Anti-Parkinson Agents

Question 0

Pramipexole

Ropinirole

Answer 0

Pramipexole - D3 >D2 agonist
Ropinirole D2, D3 agonist

Cause sudden sleep episodes, cardio side effects less common but common rxn is hypotension, can cause dyskinesia and hallucinations

Same uses as bromocriptine

Question 1

Bromocriptine

Answer 1

D2 and D3 agonist

• lower doses used to treat hyperprolactinemia
• excreted in bile and feces

Uses: first line drug for Parkinsonism . Compared to L-dopa there is less chance of response fluctuations and dyskinesia. And be combined with L- DOPA
Restless leg syndrome

Adverse effects
Cardio-hypotension, arrhythmia’s, erythromelalgia ( painful swollen feet), digital vasospasm ( cool and dusty hands and feet). Stroke and MI

GI: anorexia, nausea, vomiting - take with food .
Constipation, indigestion, peptic ulceration with bleeding

Dyskinesia - less than with l-dopa

Mental disturbances: hallucinations, confusion
Fibrosis: membrane lining of organs become thickened or scarred

Question 2

Selegiline

Answer 2

MOA: mono amine oxidase B inhibitor - slows the breakdown of dopamine, prolonging the effect of DOPA

Use: adjunctive therapy. May allow a DOPA dose reduction. May reduce mild on-off phenomena and wearing off phenomena . Could enhance the adverse effects of L-DOPA and depression

Contraindicated for pts on tricyclic antidepressants and serotonin uptake blockers and meperidine

Question 3

Amantadine

Answer 3

MOA: Antiviral drug that causes dopamine release in better striatum . May also block muscarinic and/or glutamate receptors
. Blocks NMDA receptors

Uses: initial or late treatment to control L-DOPA induced dyskinesia, influenza A

Adverse effects : restlessness, agitation, hallucination
Livedo reticuolaris ( peripheral vascular condition. - reddish blue skin)
Peripheral edema
Avoid in pts prone to seizure and those with chf

Question 4

Benztropine

Answer 4

MOA: anticholinergic- blocks muscarinic receptors on interneuron in the caudate
Uses: improves rigidity/ tremor only a minor effect on bradykinesia

Adverse effects : drowsiness, restlessness, hallucinations, dyskinesias

Avoid in pts with prostatic hypertrophy, obstructive GI disease, and glaucoma

Question 5

Tolcapone

Entacapone

Answer 5

MOA :Catechol-o-methyltransferase inhibitors - enzyme that converts DOPA to 3-o-methyldopa
INHIBITS methylation of dopamine

Uses: not effective in treating Parkinson’s . Increase duration of the effect of each dopa dose without increasing the peak level of DOPA. Never used alone. May treat wearing off phenomena

Adverse effects
May need to reduce dopa level to minimize dyskinesias and other dopamine related side effects . With tolcapone monitor liver enzymes

Question 6

Sinnemet

Atamet

Answer 6

carbidopa - inhibits dopa decarboxylase
Usually administered with L-DOPA
MOA: dopamine precursors. L- dopa is absorbed in the intestine, 1-3% reaches the Brain the rest is metabolized by DOPA decarboxylase . By inhibiting this more reaches the brain

Uses: tolerable doses diminish with time. Diminished bradykinesia (l-dopa)

Adverse effects : all pts get them
GI: anorexia, nausea, vomiting
Cardio: orthostatic hypotension , tachy

Long term- alter dosage
Dyskinesias - 80% Of pts develop these. Stereotyped behavior
Psychiatric and behavioral - nightmares, anxiety. With increased doses paranoia, hallucinations, mania-> over stim of dopamine receptors

Response fluctuations : wearing off, end of dose akinesia

Drug holidays help with some symptoms
Drug interactions : if used with Mao a inhibitor -> hypertensive crisis

Contraindications : no psychotic pts, pts with closed angle glaucoma or he of melanoma . special care in pts with closed-angle glaucoma, cardiac disease, or peptic ulcers