There are two major causes of disability in patients with Parkinson disease: motor fluctuations that occur when a dose of levodopa becomes ineffective, leading to a "wearing off," and hyperkinetic movements (dyskinesias) caused by excessive levels of dopamine. The utility of continuous levodopa treatment is therefore limited by motor complications. Pharmacologic options to treat wearing off inc...

The effects of acute levodopa withdrawal were studied in nine patients with levodopa related on-off oscillations. One patient withdrew from the study due to off period confusion and hallucinations. A marked deterioration in motor disability occurred in all patients following overnight withdrawal of levodopa and a further mild delayed deterioration was present over a mean withdrawal period of 44...

The present study investigated the effects of levodopa, a precursor of dopamine (DA) therapeutically used for the treatment of Parkinson's disease, on DA transport in the two different systems, COS-7 cells heterologously expressing rat monoamine transporter cDNA and in monoaminergic cell lines PC12 and SK-N-SH. Levodopa enhanced uptake of [3H]DA and [3H]norepinephrine (NE) but not [3H]serotonin...

Fifty four patients with idiopathic Parkinson's disease receiving levodopa therapy were studied. Thirty three of these patients displayed peak-dose dyskinesia. Neither the duration of Parkinson's disease nor the duration of levodopa therapy discriminated between patients with and patients without peak-dose dyskinesia. Consequently, these criteria could not determine whether the first appearance...

One hundred and twenty nine de novo patients with idiopathic Parkinson's disease are being followed over a 5 year period in a double-blind multicentre study comparing low-dose bromocriptine (less than 30 mg/day) with low-dose levodopa-carbidopa (less than 600/150 mg/day). Sixty six patients have been randomised to bromocriptine and 63 patients to levodopa-carbidopa. Improvement has been greater...

Intravenous levodopa has been used in a multitude of research studies due to its more predictable pharmacokinetics compared to the oral form, which is used frequently as a treatment for Parkinson's disease (PD). Levodopa is the precursor for dopamine, and intravenous dopamine would strongly affect vascular tone, but peripheral decarboxylase inhibitors are intended to block such effects. Pulse a...

BACKGROUND There is debate about whether the initial treatment for patients with Parkinson's disease should be levodopa or a dopamine agonist. METHODS In this prospective, randomized, double-blind study, we compared the safety and efficacy of the dopamine D2-receptor agonist ropinirole with that of levodopa over a period of five years in 268 patients with early Parkinson's disease. If symptom...

Levodopa effectively improves motor symptoms of Parkinson's disease. However, the beneficial effects of levodopa often erode over time with the emergence of response fluctuations. Although these response changes have been recognized from the early levodopa era, their mechanisms remain poorly understood. We investigated the role of dopamine (DA) terminal loss in the development of motor fluctuat...

D a t a e x t r a c t i o n Studies were rated for quality (class I [highquality randomized controlled trials with blinded outcome assessment] to class IV [uncontrolled studies, case series, case reports, or expert opinion]). M a i n r e s u l t s Selegiline: 2 class-II studies on the neuroprotective effects of selegiline were included. Selegiline improved symptoms, but the evidence was insuffi...

We investigated the role of dopamine neurons in the manifestation of levodopa-induced dyskinesia in a rat model of Parkinson's disease. Daily treatment with a subthreshold dose of levodopa gradually induced abnormal involuntary movements (AIM) in 6-hydroxydopamine-lesioned rats, which included stereotypy and contraversive rotation. After 4 weeks of levodopa treatment, rats with mild and severe ...