Auspex Pharmaceuticals announced quite positive results for their drug SD-109. This drug treats chorea with many fewer side effects associated with tetrabenazine. And most important it improved quality of life.

SD-109 is a chemically modified form of tetrabenazine that allows for lower dosing. Not only does this drug treat chorea effectively with only half the dose of regular tetrabenazine, it has strikingly lower side effects. Importantly, there was an impressive benefit in quality of life for those who took the drug versus those with placebo. And though more analysis needs to be done, at first glance it appears to benefit not just chorea, but perhaps other motor symptoms as well.

If final analysis confirms those reported in the press release, this is a big step forward in the treatment of chorea. It is also important to note that treating chorea with this drug also resulted in "much improved or very much improved" quality of life, suggesting that chorea is an important symptom deserving of treatment. They also showed that there were no problems switching from regular tetrabenazine to SD-109, maintaining chorea control at half the dose of regular tetrabenazine.

Author's comment: If this drug lives up to the press release, it could/should replace antipsychotic drugs as primary treatment of chorea in Huntington's disease.