SINEMET SUMMARY
SINEMET®
(CARBIDOPA-LEVODOPA)
SINEMET* (Carbidopa-Levodopa) is a combination of carbidopa and levodopa for the treatment of Parkinson's disease and syndrome.
SINEMET is indicated in the treatment of the symptoms of idiopathic Parkinson's disease (paralysis agitans), post-encephalitic parkinsonism, and symptomatic parkinsonism which may follow injury to the nervous system by carbon monoxide intoxication and/or manganese intoxication. SINEMET is indicated in these conditions to permit the administration of lower doses of levodopa with reduced nausea and vomiting, with more rapid dosage titration, with a somewhat smoother response, and with supplemental pyridoxine (vitamin B6).
In some patients a somewhat smoother antiparkinsonian effect results from therapy with SINEMET than with levodopa. However, patients with markedly irregular ("on-off") responses to levodopa have not been shown to benefit from SINEMET.
Although the administration of carbidopa 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 have improved when SINEMET was substituted. This is most likely due to decreased peripheral decarboxylation of levodopa which results from administration of carbidopa rather than to a primary effect of carbidopa on the nervous system. Carbidopa has not been shown to enhance the intrinsic efficacy of levodopa in parkinsonian syndromes.
In considering whether to give SINEMET to patients already on levodopa who have nausea and/or vomiting, the practitioner should be aware that, while many patients may be expected to improve, some do 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 SINEMET with levodopa, about half of the patients with nausea and/or vomiting on levodopa improved spontaneously despite being retained on the same dose of levodopa during the controlled portion of the trial.
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NEWS HIGHLIGHTS
Published Studies Related to Sinemet (Carbidopa / Levodopa)
Reducing dosing frequency of carbidopa/levodopa: double-blind crossover study comparing twice-daily bilayer formulation of carbidopa/levodopa (IPX054) versus 4 daily doses of standard carbidopa/levodopa in stable Parkinson disease patients. [2009.07]
OBJECTIVE: We compared IPX054, a bilayer tablet of immediate- and extended-release carbidopa/levodopa (CD/LD) given twice daily to standard CD/LD given 4 times daily in patients with stable Parkinson disease (PD)... CONCLUSIONS: In stable PD patients, no difference was detected between twice-daily treatment with IPX054 and CD/LD given 4 times daily. In this group, substitution with IPX054 reduced dosing frequency while maintaining CD/LD efficacy. In clinical practice, this ease of administration may offer improved treatment compliance.
Long-term outcome of early versus delayed rasagiline treatment in early Parkinson's disease. [2009.03.15]
The purpose of this study to compare the long-term clinical outcome of early versus delayed rasagiline treatment in early Parkinson's disease (PD). Subjects (N = 404) were randomly assigned to initial treatment with rasagiline (early-start group) or placebo for 6 months followed by rasagiline (delayed-start group) in the TEMPO study...
Entacapone prolongs the reduction of PLM by levodopa/carbidopa in restless legs syndrome. [2007.11]
OBJECTIVES: Levodopa is effective in the treatment of restless legs syndrome (RLS). However, due to the short duration of action of conventional levodopa/decarboxylase inhibitor formulations, multiple dosing may be required in individual patients with persisting symptoms. We assessed whether a new levodopa formulation containing levodopa, carbidopa, and entacapone (LCE) improves levodopa action in RLS... CONCLUSIONS: Single doses of LCE tablets decreased PLMs in a dose-related manner in RLS patients. Prolonged effects of levodopa on PLMs suggest that, compared with standard levodopa, this new levodopa formulation provides longer symptom control throughout the night in patients with previously untreated RLS.
Safety, tolerability and efficacy of levodopa-carbidopa treatment for cocaine dependence: Two double-blind, randomized, clinical trials. [2007.05.11]
RATIONALE: The role of dopamine in cocaine abuse has been long recognized. Cocaine use can profoundly alter dopaminergic functioning through depletion of this monoamine and changes in receptor functioning. Based on these facts, levodopa (L-dopa) pharmacotherapy may be helpful in reducing or abolishing cocaine use. OBJECTIVE: The current studies sought to evaluate the safety, tolerability and efficacy of L-dopa as a treatment for cocaine dependence... CONCLUSION: These two studies demonstrate the safety and tolerability of L-dopa pharmacotherapy in cocaine-dependent patients. No evidence for greater efficacy of L-dopa compared to placebo was observed. The possibility of enhancing treatment effects by combining L-dopa with other behavioral or pharmacological interventions is discussed.
Entacapone increases levodopa exposure and reduces plasma levodopa variability when used with Sinemet CR. [2005.05]
Entacapone is a catechol-O-methyltransferase (COMT) inhibitor used as an adjunct to levodopa/dopa decarboxylase inhibitors in the treatment of Parkinson's disease. Entacapone increases the bioavailability and reduces the daily variation of plasma levodopa when administered with standard levodopa preparations...
Clinical Trials Related to Sinemet (Carbidopa / Levodopa)
A Single Center, Randomized, Double-Blind, Crossover Pilot Trial Comparing the Onset of Action of Parcopa™ With Sinemet® in Subjects With Stable Parkinson's Disease [Completed]
To test whether Parcopa, a new Orally Disintegrating Tablet of Carbidopa-Levodopa, has a
faster onset of action, changes in the UPDRS Motor Exam score at intervals after a single
dose of Parcopa or Sinemet are being compared in 10 subjects with Parkinson's disease.
Subjects 40 years or older having idiopathic PD with Hoehn and Yahr state II or III are
eligible if taking a stable dose of < 200 mg carbidopa and < 2000 mg levodopa daily. At both
treatment visits, either Parcopa or Sinemet, plus a placebo of the opposite tablet (ODT or
conventional) are administered. The dose is the same as the subject's prestudy regimen. The
primary efficacy variable, time to onset of action, is the first postdose time when a 30%
decrease (30% improvement) in the total score is achieved. All UPDRS evaluations are done by
a rater blinded to the active treatment received by the subject.
A Multiple-Dose Study of Sinemet® CR (Carbidopa/Levodopa) in Healthy Subjects [Completed]
Parcopa Versus Carbidopa-Levodopa in a Single Dose Cross-Over Comparison Study [Recruiting]
To find out if a single dose of Parcopa®, a form of levodopa that dissolves in your mouth,
works faster than regular oral levodopa which is swallowed, in fluctuating PD patients.
Comparison of IPX054, Immediate-Release Carbidopa-Levodopa, and Controlled-Release Carbidopa-Levodopa in Subjects With Parkinson's Disease [Recruiting]
The objective of this study is to compare the pharmacokinetics and pharmacodynamics of
IPX054, carbidopa-levodopa immediate-release tablets, and carbidopa-levodopa
controlled-release tablets in subjects with idiopathic Parkinson's disease.
A Multicenter, Open-Label Trial to Assess Subject Preference of PARCOPA, Carbidopa/Levodopa Orally Disintegrating Tablets, Compared to Conventional Carbidopa/Levodopa Tablets in Subjects With Stable Parkinson's Disease [Completed]
The objective of this trial was to assess subject preference for PARCOPA, carbidopa/levodopa
Orally Disintegrating Tablets (ODT), compared with conventional carbidopa/levodopa tablets,
in subjects with stable Parkinson's disease.
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Page last updated: 2009-10-20
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