Carbidopa and Nausea in FD

Status: Complete, Results Published

Carbidopa for the Treatment of Nausea in Patients with Familial Dysautonomia. This was a pilot clinical trial of carbidopa to treat disabling attacks of nausea and vomiting in patients with FD. We found that resting plasma dopamine levels are high in patients with FD and increase up to 40-fold during nausea and vomiting attacks. This led us to postulate that stimulation of dopamine receptors in the chemoreceptor trigger zone of the brainstem is the likely mechanism of vomiting. Carbidopa is a reversible competitive inhibitor of aromatic L-amino acid decarboxylase (also known as dopa-decarboxylase) that cannot cross the blood brain barrier. It has been used successfully for many years to block the extra-cerebral synthesis of dopamine and to avoid nausea and vomiting in patients with Parkinson disease taking levodopa. We reasoned that carbidopa could have a similar antiemetic effect in patients with FD. We conducted a double-blind placebo controlled crossover trial and demonstrated that carbidopa is a safe, well-tolerated drug that blocks the peripheral formation of dopamine and thus prevents dopamine-induced nausea and vomiting attacks in patients with FD.

Eligibility: The study was open to people with familial dysautonomia above the age of 12 years. 

IRB#: 09-0011

Sponsor: Food & Drug Administration’s Office of Rare Diseases Product Development

Hyperdopaminergic crises in familial dysautonomia: a randomized trial of carbidopa. Norcliffe-Kaufmann L, Martinez J, Axelrod F, Kaufmann H. Neurology. 2013 Apr 23;80(17):1611-7. PMID: 23553478 
Cyclic vomiting associated with excessive dopamine in Riley-day syndrome. Norcliffe-Kaufmann LJ, Axelrod FB, Kaufmann H. J Clin Gastroenterol. 2013 Feb;47(2): PMID: 22739220