Pharm 8 & 9 - Movement Disorder Flashcards
What is the dosing regimen for Sinemet?
Sinemet (carbidopa):
- Doses start small x3/day ( 25mg/L-dopa 100mg)
- ->dose can be increased but can enhance side effects
- -> keep low and add additional drug therapies
ex. dopamine agonist/ additional enzyme inhibitors
Give a class of drugs contraindicated with L-dopa and what the combination can cause?
- Dopaminergic anti-emetics are not given as they may exacerbate the parkinsonism.
What population should be carful with L-dopa treatment and why?
- Parkinson patients?
What is an indication for selgiline?
- Prolongs anti-parkinsonism of L-dopa allowing for lower doses so should be given to reduce mild on-off or wearing off phenomena
- Should not be given with meperidine and anti-depressants (tricyclic, SSRIs)
Give the specific indication for apopmorphine?
- Apomorphine is give in an SubQ injection and enters the blood and brain quickly
- Effect seen in 10 min and lasts for ~2 hours
- Potent dopamine agonist
- Temp. relief of off-periods of akinesia inpatients on dopamine therapy
- AE - nausea; pretreatment with an antiemetic ( trimethobenzamide)
Describe the two components of Sinemet and their functions?
- Sinemet (L-dopa + Carbidopa)
- Carbidopa given to inhibit the conversion of L-dopa to dpamine in peripheral tissues
- Allows L-dopa to cross the BBB then be converted to dopamine for the brain to use
Give one reason daily doses of L-dopa are decreased over time?
To avoid side effects not present initially and because patients become less responsive and may be lost completely
Explain the “on-off phenomenon” and give one treatment for it
- “Off” periods marked by akinesia(loss of voluntary movement) which alternate with “on” periods of improved mobility but marked dyskinesia
- Off period can be treated with SubQ apomorphine
Give 2 reasons COMT inhibitors entacapone and tolcapone improve responsiveness to L-dopa.
- Entacapone decreases metabolism of L-Dopa in the periphery
- Decreases competitive 3-o-methyldopa making L-dopa more effective
- Essentially more prolonged “on-time”
Give 3 components of Stalevo?
L-dopa + carbidopa + entacapone
Give 2 advantaged of dopamine agonists over L-dopa?
- Do not require enzymatic conversion
- Do not compete with other substances to actively cross into blood and the BBB
- Have fewer AE- lower incidence of response fluctuations and/or dyskinesias
- no toxic metabolites
Give 2 indications for pramipexole?
- Can be used effectively as monotherapy for mild parkinson’s
- As adjunctive therapy in advanced Parkinson’s to lower L-dopa dose/smooth out fluctuations
- May reduce Affective symptoms of PD
What is a specific indication for apomorphine?
- SubQ injection - quickly into blood and brain
- ->Effect seen in 10 min and lasts for 2 hrs
- Potent dopamine agonist
- Temporary relief of off-periods of akinesia in patients on dopamine therapy**
- AE - nausea; pretreatment with an antiemetic
What symptoms of Parkinson’s improve with Ach blockers?
- ex. benztropine mesylate, biperiden, orphendrine, procyclindine, trihexyphenidyl
- treatment starts low and increases until benefit or AE seen
- Improve the tremor and rigidity (little effect on bradykinesia)
Give the class of drugs for postural tremor and one in this class not to give?
- Tremor - rhythmic oscillatory movements
- Physiologic postural tremor:
- -> Norm- enhanced by anxiety, fatigue, certain drugs
- -> Can be alleviated with propranolol (blocks B1 and B2 receptors); but not metoprolol - B1 receptor blocker; tremor mediated through activation B2 receptor
