istradefylline and Dyskinesia--Drug-Induced

Topics: Adenosine A2 Receptor Antagonists; Antiparkinson Agents; Dyskinesia, Drug-Induced; Humans; Parkinson Disease; Purines; Treatment Outcome

Controlling motor complications becomes increasingly difficult with disease progression. The "wearing-off" phenomenon is the most-common motor fluctuation. Wearing-off can be treated by dietary manipulation, shortening the dosing interval, substituting sustained-release levodopa, adding amantadine, or monoamine oxidase type B inhibitors, and other options, including catechol-O-methyltransferase inhibitors and the approved dopamine agonists addressed in another chapter. The rotigotine constant-delivery system is being developed to treat wearing-off symptoms. Istradefylline (KW-6002), an adenosine A(2A) receptor antagonist, has been studied for wearing-off and the results will be discussed. The on-off fluctuations can be treated with liquid levodopa and the rescue therapy of injectable apomorphine. Patients may also suffer from dyskinesias. Dyskinesias can be treated with small doses of liquefied levodopa-carbidopa, amantadine, and clozapine, an atypical neuroleptic.

Topics: Amantadine; Antiparkinson Agents; Catechol O-Methyltransferase Inhibitors; Dopamine Agonists; Dyskinesia, Drug-Induced; Gait; Humans; Levodopa; Monoamine Oxidase; Monoamine Oxidase Inhibitors; Parkinson Disease; Periodicity; Purinergic P1 Receptor Antagonists; Purines; Selegiline

Research and development of the adenosine A2A receptor selective antagonist KW6002 have focused on developing a novel nondopaminergic therapy for Parkinson's disease (PD). Salient pharmacologic features of KW6002 were investigated in several animal models of PD. In rodent and primate models, KW6002 provides symptomatic relief from parkinsonian motor deficits without provoking dyskinesia or exacerbating existing dyskinesias. The major target neurons of the A2A receptor antagonist were identified as GABAergic striatopallidal medium spiny neurons. A possible mechanism of A2A receptor antagonist action in PD has been proposed based on the involvement of striatal and pallidal presynaptic A2A receptors in the "dual" modulation of GABAergic synaptic transmission. Experiments with dopamine D2 receptor knockout mice showed that A2A receptors can function and anti-PD activities of A2A antagonists can occur independent of the dopaminergic system. Clinical studies of KW6002 in patients with advanced PD with L-dopa-related motor complications yielded promising results with regard to motor symptom relief without motor side effects. The development of KW6002 represents the first time that a concept gleaned from A2A biologic research has been applied successfully to "proof of concept" clinical studies. The selective A2A antagonist should provide a novel nondopaminergic approach to PD therapy.

Topics: Adenosine A2 Receptor Antagonists; Animals; Antiparkinson Agents; Clinical Trials as Topic; Corpus Striatum; Disease Models, Animal; Drug Evaluation, Preclinical; Dyskinesia, Drug-Induced; gamma-Aminobutyric Acid; Globus Pallidus; Humans; Levodopa; Mice; Mice, Knockout; Motor Activity; Neurons; Oxidopamine; Parkinson Disease; Parkinsonian Disorders; Primates; Purines; Rats; Receptor, Adenosine A2A; Receptors, Dopamine D2

The objective of this study was to evaluate the efficacy, safety, and tolerability of istradefylline 20 mg once daily versus placebo as an adjunct to levodopa in subjects with Parkinson's disease (PD) who have motor fluctuations. Istradefylline (KW-6002) is an adenosine A(2A) receptor antagonist that in primate models of PD improves motor function without causing or worsening dyskinesia. This 12-week, multicenter, double-blind, placebo-controlled, randomized, Phase 3 study of istradefylline was conducted in subjects experiencing an average daily OFF time of at least 3 hours (116 randomized to istradefylline; 115 to placebo). All were on stable levodopa regimens; 90% were also on stable regimens of other anti-Parkinson's medications. Istradefylline-treated subjects had significant placebo-corrected reductions in daily OFF time from baseline to endpoint: 4.6% (P = 0.03) and 0.7 hours (P = 0.03). For ON time with troublesome dyskinesia, the changes between istradefylline and placebo were not significant. Istradefylline was well tolerated, with 6 (5.2%) istradefylline-treated and 7 (6.1%) placebo-treated subjects withdrawing from the study because of adverse events. Dyskinesia, lightheadedness, tremor, constipation, and weight decrease were reported more often with istradefylline than placebo. We conclude that istradefylline is well tolerated and significantly reduces OFF time as an adjunct to levodopa in PD subjects with motor fluctuations.

Topics: Aged; Analysis of Variance; Antiparkinson Agents; Double-Blind Method; Drug-Related Side Effects and Adverse Reactions; Dyskinesia, Drug-Induced; Female; Humans; Levodopa; Male; Middle Aged; Parkinson Disease; Purines; Severity of Illness Index; Surveys and Questionnaires; Time Factors

To evaluate the safety and efficacy of the adenosine A(2A) receptor antagonist istradefylline (KW-6002) in patients with levodopa-treated Parkinson's disease (PD) with both motor fluctuations and peak-dose dyskinesias.. This was a 12-week, double-blind, randomized, placebo-controlled, exploratory study in which PD subjects with both motor fluctuations and peak-dose dyskinesias were randomized to treatment with placebo (n = 29), istradefylline up to 20 mg/day (n = 26), or istradefylline up to 40 mg/day (n = 28). There was no prespecified primary outcome measure, and 19 outcome variables were analyzed.. As assessed by home diaries, subjects assigned to istradefylline experienced a mean (+/- SE) reduction in the proportion of awake time spent in the "off" state of 7.1 +/- 2.0% compared with an increase of 2.2 +/- 2.7% in the placebo group (p = 0.008). There was a decrease in "off" time of 1.2 +/- 0.3 hours in the istradefylline group compared with an increase of 0.5 +/- 0.5 hour in the placebo group (p = 0.004). Dyskinesia severity was unchanged, but "on" time with dyskinesia increased in the istradefylline group compared with the placebo group (percent, p = 0.002; hours, p = 0.001). No differences were observed in change in Unified Parkinson's Disease Rating Scale scores or Clinical Global Impression of Change. Twenty-four percent of placebo-assigned subjects and 20% of istradefylline-assigned subjects withdrew from the study. Both dose regimens of istradefylline were generally well tolerated, and nausea was the most common adverse event.. Istradefylline was generally well tolerated and reduced "off" time as assessed by home diaries. Severity of dyskinesia was unchanged, but "on" time with dyskinesia increased.

Topics: Adenosine A2 Receptor Antagonists; Aged; Antiparkinson Agents; Catechol O-Methyltransferase Inhibitors; Chronic Disease; Dopamine Agonists; Dose-Response Relationship, Drug; Double-Blind Method; Dyskinesia, Drug-Induced; Enzyme Inhibitors; Female; Humans; Levodopa; Male; Nausea; Parkinson Disease; Purines; Safety; Selegiline; Treatment Outcome

Istradefylline (KW-6002), an adenosine A2A receptor antagonist, is used adjunct with optimal doses of L-3,4-dihydroxyphenylalanine (l-DOPA) to extend on-time in Parkinson's disease (PD) patients experiencing motor fluctuations. Clinical application of istradefylline for the management of other l-DOPA-induced complications, both motor and non-motor related (i.e. dyskinesia and cognitive impairments), remains to be determined. In this study, acute effects of istradefylline (60-100 mg/kg) alone, or with optimal and sub-optimal doses of l-DOPA, were evaluated in two monkey models of PD (i) the gold-standard 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated macaque model of parkinsonian and dyskinetic motor symptoms and (ii) the chronic low dose (CLD) MPTP-treated macaque model of cognitive (working memory and attentional) deficits. Behavioural analyses in l-DOPA-primed MPTP-treated macaques showed that istradefylline alone specifically alleviated postural deficits. When combined with an optimal l-DOPA treatment dose, istradefylline increased on-time, enhanced therapeutic effects on bradykinesia and locomotion, but exacerbated dyskinesia. Istradefylline treatment at specific doses with sub-optimal l-DOPA specifically alleviated bradykinesia. Cognitive assessments in CLD MPTP-treated macaques showed that the attentional and working memory deficits caused by l-DOPA were lowered after istradefylline administration. Taken together, these data support a broader clinical use of istradefylline as an adjunct treatment in PD, where specific treatment combinations can be utilised to manage various l-DOPA-induced complications, which importantly, maintain a desired anti-parkinsonian response.

Topics: Adenosine A2 Receptor Antagonists; Animals; Cognition Disorders; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Drug Therapy, Combination; Dyskinesia, Drug-Induced; Female; Hypokinesia; Levodopa; Macaca fascicularis; Motor Skills Disorders; MPTP Poisoning; Purines; Treatment Outcome

A number of experimental models of L-DOPA-induced dyskinesia have been proposed, but these models result in a low to medium rate of dyskinetic animals with mild to severe symptoms. The objective of this study was to combine a model of 6-OHDA-induced parkinsonism and of L-DOPA-induced dyskinesia in rats to establish a reliable preclinical model. Two stereotaxic injections of 6-OHDA were administered in the left striatum. This model led to 90-100% of rats with a marked contralateral circling behaviour, significant limb use asymmetry (20%), a decrease in ipsilateral striatal dopamine content (70%) and degeneration of dopamine neurons in the substantia nigra (70%). Chronic treatment with L-DOPA was administered for 35 days and consisted of three phases with incremental daily doses. The third phase resulted in 83-90% of rats developing severe abnormal involuntary movements (AIMs) which included limb and locomotive dyskinesia, axial dystonia and orolingual dyskinesia. Reproducibility of the model, criteria of strict blinding, placebo-controlled design, randomization of study subjects and pretrial determination of sample size were used to measure efficacy of amantadine and istradefylline and to validate the protocol design. Acute or subchronic post-treatment with amantadine reduced the severity of dyskinesia while istradefylline punctually attenuated AIMs. Our experimental conditions using gradual development of dyskinesia induced by increasing doses of L-DOPA resulted in a reliable model of L-DOPA-induced dyskinesia with a high rate of dyskinetic rats.

Topics: Adenosine A2 Receptor Antagonists; Amantadine; Animals; Antiparkinson Agents; Behavior, Animal; Benserazide; Biological Assay; Corpus Striatum; Disease Models, Animal; Dopamine; Dopamine Agents; Drug Administration Schedule; Drug Evaluation, Preclinical; Dyskinesia, Drug-Induced; Enzyme Inhibitors; Levodopa; Male; Oxidopamine; Parkinsonian Disorders; Placebos; Purines; Random Allocation; Rats; Reproducibility of Results; Rotation; Sample Size; Single-Blind Method; Sympatholytics

Adenosine and dopamine interact within the striatum to control striatopallidal output and globus pallidus GABA release. Manipulating striatal adenosine transmission via blockade of the A2A receptor subtype can compensate for the reduced dopamine activity within the striatum that underlies movement disorders such as antipsychotic-induced extrapyramidal syndrome (EPS) and Parkinson's disease (PD). Preclinical studies in the rat have demonstrated that adenosine A2A receptor antagonists can attenuate behaviors reflecting reduced dopamine activity, such as haloperidol-induced catalepsy and hypoactivity.. In the present studies using nonhuman primates, adenosine antagonists were tested against haloperidol-induced EPS in Cebus apella and haloperidol-induced catalepsy in Saimiri sciureus (squirrel monkey). Specifically, the A2A receptor antagonists, SCH 412348 (0.3-30 mg/kg PO) and KW-6002 (3-100 mg/kg PO); the A1/A2A receptor antagonist, caffeine (1-30 mg/kg PO and IM); and the A1 receptor antagonist, DPCPX (3-30 mg/kg PO) were tested in at least one of these models.. SCH 412348 (10-30 mg/kg), KW-6002 (57-100 mg/kg), and caffeine (30 mg/kg) significantly increased the time to EPS onset. Additionally, SCH 412348, KW-6002, and caffeine afforded protection from the onset of EPS for at least 6 h in some of the primates. SCH 412348 (10 mg/kg) and caffeine (10 mg/kg) significantly reduced haloperidol-induced catalepsy. DPCPX produced a very slight attenuation of EPS at 30 mg/kg, but had no effect on catalepsy.. These findings suggest that adenosine A2A receptor antagonists may represent an effective treatment for the motor impairments associated with both antipsychotic-induced EPS and PD.

Topics: Adenosine A2 Receptor Antagonists; Animals; Antipsychotic Agents; Caffeine; Catalepsy; Cebus; Corpus Striatum; Disease Models, Animal; Dose-Response Relationship, Drug; Dyskinesia, Drug-Induced; gamma-Aminobutyric Acid; Globus Pallidus; Haloperidol; Neurologic Examination; Purines; Pyrimidines; Receptor, Adenosine A2A; Saimiri; Triazoles; Xanthines

Adenosine A2A receptor antagonists provide a promising nondopaminergic approach to the treatment of Parkinson's disease (PD). Initial clinical trials of A2A antagonists targeted PD patients who had already developed treatment complications known as L-3,4-dihydroxyphenylalanine (L-DOPA)-induced dyskinesia (LID) in an effort to improve symptoms while reducing existing LID. The goal of this study is to explore the effect of A2A antagonists and targeted A2A receptor depletion on the actual development of sensitized responses to L-DOPA in mouse models of LID in PD. Hemiparkinsonian mice (unilaterally lesioned with 6-OHDA) were treated daily for 3 weeks with a low dose of L-DOPA (2 mg/kg) preceded by a low dose of selective A2A antagonist (KW-6002 [(E)-1,3-diethyl-8-(3,4-dimethoxystyryl)-7-methyl-3,7-dihydro-1H-purine-2,6-dione] at 0.03 or 0.3 mg/kg, or SCH58261 [5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine] at 0.03 mg/kg) or vehicle intraperitoneally. In control mice, contralateral rotational responses to daily L-DOPA gradually increased over the initial week before reaching a persistent maximum. Both A2A antagonists inhibited the development of sensitized contralateral turning, with KW-6002 pretreatment reducing the sensitized rotational responses by up to threefold. The development of abnormal involuntary movements (a measure of LID) as well as rotational responses was attenuated by the postnatal depletion of forebrain A2A receptors in conditional (Cre/loxP system) knock-out mice. These pharmacological and genetic data provide evidence that striatal A2A receptors play an important role in the neuroplasticity underlying behavioral sensitization to L-DOPA, supporting consideration of early adjunctive therapy with an A2A antagonist to reduce the risk of LID in PD.

Topics: Adenosine A2 Receptor Antagonists; Animals; Dyskinesia, Drug-Induced; Levodopa; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Oxidopamine; Parkinsonian Disorders; Prosencephalon; Purines; Receptor, Adenosine A2A

Dyskinesia (abnormal involuntary movements) is a common complication of l-DOPA pharmacotherapy in Parkinson's disease, and is thought to depend on abnormal cell signaling in the basal ganglia. Dopamine (DA) denervated mice can exhibit behavioral and cellular signs of dyskinesia when they are treated with l-DOPA, but the clinical relevance of this animal model remains to be established. In this study, we have examined the pharmacological profile of l-DOPA-induced abnormal involuntary movements (AIMs) in the mouse. C57BL/6 mice sustained unilateral injections of 6-hydroxydopamine (6-OHDA) in the striatum. The animals were treated chronically with daily doses of l-DOPA that were sufficient to ameliorate akinetic features without inducing overt signs of dyskinesia upon their first administration. In parallel, other groups of mice were treated with antiparkinsonian agents that do not induce dyskinesia when administered de novo, that is, the D2/D3 agonist ropinirole, and the adenosine A2a antagonist KW-6002. During 3 weeks of treatment, l-DOPA-treated mice developed AIMs affecting the head, trunk and forelimb on the side contralateral to the lesion. These movements were not expressed by animals treated with ropinirole or KW-6002 at doses that improved forelimb akinesia. The severity of l-DOPA-induced rodent AIMs was significantly reduced by the acute administration of compounds that have been shown to alleviate l-DOPA-induced dyskinesia both in parkinsonian patients and in rat and monkey models of Parkinson's disease (amantadine, -47%; buspirone, -46%; riluzole, -33%). The present data indicate that the mouse AIMs are indeed a functional equivalent of l-DOPA-induced dyskinesia.

Topics: Adenosine A2 Receptor Agonists; Adrenergic Agents; Amantadine; Animals; Antiparkinson Agents; Basal Ganglia; Buspirone; Disease Models, Animal; Disease Progression; Dopamine Agonists; Drug Administration Schedule; Dyskinesia, Drug-Induced; Indoles; Levodopa; Male; Mice; Mice, Inbred C57BL; Oxidopamine; Parkinsonian Disorders; Purines; Receptor, Adenosine A2A; Receptors, Dopamine D2; Reproducibility of Results; Riluzole; Treatment Outcome

We have examined the ability of KW-6002, an adenosine A2a antagonist, to modulate the dyskinetic effects of L-DOPA in 6-hydroxydopamine-lesioned rats. In animals rendered dyskinetic by a previous course of L-DOPA treatment, KW-6002 did not elicit any abnormal involuntary movements on its own, but failed to reduce the severity of dyskinesia when coadministered with L-DOPA. A second experiment was undertaken in order to study the effects of KW-6002 in L-DOPA-naive rats. Thirty-five animals were allotted to four groups to receive a 21-day treatment with: (i) KW-6002 (10 mg/kg/day); (ii) L-DOPA (6 mg/kg/day) i.p.; (iii) KW-6002 plus L-DOPA (same doses as above) or (iv) vehicle. Chronic treatment with KW-6002-only produced a significant relief of motor disability in the rotarod test in the absence of any abnormal involuntary movements. Combined treatment with L-DOPA and KW-6002 improved rotarod performance to a significantly higher degree than did each of the two drugs alone. However, this combined treatment induced dyskinesia to about the same degree as did L-DOPA alone. In situ hybridization histochemistry showed that KW-6002 treatment alone caused an approximately 20% reduction in the striatal levels of preproenkephalin mRNA, whereas neither the coadministration of KW-6002 and L-DOPA nor L-DOPA alone significantly altered the expression of this transcript in the dopamine-denervated striatum. Either alone or in combination with L-DOPA, KW-6002 did not have any modulatory effect on prodynorphin mRNA expression or FosB/DeltaFosB-like immunoreactivity in the dopamine-denervated striatum. These results show that monotreatment with an adenosine A2a receptor antagonist can relieve motor disability without inducing behavioural and cellular signs of dyskinesia in rats with 6-hydroxydopamine lesions. Cotreatment with KW-6002 and L-DOPA potentiates the therapeutic effect but not the dyskinesiogenic potential of the latter drug.

Topics: Animals; Behavior, Animal; Corpus Striatum; Disease Models, Animal; Drug Therapy, Combination; Dyskinesia, Drug-Induced; Enkephalins; Female; Levodopa; Motor Activity; Oxidopamine; Parkinsonian Disorders; Protein Precursors; Proto-Oncogene Proteins c-fos; Purinergic P1 Receptor Antagonists; Purines; Rats; Rats, Sprague-Dawley; Receptor, Adenosine A2A; RNA, Messenger; Treatment Outcome

Adenosine A(2A) receptors, abundantly expressed on striatal medium spiny neurons, appear to activate signaling cascades implicated in the regulation of coexpressed ionotropic glutamatergic receptors. To evaluate the contribution of adenosinergic mechanisms to the pathogenesis of the response alterations induced by dopaminergic treatment, we studied the ability of the selective adenosine A(2A) receptor antagonist KW-6002 to prevent as well as palliate these syndromes in rodent and primate models of Parkinson's disease. In rats, KW-6002 reversed the shortened motor response produced by chronic levodopa treatment while reducing levodopa-induced hyperphosphorylation at S845 residues on AMPA receptor GluR1 subunits. In primates, KW-6002 evidenced modest antiparkinsonian activity when given alone. Once-daily coadministration of KW-6002 with apomorphine prevented the development of dyskinesias, which appeared in control animals 7-10 days after initiating apomorphine treatment. Animals initially given apomorphine plus KW-6002 for 3 weeks did not begin to manifest apomorphine-induced dyskinesias until 10-12 days after discontinuing the A(2A) antagonist. These results suggest that KW-6002 can attenuate the induction as well as the expression of motor response alterations to chronic dopaminergic stimulation in parkinsonian animals, possibly by blocking A(2A) receptor-stimulated signaling pathways. Our findings strengthen the rationale for developing A(2A) antagonists as an early treatment strategy for Parkinson's disease.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Adenosine A2 Receptor Antagonists; Animals; Antiparkinson Agents; Apomorphine; Denervation; Dopamine Agonists; Dyskinesia, Drug-Induced; Levodopa; Macaca fascicularis; Male; Neurons; Oxidopamine; Parkinson Disease, Secondary; Phosphorylation; Purines; Rats; Rats, Sprague-Dawley; Receptors, AMPA; Receptors, Dopamine D1; Receptors, Dopamine D2; Sympatholytics

The A2A receptor has recently attracted considerable interest as a potential target for Parkinson's disease (PD) therapy based on the motor-enhancing and neuroprotective effects of A2A antagonists in animal models of PD. The unique neuronal localization of the adenosine A2A receptor in the basal ganglia and its extensive interactions with dopaminergic and glutamatergic systems led the authors to investigate a potential role of the A2A receptor in the development of behavioral sensitization in response to repeated dopaminergic stimulation. Because dopamine-induced behavioral sensitization shares several neurochemical and behavioral features with dyskinesia, characterizing this novel aspect of A2A receptor function may enhance understanding and management of dyskinesia in PD. Recent studies from several laboratories suggest that the A2A receptor may be an important mediator of maladaptive changes in response to long-term dopamine stimulation. The authors summarize their investigation of the role of A2A receptors in two paradigms of behavioral sensitization elicited by daily treatment with either L-dopa in hemiparkinsonian mice or amphetamine in naive mice. The results demonstrate that the A2A receptor is required for the development of behavioral sensitization in response to repeated L-dopa treatment in hemiparkinsonian mice and repeated amphetamine administration in normal mice. Together with pharmacologic studies, these results raise the possibility that the maladaptive dyskinetic responses to long-term L-dopa management of PD may be attenuated by A2A receptor blockade. Potential presynaptic, postsynaptic (cellular), and trans-synaptic (network) mechanisms are discussed.

Topics: Adenosine A2 Receptor Antagonists; Amphetamine; Animals; Antiparkinson Agents; Behavior, Animal; Disease Models, Animal; Dopamine; Dopamine Agonists; Drug Tolerance; Dyskinesia, Drug-Induced; Humans; Levodopa; Mice; Mice, Knockout; Neurons; Neuroprotective Agents; Oxidopamine; Parkinsonian Disorders; Purines; Pyrimidines; Receptor, Adenosine A2A; Synapses; Triazoles

The novel selective adenosine A(2A) receptor antagonist KW-6002 improves motor disability in MPTP-treated parkinsonian marmosets without provoking dyskinesia. In this study we have investigated whether KW-6002 in combination with l-DOPA or selective D1 or D2 dopamine receptor agonists enhances antiparkinsonian activity in MPTP-treated common marmosets. Combination of KW-6002 with the selective dopamine D2 receptor agonist quinpirole or the D1 receptor agonist SKF80723 produced an additive improvement in motor disability. Coadministration of KW-6002 with a low dose of L-DOPA also produced an additive improvement in motor disability, and increased locomotor activity. The ability of KW-6002 to enhance antiparkinsonian activity was more marked with L-DOPA and quinpirole than with the D1 agonist. However, despite producing an enhanced antiparkinsonian response KW-6002 did not exacerbate L-DOPA-induced dyskinesia in MPTP-treated common marmosets previously primed to exhibit dyskinesia by prior exposure to L-DOPA. Selective adenosine A(2A) receptor antagonists, such as KW-6002, may be one means of reducing the dosage of L-DOPA used in treating Parkinson's disease and are potentially a novel approach to treating the illness both as monotherapy and in combination with dopaminergic drugs.

Topics: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; Administration, Oral; Animals; Callithrix; Carbidopa; Disease Models, Animal; Drug Synergism; Drug Therapy, Combination; Dyskinesia, Drug-Induced; Female; Injections, Intraperitoneal; Levodopa; Male; Motor Activity; Parkinson Disease, Secondary; Purinergic P1 Receptor Antagonists; Purines; Quinpirole; Receptor, Adenosine A2A; Receptors, Dopamine D1; Receptors, Dopamine D2