PD: Levodopa Motor Complications Flashcards
1
Q
Describe the “on-off” phenomenon of Levodopa
A
ON: response to levodopa (i.e. able to gain mobility)
OFF: no response to levodopa
Unpredictable, not related to dose/dosing interval, but related to swings in drug concentration
Mechanism is unclear
Difficult to manage/control with medications
2
Q
Describe the “wearing off” phenomenon of Levodopa
A
Effect of levodopa wanes before the end of the dosing interval
Shortened “ON” time
Associated with disease progression
- in later stages of the disease, symptoms start coming back before the end of the dosing interval
3
Q
Management of the “wearing off” phenomenon of Levodopa
A
- Modify times of administration (incr frequency of administration)
- Replace with modified-release preparations at the appropriate time
- Introduce COMT inhibitors as adjunct (to increase duration of levodopa)
4
Q
Describe the presentation of levodopa-induced dyskinesia
A
- Involuntary, uncontrollable
- Twitching, jerking
- Peak dose dyskinesia
- Dystonia (uncontrolled muscle spasm)
5
Q
Management of levodopa-induced dyskinesia
A
- Introduce amantadine as adjunct (antidyskinesic)
- Replace specific doses with modified release, to achieve a more sustained low peak
- Give smaller doses more frequently
6
Q
Describe the 4 phases of PD progression, and the response to levodopa at each phase
A
- Stable phase
- typical in first 3-5y of levodopa use
- near-normal mobility, able to regain function (once threshold for symptom relief is passed)
- concentrations fluctuate without reemergence of symptoms
- no motor complications
- Wearing-off phase
- duration of motor response shortens
- parkinsonism symptoms appear between doses as the effect of levodopa wanes off before the end of the dosing interval
- Dyskinesia
- dyskinesia occurs at peak doses
- On-off fluctuations
- dyskinesia occurs often and randomly
- unpredictable, not related to dose/dosing interval, but related to swings in the drug concentration
- normal mobility is difficult to achieve
