Options in the treatment of motor fluctuations and dyskinesias in Parkinson's disease: a brief review

Review: management of Parkinson's disease

Parkinson's disease (PD) is one of the most frequent neurological diseases. Despite the modern imaging and nuclear techniques which help to diagnose it in a very early stage and lead to a better discrimination of similar diseases, PD has remained a clinical diagnosis. The increasing number of available treatment options makes the disease management often complicated even when the presence of PD seems undoubted. In addition, nonmotor symptoms and side effects of some therapies constitute some pitfalls already in the preclinical state or at the beginnings of the disease, especially with the progressive effect on patients. Therefore, this review aimed to summarize study results and depict recommended medical treatments for the most common motor and nonmotor symptoms in PD. Additionally, emerging new therapeutic options such as continuous pump therapies, eg, with apomorphine or parenteral levodopa, or the implantation of electrodes for deep brain stimulation were also considered.

Palliative Management of Parkinson Disease: Focus on Nonmotor, Distressing Symptoms

Parkinson disease is a progressive neurodegenerative disease that commonly affects elderly persons. In the absence of neuroprotective or curative therapies, currently available therapies only provide symptomatic benefit. Progression to advanced Parkinson disease is often accompanied by functional dependence with increased risk of admission to a long-term care facility. The prevalence of Parkinson disease in long-term care facilities, within the United States, has been estimated to be between 5.2% and 10%. Patients with advanced Parkinson disease also experience other distressing motor and nonmotor conditions, such as motor complications, dementia, depression, gastrointestinal distress, orthostatic hypotension, pain, and psychosis, which can be a challenge for clinicians to manage. The presence of distressing symptoms along with the fact that Parkinson disease remains incurable necessitate discussion on a palliative care approach to this disorder. This article discusses the symptomatic management of distressing symptoms encountered in the long-term care resident with Parkinson disease, including motor complications and nonmotor features.

Pharmacotherapy for Parkinson's disease

The available pharmacotherapies for Parkinson's disease address symptomatology because no agent has been demonstrated to provide definite neuroprotection against the disease. Choice of pharmacotherapy must include consideration of short-term benefits as well as long-term consequences. Patients with mild Parkinson's disease often function adequately without symptomatic treatment. However, recent data suggest that initiation of treatment with a well-tolerated agent (e.g., the monoamine oxidase [MAO]-B inhibitor rasagiline) in the absence of functional impairment is associated with improved long-term outcomes. Consideration should also be given to many patient-specific factors, including patient expectations, level of disability, employment status, functional as well as chronologic age, expected efficacy and tolerability of drugs, and response to previous Parkinson's disease therapies. Increasingly, initial monotherapy begins with a nondopaminergic agent or, if the patient is considered functionally young, a dopamine agonist. Since Parkinson's disease is a progressive disorder, adjustments to pharmacotherapy must be expected over time. When greater symptomatic relief is desired, or in the more frail elderly patient, levodopa therapy should be considered. If motor fluctuations develop, addition of a catechol-O-methyltransferase inhibitor or MAO-B inhibitor should be considered. For management of levodopa-induced dyskinesias, addition of amantadine is an option. Surgery may be considered when patients need additional symptomatic control or are experiencing severe motor complications despite pharmacologically optimized therapy.

Apomorphine in the treatment of Parkinson's disease

Motor fluctuations, refractory to conventional medical management, are one of the most troubling aspects of Parkinson's disease. Apomorphine is a dopaminergic agent that has been known to the medical community for more than a century, but has only recently been developed to treat such motor fluctuations. In this article, the authors review the historical background, structure, mechanism of action, pharmacologic properties, clinical trials, indications and side effects, as well as avenues of further research, of apomorphine.

Update on Apomorphine for the Rapid Treatment of Hypomobility (“Off”) Episodes in Parkinson's Disease

As Parkinson's disease progresses, fluctuations between akinesia, or hypomobility ("off" times), and mobility ("on" times) increase in frequency despite optimized pharmacotherapy. Motor fluctuations include predictable shortening of therapeutic effects, nocturnal or early morning akinesia, random hypomobility, and delayed mobility (variable responses to individual doses of drugs). Current oral antiparkinson drugs are inadequate for rapid and consistent relief of symptoms during hypomobility. Apomorphine, an injectable dopamine agonist recently introduced in the United States, is indicated for the management of hypomobility associated with advanced Parkinson's disease. Subcutaneous apomorphine is effective for rapid and consistent rescue from hypomobility, with a magnitude of motor improvement similar to that of levodopa. The effect begins within 20 minutes after dosing and lasts approximately 100 minutes. Therapeutic rescue doses are 2-6 mg, and patients typically require approximately three rescue doses/day. Apomorphine is associated with a clinically significant potential to cause nausea and orthostatic hypotension. These potential effects can be managed with antiemetic prophylaxis and appropriate determination of the therapeutic rescue dose.

A review of intermittent subcutaneous apomorphineinjections for the rescue management of motor fluctuations associated with advanced Parkinson's disease

BACKGROUND

As Parkinson's disease (PD) progresses,despite optimized pharmacotherapy, patients experience more frequent fluctuations between symptomatic improvement ("on" times) and the return of motor features ("off" times). Apomorphine, the first injectable dopamine agonist available in the United States, is indicated for the acute treatment of "off" episodes (eg, end-of-dose wearing-off episodes, unpredictable "on/off" episodes) in patients with advanced PD who are receiving medically optimal antiparkinsonian therapy.

OBJECTIVE

This article reviews the pharmacology,clinical efficacy, and tolerability of intermittent subcutaneous apomorphine injections for the management of "off" episodes in patients with PD.

METHODS

MEDLINE (1966-July 2005), the Cochrane Database of Systematic Reviews, and International Pharmaceutical Abstracts (1970-July 2005) were searched for original research and review articles published in English. The search terms were apomorphine and Parkinson's disease. The reference lists of articles were also consulted, as was selected information provided by the manufacturer of apomorphine. All relevant identified studies on intermittent subcutaneous administration of apomorphine were included in the review; trials of continuous subcutaneous infusion and non-subcutaneous administration of apomorphine were excluded.

RESULTS

Intermittent subcutaneous administration of apomorphine produced consistent rescue from "of" episodes in patients with advanced PD, with a symptomatic motor improvement between the predose "off" state and postdose "on" state similar to that achieved with levodopa. The onset of effect occurred within 20 minutes, and the duration of effect was approximately 100 minutes. The therapeutic rescue dose ranged from 2 to 6 mg. During the clinical development program for subcutaneously injected apomorphine, patients required a mean of approximately 3 rescue doses per day. Common adverse effects occurring in > or =20% of patients were injection-site reaction, yawning, dyskinesias, drowsiness, nausea and vomiting, dizziness or postural dizziness, and rhinorrhea.

CONCLUSIONS

The available clinical studies indicate that apomorphine is effective in providing prompt and consistent rescue from "off" episodes in patients with PD. Antiemetic prophylaxis and close medical supervision are recommended when initiating apomorphine therapy.