What is Cystadane?
Cystadane is an oral powder containing the active substance betaine anhydrous.
What is Cystadane used for?
Cystadane is used in the treatment of homocystinuria, as a supplement to other therapies, such as vitamin B6 (pyridoxine), vitamin B12 (cobalamin), folate, and a specific diet.
Homocystinuria is an inherited (genetic) disease in which the body is unable to completely metabolize the amino acid methionine. Methionine is naturally present in dietary proteins and is normally transformed into homocysteine, then into cysteine. Patients with homocystinuria are unable to transform homocysteine into cysteine; consequently, homocysteine accumulates in the blood and urine. The typical symptoms of homocystinuria include: thrombosis (formation of blood clots in the blood vessels), bone fragility, skeletal anomalies, ectopia lentis (anomaly for which the crystalline lens is displaced with respect to the normal position) and late dismantling. It is a serious disease with a high mortality rate. Cystadane is used in patients suffering from all three types of known homocystinuria, caused by a deficiency of the substances necessary for the metabolism of methionine ("cystationine beta-synthase" [CBS] or "5.10- methylentetrahydrofolate reductase" [MTHFR] ) or defects in the "metabolism of the cobalamin cofactor" (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 experienced in treating patients with homocystinuria.
The standard dose of Cystadane recommended in patients over 10 years of age is 6 g per day, divided into two equal doses. Children under the age of 10 must take 100 mg per kilogram of body weight per day, divided into two equal doses. The dose for children can be adjusted based on the response to treatment (monitored by measuring homocysteine levels in the blood); however, increasing the frequency over twice a day or the dose over 150 mg per kilogram of body weight does not improve Cystadane's benefits. The purpose of treatment is to maintain plasma homocysteine levels below 15 μM or as low as possible. This result is usually achieved within a month.
Together with Cystadane, 3 measuring spoons are supplied, delivering 100 mg, 150 mg and 1 g of
powder. The dose must be completely dissolved in water, juice, milk, foods formulated for babies or food and must be ingested immediately after mixing.
How does Cystadane work?
Betaine is a natural substance extracted from sugar beet. In the homocystinuria betaine reduces the plasma levels of homocysteine facilitating a reaction in the body called "remethylation", so that homocysteine is again transformed into methionine. In this way the symptoms of the disease improve.
What studies have been carried out on Cystadane?
The company presented data on Cystadane from the scientific literature. These included 202 reports describing the effects of Cystadane, administered at various doses, on homocysteine levels in patients with homocystinuria of different ages. Information on symptoms, dose and duration of treatment, and other medications were also provided for 140 patients
at the same time. Most patients also took vitamin B6 or B12, or folate. Information from these studies was compared with published reports describing the outcome observed in untreated patients with the same disease.
What benefit has Cystadane shown during the studies?
Patients who took Cystadane showed greater reductions in homocysteine levels than untreated patients, associated with improved cardiovascular system symptoms (heart and blood vessels) and improved nervous system reported by about three quarters of patients being treated with Cystadane. The medicine was effective in treating patients with all three types of homocystinuria.
What is the risk associated with Cystadane?
The most frequent side effects with Cystadane (seen in more than 1 patient in 10) are levels
high plasma methionine levels. Methionine levels should be monitored in patients taking Cystadane, as an increase in these levels may be associated with cerebral edema (brain swelling). Patients who present with symptoms of cerebral edema such as morning headaches with vomiting or visual changes should notify their doctor, as treatment with Cystadane may need to be stopped. For the full list of all side effects reported with Cystadane, see the Package Leaflet. Cystadane should not be used in patients who are hypersensitive (allergic) to betaine.
Why has Cystadane been approved?
The Committee for Medicinal Products for Human Use (CHMP) concluded that, despite the limited systematic studies conducted on Cystadane, the medicine is useful as an adjunctive therapy in the treatment of homocystinuria, as a supplement of vitamin-based therapies and in combination with a specific diet. The committee notes that Cystadane does not replace other treatments.
The CHMP decided that Cystadane's benefits are greater than its risks as an adjunctive treatment of homocystinuria, if used in accordance with the product indications, and therefore recommended that it be given marketing authorization.
What 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 for
monitor its safety. In particular, it will monitor cases of cerebral edema, which have been observed in a small number of patients during the trial of the medicine.
More information on Cystadane:
On 15 February 2007, the European Commission issued a marketing authorization for Cystadane, valid throughout the European Union, to Orphan Europe SARL.
For registration of the designation of Cystadane as an orphan medicine click here.
The full EPAR for Cystadane can be found here.
Last update of this summary: 01-2007.
