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NEW YORK, Jan 21 (Reuters) -- A new drug may allow people with Parkinson's disease to live each day on a more even keel, with fewer fluctuations in their symptoms, according to researchers. Patients with the disorder also need less of the main medication for Parkinson's -- levodopa -- when the drug tolcapone is added to their treatment. The new drug works by slowing the metabolism, or break down, of levodopa, thus prolonging its availability to the body. "This is an important development in the treatment of Parkinson's disease," says Dr. Mathias Kurth, a neurologist with Barrow Neurological Institute in Phoenix, Arizona. "This is another step toward making treatment better and smoother and making life better for patients," he adds. The Barrow Neurological Institute is one of several medical centers around the nation involved in the Tolcapone Fluctuation Study Group. Others include the Mayo Clinic, Scottsdale, Arizona; Boston University, Boston, Massachusetts; the University of Miami, Florida; the University of Southern California, Los Angeles; and Sinai Hospital of Detroit, Michigan. The study included 151 Parkinson's patients who each day experienced "off" periods of muscle slowness, rigidity, and trembling of the arms and legs, and "on" periods of relatively normal functioning when their levodopa dosage was working. In a report published in January's issue of Neurology, the researchers note that tolcapone reduced patients' "off" time by an average of 40% and increased their total "on" time by about 25%. Patients taking tolcapone also needed fewer doses of levodopa. Neurologists have known for some time that levodopa works well when it is first given to Parkinson's patients. The drug is converted by the body into dopamine, a nerve transmitter substance that reduces muscle tone so that movement is not jerky. In Parkinson's patients, dopamine levels are diminished in the parts of the brain -- collectively known as the basal ganglia -- affected by the disease. But after a time, the beneficial effects of levodopa often suddenly wear off, and other drugs must be given as substitutes. According to the researchers, tolcapone prolongs the effect of levodopa by blocking an enzyme that breaks down and converts levodopa to an inactive substance. This allows levodopa to remain in the bloodstream longer. Side effects of tolcapone observed in the study include nausea and abnormal muscle movements (uncontrollable twitches and jerks). But the researchers note these can be lessened or eliminated by adjusting the dose of levodopa. Tolcapone's maker is Hoffman-La Roche, of Nutley, New Jersey. The drug company expects to obtain Food and Drug Administration approval for tolcapone some time this year. According to the American Academy of Neurology in Minneapolis, Parkinson's disease affects more than 800,000 people in the U.S., with about 50,000 new cases diagnosed each year. SOURCE: Neurology (1997;48:81-87) Copyright 1997 Reuters Limited. <http://www.reutershealth.com/news/rhdn/199701/1997012104.html> ----------------------------------------------------------------------- [log in to unmask]