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...   PATIENT INFORMATION - ABOUT

PARKINSON'S DISEASE DRUGS

Principles behind choosing a drug

• Inevitable progression: Pd is inevitably a progressive condition. The rate of deterioration tends to be greatest in those who present with early postural inablity.
• Levodopa works: but only for so long: Levodopa is dramatically effective in early PD. However, its effectiveness begins to wear off in 4-7 years. Disabling side effects occur in 50% of patients after this time.
• More levodopa = more late side effects: Drug levels necessary to achieve complete absence of symptoms tend to reduce the long term effectiveness of treatment.
• Polypharmacy: Several drugs can modify the response to levodopa. As the condition deteriorates, polypharmacy is almost inevitable.

Antiparkinsonian drugs

• start them slowly
• stop them gradually
• be careful about interactions
• remember they can often cause postural hypotension and confusion

What drugs are available?

Some brief comments are included here.

Levodopa
The combination of levodopa and an enzyme inhibitor has revolutionised the treatment of PD. It remains the gold standard for management. Those with rigidity and bradykinesia generally find most benefit. Tremor may be difficult to suppress without toxic levels of levodopa.

Amantadine
Amantadine may be useful in the young mildly afflicted patient but often loses effect after 3-12 months. However it has few side effects and is recommended for mild akinseia and rigidity in those less than 60 in whom tremor is not a problem.

Anticholinergics
Anticolinergics have an additive therapeutic effect with levodopa. Useful in young patients especially those with tremor, they have no place in the elderly because of their tendency to cause mental confusion and also to worsen glaucoma and prostatism.

Dopamine Agonists (Bromocriptine and Pergolide)
can be used either instead of, or as well as levodopa. The response is generally less then that seen with levodopa, and the incidence of early side effects is much greater. However they may be valuable as an 'add-on' therapy in patient whose response to levodopa is failing or fluctuating.

Selegiline
Selegiline, a monoamine oxidase inhibitor (Type B) may slow the progress of PD if it is used from first diagnosis. These effects continue to be under close scrutiny. It has an additional role in late PD.

COMT inhibitors
This group of drugs acts to block Catechol-O-Methyl Transferase which, along with decaboxylase, breaks down extra-cerebral levodopa. It is claimed that they can reduce the dose of levodopa, smooth out motor fluctuations and improve quality of life.

The drugs are tolcapone (due in Australia in 1998) and entacapone. They seem to be well tolerated. Side effects in clinical trials relate generally to increasing levels of levodopa. Diarrhoea, headache and alteration in urine colour have been reported.

• PD inevitably progresses
• Levodopa works: but only for so long
• More levodopa = more late side effects
• Polypharmacy is almost inevitable

DRUGS TO BE GIVEN WITH CAUTION TO PEOPLE WITH PARKINSON'S DISEASE

Second Addition, September 1997

Parkinson's Disease is a neurological disorder which is characterised by tremor, stiffness and slowness of movement. The symptoms of this disorder are due to a deficiency in the brain of a chemical substance call dopamine. Many drugs are used for the treatment of other mental conditions have the potential to alter or interfere with the brain's dopamine system and are sometimes overlooked as a having a detrimental effect on Parkinson's disease. The need to effectively treat other medical conditions and the possibility of causing or worsening existing Parkinson's disease has to be considered.

Potentially fatal interactoins can occur when drugs are combined with medications to treat Parkinson's disease. These drugs or drug combinations must not be given to people with Parkinson's disease (see A below).

Some drugs such as anti-emetics and powerful tranquillisers can induce a form of Parkinsonism which may take weeks or months to appear. If given to people who already have Parkinson's disease their symptoms may worsen. Several months may elapse after the offending medication is stopped before the symptoms decrease or disappear.

When commencing cardiovascular drugs, (for example drugs to treat high blood pressure or angina) a check of lying and standing blood pressure is extremely important. The addition of these drugs to anti-Parkinson's medication may cause extreme low blood pressure.

If you are contemplating surgery, you should:

• Talk to your doctor and anaesthetist before surgery and give her/him a copy of this list;
• If admitted to hospital, give staff a copy of this list;
• Make sure your nuerologist has a copy of this drug list and is aware of your reason for surgery.

NB. There is a potentially fatal interaction between Pethidine and Selegiline

For all the above reasons you may always tell your doctor and pharmacist about all the medications you are taking, particularly if you have been started on a new medication.

This list of medication has been produced for you to have available in emergency situations and as a reminder for your doctor and pharmacist. Please discuss any concerns and questions which you may have with them.

A. The following drug combinations are contraindicated

(1) Antidepressants (to treat depression)

(1A) Monamine oxidase inhibitors- not to be used with levodopa-containing drugs (SINEMET, MADOPAR, KINSON, SINACARB) OR with selegiline (DEPRENYL/SELGENE)

Type A (non-selective)

Phenelzine NARDIL

Tranylcypromine PARNATE (in PARSTELIN)

moclobemide ARIMA, AURORIX, a Type A selective monoamine oxidase inhibitor, should not be used with selegiline. If combined with levodopa, a reduction in dosage may be required. Your doctor will advise.

(1B) Other types of antidepressants, including selective serotonin re-uptake inhibitors (SSRI'S) and serotonin-noradrenaline re-uptake inhibitors (SNRI'S) - not to be used with Selegiline.

Fluoxetine EROCAP, LOVAN, PROZAC, ZACTIN

Fluvoxamine LUVOX

Nefazodone SERZONE

Paroxetine AROPAX

Sertraline ZOLOFT

Venlafaxine EFEXOR

(2)Analgesics (for pain) - not to be used with Selegiline.

Produced for: Parkinson’s Association of WA Inc, 320 Rokeby Road, SUBIACO WA 6008