At the start of the study, the patients had an average of six hours of "off time" a day when symptoms reappeared. After 12 weeks, those on a 120-milligram or 180-milligram dose of tozadenant had about an hour less of "off time" each day than they had at the start of the study.
Tozadenant, which works on brain receptors thought to regulate motor function, merits further study in future trials, Hauser said.
In another study, Hauser looked at 321 patients with early stage Parkinson's whose symptoms weren't handled well by a medicine called a dopamine agonist, typically the first drug prescribed for Parkinson's patients. During the 18-week study, Hauser assigned them to take either their usual medicine plus an add-on drug called rasagiline (brand name Azilect) or their usual medicine and a placebo.
Azilect is approved for use in patients with early stage disease as a single therapy or as an add-on to levodopa, Hauser said, but not yet as an add-on to dopamine agonists.
Those taking the Azilect -- but not those taking the placebo -- improved by 2.4 points on a standard Parkinson's disease rating scale.
Costs of the still unapproved drugs are not known. Azilect costs about $200 monthly at the 1-milligram daily dose used in the study.
Each of the studies was funded by the pharmaceutical company making the particular drug: Chelsea Therapeutics paid for the blood-pressure study; Biotie Therapies Inc., supported the "wearing-off" study; and Teva Pharmaceutical Industries sponsored the Azilect study. Hauser is a consultant for all three companies.
Most impressive of the three studies is the use of droxidopa to prevent dizziness and fainting, said Dr. Michael Okun,
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