"The U.S. Food and Drug Administration yesterday approved Ruconest, the first recombinant C1-Esterase Inhibitor product for the treatment of acute attacks in adult and adolescent patients with hereditary angioedema (HAE).
Mechanism Of Action
Cystadane acts as a methyl group donor in the remethylation of homocysteine to methionine in patients with homocystinuria. Cystadane occurs naturally in the body. It is a metabolite of choline and is present in small amounts in foods such as beets, spinach, cereals, and seafood.
Cystadane was observed to lower plasma homocysteine levels in three types of homocystinuria, including CBS deficiency; MTHFR deficiency; and cbl defect. Patients have taken Cystadane for many years without evidence of tolerance. There has been no demonstrated correlation between Cystadane levels and homocysteine levels.
In CBS-deficient patients, large increases in methionine levels over baseline have been observed. Cystadane has also been demonstrated to increase low plasma methionine and S-adenosylmethionine (SAM) levels in patients with MTHFR deficiency and cbl defect.
Pharmacokinetic studies of Cystadane are not available. Plasma levels of Cystadane have not been measured in patients and have not been correlated to homocysteine levels.
Cystadane was studied in a double-blind, placebo-controlled, crossover study in 6 patients with CBS deficiency, ages 7 to 32 years at enrollment. Cystadane was administered at a dosage of 3 grams twice daily, for 12 months. Plasma homocystine levels were significantly reduced (p < 0.01) compared to placebo. Plasma methionine levels were variable and not significantly different compared to placebo.
No adverse events were reported in any patient.
Cystadane has also been evaluated in observational studies without concurrent controls in patients with homocystinuria due to CBS deficiency, MTHFR deficiency, or cbl defect.A review of 16 case studies and the randomized controlled trial previously described was also conducted, and the data available for each study were summarized; however, no formal statistical analyses were performed. The studies included a total of 78 male and female patients with homocystinuria who were treated with Cystadane. This included 48 patients with CBS deficiency, 13 with MTHFR deficiency, and 11 with cbl defect, ranging in age from 24 days to 53 years. The majority of patients (n=48) received 6 gm/day, 3 patients received less than 6 gm/day, 12 patients received doses from 6 to 15 gm/day, and 5 patients received doses over 15 gm/day. Most patients were treated for more than 3 months (n=57) and 30 patients were treated for 1 year or longer (range 1 month to 11 years). Homocystine is formed nonenzymatically from two molecules of homocysteine, and both have be used to evaluate the effect of Cystadane in patients with homocystinuria. Plasma homocystine or homocysteine levels were reported numerically for 62 patients, and 61 of these patients showed decreases with Cystadane treatment. Homocystine decreased by 83-88% regardless of pre-treatment level, and homocysteine decreased by 71-83%, regardless of the pre-treatment level. Clinical improvement, such as improvement in seizures, or behavioral and cognitive functioning, was reported by the treating physicians in about three-fourths of patients. Many of these patients were also taking other therapies such as vitamin B6 (pyridoxine), vitamin B12 (cobalamin), and folate with variable biochemical responses. In most cases, adding Cystadane resulted in a further reduction of either homocystine or homocysteine.
Last reviewed on RxList: 12/5/2016
This monograph has been modified to include the generic and brand name in many instances.
Additional Cystadane Information
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Find out what women really need.