysteamine bitartrate (also known as mercaptamine bitartrate). It is available as capsules (50 and 150 mg).
What is Cystagon used for?
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.
How is Cystagon used?
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/m2/day divided into four daily doses. For patients over the age of 12 and over 50 kg in weight, the recommended dose is 2 g/day, divided into four daily doses.
Starting doses should be one quarter to one sixth of the final expected doses. The starting dose should be increased gradually over four to six weeks.
How does Cystagon work?
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.
How has Cystagon been studied?
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.
What benefit has Cystagon shown during the studies?
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.
What is the risk associated with Cystagon?
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 breastfeeding, or who are or may be pregnant (particularly during the first three months) unless it is clearly necessary.
Why has Cystagon been approved?
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.
Other information about Cystagon
The European Commission granted a marketing authorisation valid throughout the European Union for Cystagon to Orphan Europe on 23 June 1997. The marketing authorisation was renewed on 23 June 2002 and on 23 June 2007.
Source: European Medicines Agency
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