Wha Are Some Medications for Parkinson’s Disease That Mimic or Replace the Dopamine Chemicals?

Question by James Bond: Wha are some medications for Parkinson’s disease that mimic or replace the dopamine chemicals?

Best answer:

Answer by Mags
First of all I know this is long – if you want to skip the narrative and the message, scroll down to the list. Even that is long because often these treatments are interlinked.

The levadopas/L-dopas are the drugs which seem to come to everyone’s mind first for treatment of Parkinson’s disease.
While some people feel that is a mistake because of the potential for increasing “off” times as the years go by, these are usually the first medication on the prescription pad when the doctor diagnoses PD. Because no one wants the symptoms. In combination with the MAO-Bs and some other meds waiting in the pipeline, there is potential for seriously impacting the progression and well as the symptoms of PD.

From the University of Tennessee Medical Center:
“Current drug therapy focuses mostly on dopamine replacement. The most powerful drug used to alleviate Parkinson’s symptoms is called levadopa (or L-dopa). Nerve cells use levadopa to make dopamine, which can then be used by the brain. Bradykinesia and rigidity are the symptoms that respond best to levadopa treatment, while problems with tremors and balance may be only marginally reduced.
There are some side effects to levadopa treatment — the most common are nausea, vomiting, low blood pressure, involuntary movements and restlessness. Sometimes, depression can be caused or made worse by levadopa therapy…adjustments to the patient’s dosage or… by prescribing carbidopa to be taken along with levadopa. After 2-5 years of treatment with levadopa, the drug’s effectiveness can … fluctuate for some patients. To help alleviate this, doctors may prescribe smaller doses … to be taken at shorter intervals”

From Wikipedia:
“L-DOPA (3,4-dihydroxy-L-phenylalanine) is a naturally occurring amino acid found in food and made from L-Tyrosine in the human body. L-DOPA is converted into dopamine in the brain and body. It is sold as a dietary supplement and as a prescription drug in the US. In clinical use, Levodopa (INN) is administered in the management of Parkinson’s disease and dopa-responsive dystonia…since it is able to cross the blood-brain barrier, whereas dopamine itself cannot.”

NAMES of MEDICATIONS – generic and brand(R) (when I have them)
There are 5 categories of drugs used to treat Parkinson’s disease while some do not mimic the actions of dopamine nor do they replace it, they can be used with that therapy to possibly slow progression of PD and not just provide symptomatic relief which is why they are included here.

DOPAMINERGIC – the antagonists, L-Dopas, which attempt to restore the levels of dopamine in order to slow/stop/reverse the symptoms of PD. Most can pass thru the Blood Brain Barrier to convert to dopamine
Pharmacology: Dopamine precursor:
levadopa (carbidopa or benserazide)
Madopar CR (levadopa and benserazide) with
several serious caveats
Releases dopamine: amantadine

DOPAMINE AGONISTS: which try to mimic the natural dopamine and are taken with the antagonists for better result since these wear off increasingly.
Pharmacology: bromocriptine (Parlodel), cabergoline, pergolide (Permax), ropinirole (Requip), pramipexole (Mirapex, Mirapexin), piribedil (Travastal retard 50, Pronoran)
rotigotine transdermal patch (Neupro)-temporarily unavailable in USA
Apomorphine – given subcutaneously to patients with dysphagia (difficulty swallowing) levadopa/crbidopa.enracapone (Stalevo)

COMT inhibitors: which are also taken with the levadopas to prolong the good effects. catechol O-menthyltransferase
Pharmacology: Entacapone – slows the elimination of DA – but may reduce off time with Levadopa

MAO INHIBITORS: which can also be used with the L-dopas but are often taken alone – They work to stop the breakdown of dopamine by monoamine oxidase B – if the breakdown of dopamine can be slowed, the dosage of the L-dopas should be reducible in patients taking both.
Pharmacology: MAO-B: Selegline (eldepryl),
rasagiline (Azilect)

ANTICHLORINGERICS: By blocking the acetylcholine the goal is a compensatory balance of the mis-firing of the neurotransmitter dopamine and the normal firing of the acetylcholine in order to relieve a variety of movement issues in PD.
Pharmacology: Muscarnic Antagonists: benzatripine, Trihexyphenidyl, orphenadrine

Here’s part of the cycle: Phenylalanine > Tyrosine > L-Dopa > Dopamine > Norepinephrine > Epinephrine
Don’t forget some of the naturals which should NOT be taken with the agonists or dopaminergics: mucuna puriens, fava beans for starters.

other reading:
http://www.medscape.com/viewarticle/439737_2
http://www.ninds.nih.gov/disorders/parkinsons_disease/detail_parkinsons_disease.htm
http://www.patient.co.uk/showdoc/40025032/

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