OBJECTIVE: To investigate the efficacy and the rate of adverse events of chronic 
low-dose levodopa-carbidopa therapy in Japanese patients with Parkinson's 
disease (PD).
PATIENTS AND METHODS: A total of 92 Japanese PD patients treated with low doses 
of levodopa from the outset were studied. Both disease-specific motor 
disabilities and quality of life (QOL) in the patients were evaluated using the 
Unified Parkinson's Disease Rating Scale (UPDRS) and the Parkinson's Disease 39 
Quality of Life Questionnaire (PDQ39), respectively.
RESULTS: In the overall patient group, the mean duration of treatment, the mean 
daily dose of levodopa, the disability scores and the motor scores of UPDRS were 
6.2 years, 186.4 mg, 8.0 and 19.2, respectively. The rates of motor 
fluctuations, dyskinesias and hallucinations were 8.7%, 6.5% and 14.1%, 
respectively. The mean summary index of PDQ39 scores was 23.1. Patients with 
motor fluctuations showed a significantly earlier disease onset. Dose of 
levodopa, age at onset, and treatment duration were not associated with the 
occurrence of dyskinesias. Patients with hallucination had higher doses of 
levodopa and dopamine agonist.
CONCLUSIONS: Our results demonstrate that chronic administration of a low-dose 
levodopa preparation can provide satisfactory benefit with a low incidence of 
motor complications, and can result in good QOL in Japanese patients with PD. 
The concomitant use of a small amount of dopamine agonist and amantadine from 
the outset has partly contributed to a reduced dose of levodopa and the lesser 
occurrence of motor complications.