MAO-B inhibitors

These are:

• selegiline (Eldepryl/Zelapar)
• rasagiline (Azilect).

Selegiline works by blocking the enzyme monoaomine oxidase type B (MAO-B), which breaks down dopamine in the brain. It is used to make the dose of Sinemet or Madopar last longer or reduce the amount required.

Sometimes a GP/consultant may treat those newly diagnosed with Parkinson's with selegiline on its own as it may improve the symptoms, delay the need for levodopa, and possibly delay the onset of fluctuations in the effectiveness of drugs.

Early research suggested that selegiline might slow down the progression of Parkinson's. Other research has suggested that it might increase mortality. There is no conclusive evidence to support these claims.

Advantages

By itself, selegiline has very few side effects. Because Zelapar is absorbed better, a smaller dose is needed.

In trials, rasagiline has shown the ability to reduce 'off' time and improve motor function in patients with motor fluctuations related to levodopa.

Disadvantages

When selegiline is taken together with Sinemet and Madopar, levodopa side effects such as dyskinesias, hallucinations or vivid dreaming may sometimes occur or worsen. To compensate for this, the dose of levodopa may be reduced.

When selegiline is given on its own it can cause blood pressure to drop. Selegiline acts as a mild stimulant, so is often prescribed as a single dose to be taken in the morning rather than in the evening when it might interfere with sleep.  

When people have taken rasagiline on its own (without levodopa), the most commonly reported side effects have been: 

• headache
• aching joints
• indigestion
• flu-like symptoms
• depression

When taken with levodopa, the most common reports were of uncontrolled movements and accidental falls. These effects may be due to the increase in dopamine caused by rasagiline, so always report such problems to your doctor.  

It should not be taken together with, or within 5 weeks of receiving, Fluoxetine (Prozac) or Fluvoxamine (Faverin).  

Rasagiline works by slowing the breakdown of dopamine in the brain, keeping it 'available' for longer. It can be taken early in Parkinson's disease on its own (as 'monotherapy') to help boost dopamine still being produced by the brain, and/or later in the disease, to boost the effect of levodopa (as' adjunct therapy').