For those under fifty, I would prescribe selegiline (Eldepryl), but I would tend to use a lower dose of this, as it can keep you awake at night if you take it late in the day. I just use 5mg of selegiline, half the usual dose, as it is enough to do the job. It may possibly slow down the progression of the disease. It definitely helps the symptoms; whether or not it slows down disease progression is as yet unproven.

I tend to be a little biased against anticholinergics. I agree that they are better tolerated in the younger patient, but in the older patient, they can affect the memory, cause constipation, dry mouth, urinary retention. They can be difficult to use, so I would use them only occasionally.

Alternatively, I would use a dopamine agonist, even in the under-fifties. I tend not to use slow-release levodopa on the basis that, if you are constipated as can happen in PD (the Lewy bodies in the brain are also found in the gut, and the nervous system in the gut is also affected in PD - it also slows down), the slow-release drugs may not be fully absorbed.

In the over-sixties, I would generally use up to 300mg levodopa a day, and try to hold it down as much as possible, for as long as possible, and supplement it with Comtess, which lengthens the effect of Sinemet/Madopar. In trying to get the best result, there are no hard and fast rules. I would use dopamine agonists even in the older age group. The newer dopamine agonists tend to have fewer side-effects, and by using them you run into less trouble with them in the long-term.

New Drug Treatments

• Dopamine agonists: Requip (ropinirole), Mirapexin (pramipexole),Cabaser (cabergoline), Apomorphine

  Mirapexin* and Cabaser have yet to be launched in Ireland. Cabaser is a long-acting dopamine agonist, which people sometimes take late at night. Most dopamine agonists will help the stiffness and soreness, but, anecdotally, Mirapexin seems to help also with tremor, which is often hard to treat. Apomorphine is a subcutaneous form of dopamine agonist. There is a much larger choice now, so if one doesn't agree you can try another.

  [Editor's note: Mirapexin has since been launched in Ireland for use with Sinemet or Madopar.]

• COMT inhibitors: Comtess (entacapone)

• Anti-Dyskinetic Drugs: glutamate (NMDA) antagonists, e.g., dextromethorphan

• Symmetrel (amantadine)

  Some more recent studies have shown this to be quite a nice drug for dyskinesias. It is sometimes a difficult drug to use, as it can cause low blood pressure, ankle swelling, photosensitivity and occasionally a rash.

• Nitric Oxide Synthase Inhibitors: Lamotrigine

  This is an anti-convulsant which has an NMDA antagonist in it, usually used in patients with seizures, but may be of benefit in patients with dyskinesias. Studies are ongoing at present.