Active Substance: betaine anhydrous
Common Name: betaine anhydrous
ATC Code: A16AA06
Marketing Authorisation Holder: Orphan Europe S.A.R.L.
Active Substance: betaine anhydrous
Authorisation Date: 2007-02-15
Therapeutic Area: Homocystinuria
Pharmacotherapeutic Group: Other alimentary-tract and metabolism products
Adjunctive treatment of homocystinuria, involving deficiencies or defects in:
- cystathionine beta-synthase (CBS);
- 5,10-methylene-tetrahydrofolate reductase (MTHFR);
- cobalamin cofactor metabolism (cbl).
Cystadane should be used as supplement to other therapies such as vitamin B6 (pyridoxine), vitamin B12 (cobalamin), folate and a specific diet.
What is Cystadane?
Cystadane is a powder for oral use that contains the active substance betaine anhydrous.
What is Cystadane used for?
Cystadane is used to treat homocystinuria. It is used with other treatments, such as vitamin B6 (pyridoxine), vitamin B12 (cobalamin), folate and a special diet.
Homocystinuria is an inherited (genetic) disease where the amino acid methionine cannot be broken down completely by the body. Methionine naturally comes from proteins in foods and is usually broken down into homocysteine, then cysteine. Patients with homocystinuria cannot convert homocysteine into cysteine, so homocysteine builds up in the blood and urine. Symptoms of homocystinuria include thrombosis (formation of blood clots in the blood vessels), weakness of the bones, abnormalities of the skeleton, ectopia lentis (a disorder where the lens of the eye is in the wrong position) and mental retardation. The disease is serious and has a high death rate. Cystadane is used in patients with all three known types of homocystinuria, caused by a lack of the substances required for the breakdown of methionine (‘cystathionine beta-synthase’ [CBS] or ‘5,10- methylene-tetrahydrofolate reductase’ [MTHFR]), or by defects in ‘cobalamin cofactor metabolism’ (cbl).
Because the number of patients with homocystinuria is low, the disease is considered ‘rare’, and Cystadane was designated an ‘orphan medicine’ (a medicine used in rare diseases) on 9 July 2001. The medicine can only be obtained with a prescription.
How is Cystadane used?
Treatment with Cystadane should be supervised by a doctor who has experience in the treatment of patients with homocystinuria.
The standard dose of Cystadane for patients aged over 10 years is 6 g a day, divided into two equal doses. Children under 10 years of age should take 100 mg per kilogram of body weight a day, divided into two equal doses. The dose for children can be adjusted depending on their response to treatment (monitored by measuring the level of homocysteine in the blood), but taking Cystadane more than twice a day or in doses above 150 mg per kilogram body weight does not improve its benefit. The aim of the treatment is to keep blood levels of homocysteine below 15 micromoles or as low as possible. This is usually achieved within a month.
Cystadane is supplied with three measuring spoons to measure 100 mg, 150 mg and 1 g of the powder. It should be dissolved fully in water, juice, milk, formula or food immediately before being taken.
How does Cystadane work?
Betaine is a natural substance that is extracted from sugar beet. In homocystinuria, betaine reduces homocysteine levels in the blood by facilitating a reaction in the body called ‘methylation’, which converts homocysteine back into methionine. This helps to improve the symptoms of the disease.
How has Cystadane been studied?
The company presented information on Cystadane from the scientific literature. This included 202 reports that described the effects of Cystadane, given at a variety of doses, on homocysteine levels in homocystinuria patients of various ages. For 140 patients, information was also provided on their symptoms, the dose and duration of treatment, and other medicines being taken. Most patients were also taking vitamins B6 or B12, or folate. The information from these studies was compared to published reports describing the outcome of untreated patients with the disease.
What benefit has Cystadane shown during the studies?
Patients taking Cystadane appeared to have greater reductions in homocysteine levels than untreated patients. This was associated with a reported improvement in symptoms affecting the cardiovascular system (heart and blood vessels) and the development of the nervous system in around three quarters of the patients taking Cystadane. The medicine was effective in patients with all three types of homocystinuria.
What is the risk associated with Cystadane?
The most common side effect when taking Cystadane (seen in more than 1 patient in 10) is elevated levels of methionine in the blood. Methionine levels should be monitored in patients taking Cystadane, as it might be related to cerebral oedema (swelling in the brain). Patients with symptoms of cerebral oedema, such as morning headaches with vomiting, or changes in vision, should speak to their doctor, as treatment with Cystadane may have to be interrupted. For the full list of all side effects reported with Cystadane, see the package leaflet.
Cystadane should not be used by patients who may be hypersensitive (allergic) to betaine.
Why has Cystadane been approved?
The Committee for Medicinal Products for Human Use (CHMP) concluded that, although there were few systematic studies of Cystadane, the medicine is useful when added to existing treatments for homocystinuria, such as vitamin supplementation and using a special diet. The committee noted that Cystadane is not a substitute for other treatments.
The committee decided that Cystadane’s benefits outweighed its risks in the adjunctive treatment of homocystinuria, when it is used according to its indication. It recommended that Cystadane be given marketing authorisation.
Which measures are being taken to ensure the safe use of Cystadane?
The company that makes Cystadane will set up a register of patients taking the medicine to monitor its safety. In particular, the company will monitor cases of cerebral oedema, which was seen in a small number of patients during the testing of the medicine.
Other information about Cystadane
The European Commission granted a marketing authorisation valid throughout the European Union for Cystadane to Orphan Europe SARL on 15 February 2007.
Source: European Medicines Agency
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