First-HD is a clinical trial testing SD-109 ER, a new extended-release form of tetrabenazine (Xenazine®). Finding the 90 participants, who must have moderately severe untreated chorea, has been difficult and slower than expected. Only 4 or 5 participants are needed for each of the 20 centers doing this trial. Why should we bother with this trial? Because we will never have better medical treatments if we don't join this, and other clinical trials.

Why we need an extended release tetrabenazine: We already know that tetrabenazine is effective, and the only FDA approved drug, for the treatment for those individuals with troublesome chorea due to Huntington's disease (HD). However there are several problems with the currently available, short-acting form of this drug that may be improved by the new extended release form. To prove this, we need to get this trial completed. Possible improvements for this new drug include:

  1. Convenience: Xenazine®, the short acting form of tetrabenazine requires taking a pill several times a day (up to 3 or 4) for effective control of chorea. The extended release form would reduce this to one or two.
  2. Smoother action: Drug levels of the short acting drug vary greatly with every pill taken: from very high shortly after taking the pill, to very low before the next one. This results in a "roller coaster" effect for control of chorea with too much drug just after taking a pill and too little before the next one. The new extended release form of tetrabenazine should prevent this roller coaster effect by preventing the highs and lows and by keeping the drug at the same effective level throughout the day and night.
  3. (Potentially) fewer side effects: This is probably the most important reason to get this trial completed. The drugs we have for chorea treatment now, including the short acting form of tetrabenazine and antipsychotic drugs have many unwanted side effects. In fact, this is the reason why expert doctors are reluctant to treat chorea. Why might the extended-release tetrabenazine have fewer side effects? High levels of many drugs -- like the high level just after taking the short acting pill -- is often associated with more side effects. The peak (highest) level of the long acting tetrabenazine is substantially lower than the peak level of shorter acting version. Indeed fewer side effects occur for many (not all) extended release drugs. The chance of fewer side effects is the most important reason to get this trial completed.

Trial information: Travel and lodging reimbursement (provided on the same day as the visit) for this trial is available. And qualified participants of First-HD (whether receiving placebo or drug in this trial) will be offered free drug during a year-long follow-up trial (ARC-HD) through the same center.

For specifics including criteria and visit schedule for either First-HD or ARC-HD trials go to or Visit the Huntington Study Group (HSG) web site for a great description and webinar presentation.

If you fit criteria, we at HDDW strongly encourage you to sign up. And just as important -- if you know someone else who might fit this trial, encourage their participation too. We need you to get this trial done.