Search

Background: Motor fluctuations are a common complication in patients with Parkinson disease (PD) receiving long-term levodopa therapy. Slowed gastric emptying and poor solubility of levodopa in the gastrointestinal tract may delay the onset of drug benefit after dosing. Etilevodopa is an ethyl-ester prodrug of levodopa that has greater gastric solubility, passes quickly into the small intestine, is rapidly hydrolyzed to levodopa, and has a shortened time to maximum levodopa concentration., Objective: To determine the efficacy, safety, and tolerability of etilevodopa in patients with PD who have motor fluctuations., Design: A double-blind, randomized, comparative clinical trial., Setting: Forty-four sites in the United States and Canada., Patients: Three hundred twenty-seven patients with PD who had a latency of at least 90 minutes total daily time to "on" (TTON) after levodopa dosing., Intervention: Treatment with either etilevodopa-carbidopa or levodopa-carbidopa for 18 weeks., Main Outcome Measure: Change from baseline in total daily TTON as measured using home diaries., Results: The reduction in mean total daily TTON from baseline to treatment was 0.58 hour in the etilevodopa-carbidopa group and 0.79 hour in the levodopa-carbidopa group (P = .24). There was no significant difference between the etilevodopa-carbidopa and levodopa-carbidopa groups in the reduction of response failures (-6.82% vs -4.69%; P = .20). Total daily "off" time improved in the etilevodopa-carbidopa (-0.85 hour) and levodopa-carbidopa (-0.87 hour) groups without an increase in on time with troublesome dyskinesias., Conclusion: Despite the theoretical pharmacokinetic advantage of etilevodopa, there was no improvement in TTON, response failures, or off time compared with levodopa.

The authors studied the pharmacokinetics of levodopa (LD) with and without pramipexole (PPX) in men and postmenopausal women with PD. Patients on stable dose of carbidopa/LD were randomized to receive escalating doses of placebo or PPX over 7 weeks. LD and PPX pharmacokinetics were performed after a single test dose 25/100 of carbidopa/LD, before initiation of PPX or placebo, at 1.5 mg/d and 4.5 mg/d of PPX or placebo. Compared to men, women had greater LD bioavailability. PPX did not alter LD bioavailability, and PPX pharmacokinetics were equivalent in men and women.

Background: Abnormal involuntary movements (dyskinesias) are common in patients with Parkinson disease (PD) as a consequence of the disease and dopaminergic replacement therapy. Early morning off-medication choreic dyskinesias have been recently reported after fetal dopaminergic cell transplantations in patients with advanced PD., Objective: To determine the frequency and severity of the early morning off-medication dyskinesias in consecutive patients with advanced PD and an insufficient response to medical management before they undergo neurosurgery., Methods: Consecutive patients with advanced idiopathic PD were examined and videotaped before undergoing neurosurgery that included pallidotomy, fetal transplantation, or deep brain stimulation. The examination took place in the morning in the practically defined off state, at least 12 hours after the last dose of dopaminergic drugs. Parkinson disease was characterized using the Unified Parkinson's Disease Rating Scale and the Hoehn and Yahr stage. Dyskinesias were rated with the Abnormal Involuntary Movements Scale and the Rush Dyskinesia Rating Scale. Patients' characteristics and medications were compared using the Wilcoxon rank sum and the Fisher exact tests., Results: Of 68 consecutive patients (44 [65%] men and 24 [35%] women), 11 (16%) had early morning off-medication dyskinesia, with a 95% upper confidence limit of 24%. Focal dystonia was the most common off-medication dyskinesia, and occurred in 10 patients (15%), with a 95% upper confidence limit of 22%; and off-choreic dyskinesia occurred in 1 patient (1.5%), with a 95% upper confidence limit of 4%. There was no difference in PD medications between the patients with and those without dyskinesias., Conclusions: The most common form of off-medication dyskinesia seen in patients with advanced PD is dystonia. Early morning off-medication choreic dyskinesias are rare but do occur in patients with advanced PD before surgical intervention. The presence and type of off-medication dyskinesias should be monitored in clinical and surgical studies in patients with PD as part of the safety and evaluation of clinical benefits.

Background: Dyskinesias are a frequent adverse effect of long-term levodopa therapy. The relative contribution of dopamine D(1) and D(2) receptor function to the pathophysiology of levodopa-induced dyskinesias remains a matter of controversy., Objective: To establish whether a selective D(1) dopamine agonist induces more or less dyskinesia than levodopa in primed dyskinetic patients with Parkinson disease., Methods: We studied ABT-431, the prodrug of a fully selective D(1) agonist, in 20 subjects with advanced Parkinson disease and a fluctuating response to levodopa complicated by dyskinesias. Eight patients were studied in a double-blind, randomized design (French centers); 12, in an open, randomized design (US centers). We assessed and compared the antiparkinsonian (Unified Parkinson's Disease Rating Scale) and dyskinetic (response induced by an acute challenge of a suprathreshold dose of levodopa and by 4 different ascending doses (5, 10, 20, and 40 mg) of ABT-431 during the 6 hours after the challenge., Results: The separate analysis of the double-blind and open data led to the same findings, ie, the antiparkinsonian and dyskinetic responses induced by ABT-431 were dose related. At the most effective doses (20 and 40 mg), ABT-431 exhibited similar antiparkinsonian benefit and produced similar dyskinesias as levodopa., Conclusion: Dopamine D(1) agonists can induce a full antiparkinsonian response but do not support previous hypotheses suggesting that D(1) agonists are more or less likely to produce dyskinesias than levodopa.

Objective: To monitor comparative progression of clinical impairment over 4 years in patients with Parkinson's disease (PD) who present on levodopa at two different levels of Hoehn and Yahr (HY) stages, II and III., Background: The rate of clinical impairment progression in patients with PD being treated with levodopa has not been studied in detail using current, standardized assessment tools. Sample size estimates for all levodopa adjunctive treatment studies and proper definition of study groups require a solid estimate of longitudinal motor impairment progression., Design/methods: From our computer database, we identified two groups of patients with PD being treated with levodopa based on their initial HY stage at presentation to our center (II or III). Fifty randomly selected subjects in each stage were monitored in the ON state with annual Unified Parkinson's Disease Rating Scale (UPDRS) motor scores, dyskinesia ratings, and antiparkinsonian medication doses using a repeated measures analysis of variance., Results: The stage II and stage III subjects had similar disease duration. In stage II subjects, parkinsonian impairment was maintained without progression over 4 years, but in association with significantly higher dyskinesia scores and dopaminergic medication doses. In stage III subjects, UPDRS motor scores deteriorated despite more medication and increased dyskinesias. Of the established six factors comprising the UPDRS motor scale, bradykinesia accounted for the increased impairment. Initial UPDRS motor score and disease duration did not influence progression of motor impairment., Conclusion: In subjects with similar disease duration, progression of PD motor impairment differs significantly between stage II and stage III subjects over 4 years. Whereas in stage II subjects, parkinsonian impairment can be stabilized at the expense of increased dyskinesia and dopaminergic drugs, once subjects reach stage III, motor impairment progresses. Power estimates and sample size calculations for these groups of patients should be calculated separately.

Catechol O-methyltransferase (COMT) is an important enzyme that is linked directly to therapy with levodopa. Considering the demonstrated mechanism of action and pharmacologic profiles of COMT inhibitors, it is reasonable to hypothesize that these agents would improve the disability associated with Parkinson's disease. Two basic classes of COMT inhibitors are being studied in patients with PD: those that act exclusively extracerebrally or peripherally (e.g., entacapone) and those that cross the blood-brain barrier (e.g., tolcapone). With COMT inhibition, greater peripheral bioavailability of levodopa occurs in humans without an enhancement of peak plasma levels. It is reasonable to suggest that COMT inhibition will be associated with prolonged effects of levodopa in PD, without increased peak dose toxicity in the form of dyskinesias and hallucinations.

In five nondemented Parkinson's disease patients with daily visual hallucinations, we tested whether high-dose IV levodopa (LD) infusions precipitated hallucinations. Two infusion paradigms were studied, each with 1.5-mg/kg hourly dose for 4 hours--steady infusion and pulse infusion of the full hour dose over 5 minutes each hour. In both protocols, plasma LD levels changed significantly during the infusion protocol. The cumulative area under the curve was equivalent for the two infusions. All patients remained alert, and none developed visual hallucinations. The two patients with peak-dose dyskinesias on oral LD developed prominent dyskinesias during the infusion. Visual hallucinations do not relate simply to high levels of LD or to sudden changes in plasma levels.

Most new pharmacological therapies in Parkinson's disease focus on the dopaminergic system. Drugs that enhance dopaminergic function fall into three primary categories: amino acid precursors to dopamine, agonists that stimulate dopamine receptors, and enzyme antagonists that prevent the metabolism of dopamine and hence permit more or prolonged neurotransmitter activity; the first two are discussed below. Within the first category, levodopa is the amino acid precursor to dopamine, and a number of modifications in its formulation have been developed to enhance dopaminergic activity. In the area of agonists, new agents pramipexole, ropinerole, and cabergoline have recently been developed to complement the currently available bromocriptine and pergolide, and these new drugs may be released in the United States.

We performed the first double-blind, crossover comparison between levodopa/carbidopa (LD/CD) in optimized liquid versus tablet doses to measure plasma LD levels and relative effects on disabilities (motor function, fluctuations, and dyskinesias) in patients with Parkinson's disease. Twenty-three subjects with motor fluctuations were optimized with open-label LD/CD tablets and liquid. In a double-dummy design, patients randomly received 2 weeks of liquid and 2 weeks of tablet LD/CD. Twice during each arm, we evaluated patients hourly 9 AM to 4 PM with the use of plasma LD levels, the Unified Parkinson's Disease Rating Scale, a dyskinesia rating scale, and "on-off" ratings. Patients receiving liquid LD/CD ingested significantly higher doses and had significantly improved motor function and total "on" time, without an increase in dyskinesia severity. The number of motor fluctuations in the two phases was not significantly different. LD levels and variability were also equivalent with the two formulations. At optimized dosing, liquid LD/CD offers a means to significantly improve motor disability in patients with Parkinson's disease without exacerbating dyskinesia.

We defined the temporal stability characteristics of levodopa/carbidopa (LD/CD) solution, and determined the effects of temperature, ascorbate, and light on LD stability over 7 days. At room temperature and without ascorbate, LD levels significantly declined by 48 h. Ascorbate prolonged stability to 72 h. Refrigeration and freezing prevented a significant decline in LD levels for the full 7 days. Light or darkness had no effect on stability. LD/CD solution, if made daily, requires no special handling and longer stability is maintained with ascorbate, refrigeration, or freezing.

Objective: To identify characteristics of patients with early, untreated Parkinson's disease that are the most important predictors of rapid functional decline., Design: Prospective observational study of a cohort of 800 patients with early, untreated Parkinson's disease who were involved in a multicenter, randomized, double-blind, controlled clinical trial of selegiline hydrochloride (L-deprenyl) and vitamin E (alpha-tocopherol)., Primary Outcome Variable: Time from randomization to the onset of disability that necessitated levodopa therapy (end point), as judged by the enrolling investigator., Methods: Stepwise Cox regression was used in combination with clinical judgment to identify the most important independent baseline predictors of the primary end point among a host of variables, including treatment with selegiline and vitamin E, global and specific clinical measures of disease severity, demographic variables, and neuropsychological test results., Results: In addition to selegiline treatment and global disease severity measures, such as the stage according to the criteria of Hoehn and Yahr, impaired domestic capacity, and the activities of daily living score, the complex of postural instability/gait difficulty and bradykinesia were found to be the factors that were most highly associated with the risk of reaching the end point., Conclusions: The findings suggest that patients with Parkinson's disease whose early clinical presentation includes either postural instability/gait difficulty or bradykinesia are at high risk for rapid functional decline.

Ten patients with Parkinson's disease suffering severe motor fluctuations completed a double-blind, placebo-controlled, crossover trial of duodenal infusion of levodopa/carbidopa to determine if this technique improved the duration of functional time by reducing plasma levodopa level variability. With infusion, seven patients experienced increased functional "on" hours and decreased number of "off" episodes; however, two patients were slightly worse and one patient experienced no benefit. All 10 patients had significantly decreased variability in levodopa levels permitting better titration of levodopa dosage to individual requirements. Five patients continued to use infusion 12 to 20 months after completion of this study. Selected patients with Parkinson's disease who experience severe motor fluctuations may benefit from duodenal infusion with an improved and prolonged response to medication.

We studied 10 regular exercising men with Parkinson's disease on levodopa (LD) under two conditions--no exercise and vigorous exercise started 1 hour after LD ingestion. We compared LD levels and motor scores on the Unified Parkinson's Disease Rating Scale (UPDRS). There was a high degree of agreement between plasma LD level and the patients' UPDRS scores 30 minutes later (mean Eta2 = 0.84) in both conditions, with no difference between the two. We conclude that LD levels accurately reflect UPDRS motor function in these patients, and that vigorous exercise started 1 hour after LD ingestion does not influence LD or motor scores.

Rats with unilateral 6-hydroxydopamine lesions (6-OHDA) of the mesencephalon and vehicle controls (SHAM) were chronically treated with carbidopa (CD) or CD plus levodopa (CD/LD) for 18 days. Seventy-two hours following the last treatment, ipsilateral striata, contralateral striata, and cerebellums from each treatment group were homogenized separately and the supernatant extracts were incubated with rostral mesencephalic tegmentum cultures. As indices of growth-promoting activity (GPA), number of viable neurons and their process lengths were measured 40 h later. In all cultures exposed to striatal extracts, the 6-OHDA lesion was associated with greater GPA than the SHAM extracts. CD/LD consumption reduced this GPA in a dose-dependent fashion in both the lesioned and the SHAM animals. These data suggest that denervation of the striatum enhances the production of a striatally derived neurotrophic factor, the production of which is sensitive to levodopa. Chronic levodopa treatment in Parkinson's disease may therefore contribute to disease progression by reducing the compensating effects of this neurotrophic factor on remaining mesencephalic neurons.

Asterixis was observed in five parkinsonian patients who were taking levodopa. A prospective study revealed that 4 of 55 consecutive patients had asterixis. Liver and metabolic functions were normal in all patients. Asterixis always occurred as part of a toxic confusional state superimposed on a parkinsonian state associated with some dementia. Insomnia, hallucinosis, and myoclonus were also prominent in the affected patients. Because of this association with other signs of chronic drug toxicity and its reversal with drug withdrawal, the asterixis seemed to be drug-related.

Chronic use of levodopa may be complicated by dyskinesias, on-off effect, or hallucinosis. Transient levodopa withdrawal (drug holiday) may increase motor responsiveness and decrease levodopa-induced side effects, and the improved state may persist for as long as 9 months. After 1 year, parkinsonian signs approached pre-holiday levels, and two of the patients required a second drug holiday; side effects began to reappear 9 to 12 months after the holiday. Four of six patients with psychiatric complications remained free of hallucinations for the entire year.

Twenty-three patients with idiopathic Parkinson disease with classic "on-off" phenomena were studied prospectively during treatment with bromocriptine (BCT). Patients were evaluated for an average of 6 to 12 months and received an average of 56.5 mg of BCT. Nine patients (39%) showed improvement in terms of "on-off". When evaluated retrospectively, it appeared that the only difference between the responders and non-responders was a younger mean age (57.1 to 63.2).

We studied 100 consecutive patients with Parkinson's disease (PD) who were not receiving levodopa and followed them until symptoms advanced and levodopa was given. Eighty-three patients eventually received levodopa; 50% started within 36 months after a mean duration of symptoms of 48 months. Patients starting on levodopa showed significant progression of their disease compared with their baseline examination. These data have direct applicability to the design and implementation of future protocols aimed at preventing disease progression of PD.

Sixteen patients with advanced Parkinson's disease (PD) and motor fluctuations were evaluated throughout 12 months of open label therapy on CR4-Sinemet. Reduced dosage frequency and significant motor improvement with reduced fluctuation occurred and were maintained with CR4-Sinemet compared with baseline on Sinemet. In a double-blind protocol using CR4-Sinemet in 20 stable PD patients, CR4-Sinemet was given twice daily and compared with Sinemet given four times daily. Patients remained stable without improvement or deterioration when the long-acting drug was substituted at 50% frequency. Plasma levodopa levels with CR4-Sinemet were smoother than with Sinemet. Although some patients receiving CR4-Sinemet found they functioned more slowly in the morning, the easier dosing schedule and improved amount of "on" time in fluctuators suggest that this formulation may become increasingly useful in managing PD.

We compared the chronic (2-year) effect of substitution with Sinemet CR with the effect of continued administration of standard Sinemet on motor fluctuations and drug-induced side effects in Parkinson's disease (PD). Twelve patients in each treatment group were pair-matched for age, PD duration, duration of levodopa therapy, dosage of Sinemet, PD disability, and side-effect prevalence at study entry. After 2 years, both groups were more disabled from their PD than at baseline; the disability scores were equivalent for the 2 treatments. The Sinemet CR group had fewer fluctuations and fewer side effects. Compared with the standard Sinemet group, Sinemet CR patients had more "on" time (mean 83% versus 62%, p less than 0.001), and had a lower prevalence of disabling chorea (p less than 0.007), dystonia (p less than 0.003) and sleep disruption (p less than 0.002). Prevalence of hallucinations was equivalent for the 2 groups. These results suggest that Sinemet CR is beneficial in ameliorating and preventing the high frequency of some side effects of standard Sinemet treatment.

Twelve parkinsonian patients on long-term levodopa therapy developed intermittent, myoclonic body jerks. The movements consisted of single unilateral or bilateral abrupt jerks of the extremities and occurred most frequently during sleep. Although directly related to daily dosage of levodopa, the myoclonus was specifically blocked by the serotonin antagonist, methysergide. Levodopa-induced myoclonus may be related to intermittent increases of activity of serotonin in the brain and results from levodopa-induced dysregulation of serotonin activity.

Long-acting levodopa/carbidopa combination (CR-4-Sinemet) was compared with traditional levodopa/carbidopa (Sinemet) open label in 20 patients with Parkinson's disease and "wearing-off" phenomena. After 4 to 6 weeks of therapy with CR-4-Sinemet, the number of daily doses of medication dropped significantly compared with traditional Sinemet, disability improved, and "on" time increased. In nine patients receiving CR-4-Sinemet for 3 months, the number of daily doses and the on time without chorea remained significantly improved. CR-4-Sinemet peaked in plasma after 2 hours, and moderately high levels remained at 4 hours after the dose. Side effects were similar between traditional Sinemet and CR-4 Sinemet.

Thirteen parkinsonian patients drawn from two large parkinsonism clinics experienced hypersexuality as a consequence of anti-parkinsonian therapy. The cases include only those whose sexual behavior on treatment became a concern to the patient's family or a social agency. The majority of patients were men and had a relatively early onset of parkinsonian symptomatology. There was no relation between functional improvement and increased sexuality. Most patients showed some element of dose dependency between antiparkinsonian drugs and the hypersexual behavior. Prior sexual profile included from no sexual outlet to hypersexuality. Neither the prior history of psychiatric illness nor brain damage predisposed to such response on treatment, and in most patients, it was not a part of hypomania or a more diffuse psychiatric disturbance. We propose that hypersexuality on antiparkinsonian drugs is consequent to inhibition of prolactin secretion.