Research Update: Treatment of MSUD with Phenylbutyrate
As reported in our Winter 2010 issue, Dr. Brendan Lee has been applying lessons learned treating urea cycle patients to those with MSUD.
It has been observed that levels of the branched-chain amino acids and their keto acids are lowered in patients treated with phenylbutyrate. This treatment was tested in 5 patients with mild presentations of MSUD. Results were variable, but some effect was observed. Given this encouraging news, Dr. Lee hopes to conduct a clinical trial in which patients with classic and intermittent MSUD will be treated with either phenylbutyrate or placebo in a crossover design (each subject will receive each treatment). This will be a 4 week study with a 2 week washout period (neither drug nor placebo) in between the trials.
Dr. Lee notes that phenylbutyrate is already FDA approved. If it is found to be effective in increasing tolerance to protein and/or preventing or mediating metabolic decompensations, approval for use would involve a label application which takes about 90 days.