Our library of drug research abstracts drawn from the medical literature is updated on a regular schedule, and you can be assured that new sinemet research articles will be listed here shortly after becoming available to us.
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Medical research on sinemet
Drugs R D. 2008; 9(6): 435-46
Vaz-da-Silva M, Loureiro AI, Nunes T, Lopes C, Rocha J, Machado R, Costa R, Torrão L, Falcão A, Wright L, Almeida L, Soares-da-Silva P
BACKGROUND AND OBJECTIVES: Levodopa is the most effective symptomatic treatment for Parkinson's disease (PD), but its use is often associated with development of motor complications. These adverse responses to fluctuations in dopaminergic stimulation can be reduced by concomitant administration of a catechol-O-methyltransferase (COMT) inhibitor. Nebicapone is a new COMT inhibitor currently being developed for use as an adjunct to levodopa/dopa decarboxylase inhibitor in the treatment of PD. This article aimed to investigate the effect of single oral doses (50 mg, 100 mg and 200 mg) of nebicapone on levodopa pharmacokinetics and erythrocyte-soluble COMT (S-COMT) activity when coadministered with a single dose of controlled-release (CR) levodopa/carbidopa 200 mg/50 mg (Sinemet((R)) CR 200/50) in healthy subjects (n = 16). METHODS: This was a randomized, double-blind, placebo-controlled, four-way crossover study in healthy subjects, with at least 5 days of washout between treatment periods. RESULTS: There was a dose-dependent and significant increase in levodopa extent of exposure (area under the plasma concentration-time curve from time zero to infinity [AUC(infinity)]) without a significant change in peak exposure (maximum plasma concentration; [C(max)]). Using placebo as a reference, levodopa geometric mean ratios (GMRs) and 90% CIs following nebicapone 50 mg, 100 mg and 200 mg were, respectively, 1.13 (0.98, 1.30), 1.04 (0.90, 1.19) and 1.10 (0.96, 1.27) for C(max) and 1.26 (1.16, 1.34), 1.37 (1.27, 1.75) and 1.47 (1.42, 1.65) for AUC(infinity). For 3-O-methyldopa (3-OMD), the GMRs and 90% CIs were, respectively, 0.61 (0.55, 0.67), 0.45 (0.41, 0.50) and 0.33 (0.30, 0.36) for C(max) and 0.69 (0.61, 0.78), 0.53 (0.41, 0.61) and 0.41 (0.37, 0.47) for AUC(infinity). Nebicapone dose dependently and significantly decreased COMT activity. Maximum COMT inhibition occurred at 1.5-2.4 hours post-dose and ranged from 56% to 73% with nebicapone 50 mg and 200 mg, respectively. There was a good correlation between plasma concentrations of nebicapone and inhibition of S-COMT activity. Treatments were well tolerated. CONCLUSION: Following concomitant administration with levodopa/carbidopa CR 200 mg/50 mg, single doses of nebicapone 50 mg, 100 mg and 200 mg significantly and dose-dependently inhibited S-COMT activity, increased systemic exposure to levodopa, and reduced 3-OMD formation.
Dopa-responsive dystonia presenting as delayed and awkward gait.
Pediatr Neurol. 2008 Apr; 38(4): 273-5
Cheyette BN, Cheyette SN, Cusmano-Ozog K, Enns GM
Dopa-responsive dystonia is a hereditary disease characterized by inadequate dopamine production. Autosomal-dominant cases result from mutations in the GCH1 gene, encoding guanosine triphosphate (GTP)-cyclohydrolase 1. The most common presenting manifestation is dystonia of a lower extremity, often worsening late in the day. The onset and clinical severity are variable, sometimes even within a single family. Gender effects on allele penetrance have been reported. We present a male toddler with dopa-responsive dystonia caused by an autosomal-dominant GCH1 mutation. Three other family members were also found to carry the mutation, with widely different functional consequences.
Acute overdose with controlled-release levodopa-carbidopa.
Clin Toxicol (Phila). 2008 Mar; 46(3): 274-7
Delmas G, Rothmann C, Flesch F
INTRODUCTION: Reports of acute levodopa-carbidopa overdose are rare and no case of an acute overdose with a controlled-release formulation has been described. We describe such a case in which serial concentrations of catecholamines were measured. CASE REPORT: A 55-year-old man ingested 89 tablets of Sinemet 50/200 (17.8 g of levodopa, 4.45 g of carbidopa). Clinical effects and plasma concentrations of dopamine, noradrenaline and adrenalin were assessed over 66 hours. On admission 2.5 hours after the ingestion, his physical examination was normal except for mydriasis and urine retention. Five hours post-ingestion he had psychomotor agitation, delirium with logorrhea, joviality, visual hallucinations, regular sinus tachycardia and xerostomia. The clinical course included two episodes hypotension and four of transient tachycardia. Treatment was symptomatic and supportive. Clinical toxicity reappeared 48 hours after the intoxication. The patient was discharged at the end of the fourth day with amnesia for the event. DISCUSSION: Dopamine showed an initial plasma concentration peak 14 hours after the toxic ingestion, followed by a second peak 38 hours after the ingestion. The initial peak of noradrenaline occurred 20 hours post-ingestion with a second lower peak at 38 hours. There were no elevations in adrenalin concentrations. CONCLUSION: There appeared to be no correlation between the intensity of the clinical signs and the blood concentrations of dopamine and noradrenaline, although the resolution of the clinical signs did correspond to these catecholamines return to normal values. Patients who ingest controlled-release formulations need to be observed until after the second catecholamine peak.
Levodopa pharmacotherapy for cocaine dependence: choosing the optimal behavioral therapy platform.
Drug Alcohol Depend. 2008 Apr 1; 94(1-3): 142-50
Schmitz JM, Mooney ME, Moeller FG, Stotts AL, Green C, Grabowski J
BACKGROUND: The dopamine precursor levodopa has shown some, albeit relatively weak, promise in treating cocaine dependence. This study sought to identify the most appropriate behavioral therapy platform for levodopa pharmacotherapy by evaluating its effect when administered in combination with behavioral platforms of varying intensities. METHOD: A total of 161 treatment-seeking cocaine dependent subjects received sustained release levodopa/carbidopa (400/100mg bid, Sinemet) or placebo delivered in combination with Clinical Management (ClinMan); ClinMan+cognitive behavioral therapy (CBT); or ClinMan+CBT+voucher-based reinforcement therapy (VBRT) in a 12-week randomized, placebo-controlled, double-blind (for medication condition) trial. Medication compliance was monitored with riboflavin (100mg/capsule) and the Medication Event Monitoring System. Protocol compliance was addressed in weekly, 10-min nurse-delivered ClinMan sessions. Weekly, 1-h CBT sessions focused on coping skills training. VBRT (with escalating reinforcer value) provided cash-valued vouchers contingent on cocaine-negative urine toxicology results. Urine benzoylecgonine assays collected thrice-weekly were analyzed by intention-to-treat criteria using generalized linear mixed models. RESULTS: Levodopa main effects were found on all outcome measures of cocaine use. Contrasts testing the levodopa-placebo difference within each behavioral platform found reliable effects, favoring levodopa, only in the VBRT platform. Levodopa treatment with vouchers produced higher proportions of cocaine-negative urines and longer periods of consecutive abstinence compared to other treatment combinations. CONCLUSION: This is the first study to find a significant treatment effect for levodopa and, in doing so, to demonstrate that the magnitude of this effect is dependent upon conditions of the behavioral therapy platform. The data support use of levodopa with abstinence-based reinforcement therapy as one efficacious combination in cocaine dependence disorder treatment.
Entacapone prolongs the reduction of PLM by levodopa/carbidopa in restless legs syndrome.
Clin Neuropharmacol. 2007 Nov-Dec; 30(6): 335-44
Polo O, Ylä-Sahra R, Hirvonen K, Karvinen J, Vahteristo M, Ellmén J
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. METHODS: Twenty-eight RLS patients with periodic limb movement (PLM) received single doses of Stalevo 50 (LCE50; 50/12.5/200 mg), Stalevo 100 (LCE100; 100/25/200 mg), Stalevo 150 (LCE150; 150/37.5/200 mg), Sinemet 100 (LC100; 100/25 mg), or placebo in a randomized, double-blind, crossover study with polysomnography. Periodic limb movements per hour (PLM/h) during total sleep time and PLM during total time in bed were the primary and secondary variables, respectively. RESULTS: Mean PLM/h during total sleep time after Stalevo 50 (12.6/h, P < 0.05), LCE100, LCE150, and LC100 (6.4/h, 3.5/h and 9.5/h, respectively; P < 0.01) were significantly reduced compared with placebo (25.7/h). Improvement was also observed in PLM/h during total time in bed for all treatments (P < 0.01) and a significant dose response observed between LCE doses (P < 0.05). Compared with LC100, LCE100 and LCE150 reduced PLMs during the second half (P = 0.06 and P < 0.001, respectively) or during the last 3 early morning hours (hours 5-7 from the start of recording) of the night (P < 0.05 and P < 0.01, respectively). All formulations were well tolerated. 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.
I couldn't sleep at all last night.
J Clin Sleep Med. 2005 Jan 15; 1(1): 95-6
Young DK
Skin rash associated with Sinemet does not equal levodopa allergy.
Neurology. 2007 Mar 27; 68(13): 1078-9
Chou KL, Stacy MA
J Psychiatry Neurosci. 2007 Mar; 32(2): 129-36
Leyton M, aan het Rot M, Booij L, Baker GB, Young SN, Benkelfat C
OBJECTIVE: Midbrain dopamine transmission is thought to regulate responses to rewarding drugs and drug-paired stimuli; however, the exact contribution, particularly in humans, remains unclear. In the present study, we tested whether decreasing dopamine synthesis, as produced by acute phenylalanine/tyrosine depletion (APTD), would alter responses to the stimulant drug, d-amphetamine. METHODS: On 3 separate days, 14 healthy men received d-amphetamine (0.3 mg/kg, given orally) plus a nutritionally balanced amino acid mixture, the phenylalanine/tyrosine-deficient mixture or the phenylalanine/tyrosine-deficient mixture followed by the immediate dopamine precursor, L-DOPA (Sinemet, 2 x 100 mg/25 mg). Responses to these treatments were assessed with visual analog scales, the Profile of Mood States, and a computerized Go/No-Go task. RESULTS: d-Amphetamine elicited its prototypical subjective effects, but these were not altered by APTD. In comparison, APTD significantly increased commission errors on the Go/No-Go task and did so uniquely in conditions where subjects were rewarded for making correct responses; this effect of APTD was prevented by L-DOPA. CONCLUSIONS: Together these results support the hypothesis that, in healthy men, dopamine is not closely linked to euphorogenic effects of abused substances but does affect the salience of reward-related cues and the ability to respond to them preferentially.
[Prevention and treatment of fluctuations in patients with Parkinson's disease]
Praxis (Bern 1994). 2006 Dec 20; 95(51-52): 2013-8
Ludin HP, Surber Ch
Fluctuations (wearing-off, on off phenomenon, dyskinesias) are a big challenge in the long term treatment of parkinsonian patients. We describe the current strategies for prevention and treatment of fluctuations. Special emphasis is put on two new methods which will soon be available. The new dopamine agonist Rotigotine (Neupro) can be transdermally applied. This is a rather simple way to achieve a continuous dopaminergic stimulation. The same goal is achieved by direct application of levodopa-/carbidopa-gelsuspension (Duodopa) in the duodenum by the help of an electronic pump.
Drug Alcohol Depend. 2007 May 11; 88(2-3): 214-23
Mooney ME, Schmitz JM, Moeller FG, Grabowski J
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. METHODS: In Study 1, 67 cocaine-dependent subjects were randomized in a 5-week, double-blind, placebo-controlled safety trial. Subjects received either placebo, or 400 mg L-dopa plus 100 mg of the peripheral decarboxylase inhibitor, carbidopa, in a sustained-release preparation (Sinemet CR). In Study 2, 122 cocaine-dependent subjects were enrolled in a 9-week, randomized, double-blind, placebo-controlled trial to compare placebo to 400/100 mg and 800/200 mg L-dopa/carbidopa treatments. Placebo or L-dopa were administered twice daily in both studies. RESULTS: L-dopa was well tolerated with similar retention and medication adherence rates compared to placebo. Only two side effects occurred more often in L-dopa-treated patients: nausea and dizziness. L-dopa lowered diastolic blood pressure in a dose-dependent fashion. In these trials, L-dopa had no effect on cocaine use, cocaine craving, or mood. 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.