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Improved delivery of levodopa and new therapies may help to reduce off time.
MIAMI—Motor fluctuations in Parkinson’s disease can arise from more than one cause, and a clinician needs to consider a range of possibilities. Most commonly, motor fluctuations arise as a consequence of chronic levodopa therapy, though the progression of parkinsonism is a contributing factor, according to an overview presented at the Second Pan American Parkinson’s Disease and Movement Disorders Congress. The pharmacokinetics of levodopa provide the basis for studying most clinical patterns of motor fluctuations, and new pharmacologic strategies are under development to improve upon existing treatment options. 
“In recent years, there have been some exciting and novel directions of Parkinson’s disease therapeutics for motor fluctuations,” said Peter A. LeWitt, MD, Director of the Parkinson’s Disease and Movement Disorder Program at Henry Ford Hospital in West Bloomfield, Michigan.
A Need to Improve Levodopa Delivery
Beyond irregular effects of levodopa, motor fluctuations may be intrinsic to Parkinson’s disease, said Dr. LeWitt. One problem experienced by some patients is freezing of gait, immobility that is often situation-specific irrespective of medication dosing, he added. The sleep-benefit phenomenon, stress-exacerbated tremors and dyskinesias, and end-of-day medication unresponsiveness are further examples. “But for the most part, most motor fluctuations tend to be closely linked to the variable delivery of levodopa to the brain, where, after a short delay, it undergoes conversion to dopamine. This neurotransmitter does not have long to carry out its intended signaling because enzymes and re-uptake mechanisms quickly dispose of it. So, consistent delivery is the key for averting dose-by-dose motor fluctuations.”
During its 50 years of service to the Parkinson’s disease patient, levodopa has revolutionized the identity of this disorder. It has improved longevity, disability, and overall quality of life, and it inspired
Because the short-duration response pattern is associated with benefits as brief as two to three hours per oral immediate-release dose, the focus for improving levodopa has been the use of extension therapies. Blocking the breakdown of peripheral levodopa metabolism (the mechanism for catechol-O-methyltransferase inhibition) or slowing the central metabolism of dopamine (by inhibiting monoamine oxidase-type B) join extended-release carbidopa-levodopa preparations as ways to improve upon the immediate-release product. “While these strategies do provide some level of effectiveness, the problems of irregular responsiveness and up to several hours of daily ‘off’ time haven’t been solved. ‘Off’ time still imposes a major burden on many patients living with Parkinson’s disease,” said Dr. LeWitt. Like delayed onset of effect and rapid wearing-off, levodopa-induced dyskinesias present another challenge for understanding their origin and optimal control. While new mechanisms of blocking dyskinesia are being sought, a simpler solution can be more continuous levodopa delivery so that drug concentration peaks causing involuntary movements are averted.
Future Therapies Undergoing Trials Today
Several new therapeutic approaches have been developed for dealing with the shortcomings of current therapies, especially levodopa. “The first of these options was a tube inserted through the stomach into the upper small intestine for continuous pumping of a carbidopa-levodopa microsuspension gel –quite effective but not an easy choice for most patients,” said Dr. LeWitt. Less cumbersome ways to extend levodopa effects have been the several sustained-release formulations now under development. One is a gastric-retention product, termed the “Accordion Pill,” which slowly leaches carbidopa and levodopa to enhance their pharmacokinetic absorption profile. Another treatment strategy for motor fluctuations that, like the Accordion Pill, is also in worldwide clinical trials, involves continuous subcutaneous infusion of solubilized levodopa and carbidopa. With the latter approach, the drug is administered by a small pump adjusted to optimized rate of delivery. Dr. LeWitt also described another novel way for administering levodopa for rapid entry into the bloodstream for treating “off” states. This involves an inhalation device for pulmonary uptake of a micro-particulate levodopa formulation. In a recently completed study, “off” states were reversed rapidly with this approach.
Subcutaneous apomorphine infusion has already been used for more than 30 years in treating motor fluctuations. However, just recently, a more complete story of what this adjunctive therapy offers was reported from a large-scale randomized clinical trial in Europe. A similar study is underway in the United States and might lead to availability of apomorphine infusion in the near future, said Dr. LeWitt. Another approach to motor fluctuations can be found in a drug for motor fluctuations that does not act on dopaminergic pathways. This medication is istradefylline, a selective inhibitor of adenosine A2a receptors (which are located in the same pathway targeted by deep brain stimulation). In Japan, istradefylline is marketed for reducing “off” time, and studies with this drug are planned for review in the US, said Dr. LeWitt.
For a nonpharmacologic approach to managing motor fluctuations, neurosurgical targeting of brain circuitry with deep brain electrical stimulation has had several decades of experience. Another direction of neurosurgical intervention is under investigation; this involves gene therapy to improve the efficacy of oral levodopa therapy. “Inserting into the putamen a gene for producing an increase of L-aromatic amino acid decarboxylase appears to offer a way for enhancing dopamine formation. The clinical investigation currently underway is testing whether producing this localized alteration of brain neurochemistry might succeed at attenuating motor fluctuations,” said Dr. LeWitt
“In talking to patients about their experiences with motor fluctuations, my advice is to think both about levodopa pharmacokinetics and how the patient uses levodopa (since schedule compliance, the interaction of meals, and drinking sufficient water with medications commonly contribute to these problems). Fortunately, new treatment options are on their way to help in fighting back against the limitations of levodopa therapy,” Dr. LeWitt concluded.
—Erica Tricarico
Suggested Reading
Anderson E, Nutt J. The long-duration response to levodopa: phenomenology, potential mechanisms and clinical implications. Parkinsonism Relat Disord. 2011;17:587-592.
Cilia R, Akpalu A, Sarfo FS, et al. The modern pre-levodopa era of Parkinson’s disease: insights into motor complications from sub-Saharan Africa. Brain. 2014;137(10);2731-2742.
LeWitt PA. Levodopa therapy for Parkinson’s disease: Pharmacokinetics and pharmacodynamics. Mov Disord. 2015;30(1):64-72.
Improved delivery of levodopa and new therapies may help to reduce off time.
Improved delivery of levodopa and new therapies may help to reduce off time.
MIAMI—Motor fluctuations in Parkinson’s disease can arise from more than one cause, and a clinician needs to consider a range of possibilities. Most commonly, motor fluctuations arise as a consequence of chronic levodopa therapy, though the progression of parkinsonism is a contributing factor, according to an overview presented at the Second Pan American Parkinson’s Disease and Movement Disorders Congress. The pharmacokinetics of levodopa provide the basis for studying most clinical patterns of motor fluctuations, and new pharmacologic strategies are under development to improve upon existing treatment options.
“In recent years, there have been some exciting and novel directions of Parkinson’s disease therapeutics for motor fluctuations,” said Peter A. LeWitt, MD, Director of the Parkinson’s Disease and Movement Disorder Program at Henry Ford Hospital in West Bloomfield, Michigan.
A Need to Improve Levodopa Delivery
Beyond irregular effects of levodopa, motor fluctuations may be intrinsic to Parkinson’s disease, said Dr. LeWitt. One problem experienced by some patients is freezing of gait, immobility that is often situation-specific irrespective of medication dosing, he added. The sleep-benefit phenomenon, stress-exacerbated tremors and dyskinesias, and end-of-day medication unresponsiveness are further examples. “But for the most part, most motor fluctuations tend to be closely linked to the variable delivery of levodopa to the brain, where, after a short delay, it undergoes conversion to dopamine. This neurotransmitter does not have long to carry out its intended signaling because enzymes and re-uptake mechanisms quickly dispose of it. So, consistent delivery is the key for averting dose-by-dose motor fluctuations.”
During its 50 years of service to the Parkinson’s disease patient, levodopa has revolutionized the identity of this disorder. It has improved longevity, disability, and overall quality of life, and it inspired
Because the short-duration response pattern is associated with benefits as brief as two to three hours per oral immediate-release dose, the focus for improving levodopa has been the use of extension therapies. Blocking the breakdown of peripheral levodopa metabolism (the mechanism for catechol-O-methyltransferase inhibition) or slowing the central metabolism of dopamine (by inhibiting monoamine oxidase-type B) join extended-release carbidopa-levodopa preparations as ways to improve upon the immediate-release product. “While these strategies do provide some level of effectiveness, the problems of irregular responsiveness and up to several hours of daily ‘off’ time haven’t been solved. ‘Off’ time still imposes a major burden on many patients living with Parkinson’s disease,” said Dr. LeWitt. Like delayed onset of effect and rapid wearing-off, levodopa-induced dyskinesias present another challenge for understanding their origin and optimal control. While new mechanisms of blocking dyskinesia are being sought, a simpler solution can be more continuous levodopa delivery so that drug concentration peaks causing involuntary movements are averted.
Future Therapies Undergoing Trials Today
Several new therapeutic approaches have been developed for dealing with the shortcomings of current therapies, especially levodopa. “The first of these options was a tube inserted through the stomach into the upper small intestine for continuous pumping of a carbidopa-levodopa microsuspension gel –quite effective but not an easy choice for most patients,” said Dr. LeWitt. Less cumbersome ways to extend levodopa effects have been the several sustained-release formulations now under development. One is a gastric-retention product, termed the “Accordion Pill,” which slowly leaches carbidopa and levodopa to enhance their pharmacokinetic absorption profile. Another treatment strategy for motor fluctuations that, like the Accordion Pill, is also in worldwide clinical trials, involves continuous subcutaneous infusion of solubilized levodopa and carbidopa. With the latter approach, the drug is administered by a small pump adjusted to optimized rate of delivery. Dr. LeWitt also described another novel way for administering levodopa for rapid entry into the bloodstream for treating “off” states. This involves an inhalation device for pulmonary uptake of a micro-particulate levodopa formulation. In a recently completed study, “off” states were reversed rapidly with this approach.
Subcutaneous apomorphine infusion has already been used for more than 30 years in treating motor fluctuations. However, just recently, a more complete story of what this adjunctive therapy offers was reported from a large-scale randomized clinical trial in Europe. A similar study is underway in the United States and might lead to availability of apomorphine infusion in the near future, said Dr. LeWitt. Another approach to motor fluctuations can be found in a drug for motor fluctuations that does not act on dopaminergic pathways. This medication is istradefylline, a selective inhibitor of adenosine A2a receptors (which are located in the same pathway targeted by deep brain stimulation). In Japan, istradefylline is marketed for reducing “off” time, and studies with this drug are planned for review in the US, said Dr. LeWitt.
For a nonpharmacologic approach to managing motor fluctuations, neurosurgical targeting of brain circuitry with deep brain electrical stimulation has had several decades of experience. Another direction of neurosurgical intervention is under investigation; this involves gene therapy to improve the efficacy of oral levodopa therapy. “Inserting into the putamen a gene for producing an increase of L-aromatic amino acid decarboxylase appears to offer a way for enhancing dopamine formation. The clinical investigation currently underway is testing whether producing this localized alteration of brain neurochemistry might succeed at attenuating motor fluctuations,” said Dr. LeWitt
“In talking to patients about their experiences with motor fluctuations, my advice is to think both about levodopa pharmacokinetics and how the patient uses levodopa (since schedule compliance, the interaction of meals, and drinking sufficient water with medications commonly contribute to these problems). Fortunately, new treatment options are on their way to help in fighting back against the limitations of levodopa therapy,” Dr. LeWitt concluded.
—Erica Tricarico
Suggested Reading
Anderson E, Nutt J. The long-duration response to levodopa: phenomenology, potential mechanisms and clinical implications. Parkinsonism Relat Disord. 2011;17:587-592.
Cilia R, Akpalu A, Sarfo FS, et al. The modern pre-levodopa era of Parkinson’s disease: insights into motor complications from sub-Saharan Africa. Brain. 2014;137(10);2731-2742.
LeWitt PA. Levodopa therapy for Parkinson’s disease: Pharmacokinetics and pharmacodynamics. Mov Disord. 2015;30(1):64-72.
MIAMI—Motor fluctuations in Parkinson’s disease can arise from more than one cause, and a clinician needs to consider a range of possibilities. Most commonly, motor fluctuations arise as a consequence of chronic levodopa therapy, though the progression of parkinsonism is a contributing factor, according to an overview presented at the Second Pan American Parkinson’s Disease and Movement Disorders Congress. The pharmacokinetics of levodopa provide the basis for studying most clinical patterns of motor fluctuations, and new pharmacologic strategies are under development to improve upon existing treatment options.
“In recent years, there have been some exciting and novel directions of Parkinson’s disease therapeutics for motor fluctuations,” said Peter A. LeWitt, MD, Director of the Parkinson’s Disease and Movement Disorder Program at Henry Ford Hospital in West Bloomfield, Michigan.
A Need to Improve Levodopa Delivery
Beyond irregular effects of levodopa, motor fluctuations may be intrinsic to Parkinson’s disease, said Dr. LeWitt. One problem experienced by some patients is freezing of gait, immobility that is often situation-specific irrespective of medication dosing, he added. The sleep-benefit phenomenon, stress-exacerbated tremors and dyskinesias, and end-of-day medication unresponsiveness are further examples. “But for the most part, most motor fluctuations tend to be closely linked to the variable delivery of levodopa to the brain, where, after a short delay, it undergoes conversion to dopamine. This neurotransmitter does not have long to carry out its intended signaling because enzymes and re-uptake mechanisms quickly dispose of it. So, consistent delivery is the key for averting dose-by-dose motor fluctuations.”
During its 50 years of service to the Parkinson’s disease patient, levodopa has revolutionized the identity of this disorder. It has improved longevity, disability, and overall quality of life, and it inspired
Because the short-duration response pattern is associated with benefits as brief as two to three hours per oral immediate-release dose, the focus for improving levodopa has been the use of extension therapies. Blocking the breakdown of peripheral levodopa metabolism (the mechanism for catechol-O-methyltransferase inhibition) or slowing the central metabolism of dopamine (by inhibiting monoamine oxidase-type B) join extended-release carbidopa-levodopa preparations as ways to improve upon the immediate-release product. “While these strategies do provide some level of effectiveness, the problems of irregular responsiveness and up to several hours of daily ‘off’ time haven’t been solved. ‘Off’ time still imposes a major burden on many patients living with Parkinson’s disease,” said Dr. LeWitt. Like delayed onset of effect and rapid wearing-off, levodopa-induced dyskinesias present another challenge for understanding their origin and optimal control. While new mechanisms of blocking dyskinesia are being sought, a simpler solution can be more continuous levodopa delivery so that drug concentration peaks causing involuntary movements are averted.
Future Therapies Undergoing Trials Today
Several new therapeutic approaches have been developed for dealing with the shortcomings of current therapies, especially levodopa. “The first of these options was a tube inserted through the stomach into the upper small intestine for continuous pumping of a carbidopa-levodopa microsuspension gel –quite effective but not an easy choice for most patients,” said Dr. LeWitt. Less cumbersome ways to extend levodopa effects have been the several sustained-release formulations now under development. One is a gastric-retention product, termed the “Accordion Pill,” which slowly leaches carbidopa and levodopa to enhance their pharmacokinetic absorption profile. Another treatment strategy for motor fluctuations that, like the Accordion Pill, is also in worldwide clinical trials, involves continuous subcutaneous infusion of solubilized levodopa and carbidopa. With the latter approach, the drug is administered by a small pump adjusted to optimized rate of delivery. Dr. LeWitt also described another novel way for administering levodopa for rapid entry into the bloodstream for treating “off” states. This involves an inhalation device for pulmonary uptake of a micro-particulate levodopa formulation. In a recently completed study, “off” states were reversed rapidly with this approach.
Subcutaneous apomorphine infusion has already been used for more than 30 years in treating motor fluctuations. However, just recently, a more complete story of what this adjunctive therapy offers was reported from a large-scale randomized clinical trial in Europe. A similar study is underway in the United States and might lead to availability of apomorphine infusion in the near future, said Dr. LeWitt. Another approach to motor fluctuations can be found in a drug for motor fluctuations that does not act on dopaminergic pathways. This medication is istradefylline, a selective inhibitor of adenosine A2a receptors (which are located in the same pathway targeted by deep brain stimulation). In Japan, istradefylline is marketed for reducing “off” time, and studies with this drug are planned for review in the US, said Dr. LeWitt.
For a nonpharmacologic approach to managing motor fluctuations, neurosurgical targeting of brain circuitry with deep brain electrical stimulation has had several decades of experience. Another direction of neurosurgical intervention is under investigation; this involves gene therapy to improve the efficacy of oral levodopa therapy. “Inserting into the putamen a gene for producing an increase of L-aromatic amino acid decarboxylase appears to offer a way for enhancing dopamine formation. The clinical investigation currently underway is testing whether producing this localized alteration of brain neurochemistry might succeed at attenuating motor fluctuations,” said Dr. LeWitt
“In talking to patients about their experiences with motor fluctuations, my advice is to think both about levodopa pharmacokinetics and how the patient uses levodopa (since schedule compliance, the interaction of meals, and drinking sufficient water with medications commonly contribute to these problems). Fortunately, new treatment options are on their way to help in fighting back against the limitations of levodopa therapy,” Dr. LeWitt concluded.
—Erica Tricarico
Suggested Reading
Anderson E, Nutt J. The long-duration response to levodopa: phenomenology, potential mechanisms and clinical implications. Parkinsonism Relat Disord. 2011;17:587-592.
Cilia R, Akpalu A, Sarfo FS, et al. The modern pre-levodopa era of Parkinson’s disease: insights into motor complications from sub-Saharan Africa. Brain. 2014;137(10);2731-2742.
LeWitt PA. Levodopa therapy for Parkinson’s disease: Pharmacokinetics and pharmacodynamics. Mov Disord. 2015;30(1):64-72.