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Lodosyn (Carbidopa) - Summary



Carbidopa, an inhibitor of aromatic amino acid decarboxylation.

LODOSYN is indicated for use with carbidopa-levodopa or with levodopa in the treatment of

the symptoms of idiopathic Parkinson’s disease (paralysis agitans), postencephalitic parkinsonism, and symptomatic parkinsonism, which may follow injury to the nervous system

by carbon monoxide intoxication and/or manganese intoxication.

LODOSYN is for use with carbidopa-levodopa in patients for whom the dosage of

carbidopa-levodopa provides less than adequate daily dosage (usually 70 mg daily) of


LODOSYN is for use with levodopa in the occasional patient whose dosage requirement of

carbidopa and levodopa necessitates separate titration of each medication

LODOSYN is used with carbidopa-levodopa or with levodopa to permit the administration

of lower doses of levodopa with reduced nausea and vomiting, more rapid dosage titration,

and with a somewhat smoother response. However, patients with markedly irregular (“on-off”)

responses to levodopa have not been shown to benefit from the addition of carbidopa.

Since carbidopa prevents the reversal of levodopa effects caused by pyridoxine, supplemental

pyridoxine (vitamin B6), can be given to patients when they are receiving carbidopa and

levodopa concomitantly or as carbidopa-levodopa.

Although the administration of LODOSYN permits control of parkinsonism and Parkinson’s

disease with much lower doses of levodopa, there is no conclusive evidence at present that this

is beneficial other than in reducing nausea and vomiting, permitting more rapid titration, and providing a somewhat smoother response to levodopa.

Certain patients who responded poorly to levodopa alone have improved when carbidopa and

levodopa were given concurrently. This was most likely due to decreased peripheral decarboxylation of levodopa rather than to a primary effect of carbidopa on the peripheral

nervous system. Carbidopa has not been shown to enhance the intrinsic efficacy of levodopa.

In deciding whether to give LODOSYN with carbidopa-levodopa or with levodopa to patients who have nausea and/or vomiting, the physician should be aware that, while many patients may be expected to improve, some may not. Since one cannot predict which patients are likely to improve, this can only be determined by a trial of therapy. It should be further noted that in controlled trials comparing carbidopa and levodopa with levodopa alone, about half the patients with nausea and/or vomiting on levodopa alone improved spontaneously despite being retained on the same dose of levodopa during the controlled portion of the trial.

See all Lodosyn indications & dosage >>


Published Studies Related to Lodosyn (Carbidopa)

[Management of complications related to intraduodenal infusion of levodopa/carbidopa in patients with Parkinson's disease]. [Article in Spanish; Abstract available in Spanish from the publisher] [2014]
Continuous infusion of intraduodenal levodopa/carbidopa is an effective treatment that improves the motor complications and the quality of life of patients in the advanced stages of Parkinson's disease. However, it is not free of complications... The aim of this review is to report on the management of the complications that can be observed in patients with advanced Parkinson's disease treated with continuous infusion of intraduodenal levodopa/carbidopa.

Extended-release carbidopa-levodopa (IPX066) compared with immediate-release carbidopa-levodopa in patients with Parkinson's disease and motor fluctuations: a phase 3 randomised, double-blind trial. [2013]
motor fluctuations... INTERPRETATION: Extended-release carbidopa-levodopa might be a useful treatment

Are high doses of carbidopa a concern? A randomized, clinical trial in Parkinson's disease. [2012]
Recommended doses of carbidopa are 75-200 mg/day...

Effects of carbidopa and entacapone on the metabolic fate of the norepinephrine prodrug L-DOPS. [2011.01]
BACKGROUND: L-threo-3,4-dihydroxyphenylserine (L-DOPS), a norepinephrine (NE) prodrug, is investigational for orthostatic hypotension, which occurs commonly in Parkinson's disease. Adjunctive anti-parkinsonian drugs might interact with L-DOPS. We tested whether L-aromatic amino-acid decarboxylase inhibition by carbidopa (CAR) attenuates L-DOPS conversion to NE and blocks the pressor effect of L-DOPS, whereas catechol-O-methyltransferase inhibition by entacapone (ENT) interferes with L-DOPS metabolism and augments the pressor effect... CONCLUSIONS: After L-DOPS administration plasma, NE levels do not increase sufficiently to increase blood pressure. Pressor responses to L-DOPS seem to reflect NE produced extraneuronally that escapes extensive enzymatic deamination and O-methylation and evokes vasoconstriction before reaching the systemic circulation.

Effects of carbidopa and entacapone on the metabolic fate of the norepinephrine prodrug L-DOPS. [2011]
interferes with L-DOPS metabolism and augments the pressor effect... CONCLUSIONS: After L-DOPS administration plasma, NE levels do not increase

more studies >>

Clinical Trials Related to Lodosyn (Carbidopa)

Study To Assess The Clinical Benefit Of Droxidopa And Droxidopa/Carbidopa In Subjects With Fibromyalgia [Completed]
A correlation between increased norepinephrine concentration in the central nervous system (CNS) and a decrease in fibromyalgia pain has been suggested in clinical studies. Therefore, as a pro-drug of norepinephrine, droxidopa could potentially benefit fibromyalgia patients by reducing pain as a result of increasing CNS levels of norepinephrine. As this benefit is presumed to be a central effect, the addition of carbidopa, a peripheral DOPA decarboxylase (DDC) inhibitor, may favorably impact the drug's treatment profile. Carbidopa is utilized as a blocker of peripheral DDC, an enzyme required for the conversion of droxidopa into norepinephrine. Therefore, inhibition of peripheral DDC should result in a reduction of any side effects resulting from the peripheral production of norepinephrine, whilst allowing for increased central levels, and hence, increased centrally mediated benefits. The purpose of the study is the obtain information regarding the proper dosing, effectiveness and safety of droxidopa and combination droxidopa/carbidopa treatments in patients with fibromyalgia.

Augmenting Effects of L-DOPS With Carbidopa and Entacapone [Terminated]
An experimental drug called L-DOPS increases production in the body of a messenger chemical called norepinephrine. Cells in the brain that make norepinephrine are often gone in Parkinson disease. The exact consequences of this loss are unknown, but they may be related to symptoms such as fatigue, depression, or decreased attention that occur commonly in Parkinson disease. This study will explore effects of L-DOPS in conjunction with carbidopa and entacapone, which are drugs used to treat Parkinson disease. We wish to find out what the effects are of increasing norepinephrine production in the brain and whether carbidopa and entacapone augment those effects. Volunteers for this study must be at least 18 years of age and able to give consent to participate in the study. To participate in the study, volunteers must discontinue use of alcohol, tobacco, and certain herbal medicines or dietary supplements, and must also taper or discontinue certain kinds of medications that might interfere with the results of the study. Candidates will be screened with a medical history and physical exam. Participants will be admitted to the National Institutes of Health Clinical Center for two weeks of testing. The study will have three testing phases in a randomly chosen order for each participant:

- Single dose of L-DOPS

- Single dose of L-DOPS in conjunction with carbidopa

- Single dose of L-DOPS in conjunction with entacapone

Each phase will last two days, with a washout day between each phase in which no drugs will be given and no testing will be performed. In each phase, participants will undergo a series of tests and measurements, including blood pressure and electrocardiogram tests. Participants who are healthy volunteers will also have blood drawn and will undergo a lumbar puncture (also known as a spinal tap) to obtain spinal fluid for chemical tests.

Carbidopa for the Treatment of Nausea and Vomiting in Familial Dysautonomia [Completed]
This is a pilot clinical trial of carbidopa to treat disabling attacks of nausea and vomiting in patients with familial dysautonomia (FD, also known as Riley Day syndrome or hereditary sensory and autonomic neuropathy type III). FD is a rare autosomal recessive disease in which the growth and development of selective nerves is impaired. Patients with FD suffer recurrent uncontrollable nausea and vomiting crises accompanied by skin flushing, tachycardia and arterial hypertension. Current treatments of nausea are ineffective or have intolerable side sides. Our long-term goal is to treat nausea effectively and without side effects, a therapeutic intervention that would markedly improve the quality of life of patients with FD. The investigators have recently found that resting plasma dopamine levels are high in patients with FD and increase up to 40-fold during nausea and vomiting attacks. This led us to postulate that stimulation of dopamine receptors in the chemoreceptor trigger zone of the brainstem is the likely mechanism of vomiting. Carbidopa is a reversible competitive inhibitor of aromatic L-amino acid decarboxylase (also known as dopa-decarboxylase) that cannot cross the blood brain barrier. It has been used successfully for many years to block the extracerebral synthesis of dopamine and avoid nausea and vomiting in patients with Parkinson's disease taking levodopa. The investigators reasoned that carbidopa could have a similar antiemetic effect in patients with FD. The investigators propose to conduct a pilot trial to assess the safety, tolerability and efficacy of carbidopa for the treatment of nausea in patients with FD. The pilot trial will recruit 25 patients with FD who complain of severe nausea that affects their quality of life. The trial will be divided into two consecutive, but independent parts. Part 1, will address the safety and tolerability of carbidopa in patients with FD using an open-label dose titration phase followed by 4-weeks of open-label treatment. Part 2, will address the efficacy of carbidopa for the treatment of nausea in patients with FD using a randomized, placebo controlled, double blind, 4-week cross over design. The investigators hope to demonstrate that carbidopa is a safe, well-tolerated drug that blocks the peripheral formation of dopamine and thus prevents dopamine-induced nausea and vomiting attacks in patients with FD.

An Exploratory Study of XP21279 (With Lodosyn) and Sinemet in Parkinson's Disease Subjects [Completed]
The purpose of the study is to assess the pharmacokinetics (PK), pharmacodynamics, and safety of XP21279 sustained release (SR3) formulation [administered with Lodosyn (carbidopa)] and Sinemet tablets in subjects with Parkinson's disease with Motor Fluctuations.

Study of Efficacy, Safety and Tolerability of Levodopa-Carbidopa Intestinal Gel in Levodopa-Responsive Parkinson's Subjects [Completed]

The primary objective of this study was to demonstrate the superiority of levodopa -

carbidopa intestinal gel over treatment with optimized oral levodopa/carbidopa during 12 weeks.

more trials >>

Page last updated: 2015-08-10

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