Cysteamine bitartrate (Cystagon) is a drug that is available by prescription only. This drug is converted in the human body to cystamine. This drug is FDA approved for treatment of a disease called cystinosis. It is used in children and adults. This drug used in Huntington’s would be “off label”.

Cystamine decreases the activity of an enzyme called transglutamase. It is thought that this enzyme helps abnormal Huntington molecules to bind, which may be an early event in disease causation. Cystamine also increases levels chemicals that protect the nerve cell from injury. This type of drug is also used to decrease injury in Tylenol over dosage and radiation exposure.

This drug has been shown to decrease brain injury and improve symptoms in the Huntington’s mouse model (Karpuj et al., 2002) and (Dedeoglu, et al., 2002). It is being studied for use in Infantile Neuronal Ceroid Lipofuscinosis which is a rare brain disorder of children. In this situation, the researchers have documented the drug in brain. (Anil Mukherjee, Principal Investigator.)

Dosage will be the same as that used in cystinosis in adults: 2 gm/day given in 4 divided doses. This drug comes in tablet form and must be taken frequently to maintain adequate blood level of this drug.

This drug causes nausea and GI upset. This side effect is common, and is greatly helped drugs that prevent acid secretion in the stomach, such as omeprazole (prilosec). As such, this drug will be required when cysteamine is used. Skin rash, headache, dehydration, low white blood cell count and elevated liver function tests occur much less frequently. Seizures have been reported in children with cystinosis, but it is not clear whether seizures are due to the primary disease or to the cysteamine use. This drug is bitter tasting and foul smelling. It will take some getting used to.

Karpuj et al., Nature Medicine: Feb. 2002, 8 (2) 143-149.
Dedeoglu et al., Journal of Neuroscience, Oct. 2002, 22 (20) 8942-8950.