Parkinson's Disease

Parkinson’s Disease

This most common form of movement disorder affects 1 in 100 people. Medical science will ensure that you are not handicapped or disabled by it, read more…..

Treatments and Drugs

Selection of medication and their dosage is tailored to each individual patient. In deciding the treatment, the physician considers factors such as severity of symptoms, the patient’s age, and presence of other medical conditions. No two patients will respond identically to any particular drug, so this process involves experimentation with different drugs, persistence and patience. As the disease progresses, drug dosages may have to be altered and a combination of drugs can be given.

A combination of Levodopa and Carbidopa  is the mainstay of treatment in Parkinson’s disease. Levodopa is rapidly converted into dopamine, by the enzyme dopa decarboxylase, which is present in the central and peripheral nervous system, however much of the levodopa is metabolized before it reaches the brain.

Carbidopa blocks the peripheral metabolism of levodopa i.e. in the liver, and increases the amount of levodopa that reaches the brain. Levodopa is most effective in treating bradykinesia and rigidity, less effective in reducing tremor, and very less effective in relieving problems with balance.

Side effects include nausea, low blood pressure (hypotension) and abnormal movement’s i.e. dyskinesias.

Slow dosage adjustment and taking medication with food can reduce these effects.  Depression, confusion and visual hallucinations are the side effects which may occur with these medications, especially in the elderly.

Medical Management of Parkinson’s Disease

  • Levodopa (drug of choice)
  • Dopamine agonists
  • Anticholinergics
  • COMT inhibitors
  • Other drugs to treat complications

Dopamine Agonists mimic dopamine’s function in the brain. They are used primarily as adjuncts to levodopa/carbidopa therapy. But in some cases, these drugs are used as monotherapy, but generally less effective in controlling symptoms. Side effects are similar to those produced by levodopa and include nausea, sleepiness, dizziness and hallucinations.

Dopamine agonists include the following:

  • Pramipexole
  • Ropinirole

Amantadine – is an antiviral drug which has dopamine agonist properties. It increases the release of dopamine and is used to treat early-stage Parkinson’s disease. It can be used either alone, with an anticholinergic drug, or with Levodopa. It is effective in reducing dyskinesias caused by Levodopa. Side effects of amantadine include mottling of the skin, edema, confusion, blurred vision, insomnia, anxiety etc.

MAO-B Inhibitors  Monoamine oxidase B (MAO-B) oxidises dopamine. Rasagiline and Selegiline inhibit MAO-B and increase the amount of available dopamine in the brain. MAO-B inhibitors boost up the effects of Levodopa. Side effects include nausea, dizziness, abdominal pain, confusion, hallucinations, and dry mouth. MAO-B inhibitors are contraindicated in patients taking tricyclic antidepressants, SSRIs or Meperidine and other opiates. Patients taking MAO-B inhibitors are advised to follow physician’s recommendations regarding a number of dietary precautions.

Anticholinergics (Trihexphenidyl) – reduce the relative over activity of the neurotransmitter acetylcholine to balance the diminished dopamine activity. This class of drugs is most effective in control of tremors and is used as adjuncts to Levodopa. Side effects associated with anticholinergic drugs are dry mouth, blurred vision, constipation and urinary retention. In higher doses, these medications may also impair memory.

COMT (catechol-O-methyl transferase) – Inhibits the COMT enzyme, which breaks down dopamine after it is released in the brain and augments the effect of levodopa. These drugs are effective only when they used with Levodopa. COMT inhibitors include Entacapone and Tolcapone. The side effects of these medications include vivid dreams, visual hallucinations, nausea, sleep disturbances, daytime drowsiness and dyskinesias.