A reliable multi-dimensional column chromatographic method employing amperometric detection using a carbon fibre microelectrode procedure was used for monitoring the plasma profiles and to evaluate the pharmacokinetics and bioavailability of levodopa (L-dopa) and carbidopa (C-dopa), after ingestion of oral formulations containing these drugs. The peak currents obtained for the different analyte...

Levodopa with carbidopa is undoubtedly the gold standard of treatment for Parkinson's disease. But an initial spectacular benefit with this drug, known as the honeymoon period, is often compromised within a few years by the occurrence of disabling fluctuations and dyskinesia. The reasons for this switch are poorly understood, but probably involve pharmacokinetic factors, including the erratic a...

The administration of l-dopa suppresses prolactin (PRL) secretion in normal subjects and in patients with hyperprolactinemia, although it is not known whether this effect, which requires the conversion of dopa to dopamine, is mediated peripherally or through the central nervous system. To distinguish between these effects, 10 normal subjects (6 male, 4 female) and 8 patients with hyperprolactin...

(6 male, 4 female) and 8 patients with hyperprolactinemia associated with pituitary tumors were given L-dopa, 0.5 g alone, or 0.1 g after a 24-h pretreatment with carbidopa, 50 mg every 6 h, which produces peripheral dopa decarboxylase inhibition. Similar degrees of PRL suppression were observed in normal subjects (basal plasma PRL 13+2 ng/ml) after L-dopa alone (48±+4%) and after L-dopa plus c...

A 14-year-old girl presented with Complex Regional Pain Syndrome, Type I (CRPS-1) of the left ankle after a remote history of sprain. Allodynia, pain, temperature and color changes, and swelling were successfully treated with physical therapy, transcutaneous electrical nerve stimulation (TENS), gabapentin, amitriptyline, and tramadol. Five weeks later, she presented with a continuous, involunta...

OBJECTIVES To compare daytime intraduodenal levodopa/carbidopa infusion as monotherapy with individually optimized conventional combination therapies in patients with advanced Parkinson disease (PD) for motor fluctuations and quality of life (QoL). METHODS Twenty-four patients with motor fluctuations and dyskinesia were studied in a randomized crossover design to compare individualized conven...

BACKGROUND A combination of levodopa (L-DOPA) and carbidopa is the most commonly-used treatment for symptom management in Parkinson's disease. Studies have shown that concomitant use of a COMT inhibitor is highly beneficial in controlling the wearing-off phenomenon by improving L-DOPA bioavailability as well as brain entry. The present study sought to determine whether (-)-epigallocatechin-3-ga...

C]-5-Hydroxytryptophan ([C]HTP) and 6-[F]fluoro-3,4dihydroxy-L-phenylalanine ([F]FDOPA) are used to image neuroendocrine tumors with positron emission tomography. The precise mechanism by which these tracers accumulate in tumor cells is unknown. We aimed to study tracer uptake via large amino acid transporters, peripheral decarboxylation (inhibited by carbidopa), and intracellular breakdown by ...

Parkinson’s disease is one of the most common progressive neurodegenerative disorder. It is characterized by the depletion of dopamine in the dopaminergic neurons of the striatum of the brain. Pharmacological treatment involves the administration of a dopamine precursor, levodopa (L-Dopa), which crosses the blood-brain barrier and replaces the loss of dopamine in the brain. One of the main draw...