Parkinson's Disease

Question 1

L-Dopa (Levodopa)

Answer 1

MOA: L-Dopa is a precursor of dopamine. Increases release of synaptic DA in the Striatum.
Side effects:Pro-dopaminergic effects 1. Motor effects. Gastrointestinal side effects. 3. Behavioral side effects.
Absorption:
Dosage forms: Oral (Can cross the BBB)
Drug interactions: Nonselective MAOIs (as used for depresion). DA reuptake transporter inhibitors. Antipsychotics (DA2R antagonists).

Question 2

Sinemet (Levodopa + Carbidopa)

Answer 2

MOA: Inhibits peripheral decarboxylases (L-AAAD) conversion of l-dopa to dopamine in gut and blood.
Pharmacology: Does not cross the BBB. Can decrease oral dose of Levodopa needed by 75% . Increases L-dopa half-life. Reduces nausea and vomiting by reducing dopamine production in GI tract.

Question 3

Stalevo (Levodopa + Carbidopa + Entacapone)

Answer 3

MOA: Inhibits peripheral COMT in gut and reduces breakdown of L-dopa in gut and blood.
Pharmacology: Does not crossed BBB. Can decreased oral dose of Levodopa needed and increases L-dopa half life. Decrease dose of L-dopa.

Question 4

Selegiline (Deprenyl)

Answer 4

MOA: irreversibly Inhibits MAOB (increases DA synaptic levels).
Side-effects: Motor effects, gastrointestinal side effects, behavioral effects.
Absorption: hepatic
Dosage forms: Oral, transdermal
Drug interactions: Drugs that increases or decrease DAergic activity. Many opioid drugs.

Question 5

Amantadine (Symmetrel)

Answer 5

MOA: Stimulates release of DA in synapse in the Striatum (increases release of synaptic DA in the striatum).
Side effects: pro-dopaminergic effects 1.Motor effects, 2. Gastrointestinal side effects, 3. Behavioral side effects.
Absorption/distribution/metabolism/excretion: Renal (unchanged).
Dosage forms: oral.
Drug interactions: drugs that increase or decrease DAergic activity.

Question 6

Rasagiline (Azilect)

Answer 6

MOA: Irreversible inhibitor of MAOB. Increases lifespan and concentration of synaptic DA in the SN.
Side effects: Motor side effects, Gastrointesitnal side effects, behavioral side effects.
Absorption/distribution/metabolism/excretion: hepatic.
Dosage forms: oral, transdermal.
Drug interactions: Drugs that increase or decrease DAergic activity. Many opoid drugs.

Question 7

Ropinirole (Requip)

Answer 7

MOA: DA R agonists. Increases DA Receptor activation in the striatum.
Side effects: Motor effects, Gastrointestinal side effects, behavorial side effects.
Absorption/distribution/metabolism/excretion: Hepatic
Dosage form: oral.
Drug interactions: Drugs that increase or decrease DAergic activity.

Question 8

Pramipexole (Mirapex)

Answer 8

MOA: DA R agonist. Increase DA receptor activation in the striatum.
Side effects: Motor effects, gastrointestinal side effects, behavioral side effects.
Absorption/distribution/metabolism/excretion/:Renal
Dosage forms: oral
Drug interactions: Drugs that increase or decrease DAergic activity.

Question 9

Apomorphine (Apokyn)

Answer 9

MOA: DA R agonists. Increase DA Receptor activation in the striatum.
Side effects: Motor effects, Gastrointestinal side effect, behavioral side effects.
Absorption/distribution/metabolism/excretion: Hepatic.
Dosage forms: s.c.
Drug interactions: Drugs that increase or decrease DAergic activity.

Question 10

Benztropine (Cogentin)

Answer 10

MOA: Anticholinergic agents. Muscarinic receptor antagonists.
Increased falls, confusion, mental decline and mortality in elderly using anticholinergics.

Question 11

Trihexyphenidyl (Artane)

Answer 11

MOA: Anticholinergic agents, Muscarinic receptor antagonists.
Increased falls, confusion, mental decline, and mortality in elderly using anticholinergics.