Pramipexole Versus Levodopa For Early Parkinson's
A DGReview of :"Pramipexole
vs Levodopa as Initial Treatment for Parkinson Disease. A Randomized Controlled
Trial"
JAMA
10/18/2000
By Elda Hauschildt
Pramipexole, as initial therapy in patients with early Parkinson's disease,
reduces risk of developing certain dopaminergic motor complications compared to
initiation with levodopa therapy.
The drug, however, is not as effective as levodopa in improving total features
of the disease as measured by the Unified Parkinson's Disease Rating Scale (UPDRS),
researchers from the Parkinson Study Group report.
They note that the absolute risk reduction seen from initial pramipexole therapy
over levodopa is 23 percent. This means doctors would have to treat four of five
Parkinson's disease patients with pramipexole, instead of levodopa, over two
years to prevent one additional dopaminergic complication.
Researchers used a multi-centre, parallel-group, randomised trial at 22 sites in
the United States and Canada to compare dopaminergic motor complications after
initial treatment with either of the two drugs. A total of 301 patients with
early Parkinson's were enrolled in the double-blind, controlled study between
October 1996 and August 1997.
A total of 151 patients were randomly assigned to receive 0.5 mg of pramipexole
three times a day, with levodopa placebo. Another 150 patients were assigned
25/100 mg carbidopa/levodopa three times per day, with pramipexole placebo.
Dosages were escalated during the first 10 weeks for patients with residual
disability. Investigators could add open-label levodopa from week 11 to month
23.5 to treat continuing or emerging disability.
Initial pramipexole therapy resulted in significantly less development of
wearing off, dyskinesias or on-off motor fluctuation (28 percent) compared to
levodopa (51 percent). Mean improvement in total UPDRS score to 23.5 months was
greater for the levodopa patients (9.2 points) than the pramipexole patients
(4.5 points).
"UPDRS scores remained worse in the pramipexole group despite the use of
open-label levodopa for treating emerging or continuing disability," the
researchers point out.
They suggest that further studies are needed to assess a variety of questions,
include whether the trade off between motor complications and efficacy favours
levodopa or dopamine-receptor agonists such as pramipexole.
Editorialist Dr. Caroline M. Tanner of the Parkinson's Institute at Sunnyvale,
California agrees. She points out that few clinical trials extend beyond one
year, yet Parkinson's patients commonly live decades after treatment is
initiated.
"As the proportion of the US population at risk for Parkinson's disease
increases, a long-term approach to therapy assumes increasing importance,"
says Dr. Tanner. "Understanding the relationship between initial treatment
and outcomes such as morbidity, mortality and responsiveness to therapies for
advanced disease will be needed."
JAMA, 2000; 284: 1931-1938; (editorial) 1971-1973.
"Pramipexole
vs Levodopa as Initial Treatment for Parkinson Disease. A Randomized Controlled
Trial"
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