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1.  Activity enhances dopaminergic long-duration response in Parkinson disease 
Jung Kang, Un | Auinger, Peggy | Fahn, Stanley | Oakes, David | Shoulson, Ira | Kieburtz, Karl | Rudolph, Alice | Marek, Kenneth | Seibyl, John | Lang, Anthony | Olanow, C. Warren | Tanner, Caroline | Schifitto, Giovanni | Zhao, Hongwei | Reyes, Lydia | Shinaman, Aileen | Comella, Cynthia L. | Goetz, Christopher | Blasucci, Lucia M. | Samanta, Johan | Stacy, Mark | Williamson, Kelli | Harrigan, Mary | Greene, Paul | Ford, Blair | Moskowitz, Carol | Truong, Daniel D. | Pathak, Mayank | Jankovic, Joseph | Ondo, William | Atassi, Farah | Hunter, Christine | Jacques, Carol | Friedman, Joseph H. | Lannon, Margaret | Russell, David S. | Jennings, Danna | Fussell, Barbara | Standaert, David | Schwarzschild, Michael A. | Growdon, John H. | Tennis, Marsha | Gauthier, Serge | Panisset, Michel | Hall, Jean | Gancher, Stephen | Hammerstad, John P. | Stone, Claudia | Alexander-Brown, Barbara | Factor, Stewart A. | Molho, Eric | Brown, Diane | Evans, Sharon | Clark, Jeffrey | Manyam, Bala | Simpson, Patricia | Wulbrecht, Brian | Whetteckey, Jacqueline | Martin, Wayne | Roberts, Ted | King, Pamela | Hauser, Robert | Zesiewicz, Theresa | Gauger, Lisa | Trugman, Joel | Wooten, G. Frederick | Rost-Ruffner, Elke | Perlmutter, Joel | Racette, Brad A. | Suchowersky, Oksana | Ranawaya, Ranjit | Wood, Susan | Pantella, Carol | Kurlan, Roger | Richard, Irene | Pearson, Nancy | Caviness, John N. | Adler, Charles | Lind, Marlene | Simuni, Tanya | Siderowf, Andrew | Colcher, Amy | Lloyd, Mary | Weiner, William | Shulman, Lisa | Koller, William | Lyons, Kelly | Feldman, Robert G. | Saint-Hilaire, Marie H. | Ellias, Samuel | Thomas, Cathi-Ann | Juncos, Jorge | Watts, Ray | Partlow, Anna | Tetrud, James | Togasaki, Daniel M. | Stewart, Tracy | Mark, Margery H. | Sage, Jacob I. | Caputo, Debbie | Gould, Harry | Rao, Jayaraman | McKendrick, Ann | Brin, Mitchell | Danisi, Fabio | Benabou, Reina | Hubble, Jean | Paulson, George W. | Reider, Carson | Birnbaum, Alex | Miyasaki, Janis | Johnston, Lisa | So, Julie | Pahwa, Rajesh | Dubinsky, Richard M. | Wszolek, Zbigniew | Uitti, Ryan | Turk, Margaret | Tuite, Paul | Rottenberg, David | Hansen, Joy | Ramos, Serrano | Waters, Cheryl | Lew, Mark | Welsh, Mickie | Kawai, Connie | O'Brien, Christopher | Kumar, Rajeev | Seeberger, Lauren | Judd, Deborah | Barclay, C. Lynn | Grimes, David A. | Sutherland, Laura | Dawson, Ted | Reich, Stephen | Dunlop, Rebecca | Albin, Roger | Frey, Kirk | Wernette, Kristine | Fahn, Stanley | Oakes, David | Shoulson, Ira | Kieburtz, Karl | Rudolph, Alice | Marek, Kenneth | Seibyl, John | Lang, Anthony | Olanow, C. Warren | Tanner, Caroline | Schifitto, Giovanni | Zhao, Hongwei | Reyes, Lydia | Shinaman, Aileen | Comella, Cynthia L. | Goetz, Christopher | Blasucci, Lucia M. | Samanta, Johan | Stacy, Mark | Williamson, Kelli | Harrigan, Mary | Greene, Paul | Ford, Blair | Moskowitz, Carol | Truong, Daniel D. | Pathak, Mayank | Jankovic, Joseph | Ondo, William | Atassi, Farah | Hunter, Christine | Jacques, Carol | Friedman, Joseph H. | Lannon, Margaret | Russell, David S. | Jennings, Danna | Fussell, Barbara | Standaert, David | Schwarzschild, Michael A. | Growdon, John H. | Tennis, Marsha | Gauthier, Serge | Panisset, Michel | Hall, Jean | Gancher, Stephen | Hammerstad, John P. | Stone, Claudia | Alexander-Brown, Barbara | Factor, Stewart A. | Molho, Eric | Brown, Diane | Evans, Sharon | Clark, Jeffrey | Manyam, Bala | Simpson, Patricia | Wulbrecht, Brian | Whetteckey, Jacqueline | Martin, Wayne | Roberts, Ted | King, Pamela | Hauser, Robert | Zesiewicz, Theresa | Gauger, Lisa | Trugman, Joel | Wooten, G. Frederick | Rost-Ruffner, Elke | Perlmutter, Joel | Racette, Brad A. | Suchowersky, Oksana | Ranawaya, Ranjit | Wood, Susan | Pantella, Carol | Kurlan, Roger | Richard, Irene | Pearson, Nancy | Caviness, John N. | Adler, Charles | Lind, Marlene | Simuni, Tanya | Siderowf, Andrew | Colcher, Amy | Lloyd, Mary | Weiner, William | Shulman, Lisa | Koller, William | Lyons, Kelly | Feldman, Robert G. | Saint-Hilaire, Marie H. | Ellias, Samuel | Thomas, Cathi-Ann | Juncos, Jorge | Watts, Ray | Partlow, Anna | Tetrud, James | Togasaki, Daniel M. | Stewart, Tracy | Mark, Margery H. | Sage, Jacob I. | Caputo, Debbie | Gould, Harry | Rao, Jayaraman | McKendrick, Ann | Brin, Mitchell | Danisi, Fabio | Benabou, Reina | Hubble, Jean | Paulson, George W. | Reider, Carson | Birnbaum, Alex | Miyasaki, Janis | Johnston, Lisa | So, Julie | Pahwa, Rajesh | Dubinsky, Richard M. | Wszolek, Zbigniew | Uitti, Ryan | Turk, Margaret | Tuite, Paul | Rottenberg, David | Hansen, Joy | Ramos, Serrano | Waters, Cheryl | Lew, Mark | Welsh, Mickie | Kawai, Connie | O'Brien, Christopher | Kumar, Rajeev | Seeberger, Lauren | Judd, Deborah | Barclay, C. Lynn | Grimes, David A. | Sutherland, Laura | Dawson, Ted | Reich, Stephen | Dunlop, Rebecca | Albin, Roger | Frey, Kirk | Wernette, Kristine | Mendis, Tilak
Neurology  2012;78(15):1146-1149.
Objective:
We tested the hypothesis that dopamine-dependent motor learning mechanism underlies the long-duration response to levodopa in Parkinson disease (PD) based on our studies in a mouse model. By data-mining the motor task performance in dominant and nondominant hands of the subjects in a double-blind randomized trial of levodopa therapy, the effects of activity and dopamine therapy were examined.
Methods:
We data-mined the Earlier versus Later Levodopa Therapy in Parkinson's Disease (ELLDOPA) study published in 2005 and performed statistical analysis comparing the effects of levodopa and dominance of handedness over 42 weeks.
Results:
The mean change in finger-tapping counts from baseline before the initiation of therapy to predose at 9 weeks and 40 weeks increased more in the dominant compared to nondominant hand in levodopa-treated subjects in a dose-dependent fashion. There was no significant difference in dominant vs nondominant hands in the placebo group. The short-duration response assessed by the difference of postdose performance compared to predose performance at the same visit did not show any significant difference between dominant vs nondominant hands.
Conclusions:
Active use of the dominant hand and dopamine replacement therapy produces synergistic effect on long-lasting motor task performance during “off” medication state. Such effect was confined to dopamine-responsive symptoms and not seen in dopamine-resistant symptoms such as gait and balance. We propose that long-lasting motor learning facilitated by activity and dopamine is a form of disease modification that is often seen in trials of medications that have symptomatic effects.
doi:10.1212/WNL.0b013e31824f8056
PMCID: PMC3466780  PMID: 22459675
2.  Mood fluctuations in Parkinson’s disease: a pilot study comparing the effects of intravenous and oral levodopa administration 
Objectives
Parkinson’s disease (PD) is associated with motor fluctuations that have been shown to improve when stable plasma levodopa levels are achieved with continuous levodopa infusions. Many patients also develop mood fluctuations. In this pilot study, we gathered preliminary information about the relationship between changing mood states and plasma levodopa levels.
Methods
Six patients with idiopathic PD and histories of motor and mood fluctuations participated in a double-blind levodopa infusion study. Subjects received active oral carbidopa/levodopa and a placebo levodopa infusion on one day and placebo oral carbidopa/levodopa and an active levodopa infusion on the other day, in a randomly determined order. Evaluations included serial plasma levodopa levels and assessments of mood and motor states.
Results
Only 4 of the 6 subjects demonstrated mood fluctuations on at least one of the treatment days. All subjects achieved more stable plasma levodopa levels on the active infusion day. Two subjects experienced fewer mood fluctuations on the active infusion day and two experienced fewer on the oral day.
Conclusions The results of this pilot study suggest that the relationship between mood state and plasma levodopa level may vary among PD patients.
PMCID: PMC2416757  PMID: 18568104
Parkinson’s disease; mood; fluctuations; levodopa
3.  Effects of a NR2B Selective NMDA Glutamate Antagonist, CP-101,606, on Dyskinesia and Parkinsonism 
Movement Disorders  2008;23(13):1860-1866.
Glutamate antagonists decrease dyskinesia and augment the antiparkinsonian effects of levodopa in animal models of Parkinson’s disease (PD). In a randomized, double-blind, placebo-controlled clinical trial we investigated the acute effects of placebo and two doses of a NR2B subunit selective NMDA glutamate antagonist, CP-101,606, on the response to two-hour levodopa infusions in 12 PD subjects with motor fluctuations and dyskinesia. Both doses of CP-101,606 reduced the maximum severity of levodopa-induced dyskinesia approximately 30% but neither dose improved parkinsonism. CP-101,606 was associated with a dose-related dissociation and amnesia. These results support the hypothesis that glutamate antagonists may be useful antidyskinetic agents. However, future studies will have to determine if the benefits of dyskinesia suppression can be achieved without adverse cognitive effects.
doi:10.1002/mds.22169
PMCID: PMC3390310  PMID: 18759356
Parkinson’s disease; levodopa; dyskinesia; NR2B subunit selective glutamate antagonist; CP-101,606; amnesia; dissociation
4.  Patient considerations in early management of Parkinson’s disease: focus on extended-release pramipexole 
This article reviews the role of an extended-release formulation of pramipexole in the treatment of Parkinson’s disease at an early stage. Pramipexole is a nonergot D2/D3 synthetic aminobenzothiazole derivative that is effective as monotherapy in early disease and as an adjunct to levodopa in patients with motor fluctuations. Although levodopa is the current “gold standard” for treatment of Parkinson’s disease, its effectiveness fades rapidly and its use results in serious motor fluctuations (on-off, wearing-off, freezing, involuntary movements) for most patients with the disease. Pramipexole has selective actions at dopamine receptors belonging to the D2 subfamily, where it possesses full activity similar to dopamine itself. Its preferential affinity for the D3 receptor subtype could contribute to its efficacy in the treatment of both the motor and psychiatric symptoms of Parkinson’s disease. The best approach to medical management of early Parkinson’s disease remains controversial. While enormous progress has been made in the treatment of the disease, challenges still remain. A variety of treatment-related and patient-related factors must be taken into account when making these decisions. The current approach to treatment of early Parkinson’s disease depends in part on individual patient factors, including age, severity and nature of symptoms and their impact, presence of cognitive dysfunction, possible underlying behavioral factors predisposing to impulse control disorders, and other comorbidities. Today, the once-daily extended-release formulation of pramipexole offers the advantages of easy continuous delivery of drug and convenience to patients, particularly early in the disease when monotherapy is the rule. Thus, a new “levodopa-sparing” paradigm for treating Parkinson’s disease may now be possible, whereby patients are initially treated with pramipexole and levodopa is added only as necessary.
doi:10.2147/PPA.S11841
PMCID: PMC3269317  PMID: 22298943
Parkinson’s disease; treatment; pramipexole; dopamine agonist; motor complications; continuous dopaminergic stimulation
5.  Caffeine Consumption and Risk of Dyskinesia in CALM-PD 
Background
Adenosine A2A receptor antagonists reduce or prevent the development of dyskinesia in animal models of levodopa-induced dyskinesia.
Methods
We examined the association between self-reported intake of the A2A receptor antagonist caffeine and time to dyskinesia in the Comparison of the Agonist Pramipexole with Levodopa on Motor Complications of Parkinson’s Disease (CALM-PD) and CALM Cohort extension studies, using a Cox proportional hazards model adjusting for age, baseline Parkinson’s severity, site, and initial treatment with pramipexole or levodopa.
Results
For subjects who consumed > 12 ounces of coffee/day, the adjusted hazard ratio for the development of dyskinesia was 0.61 (95% confidence interval, 0.37–1.01) compared to subjects who consumed < 4 ounces/day. For subjects who consumed between 4 and 12 ounces/day, the adjusted hazard ratio was 0.73 (C.I. 0.46–1.15) (test for trend, p = 0.05).
Conclusions
These results support the possibility that caffeine may reduce the likelihood of developing dyskinesia.
doi:10.1002/mds.25319
PMCID: PMC3608707  PMID: 23339054
Caffeine; adenosine; Parkinson’s disease; PD; dyskinesia
6.  High dose naltrexone for dyskinesias induced by levodopa 
Ten patients with Parkinson's disease and levodopa induced dyskinesias (LIDs) took part in this randomised, placebo controlled, double blind, crossover trial to assess the efficacy and tolerability of high dose oral naltrexone for LIDs in Parkinson's disease. Patients received naltrexone (5 mg/kg/day) or placebo for 2.5weeks with 1 week wash out in between. Dyskinesias and motor function were assessed with a levodopa challenge, unified Parkinson's disease rating scale (UPDRS), the unified dyskinesia rating scale (UDRS), and patient diaries. Eight patients completed the trial. There was a small reduction in LIDs measured by patient diaries with naltrexone (20.5 (SD 24.9)%) compared with placebo (−4.1 (SD 22.6)%), p<0.05, although no difference was found by other subjective or objective measures. Naltrexone was well tolerated and caused no significant differences in UPDRS motor scores or off time. This study suggests that short term therapy with high dose naltrexone (250-350 mg/day) has no or minimal effect on reducing LIDs in Parkinson's disease.


doi:10.1136/jnnp.70.4.554
PMCID: PMC1737317  PMID: 11254789
7.  Catechol-O-methyltransferase inhibition with tolcapone reduces the "wearing off" phenomenon and levodopa requirements in fluctuating parkinsonian patients 
BACKGROUND—More than 50% of patients with Parkinson's disease develop motor response fluctuations (the "wearing off" phenomenon) after more than five years of levodopa therapy. Inhibition of catechol-O-methyltransferase by tolcapone has been shown to increase levodopa bioavailability and plasma elimination half life, thereby prolonging the efficacy of levodopa.
OBJECTIVES—The primary objective was to evaluate the efficacy of tolcapone in reducing "wearing off" in levodopa treated, fluctuating parkinsonian patients. Secondary objectives included assessment of reduction in levodopa requirements, improvement in patients' clinical status, duration of improvements, and tolerability of tolcapone.
METHODS—In this multicentre, randomised, double blind, placebo controlled trial, 58 patients received placebo, 60 received 100 mg tolcapone three times daily (tid), and 59 received 200 mg tolcapone tid, in addition to levodopa/benserazide.
RESULTS—After three months with 200 mg tolcapone tid, "off" time decreased by 26.2% of the baseline value, "on" time increased by 20.6% (P<0.01 v placebo), and the mean total daily levodopa dose decreased by 122 mg from the baseline dose of 676 mg (P<0.01). These responses were maintained up to nine months. With 100 mg tolcapone tid, "off" time decreased by 31.5% (P<0.05), "on" time increased by 21.3% (P<0.01), and the mean total daily levodopa dose decreased by 109 mg from the baseline dose of 668 mg (P<0.05). With 200 mg tolcapone tid, unified Parkinson's disease rating scale motor and total scores were significantly reduced, and quality of life (sickness impact profile) scores were significantly improved. Both dosages were well tolerated. Dyskinesia was the most often reported levodopa induced adverse event. Diarrhoea was the most often reported non-dopaminergic adverse event and the most frequent reason for withdrawal from the study: four patients in the 100mg tolcapone tid group and six in the 200 mg tid group withdrew because of diarrhoea.
CONCLUSION—Tolcapone prolongs "on" time in fluctuating parkinsonian patients while allowing a reduction in daily levodopa dosage, thereby improving the efficacy of long term levodopa therapy.


PMCID: PMC2169755  PMID: 9343116
8.  Dyskinesia and the antiparkinsonian response always temporally coincide 
Neurology  2010;74(15):1191-1197.
Objective:
To clinically characterize the temporal relationship between dyskinesia and the antiparkinsonian response when dyskinesia first emerges during long-term levodopa therapy and to determine if it is consistent with the hypothesized mechanism by which dyskinesia develops.
Methods:
Dyskinesia and the antiparkinsonian response to levodopa during 2-hour levodopa infusions were monitored at intervals through the first 4 years of long-term levodopa therapy in 20 subjects with idiopathic Parkinson disease (PD) and previously untreated with levodopa. The onset and offset of the antiparkinsonian response and dyskinesia were compared when dyskinesia first appeared during the 4 years. The findings were compared to 20 subjects with PD on long-term levodopa with dyskinesia and motor fluctuations.
Results:
The onset and offset of the antiparkinsonian response and dyskinesia generally coincided when dyskinesia first appeared during the 4 years and did not suggest any temporal dissociation of the 2 responses. Further, the latency to the onsets of dyskinesia and the antiparkinsonian response tended to shorten during long-term levodopa therapy, suggesting that both responses were sensitized by long-term levodopa.
Conclusions:
The similar onsets and offsets of the antiparkinsonian response and dyskinesia when dyskinesia first appears are not consistent with the postulated progressive decrease in threshold for dyskinesia during long-term levodopa therapy. Other mechanisms for the development of dyskinesia need to be considered.
GLOSSARY
= General Clinical Research Center;
= Oregon Health & Science University;
= Parkinson disease.
doi:10.1212/WNL.0b013e3181d90050
PMCID: PMC2865731  PMID: 20220120
9.  Continuous subcutaneous waking day apomorphine in the long term treatment of levodopa induced interdose dyskinesias in Parkinson's disease 
OBJECTIVES—To determine whether continous waking day dopaminergic stimulation with the dopamine agonist apomorphine can reduce levodopa induced dyskinesias in Parkinson's disease
METHODS—19 patients with severe unpredictable refractory motor fluctuations and functionally disabling levodopa induced dyskinesias were treated with continuous subcutaneoius apomorphine monotherapy for a minimum duration of 2.7 years
RESULTS—A mean 65% reduction in dyskinetic severity and a mean 85% reduction in frequency and duration occurred. On discontinuing levodopa a concomitant reduction in off period time was also seen (35% of waking day "off" reduced to 10%)
CONCLUSION—Continuous waking day dopaminergic stimulation with apomorphine reset the threshold for dyskinesias and led to a pronounced reduction in their frequency. Apomorphine should be considered as a less invasive alternative to pallidotomy or deep cerebral stimulation in controlling levodopa induced interdose dose dyskinesias.


PMCID: PMC2170072  PMID: 9598668
10.  Mesulergine in early Parkinson's disease: a double blind controlled trial. 
The efficacy and tolerance of treatment with an 8-alpha-amino-ergoline derivative CU32-o85, Mesulergine, were compared with levodopa/benserazide (Madopar) in a 3 month double-blind controlled trial in 31 patients with Parkinson's disease, not previously treated with levodopa. The two treatments were equally well tolerated, and neither dyskinesias nor dose-related fluctuations developed. In 90% of the patients treated with Mesulergine, Parkinsonian symptoms improved, and at the dose given the overall therapeutical response was two-thirds that of levodopa. During further 9 months of open study the beneficial effect was maintained equally well in both groups. Compared with other dopamine agonists Mesulergine has a considerable antiparkinsonian effect. Unfortunately, further clinical evaluation of the compound recently has been stopped owing to sex and species specific histological alterations in rats. It is suggested that Mesulergine derivatives might well be of value in future treatment of early Parkinson's disease and of late incompensated stages.
PMCID: PMC1028763  PMID: 3517235
11.  Pramipexole and its Extended Release Formulation for Parkinson’s Disease 
Pramipexole has been a widely used dopamine agonist for the last decade. Recently an extended release formulation of pramipexole has been introduced as both monotherapy for patients with early Parkinson’s disease as well as for patients with more advanced disease, as an adjunct to L-DOPA. Along with the enhanced patient compliance seen with once a day dosing, there are other potential advantages of extended release preparations of dopamine agonists. Patients initiated on pramipexole have a lower incidence of developing motor fluctuations including dyskinesia than those initiated on L-DOPA. Pramipexole requires a prolonged dose titration compared to L-DOPA, and generally does not have the efficacy of L-DOPA. The extended release form of pramipexole shows comparable mean and peak serum levels with once a day dosing as seen with three times a day dosing of the immediate release preparation. The extended release preparation has been studied in randomized multicenter clinical trial against both placebo and the immediate release preparation in the setting of early Parkinson’s disease as monotherapy and in more advanced patients with motor fluctuations on L-DOPA. In both settings the extended release preparation was superior to placebo and comparable to the immediate release form in efficacy with a similar side effect profile including nausea, sleepiness, leg edema, dyskinesias, hallucinations and impulse control disorders.
doi:10.4137/JCNSD.S5210
PMCID: PMC3663603  PMID: 23861646
dopamine agonist; dyskinesia; restless leg syndrome; impulse control disorder; pharmacokinetics
12.  Dyskinesias and Treatment with Pramipexole in Patients with Parkinson's Disease 
Parkinson's Disease  2012;2012:473769.
Dopamine agonists such as pramipexole (PPX) have first been proposed as adjunctive treatment to levodopa (L-DOPA) for patients with Parkinson's disease (PD) and then as a monotherapy alternative to alleviate dyskinesia. Treatment with PPX has overall been associated with improvement in parkinsonian symptoms. Although the majority of placebo-controlled studies demonstrated that dyskinesia was more prevalent in the PPX compared to the placebo groups, some studies did not detect any dyskinesia as a side effect of this medication. PPX was consistently associated with lower risk for developing dyskinesia compared to L-DOPA. Moreover, the presence of these symptoms in the placebo groups suggests involvement of non-PPX-related factors for developing dyskinesia. It is suggested that future research should aim at ascertaining whether cotherapy with L-DOPA, PPX dosage, and other patient characteristics are contributory factors for the development of PPX-related dyskinesia in patients with PD.
doi:10.1155/2012/473769
PMCID: PMC3306931  PMID: 22496989
13.  Levodopa‐induced dyskinesia in Parkinson's disease: clinical features, pathogenesis, prevention and treatment 
Postgraduate Medical Journal  2007;83(980):384-388.
Levodopa is the most effective drug for treating Parkinson's disease. However, long‐term use of levodopa is often complicated by significantly disabling fluctuations and dyskinesias negating its beneficial effects. Younger age of Parkinson's disease onset, disease severity, and high levodopa dose increase the risk of development of levodopa‐induced dyskinesias (LID). The underlying mechanisms for LID are unclear though recent studies indicate the importance of pulsatile stimulation of striatal postsynaptic receptors in their pathogenesis. The non‐human primates with MPTP‐induced parkinsonism serve as a useful model to study dyskinesia. Once established, LID are difficult to treat and therefore efforts should be made to prevent them. The therapeutic and preventative strategies for LID include using a lower dosage of levodopa, employing dopamine agonists as initial therapy in Parkinson's disease, amantadine, atypical neuroleptics, and neurosurgery. LID can adversely affect the quality of life and increase the cost of healthcare.
doi:10.1136/pgmj.2006.054759
PMCID: PMC2600052  PMID: 17551069
14.  Serotonergic mechanisms responsible for levodopa-induced dyskinesias in Parkinson’s disease patients 
The Journal of Clinical Investigation  2014;124(3):1340-1349.
Levodopa-induced dyskinesias (LIDs) are the most common and disabling adverse motor effect of therapy in Parkinson’s disease (PD) patients. In this study, we investigated serotonergic mechanisms in LIDs development in PD patients using 11C-DASB PET to evaluate serotonin terminal function and 11C-raclopride PET to evaluate dopamine release. PD patients with LIDs showed relative preservation of serotonergic terminals throughout their disease. Identical levodopa doses induced markedly higher striatal synaptic dopamine concentrations in PD patients with LIDs compared with PD patients with stable responses to levodopa. Oral administration of the serotonin receptor type 1A agonist buspirone prior to levodopa reduced levodopa-evoked striatal synaptic dopamine increases and attenuated LIDs. PD patients with LIDs that exhibited greater decreases in synaptic dopamine after buspirone pretreatment had higher levels of serotonergic terminal functional integrity. Buspirone-associated modulation of dopamine levels was greater in PD patients with mild LIDs compared with those with more severe LIDs. These findings indicate that striatal serotonergic terminals contribute to LIDs pathophysiology via aberrant processing of exogenous levodopa and release of dopamine as false neurotransmitter in the denervated striatum of PD patients with LIDs. Our results also support the development of selective serotonin receptor type 1A agonists for use as antidyskinetic agents in PD.
doi:10.1172/JCI71640
PMCID: PMC3934188  PMID: 24531549
15.  Efficacy, safety, and tolerance of the non-ergoline dopamine agonist pramipexole in the treatment of advanced Parkinson's disease: a double blind, placebo controlled, randomised, multicentre study 
OBJECTIVES—Pramipexole, a non-ergot dopamine D2/D3 receptor agonist, was investigated as an add on drug in advanced parkinsonian patients with motor fluctuations to assess efficacy, safety, and tolerance.
METHODS—Seventy eight patients of either sex with advanced Parkinson's disease and treatment complications such as motor fluctuations were enrolled into a double blind, placebo controlled, randomised, multicentre study (phase II) and assigned to add on treatment with pramipexole (n=34) versus placebo (n=44) to a previously stabilised antiparkinsonian medication (7 week dose titration interval, 4 week maintenance period). The primary end point of efficacy was the change from baseline in the total score of the unified Parkinson's disease rating scale (UPDRS) in the on "period" (2 hours after intake of study medication). Safety and tolerability were assessed on the basis of adverse events, vital signs, laboratory measurements, and ECG recordings.
RESULTS—There was a significant improvement of the pramipexole group in UPDRS total scores, subscores part II, III (activities of daily living and motor examination), and IV (complications of therapy). Mean UPDRS total score decreased by 37.3% under pramipexole compared with 12.2% under placebo (p<0.001). Patients under pramipexole reported an overall reduction in "off" periods of 12%—resulting in 1.7 more hours "on" time a day—compared with an increase in "off" periods of 2% under placebo. There were no unexpected safety results. The adverse event profile disclosed a high tolerability. The most important adverse events under pramipexole were fatigue, dyskinesia, and vivid dreams.
CONCLUSION—Pramipexole administration is an efficacious and well tolerated add on therapy in patients with advanced Parkinson's disease with an improvement in activities of daily living, motor function, and treatment associated complications.


PMCID: PMC1736320  PMID: 10201413
16.  The catechol-O-methyltransferase (COMT) inhibitor entacapone enhances the pharmacokinetic and clinical response to Sinemet CR in Parkinson's disease 
OBJECTIVES—Entacapone is a specific, potent, peripherally acting catechol-O-methyltransferase (COMT) inhibitor. It has been shown to improve the bioavailability of plasma levodopa and extend its clinical effect when used as an adjunct to standard levodopa preparations, but there is little experience of the effect of entacapone on controlled release levodopa preparations.
METHODS—A double blind, placebo controlled, single dose, randomised, cross over trial was performed in 14 patients with Parkinson's disease with motor fluctuations to investigate the clinical effect of a single dose of entacapone (200 mg) when administered with either standard levodopa-carbidopa (SinemetTM) or controlled release levodopa-carbidopa preparations (Sinemet CRTM).
RESULTS—When entacapone was administered with standard SinemetTM the duration of the clinical response to standard SinemetTM was longer in comparison with the response after placebo (p=0.02). Moreover, in the same patients, entacapone significantly increased the duration of the clinical response to Sinemet CRTM (p=0.05) without prolonging the latency of response or enhancing dyskinesias.
CONCLUSIONS—These data confirm the clinical efficacy of entacapone-standard SinemetTM combination. They also indicate that adding entacapone to controlled release levodopa preparations might provide a useful treatment option in patients with Parkinson's disease with motor fluctuations. A double blind clinical trial with a chronically administered entacapone-Sinemet CRTM combination is, however, required to verify this viewpoint.


doi:10.1136/jnnp.68.5.589
PMCID: PMC1736905  PMID: 10766888
17.  Deprenyl in the management of response fluctuations in patients with Parkinson's disease on levodopa. 
Fluctuations in response to levodopa are a common and serious complication of long-term levodopa therapy. It may be possible to prolong the effect of each dose of levodopa by retarding the breakdown of dopamine. The selective monoamine oxidase type B inhibitor deprenyl, which is extensively metabolised to amphetamine and methamphetamine, has this effect as well as possible actions on dopamine release and re-uptake. In a double-blind crossover trial against placebo, deprenyl prolonged the action of levodopa and produced an objective improvement in mobility in five of 10 patients with dose-related response swings, and a subjective improvement in a further four patients. In another group of seven patients with random fluctuations in symptoms, only two noted subjective improvement, and there was an apparent increase in the severity of response swings in five patients. Deprenyl exacerbated dyskinesias, but had no serious side-effects. We conclude that deprenyl is unlikely to benefit patients with random response swings, and may cause deterioration in such cases. However, it may be a useful adjuvant in the management of dose-related response fluctuations in patients already on optional levodopa therapy.
PMCID: PMC490754  PMID: 6777463
18.  Drug treatment of Parkinson's disease. 
BMJ : British Medical Journal  1995;310(6979):575-579.
A wide variety of drugs is available for treating Parkinson's disease, including anticholinergics, amantadine levodopa, dopamine agonists, and selegiline. In younger patients (less than 50) levodopa is usually delayed provided that adequate relief of symptoms can be achieved with other drugs. In older patients (greater than 70) levodopa should be started as soon as symptom relief is required. Between these ages there is no consensus, but at present most such patients should probably be given controlled release levodopa before a dopamine agonist is added. Fluctuations can often be alleviated by giving controlled release preparations of levodopa, by giving small doses at frequent intervals, by adding selegiline or a long acting oral agonist, or by subcutaneous apomorphine. Dyskinesia can be peak dose, diphasic, or "off period." The diphasic form is hardest to alleviate. Psychiatric side effects should initially be managed by changing the antiparkinsonian treatment before resorting to antipsychotic drugs.
PMCID: PMC2548944  PMID: 7888935
19.  Population Pharmacodynamics of IPX066: An Oral Extended-Release Capsule Formulation of Carbidopa–Levodopa, and Immediate-Release Carbidopa–Levodopa in Patients With Advanced Parkinson’s Disease 
Journal of Clinical Pharmacology  2013;53(5):523-531.
A pharmacodynamic model is presented to describe the motor effects (tapping rate, Unified Parkinson’s Disease Rating Scale [UPDRS] Part III, and investigator-rating of ON/OFF, including dyskinesia) of levodopa (LD) in patients with advanced idiopathic Parkinson’s disease (PD) treated with immediate-release (IR) carbidopa–levodopa (CD–LD) or an extended-release (ER) formulation of CD–LD (IPX066). Twenty-seven patients participated in this open-label, randomized, single-and multiple-dose, crossover study. The pharmacodynamic models included a biophase effect site with a sigmoid Emax transduction for tapping and UPDRS and an ordered categorical model for dyskinesia. The pharmacodynamics of LD was characterized by a conduction function with a half-life of 0.59 hours for tapping rate, and 0.4 hours for UPDRS Part III and dyskinesia. The LD concentration for half-maximal effect was 1530 ng/mL, 810 ng/mL, and 600 ng/mL for tapping rate, UPDRS Part III, and dyskinesia, respectively. The sigmoidicity of the transduction was 1.53, 2.5, and 2.1 for tapping rate, UPDRS Part III, and dyskinesia, respectively. External validation of the pharmacodynamic model using tapping rate indicated good performance of the model.
doi:10.1002/jcph.63
PMCID: PMC3798100  PMID: 23426902
IPX066; levodopa; Parkinson’s disease; pharmacodynamics
20.  Pain and motor complications in Parkinson's disease 
Aims
To study the association of pain with motor complications in 117 patients with Parkinson's disease.
Methods
Patients were asked to refer any pain they experienced at the time of study and lasting since at least 2 months. Basic parkinsonian signs and motor complications (including motor fluctuations and dyskinesia) were assessed and Unified Parkinson's Disease Rating Scale (UPDRS) motor score part III (during on) and part IV were calculated. Information on age, sex, duration of disease, use of dopamine agonists and levodopa, years of levodopa treatment and current levodopa dosage, medical conditions possibly associated with pain, and depression were collected. Single and multiple explanatory variable logistic regression models were used to check the association of pain with the investigated variables.
Results
Pain was described by 47 patients (40%) and could be classified into dystonic (n.19) and non dystonic pain (n.16); in 12 patients both types coexisted. Multiple explanatory variable logistic regression models indicated a significant association of pain with motor complications (adjusted OR, 5.7; 95% CI, 2 to 16.5; p = 0.001). No association was found between pain, dystonic or non dystonic, and the other investigated variables including medical conditions known to be associated to pain in the general population. There was a significant correlation (r = 0.31, p<0.05) between severity of pain (measured on a Visual Analogue Scale) and severity of motor complications (UPDRS part IV).
Conclusions
Pain may be a representative feature of Parkinson's disease frequently associated with motor complications. The association is independent of a number of potentially relevant demographic and clinical variables.
doi:10.1136/jnnp.2005.079053
PMCID: PMC2117476  PMID: 16549416
21.  Motor response to apomorphine and levodopa in asymmetric Parkinson's disease. 
The motor responses of 14 patients with Parkinson's disease (six previously untreated and eight chronically receiving levodopa) with pronounced asymmetry in the severity of motor signs between the left and right sides of the body were studied. The effects of a short (60 minutes) and a long (16-22 hours) intravenous levodopa infusion as well as of subcutaneous apomorphine (1-6 mg bolus) were assessed. Four different tapping tests were used to measure motor function. For all pharmacological tests, the more affected side showed a shorter response duration, increased latency, and greater response magnitude than the less affected side. These differences were more pronounced in those patients receiving chronic levodopa treatment. As apomorphine is not dependent on dopamine storage capacity, these findings suggest that postsynaptic mechanisms play an important part in the origin of motor fluctuations in Parkinson's disease.
PMCID: PMC1072915  PMID: 8201324
22.  Comparison of the clinical pharmacology of (-)NPA and levodopa in Parkinson's disease. 
Direct acting dopamine agonists are generally less effective than levodopa in relieving symptoms of Parkinson's disease. In an attempt to quantitate and explain this situation, the acute motor responses to intravenous injections of the dopamine agonist, (-)-N-n-propyl-norapomorphine hydrochloride (NPA), were compared with those of the dopamine precursor, levodopa. At optimum dose levels, the acute anti-Parkinsonian efficacy of NPA averaged only about 50% of maximum, while essentially total symptom suppression was obtained with levodopa in patients previously treated with the amine precursor. Dyskinesia severity, however, was similar with the two drugs. These differences in anti-Parkinsonian efficacy may reflect the fact that while NPA acts mainly on D-2 dopamine receptors, levodopa results in stimulation of both the D-1 and D-2 subsets of receptors at a more physiological ratio. Future efforts to develop dopamine agonists for the treatment of Parkinsonian symptoms may thus have to consider focusing on drugs having pharmacological profile more similar to that of dopamine.
PMCID: PMC488537  PMID: 1865201
23.  Pramipexole in patients with early Parkinson's disease (PROUD): a randomised delayed-start trial 
Lancet Neurology  2013;12(8):747-755.
Summary
Background
In models of dopaminergic neuronal loss, the dopamine agonist pramipexole has exhibited neuroprotective properties. The Pramipexole On Underlying Disease (PROUD) study was designed to identify whether early versus delayed pramipexole initiation has clinical and neuroimaging benefits in patients with Parkinson's disease (PD).
Methods
Between May 24, 2006, and April 22, 2009, at 98 centres, we recruited patients with PD diagnosed within 2 years and aged 30–79 years. We randomly assigned eligible patients (ratio 1:1), by a centralised, computerised randomisation schedule, to receive double-blind either placebo or pramipexole (1·5 mg a day) and followed them up for 15 months. At 9 months, or as early as 6 months if considered necessary, placebo recipients were assigned to pramipexole. In a neuroimaging substudy, striatal dopamine-transporter binding was assessed by SPECT. All patients, investigators, and independent raters were masked to study treatment. The primary endpoint was the 15-month change from baseline in total score on the unified Parkinson's disease rating scale (UPDRS). This trial is registered with ClinicalTrials.gov, number NCT00321854.
Findings
Of 535 patients, 261 were randomly assigned to receive pramipexole and 274 to receive placebo. At 15 months (n=411), adjusted mean change in UPDRS total score showed no significant difference between early and delayed pramipexole (−0·4 points, 95% CI −2·2 to 1·4, p=0·65). 62 patients in the early pramipexole group and 61 patients in the delayed pramipexole group were included in the neuroimaging substudy, for which the adjusted mean 15-month change in striatal 123I-FP-CIT binding was −15·1% (SE 2·1) for early and −14·6% (2·0) for delayed pramipexole (difference −0·5 percentage points, 95% CI −5·4 to 4·4, p=0·84). Overall, 180 (81%) of patients given early pramipexole and 179 (84%) patients given delayed pramipexole reported adverse events (most frequently nausea), and 22 (10%) patients in the early pramipexole group and 17 (8%) in the delayed pramipexole group had serious events, two of which (hallucinations and orthostatic hypotension) were deemed related to study drug.
Interpretation
By clinical and neuroimaging measures, pramipexole showed little evidence differentiating 15-month usage from usage delayed for 6–9 months. The results do not support the hypothesis that pramipexole has disease-modifying effects.
Funding
Boehringer Ingelheim GmbH.
doi:10.1016/S1474-4422(13)70117-0
PMCID: PMC3714436  PMID: 23726851
24.  Carbidopa/levodopa/entacapone: the evidence for its place in the treatment of Parkinson’s disease 
Core Evidence  2010;5:1-10.
Introduction:
Parkinson’s disease (PD) is a common neurodegenerative disease. In the 1960s, it was shown that the degeneration of dopamine producing neurons in the substantia nigra (SN) caused the motor features of PD. Dopamine replacement with levodopa, a dopamine precursor, resulted in remarkable benefit. Yet, the intermittent administration of levodopa is a major cause of motor complications, such as “wearing-off” of levodopa’s benefit and involuntary movements, known as dyskinesia. Therefore, agents that prolong levodopa’s half-life were employed, such as carbidopa, an aromatic amino acid decarboxylase (AADC) inhibitor, and entacapone, a catechol-O-methyltransferase (COMT) inhibitor. The combination product carbidopa/levodopa/entacapone (CLE) was approved in 2003 for the treatment of PD patients.
Aims:
To assess the evidence for the place of CLE in the treatment of PD.
Evidence review:
CLE has a good efficacy, safety and tolerability profile, similar to that of entacapone taken separately with carbidopa/levodopa (CL). Compared to CL alone, it prolongs levodopa’s benefit, and improves the quality of life but not the motor performance in PD patients with nondebilitating “wearing-off” or dyskinesia. However, it increases the dyskinesia rate in early PD patients, and has adverse events in advanced patients with significant motor complications. There is insufficient evidence regarding cost-effectiveness.
Place in therapy:
CLE is an attractive alternative for patients with nondisabling “wearing-off” or dyskinesia taking CL with or without entacapone. It cannot be recommended for early PD patients, as it can induce more dyskinesia than CL alone, or in any patients who seem to have more adverse events.
PMCID: PMC2915499  PMID: 20694135
Parkinson’s disease; levodopa; entacapone; carbidopa; treatment
25.  Effect of entacapone, a peripherally acting catechol-O-methyltransferase inhibitor, on the motor response to acute treatment with levodopa in patients with Parkinson's disease. 
Catechol-O-methyltransferase (COMT) inhibitors may be useful in the treatment of Parkinson's disease by improving the bioavailability of levodopa and by prolonging its effects. Entacapone (OR-611), a novel COMT inhibitor, which does not cross the blood brain barrier, was assessed in 12 patients with Parkinson's disease and motor fluctuations in a randomised, double-blind, cross-over, single dose study. The magnitude and duration of the therapeutic response to a single dose of 200 mg levodopa/50 mg carbidopa was evaluated after concomitant placebo, or 200 or 800 mg entacapone. A significant increase in the duration of the motor response to levodopa was seen when 200 mg entacapone was given with levodopa/carbidopa. Plasma levodopa concentrations were increased with both doses of the COMT inhibitor. The latency to onset of motor response did not differ significantly between active drug and placebo. Entacapone may prove useful in prolonging the duration of the benefit obtained from individual doses of levodopa.
PMCID: PMC1072447  PMID: 8126502

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