Levodopa continues to be the most efficacious and widely used treatment for Parkinson's disease. Levodopa dosing is understood to be critical for the optimal control of symptoms, and increasing the levodopa dose is a common method to treat advancing disease. Escalating levodopa dosages coupled with disease progression is associated with increasing likelihood of developing levodopa-induced dyski...

OBJECTIVE The aim of this report is to discuss whether or not rectal levodopa administration is useful in some situations. BACKGROUND In situations where oral intake of levodopa formulations is not possible, the treatment options of Parkinson's disease patients are limited. The literature describes no or low rectal absorption of levodopa. CASE DESCRIPTION A patient with an ileus was unable ...

Four patients with levodopa induced fluctuations in motor performance were studied during the constant intraduodenal infusion of levodopa. The results confirm that steady plasma levodopa levels with stable motor control can be achieved. However, when patients were given oral protein loads, motor performance declined despite maintenance of plasma levodopa levels. These findings suggest that comp...

To assess the relative influence of central pharmacodynamic and peripheral pharmacokinetic factors on the duration of motor response to levodopa, the relationship between motor function and plasma levodopa levels was studied in 31 Parkinsonian patients. Duration of benefit from single levodopa doses while fasting depended on the degree to which the plasma levodopa level had declined over four h...

Lumbar cerebrospinal fluid homovanillic acid levels were estimated in 60 patients with Parkinsonism before and during levodopa treatment. There was a slight negative correlation between pretreatment CSF homovanillic acid levels and disability. There was no correlation between pretreatment homovanillic acid levels and clinical response to levodopa. Patients with high pretreatment levels did as w...

Levodopa is the "gold standard" for the symptomatic treatment of Parkinson's disease (PD). There is a theoretical concern, however, that levodopa might accelerate the rate of nigral degeneration, because it undergoes oxidative metabolism and is toxic to cultured dopaminergic neurons. Most in vivo studies do not show evidence of levodopa toxicity; levodopa is not toxic to normal rodents, nonhuma...

We hypothesized that levodopa with carbidopa, a common therapy for patients with Parkinson's disease, might contribute to the high prevalence of insulin resistance reported in patients with Parkinson's disease. We examined the effects of levodopa-carbidopa on glycogen concentration, glycogen synthase activity, and insulin-stimulated glucose transport in skeletal muscle, the predominant insulin-...

PURPOSE Levodopa is the most effective anti-Parkinsonian agent. It has also been known to exhibit analgesic properties in laboratory and clinical settings. However, studies evaluating its effects on neuropathic pain are limited. The aim of the present study was to examine the anti-allodynic effects of levodopa in neuropathic rats. MATERIALS AND METHODS Sprague-Dawley male rats underwent the s...

The long-duration response (LDR) is a sustained improvement in parkinsonism due to chronic levodopa therapy and lasts after discontinuation of treatment. We have investigated the molecular changes that underlie the LDR in rats with a unilateral 6-hydroxydopamine (6-OHDA) lesion. Animals were treated for 22 days with levodopa or saline. Forelimb akinesia was evaluated prior and following a test ...

BACKGROUND The modulation of levodopa transport across the blood brain barrier by large neutral amino acids is well documented. Protein limitation and protein redistribution diets may improve motor fluctuations in patients with Parkinson's disease but the pharmacokinetics and pharmacodynamics of levodopa and amino acids are highly variable. METHODS Clinical records of 1037 Parkinson's disease...