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Why has the conversion calculator been developed?

Medicines management is crucial in the care of the patient with Parkinson’s Disease (PD) when they are admitted to hospital either electively or in an emergency.

Parkinson's medication can be complicated, and particularly bewildering for non-specialist clinicians who find themselves caring for patients with PD.

Management of their medication can become even more tricky when Parkinson's patients are admitted to hospital for any reason and are nil-by-mouth, unable to swallow or unable to absorb their usual PD drugs due to intercurrent illness. Missed doses can impair patients’ swallow, increase their risk of aspiration, render them immobile and prone to falls and fractures, and – at worst – lead to Neuroleptic Malignant-Like Syndrome, which can lead to coma and death. To complicate matters further, some commonly prescribed drugs can in fact worsen a person's Parkinsonism.

Prescribing the correct drug preparation at the correct time is key in preventing deterioration in their PD. If your patient is unable to swallow or absorb their usual Parkinson's medication, an alternative dispersible or transdermal preparation must be given promptly. Conversion tables are already available, either tucked away on hospital intranet sites and in pharmacies, or accessible on the internet, but these are often cumbersome and confusing, and leave the prescriber vulnerable to calculation errors.

By developing a nationally available guideline and web-based conversion calculator, we aim to help non-specialist clinical staff better manage patients with PD when they are admitted to hospital, better plan for elective admissions and direct you to sources of specialist support.

Who has been involved in the development?

The guideline and calculator have been developed - and will be kept up-to-date - by a team of Parkinson's specialists and pharmacists, with the support of the Wessex Parkinson's Excellence Network and the British Geriatrics Society Movement Disorders Section. The principal developers are:

  • Dr Gayle Strike, Consultant Geriatrician, University Hospital Southampton NHS Foundation Trust
  • Dr Naomi Fox, Consultant Geriatrician, Poole Hospital NHS Foundation Trust
  • Mr James Allen, Senior Pharmacist, University Hospital Southampton NHS Foundation Trust
  • Mr Ben Fox, Software Engineer

Who is the conversion calculator for?

The guideline and conversion calculator are to help non-specialist clinicians manage their patient's Parkinson's medication until support is available from your local PD specialist or pharmacist. It is not intended to replace locally-agreed guidelines and prescribing practices, but rather offer guidance until specialist advice can be obtained.

We would like to emphasise that this resource is intended for use by clinicians only. People affected by Parkinson's are not advised to make any changes to their medication without consulting their PD specialist.

How does the conversion calculator work?

The calculator converts a patient’s usual Parkinson’s medication into an alternative that can be used by patients who are either nil by mouth, unable to swallow or unable to absorb their usual medication.

There are two options. The first converts a patient’s usual medication into a dispersible preparation to be administered via a nasogastric tube.

The second calculator is for patients who cannot tolerate a nasogastric tube or have gut absorption problems. It converts a patient’s usual medication to a transdermal patch (rotigotine).

Our guideline states that ideally a patient should be taking medications as close to their usual prescription as possible, which is best achieved using a nasogastric tube.

All you have to do is input their usual Parkinson’s medication into the calculator, and it generates a prescription for you. There is also an option to print a PDF of the calculation for filing in the patient’s notes.

How have the calculations been worked out?

The calculations have been worked out using conversion tables published in the NHS Fife Parkinson’s Guideline and cross-referenced with conversion tables from other published NHS guidelines.

How has it been tested to ensure the calculations are accurate?

The calculator has been rigorously tested to ensure that it accurately follows the NHS Fife conversion tables. The final guideline and calculator are the product of extensive testing and feedback from junior doctors, pharmacists, PD specialist nurses and Consultants.

What should I look out for if the calculated dose is too high or too low for my patient?

Every patient with Parkinson’s disease is an individual with some patients responding better to medication than others. The calculator has been created for use when patients are unwell and can’t take their usual medication in the usual way. A patient’s Parkinson’s disease may be less well controlled because they are unwell but also because the conversion medication is not an exact equivalent of their usual medication.

Dopamine agonists including rotigotine can lead to increased confusion. The calculator therefore recommends a slight dose reduction in patients with dementia or delirium.

The substitutes recommended in the calculator are intended to be used as a holding measure in the acute situation, and should not stop you from obtaining specific advice from a pharmacist or PD specialist when this becomes available.

Do I need to input all my patient's medications or just the ones for their Parkinson's?

Only the Parkinson’s medication can and should be inputted into the calculator.

Can it be hosted on our own trust intranet?

A link to http://www.parkinsonscalculator.com can be placed on your own Trust’s intranet site.

How often is this calculator updated?

The calculators are reviewed and updated annually. The last update was March 2023 with the next due May 2024.

How do I report an error or omission?

If you spot any inaccuracies or ommisions please do let us know through our Contact page.