In March the advisory panel for the US Food and Drug Administration (FDA) gave the green light for the approval of pimavanserin - trade name Nuplazid - a new drug for treating hallucinations and delusions (sometimes called psychosis) in Parkinson's.
While they would have liked a stronger effect, the panel voted 12 to 2 in favour of approving the new drug, saying the benefits outweigh the risks.
The next step is for the FDA to make their final decision, which is expected by 1 May 2016.
Hallucinations and delusions in Parkinson's
Some people with Parkinson's may experience hallucinations or delusions. This means that they may see, hear, smell or taste things that aren't there, or have thoughts and beliefs that aren't based on reality.
Hallucinations and delusions are more common in people who have had Parkinson's for a long time, though they can affect both younger and older people.
These symptoms may be caused partly by Parkinson's and partly by some Parkinson's medication.
Whilst medications for hallucinations and delusions are available they often only have limited effect in Parkinson's.
A new tool for managing Parkinson's
Dr Beckie Port, Parkinson's UK Senior Research Communications Officer, says:
"Hallucinations and delusions are difficult to treat in Parkinson's. There are a limited number of medications available, which are often prescribed with caution and require people to be continuously monitored for side effects.
"Approval of this new drug would give us one more tool for managing the symptoms of Parkinson's. And there is hope that pimavanserin could be more effective than other drugs that are currently available.
"The committee backing is promising news as the FDA usually follows the panel's recommendations when approving new drugs.
"Further regulatory approval would be needed before it is available in the UK."
When will pimavanserin be available in the UK?
Before pimavanserin can be made available as a treatment in the UK, it will also need to be approved by the European Medicines Agency (EMA). There are plans to submit pimavanserin to the EMA for approval.
We will continue to monitor the progress of pimavanserin closely and report on any developments.
If you are having problems with hallucinations or delusions, speak to your Parkinson's nurse or consultant, or call our helpline on 0808 800 0303.