Drug treatments control symptoms of Parkinsons's
As there is no cure for
Parkinson's at present, drugs are used to try to control symptoms of Parkinson's. There are no perfect
drugs, although there are many promising developments.
The main aims of drug treatments for Parkinson's are to:
- increase the level of dopamine that reaches the brain
- stimulate the parts of the brain where dopamine works
- block the action of other chemicals that affect dopamine, such as acetylcholine as well as several enzymes that reduce dopamine's effect.
In most newly diagnosed people considerable improvements can be achieved by careful introduction of anti-parkinsonian drugs. When somebody only
has mild symptoms, they may decide, together with their GP/consultant, to postpone drug treatment until symptoms increase and instead rely on a healthy lifestyle, focusing on
exercise, relaxation and
diet.
As Parkinson's disease is a very individual condition medication is prescribed and adapted to individual needs. Response to medication varies from person to person and not every
medication will be considered suitable for everyone. As branded drugs get older, they cease to be protected by patent. Once this happens, they can be 'copied' and produced slightly more cost effectively, but with the same stringent quality requirements. These may look different from the branded version and will not have the same name, but in all other ways the drug is the same.
Levodopa
Levodopa has been used to treat the symptoms of Parkinson's since the 1960s. It is a natural amino acid that the brain converts into dopamine and so it replaces the missing chemical.
The commonly prescribed forms of levodopa are:
- Madopar (co-beneldopa)
- Sinemet (co-careldopa)
Both contain an extra substance that prevents levodopa being changed to dopamine before it reaches the brain. Madopar contains levodopa plus benserazide and Sinemet contains levodopa plus carbidopa. People with Parkinson's are usually started on a
low dose and this is gradually increased until they and their GP/consultant feel that there has been a satisfactory response. There are a number of forms of Madopar and Sinemet containing different amounts of the drugs.
Dispersible Madopar
Madopar has a dispersible form that may be swallowed whole or dissolved in water. Absorption of the dispersible form is quicker and can be used to 'kick start' people with Parkinson's. It can also be used in cases where control of the Parkinson's is difficult with standard levodopa. People who have difficulty swallowing tablets or capsules may also find this beneficial. Once dispersed, the preparation leaves a chalky residue at the bottom of the glass that does not contain the drug. Madopar capsules should NOT be broken.
Controlled release (CR) preparations of Madopar and Sinemet
Controlled release preparations are recognised by the letters CR after the drug name. The drug is released over a four- to six-hour period and may result in less fluctuation of levodopa levels in the blood. When changing from standard to controlled release preparations up to 30 percent more levodopa can be needed. With controlled release preparations the time between doses can sometimes be prolonged by 30-50 percent. They may be used when a person with Parkinson's is experiencing 'wearing-off' of the dose of standard levodopa. They can also be taken before going to bed to reduce
stiffness and immobility during the night.
Advantages of levodopa
Most people can tolerate Sinemet or Madopar and experience considerable long-term improvement, especially in stiffness and slowness of movement.
Disadvantages of levodopa
In the early days of taking these tablets some feelings of sickness and nausea are common. However, in most people, they are usually mild and pass as the body adjusts to the drug. A small percentage of people cannot tolerate these drugs at all because of severe sickness, or other side effects such as confusion, hallucinations,
mood swings or
psychological changes. In the longer term, the response to these drugs can become less reliable, and people may experience increasing periods when the effect of the most recent dose wears off before the next one is due or has begun to work (end-of-dose deterioration).
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